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BUREAU OF SUGAR EXPERIMENT STATIONS QUT j 
Library I 
LABORATORY MANUAL 
FOR 
QUEENSLAND SUGAR MILLS 
FIFTH EDITION 
Registered at the General Post Office, Brisbane, for transmission by post as a book. 
Wholly set up and printed in Australia by 
WATSON, FERGUSON AND COMPANY 
Brisbane, 
1970 
PREFACE TO FIFTH EDITION 
Dur ing the past eight years the technology of the cane sugar industry has changed 
considerably. Many new items of apparatus have been introduced into sugar mil l laboratories, 
and analytical methods and techniques have been modified to take advantage of this improved 
equipment. 
This new edit ion of the Laboratory Manual has, as far as possible, been brought up to 
to date as at the middle of 1969 and, whi le the form of the Fourth Edition has been retained, 
each chapter has been subjected to a crit ical review and changed or completely re-wr i t ten 
to conform to present day knowledge. The equipment and methods of analysis set out are 
those which, in the considered opinion of the officers of the Mil l Technology Division, are the 
most suitable presently available, but there wi l l doubtless be some sections which are the 
subject of diversity of opin ion, and there are some sections which are in such a state of 
rapid change that the procedures set down w i l l be out of date in the near fu ture . 
Wherever possible, descriptions and i l lustrations of apparatus cover the most modern 
equipment available, and sections on such new equipment as the automatic polarimeter and 
the spectrophotometer have been included. The chapter on analytical methods has been 
broadened to include many new aspects of sugar analysis, and such other new subjects as 
the direct analysis of cane. W i t h the increasing importance of boiler water t reatment the 
section dealing w i t h this subject has been expanded. A new chapter has been wr i t t en to 
cover the subject of metrology, whi le the chapter dealing w i t h soil analysis has been deleted, 
as it is felt that this subject is better covered in specialized text-books. 
The Bureau of Sugar Experiment Stations wishes to acknowledge the assistance given 
by the fol lowing organizations and individuals w i t h the preparation of this manual :— 
Dr. W. H. Steel and Mr. G. A. Bell of the National Standards Laboratory. 
Dr . R. A. M. Wi lson of the Colonial Sugar Refining Co. L td . 
Mr. J. L. Clayton of the Central Sugar Cane Prices Board. 
The Sugar Research Inst i tute. 
The Colonial Sugar Refining Co. L td . 
The Queensland Health Department. 
and a number of individuals in the sugar industry who forwarded suggestions for this new 
Edit ion. 
The fol lowing reference books were used freely in the compilation of this Ed i t ion :— 
The System of Cane Sugar Factory Con t ro l , Second Edit ion (I.S.S.C.T.). 
Cane Sugar Handbook, N in th Edit ion, Spencer-Meade. 
Polarimetry, Saccharimetry and the Sugars, Circular C.440, National Bureau of Standards. 
ICUMSA Methods of Sugar Analysis, 1964 Edit ion. 
Report of the Fourteenth Session of ICUMSA, 1966. 
Various Publications of the Brit ish Standards Inst i tut ion, and the Standards Association of 
Austral ia. 
We also gratefully acknowledge the provision of i l lustrations by various distr ibutors 
of laboratory apparatus. 
Norman J. King, Director 
1st February, 1970 Bureau of Sugar Experiment Stations, Brisbane 
PREFACE TO FIRST EDITION 
The Division of Sugar Mill Technology was created in 1929. One of the early duties of 
the Division was to introduce a definite plan of campaign for mill control, which was not 
possible at that time due to the confusion of methods employed and the lack of specific 
standards. In 1930, Mr. Norman Bennett (then Mill Technologist) instituted the Mutual 
Control scheme, which was voluntarily subscribed to by the majority of the Queensland 
mills. The International Standards laid down at the Java Conference of 1929 were adopted 
as the basis for this work, and a brief statement of standard analytical methods and specifi-
cations foi laboratory apparatus was prepared and issued to the mills participating. It was 
most gratifying to find that practically all mills were eager to adopt the new standards in 
their entirety, which made possible the present standardised method of reporting mill data 
and enabled comparisons to be made of the work of different mills. Doubtless the scheme 
has been directly or indirectly responsible for many of the marked improvements in milling 
work which have characterised the accomplishments of the Queensland mills during the 
past five years. 
In order to assist the mills in obtaining accurately standardised equipment, the Division 
undertook the calibration of all glassware employed by the industry; at the present time 
practically all mills submit their apparatus for checking purposes, and hardly any new appar-
atus is obtained unless accompanied by the Bureau's guarantee. 
It is felt that the time is opportune for the publication of a Manual which will provide 
the mill chemist with the desired analytical methods, together with the tables employed 
in the subsequent calculations, in a readily accessible form. This publication of the Bureau 
is therefore presented in the hope that it may fill a long-felt want. Further, it was appreciated 
that the student in sugar chemistry often finds it difficult to obtain a work which will pro-
vide him with the fundamental principles of the subject presented in an elementary form. 
Chapters, have, therefore, been included in Definitions, Optical Instruments, Balances, 
Densimetric Methods, and Calibration of Glassware, with this end in view. 
The present work is the result of the combined efforts of members of the Bureau staff, 
who would welcome any reconstructive criticism and advice from those engaged in the 
industry. The authors wish to acknowledge their indebtedness to those excellent text-books 
of C. A. Browne, G. L. Spencer, and J. Reilly and W. N. Rae, which sources have been 
freely drawn on in the preparation of this Manual; and also to those manufacturers from 
whose catalogues several of the illustrations have been taken. 
H. W. KERR, 
Director. 
Bureau of Sugar Experiment Stations, Brisbane. 
14th July, 1934. 
CONTENTS 
PAGE 
CHAPTER I 
DEFINITIONS . . . . . . . . . . . . . . . . . . . . 1 
CHAPTER II 
OPTICAL INSTRUMENTS . . . . . . . . . . . . . . . . 8 
CHAPTER III 
T H E BALANCE . . . . . . . . . . . . . . . . . . . . 51 
CHAPTER IV 
DENSIMETRIC METHODS OF ANALYSIS . . . . . . . . . . . . 58 
CHAPTER V 
VOLUMETRIC EQUIPMENT . . . . . . . . . . . . . . . . 68 
CHAPTER VI 
T H E BUREAU'S METROLOGY LABORATORY . . .. .. . . . . . . 75 
CHAPTER VII 
SAMPLING OF SUGAR MILL PRODUCTS . . .. . . . . . . . . 78 
CHAPTER VIII 
LABORATORY REAGENTS . . . . . . . . . . .. . . . . 83 
CHAPTER IX 
ANALYTICAL METHODS .. . . . . .. . . . . . . . . 94 
CHAPTER X 
T H E DETERMINATION OF pH . . . . . . .. . . . . .. . . 144 
CHAPTER XI 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL .. .. . . .. . . 151 
CHAPTER XII 
T H E BOILER STATION . . . . .. .. .. .. . . . . . . 166 
CHAPTER XII I 
FIRST AID . . . . .. . . . . . . .. . . . . . . 181 
REFERENCE TABLES .. . . . . .. . . .. .. .. . . 184 

CHAPTER I 
DEFINITIONS 
Whilst the majority of definitions from the previous Edition have been 
carried forward, several general terms which have recently come into promi-
nence and some of the more important definitions associated with the milling 
train have been added. 
Absolute Juice—All the solids in solution in the cane, together with all the 
water in the cane; i.e. Absolute Juice = Cane - Fibre. 
Apparent—The word apparent is applied to figures and analyses based on 
Brix and pol, as distinct from dry substance and sucrose, for example, 
apparent purity. Brix and pol analyses are widely used for factory 
control purposes, and unless a specific instance arises where pol and 
Brix have to be divorced from sucrose and dry substance, the term 
"apparent" is often omitted. 
Ash—The residue remaining after burning off all organic matter. In practice 
the proportion of residue remaining as "ash" is influenced by the 
conditions of combustion, so that ash, as actually determined, is 
not an absolute quantity. 
Back Roller Juice—The juice expressed between the top and delivery 
rollers of any mill of a tandem. The term is synonymous with last 
expressed juice only when it refers to the last mill of a tandem. 
Bagacillo—A fraction of the fine particles separated from bagasse. 
Bagasse—The residue after extraction of juice from cane in one or more 
mills. Hence the terms, First Mill bagasse, Second Mill bagasse etc. 
and in the case of the last mill Final bagasse or simply bagasse, are 
used. 
Brix—The Brix of a solution is the concentration (in g solute per 100 g 
solution) of a solution of pure sucrose in water, having the same 
density as the solution at the same temperature. If refractive index 
be adopted as an alternative basis of comparison the value derived 
should be termed Refractometer Brix. 
Obviously, for solutions of pure sucrose in water, the Brix is 
equal to the dry substance, but in the presence of soluble impurities 
this may not be, and usually is not the case. Although gases and 
insoluble solids in suspension may alter the density of a solution 
the term Brix refers exclusively to soluble solids. 
Bulk Density—Prepared Cane—The bulk density of prepared cane is used 
as a measure of the degree of cane preparation and is defined as the 
weight of a prepared cane sample, divided by its bulk volume under 
standard test conditions. 
Cane—The raw material delivered to the mill, including clean cane, trash 
and any other extraneous matter. 
C C S . (Commercial Cane Sugar)—That percentage by weight of a quan-
tity of cane which would be recovered as pure sucrose (100 n.t.) if 
2 DEFINITIONS 
milling and refining operations were conducted at a prescribed 
standard of efficiency. The prescribed standard of efficiency is such 
that for every pound of soluble impurities in the cane one-half 
pound of sucrose is lost in process, there being no other losses of 
sucrose. 
Impurities per cent cane 
Hence C.C.S. = Sucrose per cent cane 2 
In the normal application of this formula the following assumptions 
are made:— 
1. Brix = Total soluble solids (dry substance). 
2. Sucrose = Pol. 
3. Impurities = Brix — Pol. 
4. Brix per cent cane 
J . . 100 - (F + 3) 
= Brix per cent first expressed juice x 100 
5. Pol per cent cane 
„ . . 100 - (F + 5) 
= Pol per cent first expressed juice X TT^TJ 
Hence 
C C S . = Pol in cane — | (Brix in cane — Pol in cane) 
2 V 109 J 2 V 100 ) 
where P — pol per cent first expressed juice 
B = Brix per cent first expressed juice 
F = fibre per cent cane. 
Clarified Juice—Juice which has passed through the clarifiers. This juice 
is fed to the evaporators and as such can also be referred to as Effect 
Supply Juice or E.S.J. 
Coefficient of Work—The percentage ratio of the weight of 94 n.t. sugar 
produced to the weight of c.c.s. in the cane from which the sugar 
was derived. Hence, 
jr - ^ r „r , Tons 94 n.t. sugar made x 100 Coefficient of Work = —: Ions c.c.s. in cane 
(A discussion on this formula is contained in the Chapter entitled 
"Calculations Involved in Chemical Control"). 
Compression Ratio (Milling)—The no-void volume of original cane, 
divided by the volume occupied by the bagasse (or cane) at the 
conditions being considered. 
Condensate—Water which has been condensed, either from vapour liberated 
from boiling juice, or from steam. 
Crystal Content—The percentage by weight of crystalline sugar present in 
a massecuite, magma or similar material. 
Crystallizer Drop—The decrease in purity of the mother liquor of a masse-
cuite resulting from treatment in a crystallizer. 
Cyclone Purity of Molasses—Usually this term refers to the purity of the 
mother liquor of a massecuite at the completion of the pan boiling 
operation. The term, suitably qualified, is often extended to refer 
to the purity of any sample of mother liquor extracted from a 
massecuite for examination, and not as part of the normal factory 
operations. 
DEFINITIONS 3 
Dextran—A polysaccharide formed by the action of certain species of 
bacteria on sucrose during cane and juice storage. 
Dilution Indicator (D.I.)—A factor used to forecast the keeping and hand-
ling quality of raw sugar. It is the ratio of moisture to dry non-
sugars expressed as a percentage. 
moisture 
Dilution indicator = —— -—— — . X 100 
100 — (pol + moisture) 
A value of dilution indicator below 40 is considered satisfactory, 
for values between 40 and 50 the keeping quality of the sugar is 
doubtful, whilst for values above 50 the probability of deterioration 
is considerable. 
Dilution Water—The quantity of added imbibition or maceration water 
which is present in mixed juice. Dilution water is usually expressed 
as dilution per cent first expressed juice. 
Dry Substance—The weight of material remaining after drying the product 
examined under specified conditions, expressed as a percentage of 
the original weight. The determination of dry substance represents 
an attempt to measure the total solids, both soluble and insoluble, 
or, in the absence of insoluble solids, the total soluble solids. The 
degree of accuracy achieved depends upon the constitution of the 
sample and the drying technique. 
Escribed Volume—The volume escribed by a pair of mill rolls in a given 
time. Escribed volume is equal to the roller length multiplied by the 
work opening multiplied by the surface speed of the rolls. 
Extraction (Pol)—The percentage of pol extracted from the incoming 
material by a train of mills either individually or cumulatively. 
Analogous definitions apply to Sucrose Extraction, Brix Extraction, 
and Juice Extraction, the juice, in the case of the last mentioned, 
being undiluted juice. 
Extraneous Matter—That portion of the material received as cane which, 
by arbitrary standards, is considered not to form part of clean cane. 
It consists of trash, tops, roots, dirt, etc. 
Fibre—Technically, fibre is the dry, water-insoluble matter in the cane. For 
commercial purposes a standard method of determination of fibre 
per cent cane is specified. 
Filling Ratio—A term used in milling calculations to define the ratio be-
tween the no-void volume of fibre passing between a pair of rolls 
in a given time, and the escribed volume for the same period of 
time. Filling ratio is actually volumetric coefficient divided by fibre 
density. 
Filterability—The filterability of a raw sugar is measured by comparing the 
filtration rate of the sugar with that of a standard sucrose solution 
under specified conditions. The result is expressed as a percentage 
of the filtration rate of the standard sugar. 
Filter Cake—The washed residue discharged from mud filters. 
Filtrate—Liquid which has passed through the filtration process. 
First Expressed Juice—The juice expressed by the first two rollers of a 
mill tandem. 
DEFINITIONS 
Gravity Purity—See Purity. 
Gravity Solids—Synonymous with Brix q.v. 
Gums—A general classification given to polymers of high molecular weight 
which can be precipitated from sugar products by a strong alcohol 
solution. Substances included in this category are pectins, hemi-
celluloses, oligosaccharides, dextrans and solubilised starches. 
Hygroscopic Water—The Brix-free water absorbed by cane fibre, the 
amount of which varies with the condition of the solution with which 
the fibre is in contact. For sugar solutions of low Brix and at normal 
temperatures, such as those experienced in bagasse analysis, it 
appears that hygroscopic wrater is some 20 to 25 per cent on fibre. 
Imbibition—The process whereby water or juice is added to bagasse to 
dilute the juice contained therein. 
Impurities (Soluble)—A collective term for all substances other than 
sucrose present in the total soluble solids contained in a sample. 
Sometimes expressed as a percentage of the whole material, as in 
the c.c.s. formula, and sometimes as a percentage of the total 
soluble solids as in 
Impurities = 100 — purity 
Frequently based on apparent analyses, in which case it is synonym-
ous with Non sugars. 
Invert Sugar—The equimolecular mixture of glucose and fructose which 
results from the hydrolysis or inversion of sucrose. 
Java Ratio—The percentage ratio of the pol per cent cane to the pol per cent 
first expressed juice. 
Hence. 
Last Expressed Juice—The juice expressed between the top and delivery 
rollers of the final mill in a tandem. 
Maceration—The process in which the bagasse is steeped in an excess of 
wyater or juice, generally at a high temperature. The water added 
for this purpose is termed maceration water. 
Magma—A mechanical mixture of sugar crystals with a liquid such as syrup, 
juice or water. 
Massecuite—The mixture of sugar crystals and mother liquor discharged 
from a vacuum pan. Massecuites are classified according to descend-
ing purity as first, second, etc., or A, B, etc. 
Milling Loss—The percentage ratio of pol in bagasse to fibre in bagasse. 
Mixed Juice—The mixture of juices leaving the milling train for further 
processing. 
Molasses—The mother liquid separated from a massecuite. It is distin-
guished by the same term as the massecuite from which it was 
extracted. 
Mud Solids—Insoluble matter other than bagacillo in subsider mud, filter 
cake and associated materials. 
Non-Sucrose—The difference between dry substance and sucrose. 
Non-Sugars—The difference between Brix and pol. 
Normal Weight—That weight of pure sucrose which, when dissolved in 
water to a total volume of 100 ml at 20 °C, gives a solution reading 
100 degrees of scale when examined in a saccharimeter, in a tube 
200 mm long, at 20 °C. 
The normal weight according to the International Sugar Scale 
is 26.000 g weighed in air with brass weights. 
No-Void Volume—The volume of cane (or bagasse) calculated on the basis 
that it consists of juice and fibre only i.e. that all air and/or gas has 
been removed. 
Other Organic Matter (O.O.M.)—The sum of the constituents of raw 
sugar other than pol, reducing sugars, ash and water. 
i.e. o.o.m. = 100 — (pol + reducing sugars -j- ash -j- water) 
Pol—The pol of a solution is the concentration (in g solute per 100 g solution) 
of a solution of pure sucrose in water having the same optical rota-
tion at the same temperature. For solutions containing only pure 
sucrose in water, pol is a measure of the concentration of sucrose 
present; for solutions containing sucrose and other optically active 
substances, pol is the algebraic sum of the rotations of the consti-
tuents piesent. 
Primary Juice—All the juice extracted without dilution. 
Primary Mud—The discharge from the underflow of a clarifier prior to the 
addition of bagacillo. 
Purity—Three classes of purity—Apparent, Gravity and True purity—are 
recognized. Ideally, purity is the percentage of sucrose in the total 
solids in a sample. The purities mentioned above are derived as 
follows:—-
DEFINITIONS 5 
Net Titre (N.T.)—An empirical value used as a measure of the percentage 
of pure sugar which may be recovered from a batch of raw sugar. 
Sugars of various qualities are commonly reduced to a common 
basis of 94 n.t. as follows:— 
The term purity alone generally signifies apparent purity. 
Gravity purity is not used in Queensland. 
6 DEFINITIONS 
Reabsorption Factor—The ratio between the no-void volume of bagasse 
leaving a mill opening in a given time, and the escribed volume for 
the opening, over the same period of time. 
Reduced Extraction—A formula used to express normal mill extractions 
on a common basis of 12.5 per cent original fibre in cane. The 
formula is usually expressed in the general form, 
(100 —extraction) (100— fibre) Reduced extraction = 100 = ^r 7 x fibre 
Reducing Sugars (R/S)—The reducing substances in cane and sugar pro-
ducts calculated as invert sugar. The most familiar examples of 
sugars having reducing power are glucose (dextrose) and fructose 
(laevulose). 
Reducing Sugar/Ash Ratio—The ratio between reducing sugars and ash. 
Refractometer Brix—See Brix. 
Remelt—A solution of low grade sugar in either syrup, clarified juice or 
water. 
Residual Juice—The juice left in bagasse after milling. 
Seed—Fine sugar crystals, generally suspended in a liquid medium, in which 
case the mixture is known as seed slurry. Seed is used either to 
provide the crystal surface for deposition of sucrose, or to promote 
spontaneous crystal formation from a super-saturated solution. The 
latter is referred to as shock seeding. 
Set Opening—The distance between the tips of the teeth of a pair of rollers. 
Where the roller teeth are set in mesh, this distance will be negative. 
Sucrose—The pure chemical compound with the formula C1 2H2 2Ou . This 
is commonly referred to in the industry as pure cane sugar. 
Sugar—The crystals of sucrose, together with any adhering molasses, as 
recovered from the massecuites. The various grades are commonly 
identified in terms of the grade of massecuite processed, or in terms 
of the avenue of disposal of the sugar—hence, A sugar, C sugar, 
Shipment sugar. 
Suspended Solids—Solids in juice or other liquid, removable by mechanical 
means. 
Syrup—The concentrated sugar solution leaving the evaporators. 
Total Sugars—The combined percentages of sucrose and reducing sugars 
in a sample. 
Turbidity—A measure of the material in suspension in a sugar solution as 
determined by a spectrophotometer. 
Undiluted Juice—The juice expressed by the mills or retained in the 
bagasse, corrected for dilution water. For purposes of calculation 
the Brix of the undiluted juice is taken to equal that of the primary 
juice, or in Queensland, the first expressed juice. 
Volumetric Coefficient—A term used to designate the fibre loading of a 
mill opening. Using the British system of measurement, it is quoted 
as pounds of fibre per cubic foot of escribed volume. 
DEFINITIONS 7 
Work Opening—The mean opening between a pair of mill rolls. This opening 
takes into account the set opening and the allowance for mill 
grooving. No allowance is made for juice grooves, but where a dirty-
top roller is employed, this must be taken into account. 
Work Ratio—Where a three roller mill has rollers of equal circumference 
rotating at a common speed, this ratio is the ratio between the feed 
work opening and the delivery work opening. Where openings with 
rollers of different diameter or different peripheral speed are to be 
compared, it is necessary to calculate the ratio from the two 
escribed volumes. 
CHAPTER II 
OPTICAL INSTRUMENTS 
The optical properties of sugar solutions afford rapid and convenient 
methods for their analysis and the chemist's most important piece of appara-
tus is the polarimeter or saccharimeter. The refractometer is used in a limited 
degree for the rapid determination of total solids in juices and syrups. The 
introduction of colorimetric methods into sugar laboratory analyses demands 
the use of the spectrophotometer, and clarification studies require the use of this 
instrument as a turbidimeter. The microscope is used where raw sugars are 
examined for grain quality. Each of these instruments will, therefore, be 
described in some detail. Recent trends to automation have resulted in the 
development of automatic polarimeters; these will be discussed fully while the 
principles involved in automatic refractometers will also be mentioned. 
Properties of Light 
Light is a form of electromagnetic radiation and it consists of trains of 
waves vibrating transversely—that is, at right angles to the direction in 
which the waves are travelling. The most familiar case of a transverse wave 
is probably that which travels along a rope or string when one end is suddenly 
jerked sideways. If the end of the rope is moved continuously, a continuous 
wave will be produced. 
Fig. 1—Illustrating the principle of a light wave. 
Fig. 1 represents a wave in which the vibration is at right angles to the 
direction of motion, P Q. The distance A B is the amplitude of the wave, 
while the distance 0 E, which includes one complete crest and trough, is 
known as the wavelength and denoted by the symbol A. For light, wavelengths 
are expressed either in nanometers (formerly called millimicrons; 1 nm = 
10-9 metre) or in angstrom units (1 A = 10-10 metre = 0 . 1 nm). Light of 
different wavelengths appears to the eye as different colours; the following 
wavelengths have the colours given: 
683 nm red 
615 nm orange 
559 nm yellow 
512 nm green 
473 nm blue 
410 nm violet 
These represent pure spectral colours; colours of most objects, however, 
are due to light having a range of wavelengths. The intensity of the light 
depends on the amplitude of the wave; in fact, it is proportional to the 
amplitude squared. 
OPTICAL INSTRUMENTS 
The number of complete waves passing any point each second is the 
frequency, denoted by v. This is measured in hertz (Hz), formerly called 
cycles per second. For visible light the frequencies range from 4 x 1014 to 
8 x 1014Hz. The speed v at which the wave advances is then given by 
v = v X. 
In a vacuum, light has a constant speed, no matter what its wavelength; 
this is denoted by c. In transparent matter, light has a lower speed and this 
speed varies with the wavelength of the light. It is this slowing down of light 
by matter that enables optical measurements to give an estimate of, for 
example, the total dissolved solids in a solution; the more material in solution 
the greater the "slowing down" of light. 
In general, the vibration of a light wave occurs in the two dimensions at 
right angles to the direction of travel. However, light can be made to vibrate 
entirely in a single plane just as a water wave vibrates only up and down. 
The light is then said to be plane polarized or linearly polarized. When such 
light passes through certain media, the orientation of this plane is changed. 
This change is caused only by special materials, said to be optically active, of 
which sugars are examples. The amount the direction is changed depends on 
the concentration of the optically active material in a solution, so polarimeter 
measurements give concentrations of active materials (such as sugars), rather 
than total solids. 
Refractive Index 
In a homogeneous medium light travels in straight lines. If, however, a 
beam of light in one medium meets the surface of a second medium, it will 
in general be refracted or bent from its original path. The incident ray of 
light, denoted by L O in Fig. 2, arrives at the boundary between the media 
Fig. 2—Illustrating the law of refraction. 
M and M' in a direction represented by the angle LOP between the ray and 
the normal (perpendicular) to the boundary. This angle is called the angle of 
incidence i. Part of the light is reflected along O L' at the same angle i on 
the opposite side of the normal. The bulk of the light, however, is transmitted 
into the second medium along O S, which makes an angle SOQ with the 
normal. This is called the angle of refraction. If this angle is smaller than the 
angle of incidence, the first medium is said to be the rarer medium and the 
second the denser. This terminology relates to the effect, discussed earlier, 
that as the concentration and hence the density of a medium increases, the 
speed of light in it decreases. (This should not be confused with the "optical 
density" of a medium, which refers to its light-absorbing properties). 
The angles of incidence and refraction are related by the expression 
n sin i = n2 sin r 
where n and n2 are constants describing each medium; they are the refractive 
indices of the media. For any transparent medium, the refractive index is 
the ratio of the speed of light in air to its speed in the medium. Thus, a 
"denser" medium, having a lower speed of light, has a higher refractive index 
than a "rarer" medium. 
For a stricter theory, the refractive index should be defined with respect 
to speed of light in vacuum rather than in air, namely 
n = c/v. 
This is the absolute refractive index and it is 1.000 28 times the refractive 
index relative to air, 1.000 28 being the absolute index of air itself. For 
practical purposes, however, it is always the index relative to air that is used 
and this is what is meant by the simple term "the refractive index". 
Another way of writing the relation between the angles of incidence and 
refraction is 
sin i 
-. = n 
sin r 
where n = n2/n1 and is the ratio of the two refractive indices or the relative 
refractive index. This ratio is the same whether absolute indices or indices 
with respect to air are used. 
Since the speed of light in any medium other than vacuum varies with 
wavelength, so does the refractive index. Light of different wavelengths is 
therefore refracted by different amounts. When a beam of white light, which 
is a mixture of all visible wavelengths, is refracted at a boundary, it is spread 
out into a series of colours, known as a spectrum. This is the phenomenon of 
dispersion, sometimes called prism dispersion to distinguish it from the rotato-
ry dispersion discussed later. When a refractive index of a material is quoted, 
it is therefore desirable to specify the wavelength for which it has been meas-
ured. Certain spectral lines are known by letters, for example, the D line of 
sodium and nD denotes the refractive index for this line. Important lines are: 
Symbol Wavelength (A) Colour Element 
C 6563 red hydrogen 
D 5893 orange sodium 
d 5876 yellow helium 
e 5461 green mercury 
F 4861 blue hydrogen 
When the line is not specified, it is commonly the D index that is meant. 
Although useful for measurements of moderate accuracy, this is really two 
lines, close together. The modern tendency, particularly for accurate work, 
is to replace the D line by either the helium d line or the mercury e line. 
The dispersion of a medium is given by the difference between the re-
fractive indices for the blue and red lines of the hydrogen spectrum, i.e. 
nF—nC. 
The refractive index of a material also varies with the temperature and 
a complete description of a refractive index should also include this, as, for 
example nD2 0°. The rate of variation for glass is small, between 1 x 10-6 and 
6 x 10-6 per degree Celsius, and is usually positive, the index increasing as 
OPTICAL INSTRUMENTS 11 
the temperature increases. For liquids, the rate of change is much greater 
and in the opposite sense; an increase of temperature by 1 degC decreases 
the refractive index of water by 8 x 10-5. For sugar solutions, the tempera-ture coefficient is of a similar order increasing with increasing concentration; 
for organic liquids it may be even greater. 
The Refractometer 
For the most accurate measurements of refractive index the material, 
if a solid, is made into the form of a prism. If liquid, it is poured into a hollow 
prism. The deviation of the light through the prism is then measured. For 
routine measurements of refractive indices of liquids, however, methods 
based on the critical angle are used. 
Critical-Angle Refractometers 
When light passes from a rarer to a denser medium, the angle of refrac-
tion is smaller than the angle of incidence. Thus, while all values up to 90° 
are possible for the angle of incidence, until the incident light grazes the 
boundary surface, the angle of refraction has a maximum value that is smaller 
than this. This maximum value is the critical angle rc and is the angle of 
refraction that corresponds to an angle of incidence of 90°. Then 
sin i — 1 
and nn1 = n2 sin rc. 
Thence an unknown index n1 can be found by measuring the critical angle rc 
for light refracted from the sample into a denser medium of known index n2. 
The method is illustrated in Fig. 3, where M1 is the rarer and M2 the 
denser medium. In Fig. 3(a) the light is incident from the rarer medium and 
rays 0x-0b are shown at increasing angles of incidence. A small amount of the 
(o ) (b) 
Fig. 3—Illustrating the measurement of critical angle, 
(a) by transmission (b) by reflection. 
energy from each ray is reflected at the boundary; the rest is transmitted in 
the refracted ray. Since the ray 05 arrives at an angle of incidence of 90°, 
it is the critical ray. No light from Mx can penetrate into M2 at a larger angle 
of refraction. Hence, if the emergent light into M2 is viewed by a telescope 
aimed along the direction 05, the observer will see light on one side of the 
field of view, darkness on the other. Obviously, it is impossible for the 
telescope to be inside the denser medium M2, but this medium can be made 
as a prism, the second surface of which refracts these emergent rays into the 
air. This second refraction will change the direction of the critical ray but the 
final direction will still depend only on the known refractive index of the 
prism M2 and the unknown index of the sample M1. The angle of the critical 
ray is measured and the index n1 of the sample found from tables provided 
with the refractometer, or the instrument is calibrated to read, instead of 
angle, the index n1 directly or a Brix value derived from n1. 
The reverse process to that described above is shown in Fig. 3(b). In this 
case the light is incident from the denser medium and the rays O1-05 are again 
part reflected and part refracted at the boundary, passing into the rarer 
medium at a larger angle to the normal until, for 05, the angle of refraction 
has reached 90° and the ray leaves grazing the boundary. The angle of inci-
dence for this ray is thus the critical angle. If the angle of incidence is in-
creased further, as in O6 or 07, no light can be refracted into the rarer medium. 
All the energy is reflected at the boundary giving the phenomenon known as 
total internal reflection. Again if the light emerging in the denser medium, 
now the reflected light, is examined by a telescope aimed along 05, a divided 
field of view is seen with one side brighter than the other. The brighter side, 
at angles greater than 05, corresponds to rays for which there is total reflec-
tion, while the darker side corresponds to partial reflection. For this case 
sin r = 1 
and n1 = n2 sin ic. 
Fig. 4—The essential parts of an Abbe refractometer. 
OPTICAL INSTRUMENTS 13 
The critical angle is now an angle of incidence. Since on reflection, the angles 
of incidence and reflection are equal in magnitude, the unknown refractive 
index is found from a measurement of the angle of reflection that corresponds 
to this critical angle of incidence, ic. 
For either method of critical-angle refractometry, the solid or liquid 
sample M1 is placed on a prism of the material M2. For the first method, the 
boundary is illuminated from the sample; for the second, from the prism. 
In both cases the illumination should cover a range of angles: in the first case 
right up to 90° incidence, and in the second the range must include the critical 
angle. The emergent light, refracted or reflected according to the method, is 
examined through a telescope, the inclination of which can be altered to set 
it in the direction of the critical ray. The field of view of the telescope has a 
light and a darker side and the boundary between them is set on a pair of 
cross lines in the telescope eyepiece. 
In the first method, the darker side of the field would be completely 
dark, but for scattered light. In the second method there is only the less 
obvious distinction between total and partial reflection. Hence the first 
Fig. 5—The principle of the Abbe refractometer. 
14 OPTICAL INSTRUMENTS 
method is therefore by far the more sensitive method of measurement and 
it is the one normally used. The second method is only used when the speci-
men is so strongly absorbing {e.g. a sample of molasses) or scattering, that 
insufficient light can be sent through it to the boundary. 
One of the most widely used refractometers that is based on the measure-
ment of the critical angle is the Abbe refractometer. An early model made by 
Zeiss Jena is shown in Fig. 4 and, in conjunction with Fig. 5, is convenient 
for explaining the operating principle. Two prisms A and B of a flint glass of 
high refractive index (nD) = 1.75) allow samples to be measured with re-
fractive indices up to 1.7. Each prism is contained in a metal mount, the 
mount of the lower prism B being hinged to that of A and held in the closed 
position by a clamp. The two prisms are connected through the main bearing 
of the instrument to the arm J, which carries a cross line and eyepiece L. 
Rotating independently about the same axis is a second arm which carries 
the telescope F and the sector S, upon which the refractometer scale is en-
graved. The angle between the prisms and the telescope is read as the position 
of the cross line on the a r m / relative to this scale, while this angle is adjusted 
to set the boundary line on the cross line in the telescope by turning the 
knob T. In Abbe refractometers, the scale is not normally graduated directly 
in angle but either in refractive index or in Brix. 
In use, the two arms are rotated together until the prism B is uppermost, 
the clamp released, and prism B opened away from A. It will be noticed that 
the top (hypotenuse) surface of A is polished while the corresponding surface 
of B is roughly ground. If a solid sample is being examined, such as the test 
piece normally supplied by the manufacturer, a drop of a liquid, such as 
monobromonaphthalene (n — 1.658), that is known to have a higher index 
than the test piece is first placed on the top of A, which should be horizontal, 
and the large polished face of the test piece is pressed down on this, the small 
face to the front of the instrument (away from the telescope). This small face 
is pointed towards a window or another diffuse source of light and the tele-
scope set on the boundary between the light and dark fields with the instru-
ment in this "upside-down" position. The same position is also used for 
absorbing liquids, when the second method of measurement is used. The light 
is sent through the window C of prism A (normally closed by a cover) from 
the mirror R. In both these measurements, prism B is not used. 
For the usual measurements on reasonably clear liquids, a drop of the 
liquid is placed on the surface of prism A. Prism B is then clamped into 
position so that the liquid forms a film about 0.15 mm thick between the faces 
of the two prisms. The instrument is swung back so that the telescope is 
upright and light is reflected from a diffuse source from the mirror R into 
the open face of prism B. This light is then scattered by the ground face of 
this prism which serves simply as a means of giving incident light inside the 
liquid at all angles up to 90°. Prism A gives the critical refraction. 
The path of the light through the instrument is shown in Fig. 5, with the 
light entering through prism B, and being scattered at the ground surface. 
In this figure, the thickness of the sample is greatly exaggerated, and in prac-
tice the rays p q and p' q' are almost parallel to the prism surface ef. 
These rays enter the prism A at the critical angle and are brought to a focus 
along a line at L in the eyepiece of the telescope. Other rays are focussed to 
the left of L, so that L represents the boundary between light and dark fields. 
This boundary is set to intersect the centre of the cross lines, as shown. 
To measure the D index, a sodium lamp may be used as the light source. 
When a source of white light is used, the boundary becomes a band of colours 
since a different critical angle is obtained for each wavelength. To compensate 
OPTICAL INSTRUMENTS 15 
for this dispersion, Abbe refractometers are equipped with a pair of compens-
ating or Amici prisms. These prisms are placed on the telescope tube, in front 
of the objective and can be rotated simultaneously in opposite directions by 
the screw head M. They then act as an adjustable prism that produces no dev-
iation of the light but has a variable dispersion that can compensate for the 
dispersion of the critical refraction. Attached to the prisms is a scale z that 
can be used to give the dispersion of the sample, that is nF — nC. The Amici 
prisms are adjusted until the boundary between the light and dark fields 
becomes as sharp as possible. It is then not quite colourless but is seen to 
have a narrow band of a magenta colour on one side, yellow-green on the 
other. 
Unless the refractometer is used in a temperature-controlled room, the 
sample should be kept at a constant temperature during the measurement 
by circulating water at a constant temperature through the metal mountings 
which carry the prisms. The temperature is indicated by the thermometer Th. 
When a measurement has been made, the liquid should be removed from 
the prism surfaces with absorbent paper, the surfaces washed with a suitable 
solvent (usually water or alcohol) and dried with a soft cloth. As the prisms 
are made of a soft flint glass, they are easily scratched and great care must 
Fig. 6—Abbe refractometer by Carl Zeiss, W. Germany. 
be taken not to wipe grit across their surfaces or close them with dust in 
between. A scratched or pitted prism will give an indistinct boundary. 
The adjustment of the refractometer should be checked periodically on 
a sample of known refractive index. This can be the glass test piece provided 
with the instrument, freshly distilled water free from air (nD20° = 1-3330) or 
another liquid that has been specially calibrated. When making this check, 
the telescope is set at the refractive index of the calibrating sample and the 
adjusting screw V turned until the boundary is at the cross line. When using 
liquids as standards, it is essential to control their temperature to that for 
which they have been calibrated. 
Fig. 7—High accuracy refractometer by Bellingham and Stanley, London. 
Provided the sample gives a clear boundary between the light and dark 
fields, an Abbe refractometer should be capable of measuring its refractive 
index to an accuracy of about two units in the fourth decimal place (2 x 10-4). 
Fig. 6 shows a modern instrument made by Carl Zeiss, Oberkochen, W. Ger-
many. 
OPTICAL INSTRUMENTS 17 
There are however more accurate critical angle refractometers which will 
measure the refractive index of solutions to an accuracy of three units in the 
fifth decimal place (less than 0.02° Brix). Figures 7 and 8 illustrate two 
types of high accuracy refractometers. The bench model (Fig. 7) is used 
with a monochromatic light source and readings may be obtained over 
the range 0 to 80° Brix with a single measuring prism. The Dipping or 
Immersion refractometer (Fig. 8) is fitted with a compensator for light 
dispersion correction, so that it may be used with white light. It is supplied 
with a series of interchangeable prisms, each one covering a portion of 
the total range of 1.32 to 1.64 refractive index. This refractometer may 
be fitted with either non-heatable or heatable prisms. In the former instance 
Fig. 8—High accuracy immersion refractometer with temperature controlled prisms by 
Carl Zeiss, \V. Germany. 
it is used with the measuring prism dipping into the solution to be tested. 
The heatable prisms are similar to those of the Abbe type refractometer 
and are water jacketed to permit temperature control of the sample. 
This heatable prism assembly is usually preferred by Queensland sugar mills. 
Flow through cells are also obtainable for these instruments. It must be 
stressed that constant temperature control is essential for precision measure-
ment. 
18 OPTICAL INSTRUMENTS 
With high accuracy refractometers the scale is not calibrated in refrac-
tive index but is an arbitrary scale of equal divisions. As the scale is linear it 
may therefore be subdivided by means of a vernier so that readings to one 
tenth of one scale division are possible. Tables are provided for conversion 
of the scale reading to refractive index from which the degrees Brix may be 
determined. 
Simpler but less accurate than the Abbe refractometer are the hand 
refractometers, an example of which is shown in Fig. 9. 
Fig. 9—Hand refractometer by Atago Optical Works, Japan. 
Tables have been prepared which show the relationship between the 
concentration and the refractive index of sugar solutions. This relationship 
varies only slightly for different sugars, so the refractometer is quite satis-
factory for determining the total sugars present in a solution of mixed sugars. 
With respect to speed, ease of manipulation, and amount of sample required, 
the procedure is superior to specific gravity methods. As recently as 19(H) 
ICUMSA has adopted new equations developed by the Physikalisch-Techni-
sche Bundesanstalt in West Germany. These now form the basis of the 
International Table of Refractive Indices (1966) of sucrose solutions from 0 
to 85 per cent. The new table is very similar to the former table based on 
work by Schonrock; however, precise refractive index values can now be 
obtained to the fifth and at lower concentrations, the sixth decimal place. 
The new table of refractive indices of sugar solutions at 200C in air at 
200C, 760 mm pressure and 50 per cent relative humidity is found in Table 
VII. Where it is necessary to correct refractometer results for temperature, 
this is done by converting the refractometer reading to its corresponding 
Brix value and applying the corrections for refractometer Brix shown in 
Table VIII. As ICUMSA has not yet studied temperature corrections in 
detail, the values shown in Table VIII are still the original ones based on 
Schonrock's work. 
With impure sugar solutions, such as low-grade molasses, it is found 
that the refractive index affords a closer approximation to the actual amount 
of dry substance present than does the specific gravity. The percentage dry 
matter in massecuites or moist sugars can be determined with the refracto-
meter after dissolving all soluble matter in a known amount of added water. 
Since the refractometer indicates the amount of dissolved solids only, any 
insoluble matter which is present will introduce an error in the estimation of 
dry substance. Where dark-coloured solutions are being examined, it is often 
difficult to eliminate completely the effects of dispersion. This may be correct-
ed in some degree by dilution with water, but with impure solutions an error 
is introduced just as is the case with specific gravity determinations. A close 
approximation is obtained if a solution of pure sugar is used for the dilution. 
Most modern refractometers can be obtained with a Brix scale for the 
direct determination of the Brix of sugar solutions. The hand refractometer, 
of which one type is illustrated in Fig. 9 is useful for the approximate checking 
of Brix, particularly for maturity testing in the field. The model illustrated 
is of the double prism type and is to be preferred to the single prism instru-
ments which are also available. In both cases, when a sample is introduced, 
OPTICAL INSTRUMENTS 19 
the eye placed to the telescope will see a division line between light and 
dark fields superimposed on a scale of the type shown in Fig. 10. The scale is 
read at the junction of the two fields. These instruments are made to cover 
various ranges of Brix, e.g., 0-30°, 0-50°, 40-80°. 
So long as an adequate number of sticks is suitably sampled, it is possible 
to obtain a reasonably accurate estimate of the dry substance present in the 
juice from a crop, and the concentration of solids from the several portions 
of the stalk of cane provides a useful guide in the determination of the state 
of maturity of the crop. The instrument is also of great value in affording a 
rapid estimate of the relative sugar content of large numbers of cane seedlings 
when these are being selected for further trials. 
Fig. 10—Typical field of a hand refractometer. 
Automatic Refractometers 
Although automatic refractometers are not yet used in the Australian 
Sugar Industry, they have found wide use in the sugar industry overseas. 
Three methods are commonly used for measuring the effect of a liquid on a 
light beam directed at the liquid surface: 
(i) the lateral shift, or sometimes the dispersion, of the transmitted 
beam as a result of refraction. 
(ii) the position of the critical angle (the angle of incidence for which 
the emergent beam is tangential to the interface). 
(iii) the intensity of the reflected beam for angles of incidence less than 
the critical angle. 
Measurement of refractive index by the "transmission principle" (i) is 
possibly the most precise of the three methods; however it is only suitable 
for light coloured solutions. For dark coloured solutions it is essential to use 
small measuring cells and this can cause difficulty if any particulate matter 
is present. Automatic refractometers using the "critical angle principle" (ii) 
of operation are generally the most robust for process control work and are 
claimed to be unaffected by aeration, turbidity, and colour. Automatic 
refractometers working on the "reflected light principle" (iii) are widely used 
as Brix controllers on clear factory streams. They are however usually affected 
by aeration, turbidity and colour. 
The principle employed by the Waters Inline Refractometer which works 
on the critical angle principle is described as follows: 
20 OPTICAL INSTRUMENTS 
A light beam from an incandescent lamp is directed through a lens to a 
glass prism in contact with a liquid sample. The beam is refracted at the 
interface between the prism and the process fluid and directed back through 
a beam deflector to two cadmium sulphide photocell detectors. As the re-
fractive index changes the critical angle changes causing more or less light 
to fall on one photocell detector. The other photocell (comparison cell) 
remains in the full intensity portion of the beam. As the light changes on the 
detector cell, a signal is generated by the photocells and amplified, causing 
a servo motor to drive a glass restorer plate in the beam. The amount of 
movement of the glass required to restore the beam to a null balancing posi-
tion is a measure of the process stream concentration. Prisms covering 
different refractive index ranges are available. 
There are many automatic refractometers currently available from well 
known manufacturers throughout the world. 
Polarized Light 
Linearly polarized light, in which the vibration occurs entirely in one 
plane, is one type only of polarized light. The vibration may be in two dimen-
sions, at right angles to the direction of travel. Thus it can be a circular 
vibration around the direction of travel, and, in the most general case, vibra-
tion in an ellipse. If all the light in a beam has its vibrations following the 
same figure (straight line, circle or ellipse) the light is polarized, either 
linearly, circularly, or elliptically. Natural light is not polarized, but consists 
of a random mixture of all polarizations. 
In practice, linearly polarized light is the most important. It is obtained 
from natural light by means of a polarizer, a system that transmits vibrations 
in one direction only. Since the random vibrations of natural light can be 
resolved into two components along two directions at right angles and these 
two components are, on the average, equally intense, a perfect polarizer will 
transmit half the intensity of natural light. 
The light reflected from the boundary between twro transparent media 
is linearly polarized for a certain angle of incidence, but only a small part of 
the intensity is reflected. A more efficient polarizer is made from dichroic 
films. A dichroic material is one that transmits light linearly polarized in a 
certain direction (with respect to the orientation of the material molecule) 
and absorbs that polarized in the direction at right angles. The early experi-
ments on polarized light used the dichroic crystal tourmaline as polarizers. 
As it proved difficult to produce large dichroic crystals artificially, later 
polarizers have been made from small crystals embedded in a plastic sheet, 
all aligned in the same direction by stretching the sheet. This is the original 
form of Polaroid, the crystals used being herapathite or iodosulphate of 
quinine. 
These microcrystalline sheet polarizers are now quite obsolete. The 
present-day polarizers made by the Polaroid Corporation use a molecular 
dichroic material. A sheet of polyvinyl alcohol is stretched to align the 
molecules and then its surface converted into a dichroic material by treat-
ment either with iodine or oxygen to give two types of Polaroid, called H or K 
sheet. For use in optical instruments, the sheet polarizer is cemented between 
discs of glass. Other manufacturers such as Zeiss in Germany and Barr and 
Stroud in Scotland also make sheet polarizers. 
The properties of sheet polarizers vary somewhat, depending on the 
dichroic material used and how much of it there is on the sheet. All absorb 
some of the linear polarization that they should transmit and transmit a 
OPTICAL INSTRUMENTS 21 
small amount of the polarization they are intended to absorb. Good sheet 
polarizers, however, are now as good as the polarizing prisms described later 
and are gradually replacing these prisms in polarimeters and other optical 
instruments. 
Prism polarizers are made of transparent crystals that have the property 
of being birefringent or doubly-refracting. The crystal commonly used is calcite 
or Iceland spar, a clear form of calcium carbonate that cleaves readily into 
rhombohedra. If an object is viewed through such a crystal, a double image 
is seen. Both images are found to be linearly polarized with their polarizations 
at right angles. The crystal thus splits natural light into two linearly polarized 
rays and refracts these rays in different directions. (A dichroic crystal does 
the same splitting, but it absorbs one ray). 
Each crystal has a direction known as the optic axis, fixed with respect 
to the rhombohedral planes, in which both rays have the same refractive 
index, 1.658 for calcite. In other directions, one ray still has the same re-
fractive index; it is called the ordinary ray. The other ray, however, the 
extraordinary ray, has a refractive index that varies with direction from 
1.658 to 1.486 and so does not obey the simple law of refraction. In Fig. 11 the 
effect of sending a beam of light through a crystal of calcite is illustrated. 
Fig. 11—Illustrating double refraction of light in calc spar. 
The natural light is split into two polarized beams that leave the crystal 
with a slight separation, about 1/9 of the thickness of the crystal. This separa-
tion is usually too small to be useful for making a polarizer, and before such 
a crystal of calcite may be utilized for this purpose, one set of emergent rays 
must be eliminated. One method is to use the phenomenon of total internal 
reflection. This is usually accomplished by the method devised by Nicol. 
A crystal is selected (Fig. 12) of which the length is about three times the 
width. Wedge shaped sections are cut or ground from each end of the crystal 
so as to reduce the acute angles GBC and FDA from 71° to 68°. The crystal 
is then halved in the direction AC, at right angles to the modified faces. The 
cut surfaces are next polished and reunited with Canada balsam which has a 
refractive index about 1.54. A beam of light PR entering such a crystal 
Fig. 12—Illustrating the principle of the Nicol prism. 
(Fig. 12) is resolved into two rays, RO and RE. That which is the more 
highly refracted (the ordinary ray, RO) meets the film of Canada balsam AC 
at such an angle that it is completely reflected and is thus eliminated. The 
22 OPTICAL INSTRUMENTS 
e x t r a o r d i n a r y r a y RE i s less h igh ly ref rac ted , a n d emerges a s p l ane polar ized 
l ight from t h e end surface of t h e compos i t e p r i sm. 
I t should b e n o t e d t h a t t h e s e p a r a t i o n o f t h e t w o r a y s a n d t h e e l imina t ion 
of t h e o r d i n a r y r a y are ach ieved by t h e half p r i s m A B C a n d t h e film of 
C a n a d a ba l sam. T h e o the r half p r i sm A D C serves on ly t o r e s to re t h e e x t r a -
o r d i n a r y r a y to i t s or iginal d i rec t ion, a n d to p r o t e c t t h e film of C a n a d a 
ba l sam. 
This early t y p e o f Nicol p r i s m does n o t need to be g r o u n d a n d pol i shed 
on t h e ou ts ide faces, on ly a long t h e d i a g o n a l — w h e r e t h e t w o half p r i sms a re 
c e m e n t e d w i t h t h e C a n a d a b a l s a m . I t h a s t h e d i s a d v a n t a g e s of a smal l useful 
angle a n d of d isp lac ing t h e b e a m of l ight to one side. I t i s n o w rep laced 
en t i re ly by r e c t a n g u l a r p r i sms , w i t h all faces pol ished. T h e s e are , however , 
still somet imes cal led "n ico l s " . 
As calci te i s a m u c h softer m a t e r i a l t h a n glass, ca lc i te p r i sms shou ld be 
c leaned on ly w i t h e x t r e m e care o r t h e y wil l s c r a t ch . T h e y are difficult to h a v e 
r econd i t ioned as t h e po l i sh ing of calc i te i s h igh ly special ized op t i ca l w o r k 
a n d each p r i s m m u s t be s e p a r a t e d t h e n r e - c e me n te d wi th a c e m e n t o f i n d e x 
su i t ab le to t h e p r i s m angle . A s impler class of m a i n t e n a n c e is s o m e t i m e s 
requi red , however , i f t h e b l ack p a i n t on t h e side of t h e p r i s m b e c o m e s de -
t ached . Th i s p a i n t i s i m p o r t a n t a s i t abso rbs t h e o r d i n a r y r a y a n d so p r e v e n t s 
i t be ing s c a t t e r e d b a c k by t h e g r o u n d surface. 
A c o m b i n a t i o n of t w o polar izers in series is t h e bas i s of a po l a r ime te r . 
W h e n l ight from t h e first po lar izer (Fig. 13 I) p roceeds to a second polar izer , 
k n o w n as an analyser, i t i s c o m p l e t e l y t r a n s m i t t e d i f t h e po la r i z ing d i r ec t ions 
of t h e t w o are paral le l , losses in imper fec t polar izers be ing neglec ted . If, 
however , t h e ana lyse r i s r o t a t e d a b o u t t h e l ight b e a m (Fig. 13 I I ) , t h e i n t e n s -
i t y o f t h e e m e r g e n t l ight will decrease u n t i l t h e t w o polar iz ing d i rec t ions a r e 
a t r igh t angles , w h e n t h e l ight i s ex t ingu i shed . In t h e first pos i t ion , t h e polar -
izers a re sa id to be parallel: in t h e second, t h e y are sa id to be crossed. 
I. Parallel Nicols. 
II. Crossed Nicols. 
Fig. 13—Illustrating the principle of polarizer and analyser. 
W h e n l inear ly polar ized l ight passes t h r o u g h a b i ref r ingent c rys t a l , i t 
also can be spl i t i n t o t w o r a y s w i t h different re f rac t ive indices . I f t h e c r y s t a l 
i s t h in , these r a y s a re n o t no t i ceab ly s e p a r a t e d a n d r e c o m b i n e a s t h e y l eave 
t h e crys ta l . Because o f t he i r different speeds , however , t h e y do n o t r e c o m b i n e 
in s t ep and , i n s t ead of l inear ly polar ized l ight , e l l ip t ical ly po la r i zed l igh t is 
obtained.* El l ip t ica l po la r iza t ion can also be o b t a i n e d i f l inear ly po la r ized 
OPTICAL INSTRUMENTS 23 
light passes through strained glass. Glass is not ordinarily doubly refracting 
but, when strained, because of poor annealing or a mount that introduces 
strain, it becomes slightly birefringent. 
Optical Activity 
Quartz is also a crystal that is birefringent with about one-twentieth the 
birefringence of calcite. As with calcite, this effect is greatest in directions at 
right angles to the optic axis. Along the optic axis, however, a new effect 
occurs; if linearly polarized light is sent through a crystal of quartz in this 
direction, the angle at which the light is polarized is changed. The amount of 
change depends on the thickness; the direction of polarization can be 
imagined as rotating around the ray like a corkscrew as the light proceeds 
through the quartz. 
This property of rotating the plane of polarization is known as optical 
activity. It is possessed by certain crystals and also by some liquids and 
solutions, including sugar solutions. Materials such as glass that are not 
ordinarily optically active, can rotate the plane of polarization when they 
are placed in a magnetic field; this is known as the Faraday effect. 
The amount of rotation depends directly on the thickness of the sample 
through which the light passes and, in the case of a solution, on the concentra-
tion of the optically active substance in the solution. It also depends on 
temperature and wavelength, so these must be specified. An active substance 
in solution is characterized by its specific rotation a, i.e. the rotation of a solution 
of unit concentration and 1 decimetre length. For the D line at 20 °C this 
20 is written ay-. If a sample has a concentration c (in g per 100 ml, weighed in 
vacuo) and a length / (in dm), the angular rotation will be 
20 
0 = a ^ C //100, 
6 being measured in degrees. In the case of the Faraday effect, the amount 
of rotation depends on the field strength and its length, and therefore for an 
electromagnetic coil, on the current in the wire and the number of turns. 
A normally non-optically active substance, such as glass or air, when placed 
in an electromagnetic coil is characterised by its Verdet constant V, i.e. the ro-
tation caused by the substance in unit field strength and 1 decimetre long. As 
20 
above the angular rotation can be expressed as 6 — V — H Z/100, where H 
is the field strength in gauss. The measurement of this rotation is the tech-
nique of polarimetry; it is a method of measuring the concentration of a 
substance of known specific rotation when placed in a tube of known length. 
Sucrose +66.54 Laevulose —92.5 
Dextrose +52.5 Invert —20.0 
A solution of sucrose or dextrose, which has a positive specific rotation, 
rotates the plane of polarization in a clockwise direction when viewed towards 
the light source, and is said to be dextrorotatory. Laevulose, on the contrary, 
rotates the plane in an anti-clockwise direction and is said to be laevorotatory. 
Crystals of quartz occur in two different forms that are either dextro- or laevo-
rotatory. They are called right-handed and left-handed quartz. In the case 
of the Faraday effect, the direction of rotation depends upon the direction 
of the magnetic field and therefore for an electromagnetic coil on the direction 
of the current in the coil. 
24 OPTICAL INSTRUMENTS 
In any method of polarimetry, the solution is placed in a cell of known 
length between two polarizers. In a polarimeter, these are set crossed with 
the cell empty and the extra rotation of the analyser, required to restore 
extinction after the sample is introduced, measures the rotation of the sample. 
In a saccharimeter, the analyser is not rotated, but the rotation due to the 
sample is compensated by the rotation in a plate of quartz of variable thick-
ness. In certain automatic polarimeters, the same principle of balancing is 
used, but instead of quartz, a rod of glass in a variable magnetic field gives a 
Faraday rotation; the current used to produce the field indicates a measure of 
the sample rotation. 
The variation of rotation with the wavelength of the light used is known 
as rotatory dispersion. It has the practical result that measurements of rota-
tion must be made with monochromatic light, as are measurements of re-
fractive index. Traditionally, the D line of sodium has been used, but there 
is a modern tendency to use the e line of mercury (5461 A) for very accurate 
measurements; it must be remembered that the specific rotations for these 
two lines are quite different. Thus a polarimeter is used with either a sodium 
or mercury lamp. In a saccharimeter, the quartz and sugar solution have 
similar rotatory dispersions, at least in the red-to-yellow part of the spectrum, 
so that white light that has been passed through an orange filter can be used. 
The Polarimeter 
The essential parts of a visual polarimeter are shown in Fig. 14. An 
aperture B is illuminated by a source of monochromatic light C, either directly 
or through a lens which focuses C on B. The light passes on through a fixed 
polarizer P, with a field stop F, and the analyser A which may be rotated; 
Fig. 14—Showing the essential parts of the simple polariscope. 
the latter is fitted with a scale S on which the rotation can be read. It is 
usually graduated so that the crossed position of the analyser corresponds 
to the zero of the scale. The light is viewed by the eye E of the observer. 
If a cell X containing an optically active solution is now placed between the 
polarizer and analyser, it will be found that the light is no longer extinguished 
by A, which will have to be rotated to a new orientation to restore extinction. 
The angle through which the analyser is rotated is the rotation of the speci-
men. The scale 5, as well as being marked in angular degrees, is often also 
marked in terms of the International Sugar Scale discussed later. 
A simple polarimeter of this type would not be very accurate, for setting 
an instrument to extinguish light cannot be done with high precision. It is 
well known in the technique of measurement that a setting to a maximum 
or a minimum, such as this, is less precise than a balancing of two quantities 
to equality or coincidence; for example, setting a needle on a scale division, 
aligning a line to a crosswire, or matching the intensity of two adjacent fields 
of view. Settings of this last type are known as null settings. 
The eye looking through the polarimeter has a field of view located at 
the stop F near the fixed polarizer. To convert the instrument into an 
OPTICAL INSTRUMENTS 25 
instrument with a null setting, this field is split into two parts as shown in 
Fig. 15 or in some cases into three parts. The polarizations of these two regions 
are in directions that differ by a small angle (when three regions are used, the 
two outer ones are polarized in the same direction and the centre one is 
different) so that, as the analyser is rotated, first one field, then the other is 
extinguished. When the analyser is crossed with the direction midway between 
the two polarizations, the two fields have equal intensity. A setting to this 
position is thus a null setting and is much more accurate than a simple 
setting to extinction. 
I II III 
Fig. 15—Illustrating the principle of the Lippich polarizer for double field. 
The three-field alternative has an even greater sensitivity but, if the 
two outer fields are not polarized exactly in the same direction, it loses its 
advantage, since two balance-points are obtained. Under ordinary laboratory 
conditions, the simpler two-field balance is preferable. 
The angle between the polarizations of the two fields is known as the 
half-shadow angle. Theory shows that, the smaller the half-shadow angle used, 
the greater is the sensitivity of the instrument. However, the smaller this 
angle, the closer the two sides of the field are to extinction at the balance 
point, and the less light there is available to judge the balance. Since the 
sensitivity also depends on the light intensity, when the light source is as 
bright as can be obtained, a compromise is required on the half-shadow angle 
between the loss of sensitivity due to too large an angle and the loss due to too 
little light. In practice angles of 1° to 10° are used. In the saccharimeter 
described later an angle about 7° to 8° has been found a good compromise 
for accuracy and available light. 
There are several methods used to make polarizers that give a split field. 
The simplest to understand are forms of the Jellet-Cornu polarizer. Imagine 
a polarizing prism with a narrow-angle V taken longitudinally from its centre. 
The two separate prisms are then cemented together to give two adjacent 
polarizers with a fixed half-shadow angle, the angle of the V cut. Another 
polarizer with a fixed half-shadow angle is made from two long natural 
rhombs of calcite; this is one example of the use of the rhomb itself, instead 
of a prism, to separate the ordinary from the extraordinary ray. 
The most common method of obtaining the split field is the Lippich 
polarizer, shown in Fig. 16. In front of the main polarizer is placed a smaller 
polarizer covering half the field. This is rotated through the half-shadow 
angle from the main polarizer. This rotation changes the direction of 
polarization across this half of the field and also slightly reduces the 
26 OPTICAL INSTRUMENTS 
intensity. The reduction of intensity affects the posit-
ion of the setting slightly; it is no longer exactly 
midway between the angles at which the two fields 
extinguished. The small polarizer is also tilted slightly 
so that the observer does not look along its face (and 
hence see a broad band separating the two fields) but 
sees only a sharp edge. When the triple field is used, 
two such small polarizers are employed. 
The Lippich system has the advantage that the 
half-shadow angle is adjustable and can be altered to 
suit the intensity of the illumination. When it is 
altered, however, there is an alteration of the zero 
point of the analyser. But, in the Bates Fric sacchar-
imeter a special set of gears is fitted so that, when 
the large polarizer is rotated to change the half-
shadow angle, the analyser is rotated by the amount 
required to correct for the change in zero point. 
The need to use monochromatic light with a 
polarimeter was a great practical disadvantage when 
it had to be obtained by feeding metal salts into a 
flame. Now spectral lamps, such as sodium and 
mercury, are readily available and easy to use. Most 
of the visible light from the sodium lamp is in a pair 
of orange lines, called the D line, and it is usually 
used with a yellow filter to cut out the light from a 
fainter pair of green lines. Sodium lamps have a fixed, 
rather low brightness. 
Mercury lamps can be obtained with a wide 
range of brightness. The bright, high-pressure lamps, 
however, give broadened spectral lines and this can 
cause errors. Thus for polarimetry, a low-pressure 
mercury lamp is required with a filter to separate out 
the green e line. 
The Saccharimeter 
Formerly a saccharimeter was considered to be a polarimeter graduated 
not in angular degrees but in relative concentration of sugar or degrees of 
sugar oS. However some polarimeters today have both angle and sugar scale 
graduations and modern automatic polarimeters can be arranged to display 
the rotation in any chosen unit. This applies equally whether the sample 
rotation is compensated by turning the analyser prism, or by placing a suit-
able amount of optically active substance, such as a piece of quartz, or a 
glass rod in a magnetic field, immediately before a fixed analyser. 
Therefore it seems best to describe a polarimeter with a sugar scale 
merely as a sugar polarimeter and to confine the term saccharimeter to an 
instrument which by virtue of its principle of operation should be used only 
on sucrose solutions. 
As a result, it is becoming common, therefore, to reserve the name 
saccharimeter for an instrument that uses quartz wedges for compensation. 
When a polarimeter is designed specifically for use with sucrose solutions, 
that is, as a saccharimeter, it becomes possible to adopt an alternative means 
of eliminating the ill-effects of rotatory dispersion and the need to use rather 
Fig. 16—Showing the 
c o n s t r u c t i o n o f 
Lippich polarizer for 
double field. 
OPTICAL INSTRUMENTS 27 
low intensity spectral lamps. (When white light is used with a simple polari-
meter, no extinction is obtained since different colours are rotated different 
amounts.) By chance, quartz has practically the same rotatory dispersion as 
sucrose solution. The rotation produced by the sugar is balanced out by a 
quartz compensator, wavelength by wavelength, and extinction can now be 
obtained with white light. The extinction is improved further if the blue end 
of the spectrum, where the dispersions match worst, is not used. The light is 
therefore filtered through a bichromate filter (15 mm thickness of a 6 per cent 
solution of potassium bichromate) or a plate of glass having similar trans-
mittance characteristics. 
The quartz compensator consists of two wedges of quartz of equal angle 
mounted so that one can be moved past the other, as shown in Fig. 17. The 
pair of wedges then acts as a parallel-sided plate of quartz of adjustable 
Fig. 1 7—Showing the construction of single wedge quartz compensation. 
I Dextrorotatory system. II Laevorotatory system. 
thickness and it gives a controlled rotation to the light going through it. 
This rotation is never zero, since the plate formed by the two wedges can 
never be zero thickness. To obtain zero rotation, the wedges are "backed off" 
by a fixed plate of quartz of the opposite hand; i.e. if the wedges are made of 
left-handed quartz, this plate is right-handed. This system, known as a 
single-wedge compensator, is the one most commonly used in commercial 
saccharimeters. 
The optical system of a saccharimeter is shown in Fig. 18. The lens a 
condenses white light from a clear filament lamp, with a ground glass disc 
in front of it, on the aperture in b; the light is brought to a focus at the objec-
tive of the telescope by a lens c; d is the polarizer (with fixed half-shadow 
angle); e is a stop to limit the size of the light beam and / a glass protecting 
Fig. 18—Illustrating the parts of a saccharimeter. 
plate. The sugar solution under examination is contained in the cell g; h is a 
second protecting plate; i and m are stops for cutting out stray light; j, k, 
and I make up the single-wedge compensator; n is the analyser; o the objective 
of the viewing telescope; p a field stop in the focal plane of the eyepiece; 
and q and r form the eyepiece of the telescope. 
Two separate optical parts of the instrument are thus in dust-proof 
enclosures, protected from juice splashes by the optically inactive protecting 
glasses. The whole system is mounted in a rigid metal tube which is held 
horizontal on a stand. Formerly, saccharimeters were supplied for both 
200 mm and 400 mm sample cells but the former has almost disappeared 
from the modern sugar-mill laboratory; the longer cell is needed for such 
solutions as bagasse extracts, which are of low optical activity. On the 
latest models (Fig. 19) the lamp housing is built on as an extension to the 
instrument so that the light source is fixed in relation to the instrument and 
is held in its correct position. With the Schmidt and Haensch instrument a 
small focusing disc is provided. This is placed at the end of the trough 
towards the analyser, and if the light be correctly placed, a sharp image of 
the filament of the lamp will coincide with the horizontal diameter marked 
on the disc. The ground glass disc with which the lamp is fitted should, of 
course, be removed when making this test. 
The scale is usually graduated from —30 °S through zero to +105 °S 
(with extended graduations at both ends), or occasionally, from —150 °S 
to +150 °S. The angular rotation that corresponds to 100 °S depends on the 
length of cell used, the normal weight specified for the instrument, and on the 
wavelength for which the rotation is measured. 
Fig. 19—Illustrating a Schmidt and Haensch saccharimeter. 
The scale is viewed through a low-
power microscope, being illuminated by 
some of the light that has been deflected 
from the main path. Two types of scale 
are now in common use. The type em-
ploying a vernier is illustrated in Fig. 20. 
It will be observed that the main scale is 
graduated at intervals of one degree of 
sugar. A centre-zero vernier is provided, 
one side for positive readings and the 
other for negative, both divided to read to 
0.1 °S. In Fig. 21 is illustrated the scale 
employed in the current Schmidt and 
Haensch saccharimeter. The scale moves 
vertically as opposed to the former hori-
zontal scale and the main scale is divided 
into 10 °S divisions. A fixed engraved scale 
Fig. 20—Illustrating the double 
vernier scale of a saccharimeter. 
Reading 73.4° S. 
OPTICAL INSTRUMENTS 
Fig. 21—Direct reading scale employed in the Schmidt and Haensch saccharimeter. 
Reading 66.3° S. 
of 10 °S subdivided into 100 divisions is also provided whereby the reading 
may be made directly to 0.1 °S and estimated to 0.02 °S. The zero adjustment 
for each scale is carried out as follows:— 
In the vernier type scale the field is set to the balance position with the 
trough empty and the zero of the vernier is adjusted, with the key provided, 
to the zero of the main scale. With the direct reading scale the zero on the 
movable scale is set to the zero on the fixed scale first and the field is then 
balanced for equal intensity by the knurled knob situated at the base of the 
analyser housing. At the balance point the two halves of the field should 
appear identical. The appearance of a difference in colours at the balance 
point, one side appearing yellowish and the other nearly white indicates the 
need for internal adjustment. This should not be attempted by unskilled 
technicians. 
Effect of Illumination 
As stated earlier, the rotatory dispersion of sucrose solution is close, but 
not exactly equal to that of quartz, the sugar having the greater dispersion. 
Since the difference in the two dispersions is greatest for blue light, the 
quartz-wedge saccharimeter is designed for use with white light filtered to 
remove the blue end of the spectrum. A movable glass filter, that approx-
imates closely to the characteristics of a six per cent potassium bichromate 
solution of 15 mm thickness, is now usually built into the saccharimeter. 
This filter transmits red, orange, and yellow light but absorbs the rest of the 
spectrum; the transmitted radiation has a mean wavelength of about 6000 A. 
If white light is used without a filter, a saccharimeter will give readings 
that are in error by about +0.12 °S at the 100 °S point. Only when the 
solution is coloured and acts as its own filter should the filter be omitted. 
If a sodium lamp is used with a quartz-wedge saccharimeter, there is again a 
small error, now about 0.03°S at 100 °S, whether a filter is used or not. 
Automatic Polarimeters 
The modern tendency in optical measuring instruments is to replace 
the eye by some photoelectric detector. Such instruments do not require as 
highly skilled an observer and are less fatiguing to use. In addition, the 
29 
30 OPTICAL INSTRUMENTS 
results obtained are more reliable and often more accurate and, being in the 
form of an electrical signal, can be recorded by means of the large variety 
of data-recording equipment now available. If calculations are made on the 
results, this is done by connecting in the appropriate calculating circuits 
and the result is obtained with very little delay. An automatic polarimeter 
is normally used with a flow-through cell so that samples can be readily 
introduced and flushed away; many installations use an automatic sample 
feeder which introduces samples to the instrument at regular intervals of, 
say, 60 seconds and actuates the read-out device. Certain instruments allow 
the polarisation to be recorded continuously as the sample flows through the 
cell. However, the precision of the measurement usually surfers seriously as 
a result of striations. 
A photoelectric polarimeter could be made by using a conventional 
split-field polarizer and taking the light from each half of the field to a 
separate photocell. At the balance point, the two electrical signals from the 
photocells would be equal. Such a system would give continuous d.c. signals 
from the photocells and would require d.c. amplifiers, which are notoriously 
more unreliable and more unstable than a.c. amplifiers. 
Modern automatic polarimeters, therefore, use a.c. balancing. Instead 
of a field split in space and two photocells, one photocell is used with a field 
"split in time". The plane of polarization changes backwards and forwards 
between the two positions it would have for the split field, either in jumps 
or continuously. The electrical signal from the photocell then consists of a 
d.c. background superimposed on which is an alternating current of the 
same frequency as that at which the polarization is being switched. This 
a.c. component of the signal is an error signal: it becomes zero at balance. 
The instrument balances itself by using the error signal to drive the 
balancing system; when the error signal vanishes, this drive stops. It is thus 
a servo-system. 
To oscillate the direction of polarization one of three methods is used. 
The first, employed by Schmidt and Haensch and also by Perkin Elmer in 
their automatic saccharimeters and polarimeters, uses a synchronous motor 
coupled to the polarising prism, which is caused to rotate backwards and 
forwards so that the direction of polarisation oscillates. The second, used 
by the National Physical Laboratory (N.P.L.) in the standard polarimeter 
that they use to calibrate quartz control plates and also by Jobin-Yvon, 
has a rotating plate, around the edge of which is a series of holes, each 
covered by a quartz plate. These plates are of equal thickness and alter-
natively left- and right-handed. As the plate rotates, these quartz plates 
pass in turn in front of the polarizer to give a direction of polarization that 
switches first to the left, then to the right. Hilger and Watts use a similar 
system consisting of a vibrating reed supporting and oscillating two pieces 
of quartz side by side, one left-handed and the other right-handed, and 
oscillating them across the light beam. 
The third method makes use of a Faraday cell and is employed by Zeiss 
and Jouan. It is also used in the polarimeter designed by N.P.L. which is 
made by Thorn Bendix. As stated earlier, if a glass rod with light passing 
through it is placed in a magnetic field, the field being in the direction of the 
light, the plane of polarization of the light is rotated by an amount that de-
pends on the type of glass and the strength of the magnetic field. Very dense 
flint glasses give the largest rotation. The sense of rotation depends on the di-
rection of the field and, if this is alternated, the rotation alternates. To give an 
oscillating direction of polarization the glass rod is enclosed in a solenoid 
through which passes an alternating current. 
OPTICAL INSTRUMENTS 31 
The polarimeter is balanced in one of three ways, corresponding to the 
above methods of modulation: Either a conventional analysing prism is 
rotated (Hilger and Watts, Zeiss, Perkin Elmer), or compensating quartz 
wedges are driven up and down (Schmidt and Haensch, Jobin-Yvon), or a 
d.c. Faraday cell is used as a compensator to balance the rotation due to the 
sample (Bendix, Jouan). The rotating analyser is turned to balance by a 
motor that is driven by the amplified error-signal, and the rotation can be 
read from an angle scale by an electrical method e.g. by using a potentiometer. 
In the Hilger and Zeiss instruments a digital output of the rotation in sugar 
degrees is obtained using a shaft encoder. The compensation quartz wedges 
are driven to balance by a motor in a similar fashion to the rotating analyser, 
and the sugar value of the rotation of the sample is read from a linear scale. 
(The Schmidt and Haensch instrument uses moire gratings, for example). 
In the Bendix polarimeter, the current in the compensating Faraday cell is 
a measure of the rotation. 
In the Hilger and Zeiss instruments, the servo motor drives the rotating 
analyser at a constant rate, and so the time taken to reach a balance depends 
on the range to be traversed: for instance if a cane juice sample reads 90 °S, 
the instrument will take twice as long to give a reading if the previous sample 
read 70 °S than if it had read 80 °S. In the Bendix instrument the balancing 
is done electronically, not mechanically, and equilibrium is approached at an 
exponentially decreasing rate. Therefore the time taken to reach balance 
depends only slightly on the range to be traversed. The accuracy of the final 
setting depends, however, on the time allowed for the equipment to reach a 
balance; the longer the time permitted, the higher the accuracy that can be 
obtained, until the instrument's limit of accuracy is reached. To be precise, 
the accuracy increases as the square-root of the time, so that, to double the 
accuracy, the instrument would take four times as long to reach a balance. 
The Hilger M560, Zeiss OLD 3 and Bendix-NPL 700 A automatic polari-
meters have been built to comply with the Australian Standard Specification 
for an Automatic Sugar Polarimeter, AS K157 - 1968. Australian Standard 
Specification AS K157 - 1968 "Automatic Sugar Polarimeter" covers the 
requirements which are considered desirable for an automatic sugar polari-
meter suitable for use in the analysis of cane juice and sugar products 
in Australian sugar factories. It was approved by the Standards Association 
of Australia in 1968. They have a range of —120 °S to +120 °S with a digital 
readout to 0.01 °S, and are suitable for cane juice, raw sugar and molasses. 
Most of the other commercially available automatic polarimeters are built 
for the European beet sugar industry, and have a range of 0 to 30 °S or 0 to 
100 °S, with a readout to the nearest 0.05 °S or 0.10 °S. 
The Hilger and Zeiss instruments are basically automated verisons of 
conventional polarimeters. Their components are shown in Figs. 22 and 23, 
respectively. 
The Hilger M560 polarimeter normally uses a mercury vapour lamp 
and an absorption filter to provide monochromatic radiation of 546 nm. 
However, it can be fitted with a sodium light source. The light is linearly 
polarised by a calcite prism of the Lippich type. A small oscillating biplate 
of left- and right- rotating quartz modulates the beam, which passes through 
the sample, normally contained in a 200 mm tube, and on to the analyser 
prism and the photomultiplier. Jacketed flow-through cells are available, 
and the tube trough is also provided with a water jacket for more effective 
temperature control. The "out of balance" signal from the photomultiplier 
is amplified and used to drive a servo motor which rotates the analyser prism 
until balance is reached. The shaft of the servo motor also drives the electro-
OPTICAL INSTRUMENTS 
SCHEMATIC LAYOUT OF 
M560 AUTOMATIC 
POLARIMETER 
Fig. 22—Schematic layout of Hilger M560 automatic polarimeter. 
mechanical digitizer disc; this consists of a number of miniature commutator 
type brushes which touch contacts on an opposing fixed disc. This instrument 
is not being commercially produced. 
The Zeiss OLD 3 polarimeter uses a mercury spectral lamp and an 
interference double-band filter for a wavelength of 546 nm. The light is 
polarised by a prism of the Glan-Thompson type, and then passes through a 
Faraday modulation coil. The modulator rod is made of special stress-free 
glass, 50 mm long; the modulation is at 50 Hz and the angle is about ±2° at 
Fig. 23—Diagram of Zeiss OLD digital polarimeter. 
32 
OPTICAL INSTRUMENTS 33 
546 nm. The modulated beam then passes through a sample cell, 98.13 mm 
long; this length being chosen so that 100 °S is equivalent to 20° of angle. 
Jacketed flow-through cells are available, and the sample space is also pro-
vided with a water jacket for more effective temperature control. From the 
cell the light passes through the analyser prism to the photomultiplier. The 
Zeiss is a full circle polarimeter; the analyser is permanently coupled to an 
analogue-digital convertor (shaft encoder) with 5 decades and a transmitting 
potentiometer. The two decades representing the most significant figures 
(tenths and hundredths of a sugar degree) are photoelectric: the other three 
decades are electro-mechanical with suitable reduction by epicyclic gears. 
The components of the Bendix-NPL polarimeter are shown in Fig. 24. 
Since the instrument uses a magnetic field to give the balance, it is itself 
sensitive to the earth's magnetic field and, if horizontal, the reading given 
Fig. 24—Diagram of Bendix-NPL automatic polarimeter Type 700. 
would change if the instrument were turned around on a table. It is therefore 
made upright so that it always stands vertical at a constant angle to the earth's 
field (at one place). In addition it is made of non-ferrous metals. It should be 
kept away from large pieces of iron or steel during use since, if these are 
moved near it, the field through the Faraday compensation coil could be 
changed in the middle of a measurement. Road traffic closer than 15 ft may 
also affect the reading. 
The light source, a filament lamp with a stabilized electrical supply, is at 
the top. This light is passed through an interference filter to give a band of 
mean wavelength corresponding to the mercury e line (546 nm), with a band 
width at 50 per cent transmission of about 20 nm. An interference filter can 
be fitted to give a mean wavelength corresponding to the sodium D line 
(589 nm). The light then passes through two stops and a condenser lens, 
which control the beam size, the polarizer (a sheet polarizer), and the first 
Faraday cell (the modulator cell). An alternating current through the coil of 
this cell provides the required oscillation of the direction of polarization 
34 OPTICAL INSTRUMENTS 
about the direction given by the polarizer. A modulation frequency of 380 Hz 
is chosen because it is not harmonic with either 50 Hz or 60 Hz. 
Below this Faraday cell is the compartment for the sample cell. This is 
much shorter than those used with visual polarimeters and saccharimeters. 
The Faraday cell type of automatic polarimeter is much more precise than 
the visual type instrument for the measurement of angle; it can therefore use 
a shorter sample and still achieve the same precision in terms of the sugar 
scale. The shorter cell is really forced on the instrument; a large range of 
rotations cannot be covered because of the limitation in rotation imposed 
by the Faraday compensator cell. 
Below the sample chamber is the compensator which is followed in turn 
by the fixed analyser and photomultiplier. The polariser and analyser are 
normally in the crossed position, and when modulation is applied the intensity 
of light reaching the photomultiplier varies sinusoidally. In one period of 
oscillation the plane of polarisation passes twice through the null position, 
and the light intensity at the photomultiplier therefore has a frequency of 
760 Hz. The output signal from the photomultiplier includes a 760 Hz in-
balance component, and a 380 Hz out-of-balance component when a sample 
is introduced. 
The signal is fed to the input of a selective amplifier in the electronic 
unit. The amplifier only accepts a narrow band of frequencies centred on 
380 Hz. After passing through a phase sensitive detector, followed by recti-
fication and amplification, the out-of-balance signal is fed back to the 
Faraday compensator cell until null balance is restored. The current in the 
compensator is then a measure of the rotation, which can be read from a 
meter on the electronic unit, recorded on a separate chart recorder, or fed to 
and displayed on a digital voltmeter from which a print-out or punch-out can 
be obtained. 
The small Bendix Model 143 C polarimeter covers a range of rotations 
of ±.5° and has a sensitivity of 0.0001°. Thus, if the sample cell were 2 mm 
thick only, it would allow measurements on solutions up to about 120 °S 
(with the mercury e line) to an accuracy of about 0.025 °S; such a thin cell 
is very difficult to make accurately. The angular range has been increased 
in the large Model 700 A polarimeter by providing water cooling on the 
compensator cell so that larger currents can be used without generating too 
much heat, and ±.5° of rotation is covered. 
In use, the amplifier must be switched on at least 30 minutes before use, 
so that it can stabilize. When used frequently, it should be left on continu-
ously, that is 24 hours a day seven days a week. With each set of readings, 
it is advisable to check the zero of the instrument with the sample cell 
containing distilled water. The coarse adjustment to the zero is done by 
rotating the polarizer. An additional Faraday cell between the compensator 
and the analyser allows fine control of the zero to be made electrically (see 
Fig. 24). 
Effects of Birefringence 
As stated earlier, materials such as glass become doubly refracting if 
they are strained. If linearly polarized light passes through such strained 
glass, it may come out elliptically polarized. If it is now followed by an 
analyser, the intensity seen varies as the analyser is rotated, but it no longer 
drops to zero at any position; the extinction is only partial, not complete. 
At the position of minimum intensity, the analyser is crossed with the direc-
tion of the longer axis of the ellipse of polarization. This may not be in the 
same direction as the original linear polarization, so that the strained glass 
OPTICAL INSTRUMENTS 35 
h a s i n t r o d u c e d a n e r ror i n t o t h e m e a s u r e m e n t . I t i s n o t possible t o e l imina te 
th i s er ror by r e -ad jus t ing t h e zero of t h e po l a r ime te r since t h e d i rec t ion of 
t h e ellipse a n d hence t h e er ror can c h a n g e w h e n t h e s ample i s i n t r o d u c e d 
a n d r o t a t e s t h e po la r iza t ion . 
These er rors d u e to birefr ingence can be caused by s t r a ined glass i n t h e 
e n d p l a t e s of t h e s ample cells or in o t h e r p ro t e c t i ve p la te s b e t w e e n t h e 
polar izer a n d t h e ana lyser . I n v i sua l po l a r ime te r s a n d saccha r ime te r s t h e y 
are n o t usua l ly large enough to be serious, b u t i n a u t o m a t i c po la r imete r s , 
where t h e a c c u r a c y of angle m e a s u r e m e n t m u s t be g r e a t e r to al low for t h e 
shor t e r s ample , t h e y can be significant. T h e e r rors i n t e r a c t so t h a t s t r a in in 
glass p la tes before a n d after t h e c o m p e n s a t i o n cell can give rise to t w o sets 
of er rors , one fixed, t h e o t h e r d e p e n d i n g on t h e sample . To avo id birefr ingence 
errors in a u t o m a t i c po la r ime te r s , n o t on ly m u s t all glass used be v e r y well 
annea led , b u t i t m u s t also be m o u n t e d w i t h o u t s t r a in a n d c leaned co r rec t ly ; 
wip ing w i t h a c i rcular m o t i o n i n t roduces less bi refr ingence t h a n wip ing 
a lways in t h e one di rec t ion. 
S t a n d a r d i z a t i o n o f P o l a r i m e t e r s 
J u s t as t h e r ead ing of a r e f rac tomete r i s checked per iodica l ly by m a k i n g 
a m e a s u r e m e n t on a t e s t piece, a po l a r ime te r shou ld be checked regu la r ly 
wi th a s t a n d a r d of k n o w n r o t a t i o n . F o r v isua l po la r ime te r s , th i s is a q u a r t z 
con t ro l p la te , a p l a t e of q u a r t z of k n o w n r o t a t i o n m o u n t e d in a t u b e t h a t 
f i t s i n t o t h e po l a r ime te r in p lace of t h e s a m p l e cell. These con t ro l p l a t e s a r e 
no rma l ly m a d e close to 25 °S, 50 °S, 75 °S a n d 100 °S a n d t h e las t t w o a t 
least should be ava i lab le for use. T h e q u a r t z con t ro l p la t e s a re themse lves 
checked by a s t a n d a r d i z i n g l a b o r a t o r y . In Aus t r a l i a , t h e recognized 
s t a n d a r d i z i n g l abora to r i es a re t h e N a t i o n a l S t a n d a r d s L a b o r a t o r y a n d those 
regis tered by t h e N a t i o n a l Associa t ion of Tes t i ng Au tho r i t i e s . 
Q u a r t z p l a t e s a re n o r m a l l y used t o s t a n d a r d i z e t h e Hi lger a n d Zeiss 
a u t o m a t i c po la r ime te r s . T h e a c c u r a c y r e q u i r e d for B e n d i x po l a r ime te r s i s so 
high t h a t q u a r t z could no t , i n t h e p a s t , be g r o u n d a n d pol ished sufficiently 
flat a n d para l le l for v a r i a t i o n s of r o t a t i o n to be negligible. T h e N a t i o n a l 
Phys ica l L a b o r a t o r y (London) h a s recently- ove rcome these p rob l e ms , a n d 
h a v e a su i t ab l e p l a t e ava i l ab le . 
T h e I n t e r n a t i o n a l S u g a r S c a l e 
At t h e 1932 m e e t i n g of t h e I n t e r n a t i o n a l Commiss ion for Un i fo rm 
Methods of Sugar Analys is , t h e following resolu t ions were agreed t o : — 
(1) T h a t t h e Commiss ion a d o p t a s t a n d a r d scale for t h e s accha r ime te r 
a n d t h a t t h e scale b e k n o w n a s t h e " I n t e r n a t i o n a l Suga r Sca le" . 
R o t a t i o n s expressed in th i s scale shal l be des igna ted as degrees 
sugar (°S). 
(2) T h a t t h e po la r i za t ion of t h e n o r m a l so lu t ion (26.000 g of p u r e 
sucrose dissolved in 100 ml . , a n d polar ized at 20 °C in a 200 mm t u b e , 
us ing w h i t e l ight a n d t h e d i c h r o m a t e filter a s defined by t h e Commis -
sion) be accep t ed as t h e bas is of ca l ib ra t ion of t h e 100° po in t on t h e 
I n t e r n a t i o n a l Suga r Scale. 
(3) T h a t t h e following r o t a t i o n s shal l ho ld for t h e n o r m a l q u a r t z p l a t e 
of t h e I n t e r n a t i o n a l Suga r S c a l e : — 
N o r m a l Q u a r t z P l a t e = 100 °S = 4 0 . 6 9 0 ° ± 0 . 0 0 2 ° (A = 5461 A) at 20°C 
N o r m a l Q u a r t z P l a t e = 100 °S = 3 4 . 6 2 0 ° ± 0 . 0 0 2 ° (A = 5892.5A) at 20°C 
Th i s definit ion o f t h e " I n t e r n a t i o n a l S u g a r S c a l e " does n o t howeve r 
m a k e m e n t i o n o f t h e r o t a t i o n s o f t h e n o r m a l s u g a r so lu t ion , a t t h e n o r m a l 
OPTICAL INSTRUMENTS 
Fig. 25—Polarimeter tubes, a 
Fig. 25 c 
Fig. 25 lid 
Temperature Effects. 
When a sugar solution is made up and polarized at temperatures other 
than 20 °C, the reading obtained will be influenced by the temperature 
difference on the instrument, the apparatus used and the substance in solu-
tion. Therefore the reading obtained must be corrected to 20 °C to give the 
true polarization in °S of the solution under consideration and in addition 
this corrected polarization reading must be corrected further if the solution 
was not made up at 20 °C. 
R. A. M. Wilson (1965) of the Colonial Sugar Refining Coy. Ltd. has 
classified the corrections for temperature effects into the "polarization reading 
38 
Fig. 25 b 
Fig. 25 Id 
40 OPTICAL INSTRUMENTS 
T r = T e m p e r a t u r e of so lu t ion or q u a r t z p l a t e w h e n r e a d i n g t h e po la r iza -
t ion (°C) 
N = N o r m a l i t y of so lu t ion . A n o r m a l so lu t ion c o n t a i n s 26g of s a m p l e 
in 100 m l 
5 = W e i g h t p e r c e n t sucrose in t h e s a m p l e 
R = W e i g h t p e r cen t r educ ing s u g a r in t h e s a m p l e 
Tp = T e m p e r a t u r e of p o l a r i m e t e r (°C) 
Tm = T e m p e r a t u r e of so lu t ion w h e n m a k i n g to t h e m a r k (°C) 
T] = C o n s t a n t e q u a l to 1 for q u a r t z wedge s a c c h a r i m e t e r s a n d e q u a l to 
0 for o t h e r t y p e s of p o l a r i m e t e r s a n d s a c c h a r i m e t e r s 
Fol lowing on t h e w o r k of Wi lson a n d a submiss ion to I C U M S A in 1966 
by t h e A u s t r a l i a n N a t i o n a l C o m m i t t e e o f I C U M S A , t h e following simplified 
fo rmulae were a d o p t e d a s u s u a l l y sufficient for t e m p e r a t u r e co r rec t ions to 
t h e po la r i za t ion o f r a w sugar . F o r o t h e r p r o d u c t s , for q u a r t z con t ro l p l a t e s 
a n d for h igh precis ion work , a p p r o p r i a t e fo rmulae m a y b e o b t a i n e d b y 
su i t ab l e c o m b i n a t i o n o f t h e e q u a t i o n s a b o v e . 
F o r q u a r t z wedge s a c c h a r i m e t e r s t h e t e m p e r a t u r e co r rec t ion t o b e m a d e 
t o t h e obse rved po la r i za t ion shal l b e : — 
(tr — 20) (0.00033 S — 0.004 R) 
where 
t r (°C) is t h e t e m p e r a t u r e of t h e so lu t ion as r e a d in t h e s a c c h a r i m e t e r 
S is t h e a p p r o x i m a t e per cen t sucrose in t h e s a m p l e 
R i s t h e a p p r o x i m a t e p e r cen t r e d u c i n g s u g a r s (as i n v e r t sugar ) in 
t h e s a m p l e . 
F o r s u g a r po l a r ime te r s (wi thou t q u a r t z wedge c o m p e n s a t i o n ) t h e cor rec-
t i o n t o b e m a d e t o t h e o b s e r v e d po la r i za t ion shal l be:-— 
(tr — 20) (0.00019 5 — 0.004 R) 
w h e r e t h e s y m b o l s a re a s defined a b o v e . 
F o r a c c u r a t e w o r k i t i s des i rab le t h a t con t ro l o f t e m p e r a t u r e to 2 0 . 0 - ^ 
0.5 °C be o b t a i n e d for all po l a r ime t r i c ana lyses of n o r m a l s u g a r so lu t ions t h u s 
e l im ina t i ng a n y m a j o r t e m p e r a t u r e cor rec t ions . 
I C U M S A h a s r e c o m m e n d e d t h a t for t h e po la r i za t ion o f r a w suga r t h e 
t e m p e r a t u r e of po la r i za t ion shal l be as close to 20.0 °C as possible a n d in 
a n y case i t shal l n o t be ou t s ide t h e r a n g e 15 to 25 °C. 
T h e S p e c t r o p h o t o m e t e r 
Q u a n t i t a t i v e m e a s u r e m e n t s ba sed on t h e colour o f so lu t ions h a v e been 
e m p l o y e d b y chemis t s for m a n y yea r s . These m e a s u r e m e n t s , wh ich a re 
covered by t h e genera l t e r m color imetr ic ana lys i s , m a y be ca r r i ed o u t in a 
n u m b e r of different ways . 
T h e s imples t m e t h o d s o f co lor imet r ic ana lys i s a r e v i sua l m e t h o d s , w h i c h 
m a y involve m a t c h i n g of an u n k n o w n colour w i t h a series of s t a n d a r d colours , 
d i lu t ion of an u n k n o w n colour in a para l le l - s ided t u b e un t i l i t m a t c h e s a t u b e 
filled w i t h a s t a n d a r d colour a n d t h e n ca l cu la t ing t h e s t r e n g t h of t h e u n -
k n o w n solut ion from t h e he igh t s of t h e l iquids in t h e t u b e s , or by t h e use of a 
colour c o m p a r a t o r such as t h e D u b o s c q . A m o r e a d v a n c e d form of co lour 
m e a s u r e m e n t i s one where t h e h u m a n eye i s r ep l aced by a pho toe lec t r i c cell, 
t h u s largely e l imina t ing t h e e r rors d u e to t h e pe r sona l cha rac te r i s t i c s o f e a c h 
observer . I n s t r u m e n t s ba sed on th i s pr inc ip le a re k n o w n as pho toe lec t r i c 
OPTICAL INSTRUMENTS 41 
colorimeters, or, more correctly, photoelectric absorptiometers. These instru-
ments usually employ light consisting of a comparatively narrow range of 
wavelengths, and this is achieved by passing white light through filters. 
The most modern instruments employed for colorimetric analysis operate 
with light of a definite wavelength, with a very narrow band-width, and these 
instruments are called spectrophotometers. A spectrophotometer, as its name 
implies, is a combination of a spectrometer and a photometer. The spectro-
meter portion of the instrument provides light of any selected colour, by 
employing a prism or a diffraction grating, and is usually termed a mono-
chromator, while the photometer portion of the instrument measures the 
intensity of the monochromatic light produced. 
The spectrophotometer most commonly in use in Queensland mills is 
the Bausch and Lomb Spectronic 20, which is shown in Fig. 26. A schematic 
diagram of the optical system of this instrument is shown in Fig. 27. The 
Fig. 26—The Spectronic 20, Bausch and Lomb 
operation of the instrument is as follows:—White light emanating from the 
tungsten lamp passes through the entrance slit, being focused by the field 
lens onto the objective lens. The objective lens is of such a focal length as to 
focus an image of the entrance slit at the exit slit, the reflection-type diffrac-
tion grating being interposed before the exit slit in order to reflect and 
Fig. 27—Schematic optical diagram of Spectronic 20. 
42 OPTICAL INSTRUMENTS 
disperse t h e l ight . T o o b t a i n t h e va r ious w a v e l e n g t h s a t t h e ex i t sli t , t h e 
g r a t i n g i s r o t a t e d , by m e a n s o f an a r m wh ich r ides on t h e w a v e l e n g t h c a m . 
In se t t ing t h e wave leng th , t h e c a m r o t a t e s t h e g r a t i n g so t h a t l igh t o f t h e 
des i red w a v e l e n g t h passes o u t t h r o u g h t h e ex i t slit . Th i s m o n o c h r o m a t i c 
l ight which passes t h r o u g h t h e ex i t slit con t inues on t h r o u g h w h a t e v e r 
s a m p l e m a y be c o n t a i n e d i n a t e s t t u b e o r c u v e t t e p l aced i n t h e l ight p a t h , a n d 
finally t e r m i n a t e s a t t h e m e a s u r i n g p h o t o t u b e , w h e r e t h e l ight e n e r g y i s 
conve r t ed i n t o an electr ic s ignal . W h e n e v e r t h e s a m p l e i s r e m o v e d from t h e 
i n s t r u m e n t , a n occluder a u t o m a t i c a l l y falls i n t o t h e l igh t b e a m s o t h a t t h e 
zero m a y be set w i t h o u t fu r the r m a n i p u l a t i o n . A l ight con t ro l i s also p r o v i d e d 
in order t h a t t h e i n s t r u m e n t m a y be set a t zero a b s o r b a n c e w i t h a b l a n k o r 
reference so lu t ion in t h e s a m p l e c o m p a r t m e n t . Var ious o t h e r s p e c t r o p h o t o -
m e t e r s a re ava i lab le , some w i t h a wider r a n g e of l ight w a v e l e n g t h s t h a n is 
o b t a i n a b l e w i t h t h e Spec t ron ic 20, b u t all w o r k on t h e s a m e pr inc ip le of a 
p r i sm or diffraction g r a t i n g m o n o c h r o m a t o r p r o v i d i n g a source of m o n o -
c h r o m a t i c l ight for a l ight sens i t ive p h o t o t u b e . Ac tua l ly , to refer to these 
i n s t r u m e n t s in t e r m s of " l i g h t " i s r a t h e r mis leading , because even t h e s imple 
Spec t ron ic 20 i n s t r u m e n t h a s a scale r a n g e f rom 325 nm ( the u l t r a v i o l e t 
region) up to 975 n m , wh ich i s well i n t o t h e inf ra- red reg ion . 
Colorimetry 
The operation of such instruments for colour determination is relatively 
simple, but several points must be borne in mind, in the interests of accuracy. 
Firstly, for the instrument to be stable, the light output from the lamp must 
be constant. This requires a stable power supply, and voltage stabilizers may 
have to be installed to ensure this, or in some instances battery operation of 
the lamp must be reverted to in order to overcome line voltage variations. 
Secondly, for accurate results, scrupulous cleanliness must be practised with 
the handling of the delicate and expensive glass cuvettes used as sample 
containers, and, whenever possible, these cuvettes should be kept in their 
matched sets. This last factor will avoid errors caused by standardization of 
the instrument with a blank in one cuvette and reading the unknown in 
another cuvette which does not have a precisely equal cell width. When using 
spectrophotometers for colour measurement the manufacturer's instructions 
should, of course, be adhered to, but the procedure basically consists of 
setting the wavelength to that specified for the determination, setting the 
zero of the instrument, setting the optical density to zero with a blank solu-
tion as sample, and then reading the optical density of the unknown sample. 
The concentration of the unknown solution is then read off a standard graph 
prepared from solutions of known concentration. 
Turbidity Measurement 
Spectrophotometers are also used to measure the turbidity of such mill 
products as clarified juice. For this determination the wavelength is set to 
975 nm, well into the infra-red region, to avoid the effect of juice colour, and 
the amount of "light" absorbed, read as an optical density, gives a measure 
of turbidity. For convenience, turbidity is usually recorded as one hundred 
times the optical density. 
The Microscope 
In sugar factory operations the most important use of the microscope 
is for the examination of proof samples withdrawn from vacuum pans and 
for the determination of the sizes of crystals in sugar, massecuite, magma, 
seed, etc. For these purposes a comparatively low order of magnification is 
required. The microscope also enters essentially into the determination of 
saturation temperature by the optical method and has numerous other casual 
OPTICAL INSTRUMENTS 
ACTUAL PATH OF LIGHT. 
RAY PATH OF VIRTUAL IMAGE. 
i 
Fig. 28—The essential parts of a microscope. 
43 
44 OPTICAL INSTRUMENTS 
uses for wh ich a fairly h igh degree of magnif ica t ion is requ i red . Hence , whi l s t 
t h e provis ion of a s imple low powered microscope for use on t h e p a n s t age 
is un iversa l ly accep ted , t h e r e is also need for a m o r e versa t i l e i n s t r u m e n t of 
b e t t e r q u a l i t y for l a b o r a t o r y use. 
T h e S t r u c t u r e a n d O p e r a t i o n o f t h e M i c r o s c o p e 
T h e essent ia l p a r t s of t h e t y p e of microscope in genera l use in t h e 
l a b o r a t o r y a re i l l u s t r a t ed in Fig . 28. T h e h e a v y b o x of cas t m e t a l A s u p p o r t s 
a sho r t r igid u p r i g h t pi l lar B to which t h e a r m or l i m b D is h inged at C. 
T h e a r m which i s conven ien t ly c u r v e d for easy g rasp ing by t h e h a n d when 
t h e microscope h a s to be m o v e d f rom p lace to place, i s also o f h e a v y m e t a l 
a n d t h e h inge C shou ld allow only a stiff m o v e m e n t in a ve r t i ca l p l ane a n d 
n o m o v e m e n t w h a t s o e v e r s ideways . A t t h e u p p e r e n d t h e a r m be a r s t h e 
t u b u l a r b o d y E , which carr ies t h e magni fy ing lenses, a n d jus t nea r t h e h inge 
t h e s t age F i s r ig idly a t t a c h e d to it . B e n e a t h t h e s t age a n d f i t ted to i t i s t h e 
condenser G , c o m m o n l y k n o w n as t h e subs t age condenser , a n d below t h a t 
t h e doub le mi r ro r H, wh ich is flat on one side a n d concave on t h e o the r . 
M o v e m e n t of t h e b o d y d o w n to, a n d up from, t h e s t age i s p r o v i d e d by a 
coarse a d j u s t m e n t o p e r a t e d by t u r n i n g t h e mil led h e a d I a n d a fine ad ju s t -
m e n t work ing t h r o u g h a smal ler h e a d J . At t h e t o p t h e t u b e s of m o s t m ic ro -
scopes are fi t ted w i t h a g r a d u a t e d d r a w t u b e so t h a t t h e d i s t ance b e t w e e n t h e 
eye-piece K a n d t h e nose-piece M in which t h e objec t ives N are m o u n t e d , 
can be va r i ed to sui t t h e r e c o m m e n d a t i o n s of t h e m a n u f a c t u r e r of t h e lenses. 
T h e eye-piece fits easi ly i n to t h e t o p of t h e t u b e . T h e objec t ives do n o t lit 
d i rec t ly i n t o t h e t u b e , b u t are screwed in to a r evo lv ing p l a t e called t h e nose-
piece. Th i s m a y ho ld from one to four object ives . Fo r pu re ly r o u t i n e use a t 
t h e one magnif ica t ion a s ingle-object ive nose-piece is qu i t e su i t ab le , b u t 
when a r ange of magnif ica t ion is r equ i r ed t h e mul t i -ob jec t ive nose-piece is 
essent ia l in t h a t i t al lows t h e r e a d y chang ing of objec t ives w i t h o u t r isk of 
d a m a g e to t h e objec t a n d w i t h a m i n i m u m of de lay . T h e subs t age condenser 
is not necessary w i t h low-power objec t ives (when t h e concave side of t h e 
mi r ro r per forms t h e s ame funct ion) , b u t i t i s essent ia l for h igh -power 
objec t ives which m u s t h a v e a c o n c e n t r a t e d b e a m of in tense l ight . T h e 
condenser m u s t be used on ly w i t h t h e p l ane mir ror , o the rwise i t loses m u c h 
of i ts efficiency. T h e r ack a n d p in ion gear O is used for m o v i n g t h e condenser 
up a n d d o w n a n d t h e r e i s u s u a l l y some provis ion for swinging t h e condense r 
o u t of t h e opt ica l axis when n o t r equ i red . T h e ve r t i ca l m o v e m e n t of t h e 
condenser i s v e r y i m p o r t a n t because t h e s y s t e m of lenses fo rming t h e 
condenser has to be focused jus t as carefully as t h e objec t ives if a h igh-
q u a l i t y image of t h e object i s to be o b t a i n e d . T h e iris d i a p h r a g m P u s e d to 
regu la te t h e a m o u n t of l ight coming i n t o t h e condenser , i s an in t eg ra l p a r t 
of i t a n d is o p e r a t e d by a smal l lever facing t o w a r d s t h e front of t h e i n s t r u m e n t . 
General Principle of Operation: By su i t ab le pos i t ion ing of t h e m i r r o r in 
re la t ion to t h e condenser a n d t h e source of l ight , r a y s of l ight a re reflected 
from i t a n d i n to t h e condenser where t h e y a re c o n c e n t r a t e d i n to a m o r e 
in tense b e a m a n d so pass t h r o u g h t h e ob jec t u n d e r e x a m i n a t i o n . Th i s i s 
m o u n t e d on a glass slide, usua l ly m e a s u r i n g 3 x 1 in he ld firmly by spr ing 
clips to t h e s tage , a n d for sa t i s fac to ry e x a m i n a t i o n shou ld be e i the r com-
p a r a t i v e l y t r a n s p a r e n t , or consist of smal l par t ic les s e p a r a t e d by clear l iquid. 
T h e l ight pass ing t h r o u g h t h e m o u n t e d object en t e r s t h e ob jec t ive , t h e 
funct ion of which is to form an en l a rged image of t h e objec t for fu r the r 
magnif ica t ion by t h e eye-piece. T h e front lens of t h e eye collects t h e l ight 
r ays coming t h r o u g h t h e eye-piece a n d pro jec t s an image on t h e r e t i n a which 
t h e b ra in r eco rds as an object s i t u a t e d a b o u t 10 in a w a y from t h e eye . T h e 
a c t u a l p i c tu re seen by looking down a microscope is in reverse a n d if one 
OPTICAL INSTRUMENTS 45 
wishes to move an object from, say, the left edge of the field of view to the 
centre, one must move the stage (and slide) from right to left and not left to 
right. The same reversal, of course, occurs for other movements also. 
Lenses and Magnification: The objectives are the most important com-
ponents of the microscope since on their perfection depends the efficiency of 
the instrument. They each consist of a series of lenses in a brass cylinder 
and are made to give various degrees of magnification: the higher the magni-
fication the more lenses have to be incorporated, and so the more expensive 
the objectives become. The lower powered objectives are known as "dry" 
lenses, but objectives giving a magnification of 80 of more are always "oil 
immersion", i.e., they can only operate when a film of special oil, having a 
refractive index the same as glass, makes contact with both the front of the 
lens and the top of the glass slip covering the object. Oil immersion lenses 
represent the peak of the lens maker's skill and are essential for critical work 
at high magnifications, but they are quite unnecessary for practical sugar-
house control, and the special conditions for their satisfactory use will not be 
considered here. Two types of dry lens are obtainable, viz., achromatic and 
apochromatic. The aprochromats are more corrected for colour errors in-
herent in any glass magnification system, but their advantage is only appa-
rent in critical work at the higher magnifications and for the practical 
requirements of a sugar mill the much cheaper achromats are quite suitable. 
Objectives are designated by a number—expressed in inches or milli-
metres, and engraved on the objective—which represents the "focal length" 
of the particular lens and indicates its magnifying power. The common 
objectives are the 2/3 in (16 mm) or lower power, the 1/6 in (4 mm) or high 
power and the 1/12 in (2 mm) which is an oil immersion. The focal length is 
measured from a point within the objective so that when the object is in 
focus the distance between it and the front lens of the objective is always 
less than the focal length. This reduced distance is called the working distance 
of the lens and becomes quite an important factor in the use of super-
saturation apparatus. 
The table below shows the approximate magnification obtained with 
various objectives and eye-pieces: 
Objective focal Objective or initial | 
length magnification Final magnification 
in 
2/3 
1/3 
1/6 
1/12 
! 
mm ! 
16 
8 
4 
2 
10 
2 0 
40 
8 0 
x 6 eye-
! 60 
120 
240 
4 8 0 
piece | X 10 eye-piece 
100 
200 
4 0 0 
8 0 0 
An objective is always designed to be used with a certain tube length, 
usually 160 mm, but objectives for a 200 mm length are also obtainable. 
Increasing the tube length by withdrawing the sliding drawtube L increases 
the magnification of the object, but it does not increase the amount of detail 
that can be seen; in other words, the resolution, which is a function of the 
objective alone, is not altered. Like the objectives the eye-pieces are also 
compound lenses. Their function is to pick up the enlarged image of the 
object formed by the objective and magnify it still further. The total magnifi-
cation thus obtained is the product of the objective magnification multiplied 
by the eye-piece magnification. Eye-pieces are made with various powers of 
46 OPTICAL INSTRUMENTS 
magni f i ca t ion ; x 6 a n d X 10 a re t h e m o s t c o m m o n , b u t for c e r t a in w o r k 
in t h e mill i t m a y be des i rable to o b t a i n one w i t h a h igher magni f ica t ion . 
T h e a d v a n t a g e o f t h e h igh magni f ica t ion in t h e eye-piece c o m p a r e d w i t h t h a t 
o b t a i n e d w i t h a h igher powered ob jec t ive a n d a low power eye-piece is t h a t 
w i t h t h e former a r r a n g e m e n t t h e w o r k i n g d i s t ance i s m u c h t h e g rea t e r . 
Source of Light: Whi l e o r d i n a r y day l igh t , n o t d i rec t sun l igh t , is often 
used as a source of i l lumina t ion for microscopic work , artificial l ight is g r e a t l y 
t o be preferred. I t s use al lows t h e genera l l igh t ing i n t h e r o o m to be r e d u c e d 
to a comfor tab le level for microscope w o r k a n d so e x t r a n e o u s a n n o y i n g g la re 
can be e l imina ted . I t also gives t h e o p e r a t o r c o m p l e t e con t ro l over t h e 
i n t e n s i t y o f t h e i l lumina t ion a n d allows t h e microscope to be s i t ed w h e r e v e r 
conven ien t . T h e r e a re va r ious t y p e s o f microscope l a m p s on t h e m a r k e t , some 
of t h e m v e r y expens ive , b u t a c h e a p a n d q u i t e sa t i s f ac to ry l a m p can be 
easi ly m a d e by m o u n t i n g a b u l b , p re fe rab ly w i t h pea r l glass, in a smal l box 
o r t in . Some ven t i l a t i on i s necessa ry a n d t h e l ight shou ld come o u t t h r o u g h 
a piece of g r o u n d glass se t a t t h e s a m e level as , or s l igh t ly below, t h e f i l ament 
of t h e b u l b . A smal l hood a r o u n d t h e g r o u n d glass will confine t h e l ight to a 
b e a m n o t m u c h wider t h a n t h e microscope mi r ro r . 
Operation: T h e microscope m u s t be set on a firm t a b l e or b e n c h at a 
comfor tab le he igh t for t h e ope ra to r , a n d v i b r a t i o n f rom m a c h i n e r y , people 
wa lk ing on t h e floor, e tc . , e l imina ted as far as possible. An eye-piece and t h e 
objec t ives h a v i n g been p laced in posi t ion, t h e o p e r a t o r p u t s t h e mic roscope 
square ly in front o f h i m w i t h t h e mi r ro r facing d i r ec t ly t o w a r d s t h e source 
of l ight . T h e d i a p h r a g m P i s opened to i t s fullest e x t e n t a n d t h e p l ane 
mi r ro r ad jus t ed so t h a t t h e m a x i m u m a m o u n t o f l ight i s reflected t h r o u g h t h e 
condenser a n d t h e whole field of v iew is i l l u m i n a t e d as even ly as possible . 
I t i s conven ien t a t t h i s j u n c t u r e to focus an object on a slide w i t h t h e low 
power objec t ive even t h o u g h t h e l ight m a y n o t be sa t i s fac tory . When bringing 
an object into focus never rack the tube downwards with the eye looking through 
the eye-piece; always rack down carefully as close to the object as possible with 
the eye on a level with the stage and then rack upwards until the object is in focus. 
M a n y expens ive lenses a n d i r rep laceable ob jec t s h a v e b e e n r u i n e d by fai lure 
to obey th i s s imple rule . 
W i t h t h e object in focus t h e condenser i s t h e n b r o u g h t i n t o focus also. 
Th is i s done by m o v i n g t h e condenser u p w a r d s t o w a r d s t h e slide a n d con-
c u r r e n t l y m o v i n g t h e m i r r o r s l ight ly from t i m e to t i m e un t i l t h e edge o f t h e 
l a m p or t h e f i lament of t h e b u l b or, if d a y l i gh t is be ing used, a p o r t i o n of t h e 
window f rame or a m a r k on t h e w i n d o w glass, comes i n t o view. Th i s i m a g e 
i s t h e n m a d e t o d i s appea r b y m o v i n g t h e condense r d o w n w a r d s s l ight ly , 
a n d t h e i l l umina t ion res to red t o i t s p rev ious u n i f o r m i t y b y m a n i p u l a t i o n 
o f t h e mi r ro r . T h e condenser i s t h e n t r a n s m i t t i n g t h e m a x i m u m a m o u n t o f 
l ight , which in genera l will be t o o m u c h for use w i t h t h e low powers a n d 
should be r educed by use of t h e d i a p h r a g m , or a screen of g r o u n d or co loured 
glass inser ted be tween t h e source of l ight a n d t h e mi r ro r . 
T h e coarse a d j u s t m e n t i s o p e r a t e d by t h e mi l led h e a d s I a n d i s all t h a t 
i s necessary for t h e lower powers . F o r t h e h igher powers t h e fine a d j u s t m e n t 
/ i s necessary to b r i n g t h e object i n to s h a r p focus. T h e low power ob jec t ive 
shou ld a lways be engaged first a n d shou ld i t be des i red to v iew a sect ion of 
t h e field in g rea t e r deta i l , t h e sect ion is m o v e d i n t o t h e cen t r e of t h e field, 
an objec t ive of h igher power t u r n e d i n to pos i t ion , a n d t h e focus careful ly 
ad jus ted . T h e low power i s t h e reconna i s sance lens a n d t h e e x a m i n a t i o n of 
a n y object should c o m m e n c e w i t h th i s before us ing t h e h igher power . 
Objec t s m o u n t e d on t h e u s u a l 3 X 1 inch glass sl ides m a y b e s t be obse rv -
ed by submerg ing t h e m in a t h i n film of a colourless l iqu id a n d careful ly p l ac -
OPTICAL INSTRUMENTS 47 
i n g a covers l ip ove r t h e whole . F o r p a n - s t a g e obs e rva t i ons w i t h v e r y low 
powers , e.g., i n c h focal l e n g t h lens m a g n i f y i n g four t imes , a covers l ip is n o t 
necessa ry , b u t c rys t a l s a re seen m u c h m o r e c lear ly i f m o u n t e d in a couple of 
d r o p s of a s a t u r a t e d so lu t ion of ref ined suga r . Massecui tes m a y be t h i n n e d 
d o w n for e x a m i n a t i o n by m i x i n g w i t h a d r o p o f t h e s a t u r a t e d so lu t ion . B l a c k 
c i rcular a i r b u b b l e s m a y in te r fe re w i t h t h e obse rva t i on o f some p r e p a r a t i o n s , 
b u t a d r o p of a lcohol e i the r n e a t o r s u g a r - s a t u r a t e d wil l u s u a l l y cause t h e m 
t o d i sappea r . 
Direct Measurement of Objects: It is f r equen t ly des i red to m e a s u r e 
a c c u r a t e l y t h e d imens ions o f an object u n d e r t h e microscope . I t i s man i f e s t l y 
impossible to p lace a fine ru le r in t h e s a m e field a n d m a k e d i rec t r ead ings as 
one would do were t h e objec t of a size eas i ly m e a s u r a b l e by c o m p a r a t i v e l y 
gross i n s t r u m e n t s such a s cal ipers a n d rules . Recou r se h a s t h e n t o be m a d e 
to an eye-piece mic rome te r . Th i s is a glass disc on one surface of which a re 
a c c u r a t e l y e t ched lines or squa res of un i fo rm spac ing . T h e t o p of t h e eye-piece 
i s unsc rewed a n d t h e m i c r o m e t e r d r o p p e d in to c o m e to res t on a ledge w i th in 
t h e eye-piece. T h e t o p i s t h e n rep laced a n d t h e eye-p iece looked i n to while 
held ver t ica l ly over a source of l ight . T h e m i c r o m e t e r ru l ings shou ld n o w be 
in s h a r p focus: i f t h e y a r e no t , t h e m i c r o m e t e r m a y be found to h a v e l a n d e d 
ups ide down on t h e ledge o r i t m a y be necessa ry to screw t h e t o p ou t s l igh t ly 
to give a s h a r p focus. I t will be found t h a t w h e n p r o p e r l y pos i t ioned a n d in 
s h a r p focus t h e m i c r o m e t e r ru l ings will lie in t h e s a m e p l ane as t h e i m a g e 
of t h e objec t a n d t h e size of t h e object in t e r m s of divis ions can be r e a d 
di rect ly . T h e a p p a r e n t size of these divis ions in mi l l imet res or f rac t ions of an 
inch is, however , no t k n o w n a n d m u s t be a sce r t a ined by reference to a s t age 
m i c r o m e t e r . Th is cons is t s o f a s t o u t 3 x 1 inch glass sl ide w i t h a p o r t i o n in t h e 
cen t r e ru led a c c u r a t e l y w i th l ines a k n o w n d i s t ance a p a r t . A c o m m o n t y p e 
has lines several mi l l imet res long 0.1 mm a p a r t w i t h one 0.1 mm sect ion 
subd iv ided i n to 0.01 m m . By focusing on th i s m i c r o m e t e r on t h e s t age t h e 
eye-piece rul ings can be supe r imposed on t h e scale read ings a n d t h e va lue of 
t h e eye-piece m i c r o m e t e r divis ions easi ly m e a s u r e d . Th i s m e a s u r e m e n t of t h e 
a p p a r e n t ac tua l size of t h e eye-piece m i c r o m e t e r divis ion is t e r m e d "ca l ib ra -
t i o n " of t h e eye-piece m i c r o m e t e r a n d var ies w i t h t h e magnif ica t ion , so a 
s e p a r a t e d e t e r m i n a t i o n m u s t be m a d e for each c o m b i n a t i o n o f eye-piece a n d 
objec t ive a t a pa r t i cu l a r t u b e leng th . Eye-p iece m i c r o m e t e r s a re n o t expens ive 
a n d should be p a r t of t h e e q u i p m e n t of e v e r y mic roscope : as a m a t t e r of fact 
t h e y can be k e p t p e r m a n e n t l y in t h e eye-piece a n d so r u n no r isk o f be ing 
misla id . T h e s tage m i c r o m e t e r s a re m o r e expens ive b u t officers of t h e B u r e a u 
will be p leased to ca l ib ra te a n y microscopes a n d eye-piece m i c r o m e t e r s u p o n 
reques t . 
T h e ca l ib ra t ion does n o t p rov ide a m e a s u r e of t h e magnif ica t ion , i.e,. 
t h e size o f t h e object a s seen by t h e eye t h r o u g h t h e microscope c o m p a r e d 
wi th i t s a c t u a l size. Th i s c a n often be o b t a i n e d by a knowledge of t h e 
magni f ica t ion p r o v i d e d b y t h e ob jec t ive a n d t h e eye-piece, b u t some t imes 
th i s i s n o t ava i lab le . A rough a p p r o x i m a t i o n c a n t h e n be m a d e w i t h low-
powered objec t ives b y t h e following m e t h o d : — 
Place an objec t of k n o w n su i t ab l e size, e.g., a d ivis ion on an eng inee r ing 
rule, on t h e s t age a n d b r i n g i t i n t o s h a r p focus. T h e n ho ld a shee t of w h i t e 
c a r d or stiff p a p e r a t a d i s t ance of 10 in f rom t h e eye a n d close to t h e l ine of 
t h e microscope b o d y . B y looking i n t o t h e mic roscope w i t h one eye a n d 
focusing t h e o the r on t h e w h i t e p a p e r a t t h e s a m e t ime , an i m a g e o f t h e 
ob jec t will be seen t o be supe r - imposed on t h e p a p e r . T h e e n d s can be m a r k e d 
wi th a penci l a s one w a t c h e s a n d t h e n t h e d i s t a n c e m e a s u r e d b e t w e e n t h e 
t w o penci l l ines. T h e r a t i o of th i s d i s t ance to t h e a c t u a l size of t h e ob jec t 
48 OPTICAL INSTRUMENTS 
gives the magnification of the particular optical set-up of the microscope. 
The method sounds rather complicated but after a little practice it is found 
possible to reproduce the measurements quite readily. 
The Projection Microscope 
A projection microscope is of value when a large image is to be thrown 
on a screen for demonstration purposes or on to a table for the purpose of 
making a drawing. 
Outfits are available for converting a standard microscope into a projec-
tor, the main requirements being a stand to provide rigid mounting and an 
efficient illumination train of high intensity. Complete projection microscopes 
may also be obtained. Various models are available ranging from expensive 
high power units to much simpler ones when only low to medium magnifica-
tion is required. A projection microscope of medium cost is shown in Fig. 29. 
This microscope is of a type suitable for use in the examination of proof 
samples withdrawn from vacuum pans etc. The slide with the sample to be 
examined is placed on the stage and brought into focus on the viewing screen 
Fig. 29—A projection microscope of medium cost (Maruzen). 
OPTICAL INSTRUMENTS 49 
of nearly 7 in diameter. The standard lens supplied (x 10) is of sufficient 
power for pan stage operation, however, other objectives up to x 40 are 
also available. A squared grid may be placed over the screen and calibrated 
for size depending on the objective used. 
Photomicrography 
Photomicrography is the process of recording on film the image produced 
by the microscope. The fact that a real image of the microscopical object is 
projected, without the aid of any equipment other than a brilliant source of 
illumination, by the eye-piece onto a screen located above it, makes photo-
graphic reproduction possible. 
If a light-sensitive plate or film is substituted for the screen and all 
extraneous light excluded a negative can be secured. 
The simplest form of equipment consists of a light-tight box with a ground 
glass screen fitted into the top, which can be exchanged for a film pack or 
plate holder. The box is arranged over the microscope so that the image can 
be focused onto the screen, which is then exchanged for the film. The 
exposure can be made by turning the microscope light on for the required 
period. 
Another simple method involves a camera with the lens removed, 
connected in a light-tight manner to the microscope tube. A single-lens reflex 
camera or one with a ground glass focusing screen is required so that accurate 
focusing on the focal plane of the camera can be done, for the point of best 
focus for the camera will not be identical with the best visual focus through 
the microscope. If a camera with a focal plane shutter is used this can be used 
for making the exposure, otherwise the microscope light can be used. 
Complete photomicrographic equipment, ranging from extremely simple 
to very elaborate, is available from microscope manufacturers. If serious 
work is contemplated these commercial products are to be preferred, however 
very good results can be obtained with improvised outfits. 
The Care of Optical Instruments 
All too frequently optical instruments are treated as though they were 
a piece of laboratory furniture and not as delicate instruments built by 
the manufacturers to a degree of high precision. If treated and used carefully 
the life of a good instrument is practically unlimited. 
Optical instruments should be set up in situations which are not exposed 
to dampness or corrosive fumes, or subjected to jarring or vibration. In 
tropical conditions dampness favours mould growth which etches the polished 
surfaces of prisms. It has been found in practice that mould growths on calcite 
prisms will render a saccharimeter useless within a short period of time from 
when they first become visible. The instrument should be forwarded for 
attention to an instrument maker who is thoroughly conversant with it. 
If the instrument is subjected to vibration or jarring the optical system 
may be thrown out of adjustment. Where it is not practicable to build the 
laboratory sufficiently far from the mill to avoid all vibration, the instrument 
should be mounted on a suitable anti-vibration table. 
The instrument should be examined regularly and kept scrupulously 
clean. This applies, in the case of saccharimeters, to splash glasses and the 
trough. If juice is allowed to accumulate in the trough thus penetrating to 
the threads of the screw caps holding the splash glasses, great difficulty will 
50 OPTICAL INSTRUMENTS 
be experienced when an attempt is made to remove them. In some sacchari-
meters the splash glass holder is held in position by means of a tension spring 
and is constructed for ready removal by the fingers. It should be maintained 
in such a condition. 
The prisms of a refractometer should always be thoroughly cleaned and 
dried after use and a piece of lens tissue placed between the prisms before 
closing them. This assists in keeping the polished face of the measuring prism 
in good condition. 
A microscope, even one in the cheaper range, is an instrument of precision 
and as such should be treated with every care, if it is to give satisfactory 
results over a long period. The operation and manipulation should be 
entrusted only to people who have shown themselves capable of handling it 
with the respect it deserves. Special precautions should be taken to ensure 
that dust is kept out of the lenses at all times and they should never be 
exposed to direct sunlight, for this will quickly result in permanent fogging. 
When not in use, objectives should be placed carefully in the small plastic or 
metal cans provided by the manufacturers. There should always be an eye-
piece in position otherwise damaging grit is likely to enter the draw tube, 
body, nose-piece and objectives. Eye-pieces should never be left dismantled, 
for dust inside the eye-piece will spoil the image. The condenser remains 
attached to the microscope permanently and should be wiped over from time 
to time with a dust-free silk or cotton cloth or cigarette paper, care being 
taken that the top lens surface is not scratched. The diaphragm and mirrors 
should be quite dry and dust-free. While a very small amount of lubrication 
is required for the adjustment threads and racks, oil or grease elsewhere is 
to be avoided at all costs. Not only is it unnecessary, but it damages lenses 
and specimens and in removing it permanent harm can easily occur to the 
instrument. 
Care in the actual use of the microscope is also of importance in main-
taining the instrument in a good working condition. It should never be 
subjected to sudden jolts or bumps and never allowed to get sticky or dirty. 
The under side of the slides should always be dry and clean before being 
placed on the stage and no liquid should be allowed to run off the. mounted 
slide. The technique for avoiding the fouling of the front lens of the objective 
when bringing the object into focus has been explained and it should be 
followed at all times. 
When not in continuous use, all optical instruments should be kept under 
a cover. At the end of the season they should be cleaned and stored away in 
a dry atmosphere. 
REFERENCE 
Wilson, Robert A. M. (1965), Polarization Temperature Corrections. Int. Sug. J. 67, 
234-6, 265-8. 
CHAPTER III 
THE BALANCE 
A sugar laboratory should be provided with three balances of the follow-
ing general types— 
(1) An analytical balance for accurate work; 
(2) A sampling balance for work of moderate accuracy; 
(3) A balance of higher capacity for coarse weighing of large masses. 
The Analytical Balance 
This balance is required for all analytical purposes, for determination 
of specific rotations, for calibration of small items of volumetric glassware, 
Fig. 30—-A modern single pan constant load balance (Sartorius). 
52 T H E BALANCE 
for the weighing of pycnometers and all other operations where precision 
weighing is required. It should have a capacity of at least 160 grammes and 
a sensitivity reciprocal of 0.1 rnilligramme per scale division or less. The great 
majority of balances of this class utilise the two knife edge, constant load 
principle, employing built in weights, critical damping of the swing of the 
beam and an optical projection system for reading the beam deflection. A 
modern balance of this type is shown in Fig. 30 while the diagrammatic 
representation in Fig. 31 shows the components. 
Fig. 31—Diagrammatic representation of a single pan constant load balance (Sartorius). 
The sensitivity of a balance is defined as the deflection produced by the 
addition of unit mass to the pan and is usually expressed in divisions per 
milligramme. The more useful term sensitivity reciprocal, S.R., is the mass 
which must be added to the pan to change the reading by one scale division. 
The value of the sensitivity depends on the position of the centre of gravity 
of the moving system in relation to the axis of rotation of the beam. For 
stability, the centre of gravity of the beam must lie below the axis but the 
smaller the separation the more sensitive the balance becomes. In a three 
knife edge equal arm balance the sensitivity varies with the load being 
weighed unless the three knife edges are accurately co-planar. The two knife 
edge balances, in which weighing is made by substitution, operate at constant 
load and the sensitivity remains constant irrespective of the value of the 
load being weighed. 
A small weight moving on a vertical screw fixed to the beam is provided 
to vary the vertical distance of the centre of gravity from the main knife and 
hence the sensitivity of the balance. A constant load balance having a 
sensitivity reciprocal of 0.1 mg per division should be adjusted so that the 
error in reading at the full deflection of the beam is less than 0.2 mg. A three 
knife edge balance should be adjusted, with half full load in each pan, to the 
same order of accuracy. 
1 Compensating stirrup 
2 Front knife edge 
3 Pan brake 
4 Weight carriage 
5 Built-in weights 
6 Pan 
7 Weight control mechanism 
8 Recording disc 
9 Projecting scale 
10 Micrometer mirror 
11 Weight shaft 
12 Arrestment shaft 
14 Bulb 
15 Arrestment 
16 Objective regulator 
17 Scale and objective 
19 Damping 
19 Sensitivity adjustment 
20 Zero adjustment 
21 Beam 
22 Center bearing plate 
23 Center knife edge 
THE BALANCE 53 
In all balances provision is made for poising the beam and adjusting 
the zero reading by means of poising nuts carried on horizontal screwed rods 
parallel with the beam. In all balances with optical projection reading, fine 
adjustment of the zero is made by moving the reading index of the balance. 
All precision balances are equipped with an arresting mechanism which 
supports the pans, stirrups and beam of the balance, so protecting the knife 
edges and bearings from damage when the pan or pans are loaded and un-
loaded. When loading has been completed and the case closed the balance is 
released and the pan, stirrup and beam are released, preferably in that order. 
Weights : The majority of modern balances have the weights built in to 
the balance, the weights being applied and removed by the manipulation of 
controls external to the case. Balances of the older type require to be used 
in conjunction with a set of standard weights. 
Irrespective of which type of weights is used they must conform with 
certain basic requirements. To ensure both long and short term stability the 
weight must be constructed in one piece from a hard inoxidisable material, 
the surface must be smooth and free from sharp edges and the material must 
be non-magnetic. These requirements are met by well made weights of non-
magnetic stainless steel containing approximately 25% chromium, 20% 
nickel, which has a density between 7.8 and 8.0 g cm - 3 a t 20°C. Weights of 
this material are far superior to those of brass, either plain or with a protective 
plating of gold, chromium or any other material. 
It is customary for precision weights to be adjusted to their nominal 
value on the assumption that they are all of uniform density—8.0 g cm - 3 . 
That is, the weights are adjusted to balance a standard weight of true 
nominal mass and of density 8.0 g cm - 3 when in air of density 0.0012 g cm -3 . 
This practice is followed by N.S.L. Australia, and by most national standard-
izing laboratories. 
It follows from this that in weighing of the highest precision, where air 
buoyancy corrections must be applied, they should be calculated on the 
basis that the density of the weights is 8.0g cm~3 and using the actual value 
of the density of the air in the balance case. 
Weights must never under any circumstances be touched with the 
fingers. They should be manipulated only with plastic-tipped or chamois 
covered forceps. 
Setting up the Balance: In the case of a new balance it is most desirable 
if possible to have the balance set up and adjusted by the maker's re-
presentative. 
The balance must be set up on a firm bench, free from vibration and in 
a room in which the temperature is reasonably constant or varies only slowly 
during the day. A good criterion for an acceptable level of vibration is the 
appearance of the image of the optical scale. This should, of course, be focus-
sed until the lines appear quite sharp, and the balance then released. The 
appearance of the lines is closely observed and any slight blurring is a good 
indication of the presence of excessive vibration. If this occurs, steps should 
be taken to isolate the balance from the bench by means of anti-vibration 
mountings. 
The balance should be placed on the bench and the inside of the case 
thoroughly cleaned. The case should be levelled using the circular level bubble 
or plumb bob provided and the rest point adjusted to zero. The sensitivity 
should be adjusted to its nominal value by placing on the pans a weight 
which should give full scale deflection of the reading index. 
54 THE BALANCE 
After these adjustments have been made the balance case should be 
closed and (he balance left to stand for at least one hour to settle down. 
After this period the zero reading and sensitivity should be re-checked and 
any further minor adjustments made if required. 
General Precautions in Weighing 
Objects should never be weighed until they have attained the temper-
ature of the balance case. Hot bodies should never be placed on the balance 
case but should be allowed to cool, preferably in a desiccator, until they are 
approximately at ambient temperature. The time taken by a body to cool 
to room temperature depends on its initial temperature, its size, and the 
material from which it is made. 
Hygroscopic materials can only be weighed when contained in an air-
tight vessel. Under no circumstances should any chemical come into contact 
with the scale pan. All material to be weighed should be placed in a clean 
dry tared container of suitable material such as platinum, glass, aluminium 
etc. In the case of non-hygroscopic crystals a piece of clean dry paper may be 
used. 
Method of Weighing : The operator must first make sure that the pan 
and the interior of the weighing compartment are clean. 
The operation of weighing with a direct reading balance with weight 
loading facility is very simple. With the weight selector dials set to zero, 
release the balance, and when the image comes to rest adjust the balance to 
read zero. Arrest the balance. Place the object to be weighed on the balance 
pan, and close the balance case. Select a weight which is judged to be close 
in value to the mass of the object being weighed. Release the balance and 
note whether the object is heavier or lighter than the weight selected. Arrest 
the balance and select the appropriate greater or smaller weight and read 
again. Repeat the process until a reading on the scale is obtained. Allow the 
beam to come completely to rest and read the weight of the body. 
Some balances of this type have a partially released position of the beam 
in which it is possible to change the dial settings and watch the change in 
scale reading without having to arrest the beam between settings. 
In making weighings with an equal arm three knife edge balance the 
following procedure is observed. The pans are wiped with a small camel-hair 
brush, the case is closed, and the beam is carefully released. The pointer will 
now swing slowiy over the scale, and when the amplitude has fallen to about 
five scale divisions, the readings of the extremities of the swing are taken for 
five successive swings. Care should be taken to avoid parallax in the readings. 
It is best to number the scale continuously from left to right rather than to 
call the centre division O and those to the right positive and to the left 
negative. Suppose the central point to be numbered 10, and that the following 
numbers represent observations: — 
THE BALANCE 
The beam is then arrested, taking care that this is done when the pointer 
is at the centre of the scale, so as to avoid damaging the knife-edges. 
The object to be weighed should be removed from a desiccator in which 
it has been placed in order that it may be free from moisture, and at the same 
temperature as the balance. The object is placed on the left-hand pan. A large 
weight should then be put on the right-hand pan, and the beam released just 
sufficiently to determine the direction in which the beam will move. The beam 
is again arrested and a larger or smaller weight applied as required. Each 
weight is tried in turn until equilibrium has been obtained as closely as 
possible. The balance case is then closed, and the further adjustments made 
by means of the rider. 
It is not necessary to adjust the weight so that the resting point is 
identical with that initially found, provided the precise sensitivity of the 
balance is known. Suppose the following turning-points were determined 
with a mass of 21.682 g on the right hand pan:— 
Right 
Mean 9.53 12.05 
The weight is, therefore, insufficient and should be increased by an amount 
which would change the resting point by 10.79-10.03 or 0.76 division. If, from 
a previous determination, it has been found that the sensitivity at 20 g load 
is 4.0 scale divisions per mg the correction to be added is:—-
It will be observed that the average of the last left-hand and the last 
right-hand swing of the balance gives a result which would be indistinguish-
able on the scale from the true resting point. A skilled operator makes use 
of this fact to determine when the correct mass is on the scale pan. By a 
careful release of the mechanism he may confine the first deflection to one 
or two divisions and observe if the next two are at equal distances from the 
centre of the scale. 
Testing a Precision Balance 
The essential attributes of any precision balance are:— 
(1) The reading of the balance must be consistent for any given condition 
of loading. 
(2) The balance must give weighings which are closely reproducible. 
In the case of balances fitted with optical projection reading and inbuilt 
weights the following are additional requirements. 
(3) The sensitivity must be close to its nominal value and must be 
constant over the full range of the scale. 
56 THE BALANCE 
(4) T h e er ror in a n y weigh t or c o m b i n a t i o n of we igh t s shou ld n o t exceed 
t h e co r re spond ing Class A to l e r ance specified by t h e Nat ional 
S t a n d a r d L a b o r a t o r y . 
(5) In t h e case of t w o p a n t h r e e knife edge b a l a n c e s t h e effective l eng ths 
of t h e b a l a n c e a r m s shou ld be e q u a l to w i t h i n 10 p a r t s in a mil l ion. 
Methods of Test: (1) T h e genera l cond i t ion of a b a l a n c e c a n n o t be checked 
q u a n t i t a t i v e l y b u t a n inspec t ion shou ld se rve t o check t h e following po in t s . 
T h e b a l a n c e shou ld be c lean a n d all p a r t s shou ld be free f rom corrosion. 
T h e a r r e s t m e n t should o p e r a t e s m o o t h l y a n d shou ld n o t cause a n y u n -
w a n t e d m o t i o n of t h e po in t e r or p a n s . 
Man ipu la t ion of t h e bu i l t in we igh t s shou ld n o t cause a n y signif icant 
jo l t ing or swing of t h e p a n . 
(2) Rep roduc ib i l i t y of read ings . Th i s i s checked by t a k i n g t w e n t y con-
secut ive res t po in t r ead ings , t h e ba l a nc e case be ing k e p t closed a n d t h e 
ba lance a r r e s t ed b e t w e e n each r ead ing . 
T w o cr i ter ia of s t ab i l i ty a re u sed : 
(a) T h e m a x i m u m difference b e t w e e n a n y t w o consecu t ive res t po in t s a n d 
(b) T h e s t a n d a r d dev ia t ion of t h e res t po in t s . 
(a) is a m e a s u r e of e r ra t i c va r i a t i on in t h e res t po in t a n d 
(b) gives a m e a s u r e of drif t or slow c h a n g e in t h e res t po in t . 
If S is t h e a c c u r a c y of e s t ima t ion of t h e r ead ing e i t he r by vern ie r or by 
v isua l e s t ima t ion , b o t h cr i te r ia (a) a n d (b) shou ld be less t h a n 2 8 for a good 
ba lance . 
(3) T h e sens i t iv i ty of t h e ba l a nc e is m e a s u r e d by se t t i ng t h e op t i ca l scale 
t o zero a n d t h e n a d d i n g t o t h e p a n a we igh t e q u i v a l e n t t o t h e m a x i m u m 
deflection of t h e scale. T h e d e p a r t u r e of t h e full scale deflection f rom i t s 
n o m i n a l va lue shou ld n o t exceed 2 S in t h e case of a c o n s t a n t load b a l a n c e 
a n d 10 8 in t h e case of t h r ee knife edge ba l ances w i t h op t ica l p ro jec t ion . 
(4) T h e l inea r i ty of response of t h e b a l a n c e is t e s t e d by us ing successive 
r a n g e of t h e scale. 
(5) T h e t e s t i ng of t h e a c c u r a c y of t h e i nd iv idua l we igh t s is a m o s t in-
volved process b u t an ind ica t ion of t h e p resence of a n y gross e r rors can be 
o b t a i n e d by check ing t h e s u m of va r ious g r o u p s of we igh t s aga ins t a p p r o p -
r ia te s t a n d a r d s . F o r e x a m p l e if a ba l a nc e h a s an op t i ca l r a n g e of 0.100 
g r a m m e a n d g roups of we igh t s 
0, 0 . 1 - 0 . 9 g 
0, 1 - 9 g 
0, 1 0 - 9 0 g 
check 0.9 + scale aga ins t 1 g 
9.9 + scale aga ins t 10 g 
99.9 + scale aga ins t 100 g 
A m e t h o d of ca l ib ra t ion of inbu i l t we igh t s , us ing all ava i l ab le d a t a , h a s 
been descr ibed ( H u m p h r i e s , 1961), wh ich yie lds self cons i s ten t resu l t s of an 
accuracy c o m p a r a b l e w i t h t h e d i sc r imina t ion o f t h e ba l ance . 
THE BALANCE 57 
Balance for Coarse Weighing 
For general approximate work at heavier loads a speedier balance of 
more robust construction is used. A balance having a maximum load of 3 or 4 
kilogrammes and a discrimination of 0.1 gramme is suitable for this purpose. 
Single pan balances with optical scale and taring facility are available and 
they are very suitable for this purpose. 
Although these balances are robust they should nevertheless be kept 
clean and their accuracy periodically checked with known weights. 
REFERENCE 
Humphries, J. W. (1961). The calibration of the weights built into a balance. 
Aust. Jour, of Ap. Sci. 2, 3, 360 
CHAPTER IV 
By reference to tables showing the density of water at various tempera-
tures it is possible to derive a factor for the conversion of specific gravities 
based on water at 4 °C to values based on water at some other selected 
temperature, e.g., s.g. 20 °C. 
The relationship between two masses is correctly expressed by the ratio 
of their weights in vacuo. When a weighing operation is conducted under 
normal laboratory conditions, the buoyant effect of the atmosphere is exerted 
on both the sample and the weights, and as these usually differ in volume, 
the resultant force creates a difference between the weight of the sample in 
air and its weight in vacuo. A weight "in air, with brass weights" is con-
*This follows from the old definition of the millilitre, i.e., the volume occupied by 
1 g of water at the temperature of its maximum density. 
DENSIMETRIC METHODS OF ANALYSIS 
The quantity of mass in unit volume of a substance is known as the 
density of that substance, and is expressed in such units as grammes per milli-
litre, or pounds per cubic foot. Mathematically where d is the dens-
ity, m the mass and v the volume of the substance. The volume of a given 
mass may, and almost invariably does, vary with temperature and pressure. 
For liquids and solids the change of volume with temperature is quite 
significant, but the effect of variation in pressure is usually negligible, so that 
it suffices to specify the temperature to which any statement of density is 
related. 
At any given place the mass of any body is proportional to its weight 
in vacuo. The ratio of the masses (weights in vacuo) of equal volumes of a 
substance and some standard material is known as the relative density of the 
substance. Customarily, when the standard material is water, the ratio is 
known as specific gravity, so that specific gravity (s.g.) may be defined as a 
number which indicates how much heavier or lighter a material is than 
water. 
The derivation of specific gravity involves two densities each of which 
must be qualified by a temperature and so the ratio 
are numerically the same. ts in g per ml and its specific gravity 
Since one ml of pure water at 4 °C (the temperature at which the density 
of water is a maximum) weighs one gramme in vacuo* and thus has a density 
of 1 g per ml, the temperature of 4 °C is frequently adopted as a basis for 
expression of specific gravities. It follows that the density of a substance at 
are usually quoted as s.g 
For convenience it is customary to adopt a standard temperature for 
which the density of the test material is specified. In the Queensland sugar 
industry the accepted standard temperature is 20 °C and specific gravities 
DENSIMETRIC METHODS OF ANALYSIS 
vertible to the weight in vacuo if the density of the test sample is known. 
Hence, densities and specific gravities may be expressed in terms of weight 
in air with brass weights, and as most weighings are conducted under these 
conditions, tables of density on this basis have great practical value. Great 
care should be taken to avoid confusion between density figures based on 
weight in vacuo and those based on weight in air with brass weights. 
The determination of specific gravity is one of considerable importance 
in sugar analyses. This is due to the interesting fact that solutions of different 
sugars of equal concentrations have almost identical specific gravities. The 
following values for 10 per cent solutions of nine distinct sugars illustrate 
this fact:— 
Further, the mean value for all sugars approximates closely to that 
for sucrose. It is possible, therefore, to determine very closely the percentage 
of dissolved substance in any solution of sugar or mixture of sugars simply 
by determining its specific gravity. 
While the application of specific gravity tables established for sucrose 
may be applied with reasonable accuracy for the estimation of dissolved 
substance in a solution of mixed sugars, this is not the case where other 
dissolved substances are present. The errors resulting from this cause are 
at times very great as, for example, with final molasses. The influence of 
the salts present in such a solution may be gauged from the following data 
showing the concentration of solutions of sodium-potassium tartrate and 
potassium carbonate in comparison with sucrose solutions of equal specific 
gravity. 
When the specific gravity of such solutions is determined after dilution 
with water, the error is still further intensified, owing to the difference in 
contraction between sugar and dissolved impurities in aqueous solution, 
as is seen from the above table. Concentrations determined by this method 
for other than pure sugar solutions must, therefore, be regarded as rough 
estimates only. 
60 DENSIMETRIC METHODS OF ANALYSIS 
The Pycnometer 
A highly accurate instrument for the determination of specific gravity 
is the pycnometer or specific gravity bottle (Fig. 32). 
Fig. 32—Illustrating the types of pycnometer in use in Queensland. 
It is simply a glass vessel which is designed to contain an accurately 
reproducible volume of liquid at any particular temperature. The best 
pycnometers are vacuum jacketed for thermal insulation, and are fitted 
with a thermometer. By weighing the bottle filled first with water and then 
the given solution at constant tempeiature the weights of equal volumes of 
the two fluids may be determined, and hence the specific gravity of the test 
solution. 
The pycnometer is mainly used in the sugar mill laboratory for the 
determination of the Brix of dilute sugar solutions extracted in the analysis 
of cane or bagasse. 
To Determine the Volume of the Pycnometer at a Standard 
Temperature.—This determination has little practical use, but serves to 
describe the technique and develop the theory. The bottle is thoroughly 
cleansed, using in turn glass cleaning solution, water and alcohol. It is then 
dried in a stream of dry air and weighed. It is next filled with distilled water 
which has recently been boiled to expel dissolved air and cooled to 2 to 3 °C 
above ambient temperature. The stopper is inserted*, care being taken to 
prevent the introduction of air bubbles, and the excess water is carefully 
removed by means of a filter paper (from the stopper and also from the 
capillary in the side-arm type). 
*The temperature of the water must be determined at the instant the stopper is 
fully inserted. Where a thermometer is incorporated in the stopper, the stopper is 
lightly set in place and the thermometer allowed to come to reading; where a stopper 
only is provided, a thermometer is inserted first, read and withdrawn. The stopper 
is inserted immediately. 
DENSIMETRIC METHODS OF ANALYSIS 61 
The pycnometer is then placed in a water bath at a temperature lower 
than that of the water employed to fill the bottle (ambient or preferably a 
lower temperature). The liquid meniscus is thus drawn down the ground 
glass joint or the capillary depending on the type of pycnometer used. The 
pycnometer is then wiped perfectly dry. 
In drying the surface considerable care must be taken and the following 
technique is recommended. The outside is first wiped thoroughly with a 
piece of clean, damp flannel, then the damp surface is dried with a clean 
chamois, after which a final rub is given with a second chamois. During these 
manipulations and the subsequent weighing the pycnometer must not come 
in contact with the fingers. 
Several determinations are made with distilled water, the temperature 
being noted to 0 • 1 °C for each weighing. The total weight minus the weight 
of the empty vessel is the weight, in air, of the water contained, at the 
observed temperature. 
This weight in air has to be converted to weight in vacuo by applying 
corrections for the buoyancy of the water and the weights.* 
This volume VT is fixed for any pycnometer. It will be noted that the 
measured weight of water W1 is related to the standard volume VT by a 
complex factor which involves the density of water, the correction for 
buoyancy and the thermal expansion of glass. The value of this factor for 
water in a glass vessel is fixed for any temperature t1 referred to a standard 
temperature T. Values for various temperatures are available from tables. 
For added convenience, tables have been prepared in which the correction 
is made additive or subtractive (see Tables XXIII and XXIV). Hence, in 
practice the measured weight of water contained at t1 (in grammes) is con-
verted, either by a factor or a correction, directly to the standard volume of 
the pycnometer at T (in millilitres). This procedure is adopted as the basis 
in the testing of standard volumetric glassware. 
|The accepted values for y are (B.S.S. 1797: 1952) soda glass + 0.00003, borosili-
cate glass + 0.00001 per 1 °C rise in temperature. 
*It being assumed that the weighings have been made in air of average density 
0.0012 g/ml using weights of density 8.0 g/ml. 
Without special precautions, it is very difficult to conduct two deter-
minations at the same temperature. Hence, in general, the test with water 
will be conducted at t1 and that with the solution at t2. Then, if the density 
of the solution at t2 be designated D, 
Determination of Brix. 
In using the pycnometer for the determination of the Brix of sugar 
solutions a modified procedure is adopted for simplicity. If the true weight 
of the contents of a pycnometer at t2 be divided by the standard volume of 
the pycnometer at T, the result derived is known as the apparent density 
at t2. It is assumed that, as before, the weight of pure water contained at 
t1 is W1. 
62 DENSIMETRIC METHODS OF ANALYSIS 
To Determine the Specific Gravity of a Test Solution. 
The pycnometer is filled with the solution at a temperature 2 to 3 °C 
above ainbient and the weight of the contents determined as before. Let 
the weight of the contents be W2 at t2. 
The density of the solution at the temperature of the determination t2 
may be determined by dividing the true weight of the contents at t2 by the 
volume of the pycnometer at t2, the latter being determined either by direct 
measurement using pure water at t2 or by correction of the volume at the 
standard temperature to the volume at t2 in accordance with the coefficient 
of expansion of the glass of which the vessel is made. This procedure has the 
disadvantage that the observed weight of the solution must first be converted 
to weight in vacuo. If it were convenient to conduct tests on the solution and 
on pure water at temperature t2, the buoyancy corrections on the two weights 
would be practically equal and could be neglected. Hence, 
DENSIMETRIC METHODS OF ANALYSIS 63 
The apparent density at t2 is the value which would be observed by 
taking a glass hydrometer calibrated to read correctly at the standard 
temperature T and immersing it in the test solution at t2. A Brix hydrometer 
is calibrated to read correctly at a standard temperature T, and, if used at 
another temperature t2 will give a reading which differs from the actual Brix. 
If the apparent density at t2, referred to above, be converted to Brix by using 
the standard tables for conversion at temperature T the value derived will 
coincide with the actual reading of the Brix hydrometer at t2. 
Thus, in the determination of Brix, the apparent density is first derived. 
This apparent density is converted to "observed" Brix, using the standard 
table, and the observed Brix is then corrected for temperature according to 
the normal method for the Brix hydrometer. 
It will be noted that, to derive the apparent density, the observed 
weight W2 must be divided by the term 
culated for various values of t1 and a table of factors could be compiled. 
However, it is simpler, and sufficiently accurate, to make use of Table XXIII , 
subtracting 1.05 from the values listed therein and then reducing the correction 
as usual in proportion to the approximate volume of the pycnometer. The proce-
dure is most easily followed by reference to the examples. 
In the compilation of Table XXII I it has been assumed that the co-
efficient of expansion of glass is 0.00003. Such a coefficient is not likely to be 
associated with any borosilicate glass, and even some glasses nominally of 
the soda type display coefficients of expansion significantly different from 
the figure stated. The existence of a coefficient different from 0.00003 will be 
manifested in systematic variation of the determined pycnometer constant 
with the temperature at which it is determined. 
*ln the second edition of the Laboratory Manual this characteristic constant of 
the pycnometer was referred to incorrectly as the Volume. It might leniently be re-
garded as an "apparent volume" but the word "apparent" is overworked, and the term 
pycnometer constant is preferred. 
64 DENSIMETRIC METHODS OF ANALYSIS 
For general scientific work it is possible and would be desirable to 
analyse the results of tests over a range of temperatures to determine the 
actual coefficient of expansion of the glass, and hence the true constant. 
However, in the sugar laboratory the pycnometer is used almost exclusively 
for the determination of Brix, in the course of which reference is made to 
Table I. This table incorporates an allowance of 0.000025 for the coefficient 
of expansion of glass. 
Hence in practice, whatever be the material of construction of the 
pycnometer, the coefficient of expansion of the material should be taken as 
0.000025 for the calculation of the constant. If the coefficient of expansion of 
the material is, in fact, 0.000025 the constant will be independent of tempera-
ture. For all other cases the so-called constant will vary with temperature. 
For any vessel displaying this characteristic it is necessary, from the results 
of tests over a range of temperatures, to draw up a temperature scale of 
constants and, in practice, to adopt the value of constant corresponding to 
the temperature of a determination. The apparent density thus derived 
may be converted to observed Brix with the aid of Table XIV and the Brix 
may then be adjusted by reference to Table I. 
Examples : 
For the purposes of the following examples the pycnometer is constructed 
of glass having a coefficient of expansion of 0.00003 per 1 °C rise in temper-
ature. 
Determination of Volume of Pycnometer.--
temperature for the water, but, without tables applying specifically to the 
solution, the reference temperature of 25 °C for the solution may not be 
converted to any other temperature. If a value for density at a selected 
temperature t is required, a density determination must be conducted at 
that temperature. This does not apply to sugar solutions for which temper-
ature correction tables are available. 
This specific gravity may be converted to or any other reference 
Hydrometers. 
A second method of determining the specific gravity of solutions, and 
the one most commonly employed in sugar laboratories, is by means of the 
hydrometer. It provides by far the easiest and most direct method of deter-
mination of this factor. 
In its usual form this instrument consists of a hollow glass body, 
cylindrical in shape, and terminating at its lower extremity in a bulb, which 
can be weighted with mercury or lead shot and at its upper extremity in 
a slender, hollow stem within which a paper scale is sealed. If this instrument 
be allowed to float in a solution, the weight of liquid displaced is equal to 
the weight of the hydrometer. If placed in solutions of different specific 
gravity the instrument will sink to varying depths; and the scale is so 
graduated that the point on the stem which corresponds with the liquid sur-
face indicates the density or percentage of dissolved substance for the given 
temperature. 
In practice the hydrometer scale is standardized at a few points only, 
and the intermediate divisions are determined by interpolation. The density 
of a solution is equal to the weight W of the hydrometer divided by the 
volume V of the portion submerged. 
DENSIMETRIC METHODS OF ANALYSIS 65 
66 DENSIMETRIC METHODS OF ANALYSIS 
Then-
The difference between the volume submerged for any two divisions v is— 
v =nr2d 
where d = distance between divisions 
and r = the radius of the stem. 
The following table shows the relationship between the stem divisions 
of a hydrometer weighing 75 g and with a cross sectional area of stem (nr2) 
equal to 0-2 cm2. 
It is clear that as the density increases the distance between scale 
divisions decreases. To effect this progressive reduction it is customary, in 
practice, to employ a dividing engine. 
In the graduation of a hydrometer scale for indicating direct percentages 
of sugar (Brix) the distance between scale divisions is more uniform, due to 
the partial compensating effect of the non-linear relationship between Brix 
and density. At 20 °C the change in density from 0 to 10 °Brix is 0-03901 g 
per ml, whilst the corresponding change from 50 to 60 °Brix is 0-05089 g 
per ml. This effect is illustrated in the following table, where the dimensions 
of the hydrometer are the same as before:— 
DENSIMETRIC METHODS OF ANALYSIS 
It is, therefore, customaryingraduating hydrometers which 
read direct percentages of sugar, to calibrate at, say, three 
points, and then divide the intervals between these points into 
equal subdivisions. Though not absolutely accurate, the error 
introduced is probably less than the errors of observation. 
Brix Hydrometer 
The construction of the hydrometer which reads direct 
percentages of cane sugar is due to Balling. The scale as later 
recalculated by Brix constitutes the form at present in general 
use. The divisions of the scale are called degrees Brix, and 
express weight per cent of sugar; that is, a sucrose solution of 
20 °Brix is composed of 20 g of pure sucrose dissolved in 80 g 
of pure water. It should be observed that there is no reference 
in this definition to volume. A solution of 20 °Brix at 20 °C is 
still a 20 °Brix solution at 80 °C. 
The confusion which frequently arises in this connection 
is due to the fact that the Brix hydrometer responds primarily 
to the density of the solution tested, which varies with temper-
ature. As the glass of which the hydrometer is made has a 
much lower temperature coefficient of volume than sugar 
solutions, it follows that, with increasing temperature, the 
hydrometer will sink deeper and yield lower readings. The 
Brix scale marked on the hydrometer is related to the 
density of the solution at the standard temperature (20 °C). 
Hence, at any other temperature, whilst the equilibrium posi-
tion of the hydrometer is closely related to the actual density 
of the solution, the reading cannot be interpreted directly as 
Brix. A correction must be applied to the observed reading to 
compensate for the change in reading which would result from 
bringing the temperature of the solution to 20 °C. In the deriva-
tion of temperature correction tables it is assumed that a 
hydrometer of a standard type of glass is immersed in a solu-
tion of sucrose in water. 
One type of hydrometer which is used in Queensland mills 
is illustrated in Fig. 33. The approximate dimensions are:— 
Overall length—36 cm 
Length of scale—15 cm 
Diameter of cylindrical bulb—3 cm 
Diameter of upper tube—5 mm 
Length of scale division (0.1 °Brix)—1 -5 mm 
The following ranges have been specified as the most 
convenient for sugar-mill laboratory use:— 
0—10°, 10—20°, 15—25°, 20—30°, 30—40°, 
40—50°, 50—60°, 60—70°. 
Fig. 33—Illustrating 
a Brix hydrometer. 
67 
CHAPTER V 
VOLUMETRIC EQUIPMENT 
The Units of Volume 
The units of volume should be based, theoretically at least, on units of 
length, and, in the metric system, the cubic metre, cubic decimetre and cubic 
centimetre are recognized units purely based on length. However, for a major 
part of the last century, units of volume based on mass have not only been 
recognized but accepted as standard. In the metric system, the familiar ones 
are the litre and millilitre. 
The originators of the metric system of weights and measures attempted 
to make mass units compatible with volume units by defining the kilogramme 
as the mass of one cubic decimetre of water at the temperature of its maxi-
mum density (4 °C). With the best accuracy available at the time this mass 
unit was determined and reproduced in a mass of metal—the standard 
kilogramme. 
Subsequent experience with masses based on the standard kilogramme 
and volumes based on the standard metre revealed small discrepancies, 
indicating that the original correlation was slightly in error. The volume of 
one kilogramme of water at 4C was demonstrated to measure 1.000027 
cubic decimetres. This volume, based on the kilogramme was designated the 
litre, with a sub-unit, the millilitre. 
Two slightly different sets of units were then available, and in 1901 the 
litre was officially defined and adopted for volumetric work. This was 
apparently not regarded as of much significance at the time, for, at least 20 
years later, volumetric glassware was still being calibrated in cc. now written 
as cm3. However the millilitre triumphed, and, for the past generation, 
volume and derived quantities such as density have been expressed in terms 
of the litre. In 1950 the conversion factor was amended to 1. 000028. 
In 1964 the 12th General Conference of Weights and Measures resolved 
to revert to the purely linear basis of volume and redefined the litre to be 
exactly one cubic decimetre. This means that the term litre may now re-
present either of two volumes, and for clarity it is necessary to invoke the 
officially unrecognized terms "old" litre and "new" litre. 
Once again, public response is very slow and even now (1969) many 
chemists are hardly aware of the change. Confusion will be avoided by the 
use of the term cm3 rather than ml, and for the most part, the difference 
between the cm3 and the old ml does not matter anyway. 
The Laboratory Manual, in all editions to date, has used the old litre 
and millilitre as units; that policy has been adhered to in the current edition 
because it does not yet appear possible to adopt the new standards through-
out. The normal solution for the International Sugar Scale is 26.000 g in 100 
old ml; is it to become 25.999 g in 100 cm3? It may be decided to let the 
weight stand unchanged. 
This book deals with a variety of subjects, involving a wide range of 
precision of results. In the analysis of factory products the difference between 
the old ml and the cm3 matters not one bit; in pycnometry it cannot be 
ignored. It must be left to the reader, conscious of the different units, to 
VOLUMETRIC EQUIPMENT 69 
decide when they are interchangeable, when not. The important item of 
record is that the volume units are of the pre-1964 era, the old litre and the 
old millilitre, based on the kilogramme. 
It should be stressed that the ml is absolute, and does not alter with 
change of temperature. At 4 °C the volume occupied by 100 g of pure water 
is exactly 100 ml. If the temperature be raised the water will expand and 
occupy a greater volume than 100 ml, but the unit itself does not alter.* 
As 20 °C is the standard temperature for all sugar laboratory apparatus, 
all volumetric glassware must be standardized at this temperature. For 
example, the 100 ml flask used in determining the polarization of sugars 
will contain, at 20 °C, 100 times the volume occupied by 1 g of water at 4 °C. 
Volumetric Glassware 
The volumetric glassware used in the sugar laboratory includes flasks, 
burettes, pipettes and measuring cylinders. 
For general purposes, volumetric equipment of class B standard is 
satisfactory and it is recommended that the use of class A glassware be 
restricted to those operations which necessitate the highest degree of accuracy 
being attained. Various standards authorities—The National Physical 
Laboratory England, National Standards Laboratory Australia, The Na-
tional Bureau of Standards USA, The British Standards Institution, the 
Standards Association of Australia and others have developed and laid down 
specifications for class A and class B volumetric glassware. However the 
accuracy of an individual piece of equipment is not guaranteed by any more 
than the reputation of the manufacturer. 
The first essential in standardization is to have the glassware thoroughly 
clean. Traces of grease are particularly to be avoided. The vessel should be 
rinsed with water and loose contamination should be removed mechanically 
as far as possible in the usual way. The vessel should then be filled with an 
aqueous solution of a soapless detergent, shaken vigorously and allowed to 
stand for several hours. After pouring off the solution the vessel should be 
rinsed with distilled water several times until all traces of the detergent have 
been removed. If the vessel is not sufficiently clean after this treatment it 
should be filled with chromic acid cleansing solutionf, allowed to stand over-
night if possible and then repeatedly washed with distilled water. The vessel 
is rinsed with pure alcohol, then with pure ether and finally dried by a current 
of dry air free from dust. The vessel should not be heated. 
The capacity of a graduated glass vessel is defined by the volume of 
water (or mercury) it contains or delivers at its standard temperature, when 
the meniscus i.e. the concave (or convex) liquid surface in the vessel is brought 
to the graduation line in a specified manner. In the case of a water meniscus 
the top edge of the graduation line is set tangentially to the lowest point of 
the meniscus. The provision of a strip of black paper 1 mm below the meniscus 
and viewed against a white background will be found to facilitate the setting. 
It should be noted that volumetric apparatus is graduated either to 
contain or to deliver the particular volume. This is usually indicated on 
apparatus made to British or Australian specifications by the inscription " In" 
which has been adopted in place of "C" to indicate that the vessel is graduated 
to contain, and " D " is used as the inscription to indicate to deliver. Pipettes 
*It may appear superflous to labour this point, but the true significance of this 
fact is so frequently overlooked that students fail to make intelligent use of it. 
See p. 86 for the preparation of this solution. 
70 VOLUMETRIC EQUIPMENT 
and burettes are obviously used only to deliver known volumes, but gradu-
ated flasks and more especially cylinders are used either to contain or to 
deliver, and when ordering these goods the method of using them should be 
considered. 
Since the capacity of a glass vessel varies with the change of temper-
ature, any given vessel can be correct at only one temperature. The particular 
temperature at which a vessel is intended to contain or deliver its nominal 
capacity is the "standard temperature" of the vessel. In Australia 20 °C has 
been adopted as the standard temperature for volumetric glassware. 
Flasks 
The volumetric flask is a vessel designed to contain a known volume of 
liquid. The usual form of flask consists of a pear shaped body with a long 
narrow neck of approximately cylindrical shape on which a mark is etched 
to indicate the required capacity at a given temperature. The bottom should 
be flat or slightly dished to allow the flask to stand stably. The neck of the 
flask is made as narrow as is consistent with convenience in order that the 
error involved in filling to the mark may be as small as possible. 
The method usually employed in standardizing a flask is to first weigh the 
vessel empty and again when filled to the mark with a liquid of known density. 
Corrections must be applied for the buoyancy of air and the temperature of 
the liquid. Pure water, either distilled or demineralized, is most generally 
used, although mercury gives a higher degree of accuracy, particularly with 
vessels of low capacity. The flask should be weighed to a precision better 
than 10 per cent of the tolerance prescribed. This can be achieved with a 
good quality analytical balance having a capacity suitable to the require-
ments. 
A substitution method of weighing is generally used. With modern 
single pan balances of constant load it is the only method which can be 
employed, whilst with a two pan balance it avoids any errors due to inequality 
in the lengths of the arms. When using an ordinary two pan balance the clean 
dry flask is placed on one pan together with standard weights slightly in 
excess of the amount of water to be weighed. Tare weights are added to the 
other pan until the balance is in equilibrium. The flask is then removed from 
the pan, filled with water to a distance of a few millimetres above the gradua-
tion line and the surplus water is withdrawn by means of a fine jet so that the 
lowest point of the meniscus is well formed and distinct in outline. After 
filling, the flask is replaced on the pan and the weights are readjusted so that 
the balance is again in equilibrium. The tare weights are left undisturbed. 
The difference between the weights used in the first and second weighings is 
equal to the weight of water contained in the flask. The temperature is noted 
immediately after completion of the last weighing. The weight of water may 
then be converted to the volume at 20 °C by adding or subtracting corrections 
from Tables XXIII and XXIV. The main correction compensates for the 
expansion of water at temperatures rising above 4 °C and the buoyancy 
effect of a standard atmosphere on the flask and weights. The smaller correc-
tion is for departure of the atmospheric conditions from the standard. The 
latter correction is negligible for most flasks used in sugar laboratories. The 
tables apply to a unit volume of 1000 ml and for other volumes the correc-
tions must be reduced or increased in the ratio of the volumes. 
Example for 100 ml flask filled with water at a temperature of 23 °C 
and an atmospheric pressure of 755 mm of mercury. 
Empty flask + standard weights on pan = 100.000 g 
Filled flask + readjusted weights on pan = 0.385 g 
VOLUMETRIC EQUIPMENT 71 
Weight of water contained in flask = 99.615 g 
Correction for 100 ml at 23 °C (Table XXIII) = +0.340 g 
Correction for 755 mm pressure (Table XXIV) = —0.002 g 
Capacity of flask at 20 °C = 99.953 ml 
When a single pan balance is used normal weighings are made with the 
flask empty and when it is filled. To minimize errors due to changes in the 
buoyancy of air the second weighing should follow the first without delay. 
The tolerances permitted for class B flasks are specified in Table XXV. 
Burettes 
The burette is employed either to deliver a measured volume of liquid 
or to measure a volume of liquid delivered. It consists of a cylindrical tube 
graduated usually in tenths of a ml and with a total capacity of 25 or 50 ml. 
It is provided at the lower end with a glass tap, or for use with alkaline 
solutions, with a rubber tube connected to a glass outlet jet and closed with 
a pinch clip. A good burette is of uniform bore, the tap is well fitting and the 
graduations are accurate. The fit of the tap may be improved when necessary 
by using the finest grade of carborundum paste as a grinding material. 
In reading a burette, care should be exercised to avoid errors due to 
parallax. Various devices are employed to ensure this; the best burettes have 
the graduation marks etched completely around them, so that in reading, 
the front of the etching conceals the back portion. Some burettes (Schellbach 
type) are manufactured with a longitudinal strip of white glass with a blue 
stripe running down the centre of it. The meniscus then presents the appear-
ance illustrated in Fig. 34. This and similar devices are, however, not recom-
mended for precise work, as they introduce the possibility of irregularity in 
bore. 
The accuracy of a burette is also a function of its rate 
of delivery; a satisfactory rate for a 50 ml burette of B 
class accuracy is between 75 and 150 seconds. The delivery 
time is determined from the zero line to the lowest gradu-
ation line and is taken with the stopcock fully open with the 
jet NOT in contact with the side of the receiving vessel. 
A burette is first tested for leakage. It is clamped in a 
vertical position with the stopcock free from grease, the 
barrel and key wetted with water and the burette filled 
initially to the zero line with water. The rate of leakage 
with the key in the closed position shall not exceed one 
half of one scale subdivision in 10 minutes for class B 
burettes during a test of at least 20 minutes. 
The tolerances permitted for class B burettes are set 
down in Table XXV. 
In order to record corrections from point to point through the length of 
the burette, the errors (positive or negative) may be plotted as ordinates, 
against the burette scale graduations as abscissae. 
For calibration, the burette is clamped in a vertical position with the jet 
downwards and filled through the jet to a few millimetres above the zero 
graduation line. It is usual to test at five points of the scale, starting from zero 
on each occasion. Delivery is made into a tared weighing vessel, the outflow 
being unrestricted until the meniscus is about 1 cm above the graduation line 
of the test point. The rate of flow is then reduced to allow the final setting 
Fig. 34 — Illus-
trating the ap-
pearance of the 
meniscus of the 
Schellbach 
burette. 
72 VOLUMETRIC EQUIPMENT 
Fig. 35—Illustrat-
ing common types 
of pipette. 
to be made without any allowance for drainage time. 
The drop adhering to the jet of the burette is removed 
by bringing the side of the weighing vessel in contact 
with the tip of the burette. The weighing vessel is then 
weighed, the temperature noted and the volume delivered 
at 20 C is calculated from Tables XXII I and XXIV. 
The substitution method of weighing as outlined for 
flasks is recommended. 
Pipettes 
The function of the pipette is to deliver a particular 
volume or a range of measured volumes of liquid; it may 
be of the bulb type shown in Fig. 35(1) or a graduated 
type illustrated in Fig. 35(11). In construction the bulb 
pipette consists of a straight suction tube above the 
bulb and a straight delivery tube below the bulb. The 
top of the suction tube should be ground smooth and 
square with the axis of the tube, the outer edge of the 
top being slightly bevelled. The graduation mark should 
be a fine clean line of uniform thickness completely 
encircling the suction tube. The delivery tube should 
terminate at its lower end in a delivery jet made with a 
gradual taper. The end of the jet should be ground 
smooth and square with the axis of the jet. The outer 
edge of the jet should be slightly bevelled. 
The delivery time of a pipette is important for the 
volume of liquid delivered is less than the volume con-
tained, by an amount equal to that adhering to the walls 
of the pipette. This volume of adhering liquid will vary 
if the delivery time is reduced or increased. However 
provided the delivery time is within the specified limits, 
the change in volume of the film adhering to the walls 
will not introduce any gross errors into the volume 
delivered. 
The delivery time is the time occupied by the des-
cent of the water meniscus from the graduation line to 
the position at which it appears to come to rest in the 
jet. The determination of the delivery time is made with 
the pipette in a vertical position and the jet in contact 
with the side of the receiving vessel. 
For the determination of capacity, the pipette is 
clamped in a vertical position with the jet downwards 
and filled as described for a burette. The water is retained 
by pressure of the finger on the tip of the suction tube 
and the outside of the jet is wiped free of water with a 
cloth. The pressure of the finger is reduced and the water 
allowed to run out slowly until the lowest point of the 
meniscus coincides with the top of the graduation line. 
The drop of water adhering to the jet is removed and 
the volume now contained in the pipette is delivered 
into a tared vessel with the tip of the jet in contact with 
the inside of the vessel. A waiting time of approximately 
3 seconds after movement of the water has ceased, before 
removing the pipette, is now specified in international 
VOLUMETRIC EQUIPMENT 73 
recommendations for one mark pipettes. The natural rate of delivery 
should not be increased by force such as blowing and the small quantity of 
water remaining in the jet should not be expelled. The vessel is now weighed 
and the weight of water may then be converted to the volume at 20 °C by 
adding or subtracting corrections from Tables XXII I and XXIV. The toler-
ances for capacity and delivery time for pipettes are specified in Table XXV. 
Graduated Pipettes 
Graduated pipettes may be obtained in various types, some examples 
being as follows:— 
(a) Calibrated downwards from a zero graduation. 
(b) Calibrated upwards with the residual volume in the jet as the zero 
datum. 
Standardization of these graduated pipettes is carried out in a similar 
manner to burettes for delivery times and for the volume of water delivered 
at 20 °C corresponding to the graduation mark tested. The tip of the jet is 
held in contact with the receiving vessel and no drainage time is allowed. 
The tolerances allowed for graduated pipettes are shown in Table XXV. 
Measuring Cylinders 
Cylinders are in common use for rapid approximate estimation of liquid 
volumes but they cannot be employed for accurate work. They may be 
standardized by the usual method of weighing the water which they contain 
or deliver. 
Thermometers 
Although not a volumetric instrument, the thermometer is so often 
closely associated with volumetric determinations that it may well be 
considered in this connection. 
A good thermometer must be made of sound glass, contain pure mercury 
and be filled with inert gas at a suitable pressure. The mercury thread must 
be free from breaks. The dividing and figuring of the scale should be clear 
and distinct and graduation lines should be of uniform thickness. If the 
thermometer is of the solid stem type the graduations are etched on the stem, 
or if of the enclosed scale type the scale is permanently marked on suitable 
material and rigidly supported within the glass tube carrying the capillary. 
The divisions should be at equal spacing. 
For routine laboratory work a general purpose thermometer as described 
in British Standard 1704 is most suitable. The maximum error of 1°C is 
allowed for general purpose thermometers in the range —5 to +105 °C 
graduated at each degree. For more accurate work thermometers as described 
in British Standard 593 are recommended where the maximum error allowed 
for a thermometer in the range —5 to +105 °C graduated at each degree, 
is 0.3 °C. 
A thermometer is subject to changes in bulb volume caused by the 
gradual recovery of the glass from the strain introduced during the treatment 
it receives in manufacture. This slow alteration is most noticeable in the first 
year or two after the thermometer is made but may proceed for years. Such 
changes are also modified by the heat treatments to which the thermometer 
is subjected in practice. 
In using a thermometer which is calibrated for total immersion it should 
be arranged as far as practicable for the entire mercury column to be immersed 
74 VOLUMETRIC EQUIPMENT 
in t h e l iquid . W h e r e t h i s i s n o t possible i t becomes necessary to a p p l y a 
correc t ion for t h e emergen t po r t ion of t h e co lumn wh ich i s n o t a t t h e s a m e 
t e m p e r a t u r e as t h e b u l b . T h e following formula i s appl icable for a p p r o x i m a t e 
correct ions:—• 
T c = T 0 + 0.000156L (To — T m ) 
where T c = cor rec ted t e m p e r a t u r e 
To — observed t e m p e r a t u r e 
T m = t e m p e r a t u r e o f t h e m i d po in t o f t h e e m e r g e n t t h r e a d 
t a k e n b y a n o t h e r shor t t h e r m o m e t e r 
a n d L = l eng th in degrees of t h e emergen t co lumn. 
In genera l for t e m p e r a t u r e s be low 100 °C, t h e m a g n i t u d e of th i s correc-
t ion will n o t exceed one or t w o t e n t h s of a degree . T h e r m o m e t e r s des igned 
for a l imi ted degree of immers ion are a v a i l a b l e — t h e correct d e p t h of immer -
sion be ing ind ica t ed by a l ine e n g r a v e d on t h e s t em. 
CHAPTER VI 
THE BUREAU'S METROLOGY LABORATORY 
The Bureau maintains a testing service for certain apparatus used in 
sugar mill laboratories. According to Regulation 57 of "The Regulation of 
Sugar Cane Prices Act 1962-1966", "Only such measuring instruments as 
are certified by the Bureau of Sugar Experiment Stations to be within the 
required limits of accuracy shall be used in the determination of Brix, pol 
and fibre for cane payment purposes". Such instruments include volumetric 
glassware, Brix hydrometers, polarimeters or saccharimeters, polarimeter 
tubes, refractometers, balances, weights and thermometers. 
The metrology laboratory of the Bureau retains standard equipment 
certified by the National Standards Laboratory, Sydney, and is registered 
with the National Association of Testing Authorities Australia for classes of 
tests for the examination of all the abovementioned apparatus. 
Examination of apparatus calibrated at 20 °C is conducted in a room 
in which the temperature is controlled at 20 + 1 °C and the relative humidity 
at 5 5 + 5 per cent. 
When the equipment being tested is made to a specified standard the 
tests are conducted for compliance with that standard. In the absence of any 
nominated standard, the equipment is examined for compliance with toler-
ances which apply to Class B requirements of the relevant British or Aus-
tralian standards for the particular item of apparatus, or for compliance 
with the specifications for apparatus used in the analysis of cane for payment 
purposes as outlined in Table XXV. 
Reports are issued for all apparatus tested and when the tests are 
conducted in accordance with the terms of registration with NATA, the 
reports are endorsed to this effect. In addition if the apparatus is approved 
for use in the analysis of cane for payment purposes the report is endorsed 
accordingly. 
As outlined in the introduction to Chapter V the unit of volume is based 
on the kilogramme, i.e. the old litre and millilitre have been retained through-
out this edition of the manual. 
Thermometers 
All thermometers should be carefully tested before being put into use. 
The service available at the Bureau is for thermometers in the range 0 to 
110 °C. They are calibrated for use in the vertical position either partially 
immersed or immersed to the reading, by comparison with mercury-in-glass 
thermometers which have been standardized by the National Standards 
Laboratory Australia. It is customary to test at the icepoint (0 °C) and the 
highest graduation mark, as well as at three or four intermediate points. 
Brix Hydrometers 
The testing of Brix hydrometers covers all ranges within the limits of 
0 to 70° Brix. 
The method of standardization is by comparison of readings of the test 
hydrometer with those of a standard hydrometer of known corrections. 
This is carried out in solutions contained in glass cylinders of sufficient size 
76 THE BUREAU'S METROLOGY LABORATORY 
The reading of each hydrometer is obtained by viewing, from below the liquid 
surface, the point where the level of the liquid surface intersects the stem of 
the hydrometer. This point is clearly defined when a screen painted with the 
top section white and the lower section black is placed behind the cylinder 
fig. 36- A dual comparator used by the Bureau for checking the length of sacchari 
meter tubes. 
Bureau the testing is carried out in a constant temperature room at 
to allow both hydrometers to float freely side by side. This method is in-
dependent of temperature but a constant temperature is desirable. At the 
THE BUREAU'S METROLOGY LABORATORY 77 
with the junction of the black and white sections slightly below the surface 
of the solution when both hydrometers are immersed. This screen provides 
a dark ellipse around the stem of the hydrometer. This ellipse becomes a thin 
straight line as the head is raised to bring the eye to a position exactly on the 
level of the surface of the liquid. With the eye at this level the reading of each 
hydrometer is taken without altering the position of the head. Readings are 
thus obtained on the two hydrometers under identical conditions. 
The scale is checked at each end of the range and at a third point 
approximately in the middle. 
Polarimeter Tubes 
For the calibration of length of polarimeter tubes a comparator (Fig. 30) 
which incorporates two dial gauges is employed. Each tube is compared with 
a standard bar of known length, the dial gauge measuring the difference 
between the lengths of the tube and the bar to an accuracy better than 0.01 
mm. The two dial gauges provide a check on the accuracy of measurement; 
a difference between the two readings indicates that a check on the dial gauges 
is necessary. This calibration is carried out in the constant temperature room 
Tolerances for tubes are shown in Table XXV. 
Cover Glasses 
("over glasses for polarimeter tubes are checked for strain by means of a 
strain viewer. They are also examined to ensure that the surfaces are plane 
parallel and free from scratches or other defects. 
Saccharimeters 
The scales of saccharimeters are calibrated by means of live standard 
quartz plates. These plates cover a range from 
Saccharimeters are also examined for correct mechanical and optical 
operation and anv defective parts are replaced where possible. The tolerance 
is shown in Table XXV. 
Quartz Plates 
Ouartz control plates for use with quartz wedge saccharimeters are 
tested in a Hates Fric saccharimeter for S rotation. The rotation in angular 
degrees for subsequent conversion to S is also determined in a Schmidt and 
Haensch polarimeter using the sodium yellow 5892 A or the mercury green 
5461 A wavelengths of light. Ouartz plates are also tested for uniform thick-
ness and lor any strain due to incorrect mounting. 
Refractometers 
Abbe refractometers are tested against calibrated liquids and glass 
standards covering the range 1.33 to 1.65 refractive index at 20 C. 
Balances 
Balances up to a maximum capacity of five kilogrammes are tested 
according to the principles set out in Chapter III. 
Weights 
Weights of values up to 1(H) gramme are standardized on the basis of 
weighings made in air of density 0.00120 g/ml against standard weights of 
density S.O g/ml. The method of double weighing is used. 
Volumetric Glassware 
Calibration of volumetric glassware is determined according to the 
method set out in Chapter V for each item of glassware. 
v
artz nlates. ese lates c er a ra e fr  
y
CHAPTER VII 
SAMPLING OF SUGAR MILL PRODUCTS 
In the preceding chapters considerable attention has been paid to the 
necessity for precision in all apparatus employed in sugar laboratory control 
work. However, accurate apparatus and refined methods of analysis are 
totally worthless if the material analysed is not representative of the total 
substance, the composition of which it is desired to determine. Sugar-mill 
products in particular present a most difficult problem in this regard, but 
unless complete and accurate methods of sampling are employed the labora-
tory control must be regarded as only approximate and indefinite. 
The method of sampling depends, of course, on the nature of the partic-
ular product; and further, an accurate analytical result is of little value for 
control purposes if the total quantity of substance is not, in turn, accurately 
determined. Thus, a true analysis of a representative sample of mixed juice 
gives no measure of the quantity of sugar entering manufacture, unless the 
true quantity of such juice is also known. The necessity for the highest 
degree of precision in both sampling and measuring cannot be overemphasized. 
Yet all too often one finds that the supervision of these operations is placed 
in the hands of juniors, while the expert technician performs the analyses. 
It is certainly true that greater precision in results is often obtained by 
having the chief chemist carry out the sampling and by leaving the analyses 
to the laboratory junior, but it must be emphasized that, whoever takes the 
sample, it must be taken in a completely unbiased manner. 
It must always be remembered that even the best sampling methods are 
approximate, and chemists should be continually on the watch for improve-
ments in technique. The following methods are regarded by the Bureau as 
being simple and practicable, and at the same time, not unscientific. 
Cane 
The correct sampling of a field of cane is quite a difficult matter. As the 
result of studies which have been carried out, it has been found that a large 
number of individual sticks must be selected at random from all parts of the 
field if an accurate estimate of its c.c.s. is desired. The number of stalks 
necessary depends on the degree of variation in crop growth from point to 
point in the block, particularly if the crop is far removed from maturity. 
From 20 to 50 sticks should be regarded as the range of sampling necessary. 
The best method for determining the degree of maturity of a crop is to carry 
through a series of systematic tests. 
The collection of stick samples for fibre analysis was formerly a universal 
practice at Queensland mills. This method of cane sampling is fully described 
in Regulation 57 of the Regulation of Sugar Cane Prices Act, but it has been 
largely replaced by the practice of sampling prepared cane. Prepared cane 
samples can be used for the determination of cane fibre by disintegrating the 
sample in a hammermill or cutter grinder, transferring the sample to a fibre 
bag and determining fibre in the usual manner; or the prepared cane samples 
can be used for direct analysis of cane, utilizing the wet disintegrator to 
determine Brix and pol and a Spencer or similar type of air stream oven to 
determine moisture. Prepared cane is usually obtained from the elevator 
feeding into the number one mill hopper by means of a hydraulically or 
SAMPLING OF SUGAR MILL PRODUCTS 79 
p n e u m a t i c a l l y o p e r a t e d door in t h e b o t t o m of t h e e levator . In o rde r to avo id 
t h e risk of incor rec t s ampl ing caused by t h e possibi l i ty of segregat ion in t h e 
carr ier , i t i s i m p o r t a n t t h a t t h e door cover as m u c h of t h e w i d t h of t h e 
e leva tor as possible. T h e door open ing shou ld also be sufficiently wide t h a t 
a free fall of t h e full d e p t h of t h e cane in t h e e l eva to r occurs . T h e p r e p a r e d 
cane is u sua l ly al lowed to fall o n t o a la rge s ampl ing t a b l e where i t is s p r e a d 
ou t a n d sub - sampled by h a n d for hammer -mi l l i ng o r d i s in tegra t ion . Var ious 
avenues for a u t o m a t i c mechan ica l sub- sampl ing a re a t p r e sen t be ing in -
ves t iga ted . 
Juice 
Various devices are employed for obtaining continuous samples of juice 
from the mills and juice gutters. The simplest form is probably a metal 
container provided with a conical lid in which a small hole has been drilled. 
This hole is covered with fine gauze to exclude bagasse particles. The con-
tainer is usually suspended in the stream of juice from the first roller of the 
train. Tests have shown that if three such vessels are suspended beneath the 
same roller the samples collected may vary in composition within relatively 
wide limits, and, therefore, it is essential to collect a sample from the full 
length of the roller. 
This may be done by fitting a trough beneath the roller in such a way 
that the entire quantity of juice expressed by the roller is collected. At the 
centre of the trough a cup is provided to which is attached a large downpipe 
several inches long. The sampler is placed directly below the centre of the 
outlet. 
This method suffers from a serious disability. The sample is collected 
at a uniform rate, irrespective of the rate of juice flow. With normal crushing 
the variation will not be great, and the sample obtained should be fairly 
representative of the entire juice; but this limitation should be borne in 
mind in those areas where the cane supply is frequently highly variable. 
The size of the hole in the container determines the capacity of the 
sampler. If the hole is too large frequent changes are necessary, while if too 
small the sample is insufficient. For normal sampling the hole is made of such 
dimensions as to provide a gallon of sample juice every four hours. 
For first expressed juice sampling this method has now been superseded 
by automatic continuous devices. Several types are in use in Queensland, 
but in all the collection of the sample involves the use of a trough to catch the 
juice, this trough being constructed to conform with Regulation 57 of the 
Regulation of Sugar Cane Prices Act. All of the juice flow from this trough 
is collected and fed into the suction of a juice sampling pump. By means of a 
proportioning device, part of the juice flow from the pump is diverted to a 
sample can system located adjacent to the first mill or in the laboratory, and 
the remainder returned to the mill bed. Normally the sample cans are held 
in an automatic sampling device which changes the sample flow from one 
can to the next as each successive rake of cane comes through the first mill. 
The samples are identified by means of pins or balls in sample wheels which 
have their speeds geared to the speed of the carrier or elevators, or, in the 
most recent type of automatic sampler, the samples are tracked through the 
conveying system electronically. This electronic sampler also has the facility 
of being able to alter the proportioning device so that a more or less constant 
quantity of juice is collected for each rake of cane, irrespective of the length 
of the rake. 
Sampling from juice gutters also presents difficulties. The best device 
for this purpose is a small under-shot water wheel. One of the spokes is made 
S O S A M P L I N G O F S U G A R M I L L P R O D U C T S 
hollow and terminates in a spoon-shaped blade. This spoon takes up a little 
of the juice, which flows down the spoke to the hollow axle which is provided, 
and thence into the container. The main objection to this type is that the 
small pipes are liable to become choked, after which sampling will cease. 
In order to ensure a true average sample, small baffles should be fitted in the 
trough upstream from the wheel to effect a thorough mixing of the juice. 
Sampling of mixed juice, particularly where suspended matter deter 
minations are to be carried out on the juice, is best accomplished by means 
of a pitot-tube type sampler placed in the delivery pipe from the mixed juice 
pump. In this way, a sample of the juice is taken before the suspended solids 
have had a chance to settle, and a reasonably accurate sample can be obtain-
ed. A moving receiving tube which passes at regular intervals through the 
juice flowing from the sampling tube comprises an efficient method of sub-
sampling the main sample flow. 
Syrup 
With the replacement of reciprocating syrup pumps by centrifugal 
pumps, samplers such as the Calumet described in earlier editions of this 
Manual are no longer applicable for the purpose of syrup sampling. Continu-
ous sampling of syrup may be effectively carried out by piping a small sample 
of syrup from the pump delivery line and sub-sampling this smaller flow by 
means of a sample splitter. Syrup samplers must be checked and cleaned 
at regular intervals to ensure that crystallization does not occur, thus blocking 
the sampler. If continuous sampling is not used, syrup may be snap sampled 
at regular intervals and the snap samples composited over a period. Preserv-
ative is not required for syrup, molasses, or massecuite samples. 
Massecuites and Molasses 
The composition of massecuite varies from point to point within the pan, 
due to imperfect circulation, and therefore the sample should be taken 
continuously as the massecuite is discharging. For control purposes a "snap" 
sample is usually sufficient, though for preference three such samples should 
be taken and composited for each strike. These should be drawn at regular 
intervals as the massecuite is discharged, but the first should not be taken 
from the first flow of massecuite. In compositing samples of massecuite, care 
must be taken that the respective portions are proportional to the quantity 
of massecuite which each represents. 
Molasses may be sampled similarly to syrup (q.v.) and similar precautions 
as with syrups should be taken in preparing a representative composite 
sample. It is preferable to obtain a continuous sample of final molasses. A 
convenient sampler for those mills using molasses scales is to fit a small pipe 
leading from the receiving tank to a sample container. Each time the weighing 
tank discharges, the inlet to this pipe is submerged to a similar depth, and 
the quantity of molasses transferred to the container is uniform. 
Raw Sugar 
Raw sugar is now handled in bulk in Queensland, and sugar sampling 
at the bulk terminals is carried out by removing a portion of the sugar from 
the bulk containers as they are being discharged. At the mill various devices 
are being used for sugar sampling. Theoretically, it is best to sample from a 
stream in free fall, and, if the practical difficulties could be overcome, this 
could be achieved on a sugar belt if the belt were fitted with a sampling gap, 
almost the full width of the belt, and a sample can placed under the belt at the 
feed point. This is however, a rather difficult and expensive method of 
SAMPLING OF SUGAR MILL PRODUCTS 81 
sampling and samples are usually obtained by means of motor-driven samp-
ling spoons or other devices. The disadvantages of these devices are that, 
unless very sophisticated control equipment is used, they are not strictly 
proportional to sugar rate and are easily fouled by wet sugar. 
Bagasse 
The accurate sampling of bagasse is a very difficult problem. Here, 
again, no satisfactory continuous sampler has been devised and hand 
sampling is necessary. In general the analyses of final bagasse samples are 
not considered individually, but only with reference to their average value, 
hence advantage may be taken of the fact that bagasse can be preserved for 
reasonable periods. In this way samples may be taken at frequent intervals 
without increasing the number of analyses to be made by the chemist. 
For final bagasse the compositing of samples taken at short intervals, 
and the subsequent analysis of the well mixed sample, is strongly recom-
mended in preference to the taking of "snap" samples once or twice per shift. 
The former method is far more representative of the bagasse in process, and 
the sampling procedure described below does not inflict any extra work on 
the analyst. 
For sampling bagasse a small chute the width of the bagasse blanket is 
provided. This chute is held across and below the falling bagasse, and when 
it is full the contents are transferred to a closed container containing pre-
servative. A suitable type is shown in Fig. 37. The chute should hold 2 or 3 lb 
of final bagasse so that the resulting 
total sample is about 30-50 lb. 
When the composite is completed 
the large sample is spread out, 
rapidly but effectively mixed, and 
then sub-sampled for analysis. 
The mixing must be carried out 
thoroughly, otherwise the whole 
sampling process will have been 
wasted; but it must be done 
quickly to avoid moisture loss by 
evaporation. This loss is to a 
certain extent minimized by the 
fact that, by the time mixing is 
carried out, the temperature of 
the sample will have dropped to 
approximately that of its sur-
roundings. 
In mills where sudden 
changes in varieties and condi-
tions occur, half an hour should 
be the maximum interval, whilst 
in others where conditions are 
comparatively uniform a one-hour 
period is permissible. The time 
schedule for sampling should be 
adhered to, irrespective of milling 
conditions, as long as the mill is 
crushing. The composite sample Fig. 37—Illustrating container recommended 
is preserved by means of a pad for compositing samples of bagasse. 
82 SAMPLING OF SUGAR MILL PRODUCTS 
s a t u r a t e d w i t h s t rong a m m o n i a a n d chloroform (p ropor t ions 6 : 1) or 
to luene . Whi le , a s m e n t i o n e d prev ious ly , final bagasse c a n be p r e s e r v e d 
for a r easonab le l eng th of t ime , four h o u r l y ana lys is per iods are cons ide red 
preferable to a once per shift ana lys is of t h e compos i te . 
Samples f rom earl ier mills in t h e t r a i n are usua l ly i n t e n d e d to s u p p l y 
t h e engineer w i t h specific in fo rmat ion a n d m a y n o t be i n t e n d e d for c o n t r o l 
purposes . However , so t h a t t hese samples can be rel iable, t h e y shou ld be 
t a k e n over a per iod of t i m e w i t h a shovel . I t i s i m p o r t a n t t h a t t h e full d e p t h 
of bagasse be s ampled since t h e t o p surface m a t e r i a l h a s a h igher ju ice c o n t e n t 
t h a n t h e r ema inde r . Also s a m p l i n g shou ld be ca r r i ed o u t across t h e full 
w i d t h of t h e roller. 
Filter Cake 
With the rotary filter, next to weighing at regular intervals the complete 
out-turn of cake in a given time, the following procedure is recommended. 
The length of the filter is divided into a suitable number of equal portions. 
At half hourly intervals the mud from one or more screen segments (depend-
ing on the size of the screens and the length of the portion) is caught on a 
suitable tray. This quantity of mud from the known area of screen is then 
weighed, and a small area removed by means of a sampler resembling a scone 
cutter. The weight of mud in each trayful is recorded and the small samples 
composited in a closed container for subsequent analysis. At the end of a 
period the total weight of cake produced by the filter can be calculated from 
the following expression:— 
where W = total weight of cake for the period, in tons 
w = average weight contained on mud sample tray in pounds 
n — revolutions of filter during period (preferably obtained 
from revolution counters) 
a = area of cake removed by the mud sample tray 
A = area of screen surface on the filter. 
The weight of pol in mud can then be calculated from the cake weight 
and the pol per cent cake determined on the composited sample. Composite 
mud samples cannot be effectively held for pol determination for periods 
much longer than four hours, and analysis of mud samples for pol twice per 
shift is recommended. 
Care of Samplers and Containers 
All sugar-mill products are susceptible to rapid deterioration due to 
bacterial activity; it is therefore imperative that all sample containers be 
maintained in a thoroughly clean condition and be subjected to frequent 
sterilization. Sample jars should be washed with hot water after each usage 
and thoroughly dried. Metal containers (preferably of stainless steel) should 
be frequently washed and steamed. 
Preservation of Samples 
Preservation of certain specific samples has been discussed in this 
chapter, but details of common preservatives and recommendations for their 
use will be found in the chapter on laboratory reagents. 
CHAPTER VIII 
LABORATORY REAGENTS 
This chapter has been re-arranged by listing, wherever possible, the 
various reagents under each specific analysis. Celite and Triethanolamine, 
for example, are included under the heading of "Filterability Determination". 
It is anticipated that this method of presentation will expedite analytical 
procedure. 
Poisons: A good analyst is familiar with the reagents being used and 
their individual properties. The repeated use of common reagents, however, 
Common Toxic Materials 
General Toxicity 
Highly toxic. Avoid inhalation of the vapour. 
Poisonous, combustible, volatile with steam. 
A narcotic agent with insidious chronic 
effects. 
Prolonged exposure to low concentrations 
can result in chronic irritation of the 
nervous system—an acute narcotic agent 
in high concentrations. 
Highly toxic gas. Not readily detected by 
the senses at a concentration of one p.p.m. 
Highly corrosive. Explosive when mixed 
with certain organic solvents. 
Toxic. Included in this table for compara-
tive purposes. 
A very poisonous gas. A chemical commonly 
taken too lightly. Higher concentrations 
are very dangerous as the sense of smell 
becomes paralysed. 
Cumulative poisons. Refer to the special 
precautions listed in this chapter. 
Highly toxic. Can be absorbed via the re-
spiratory tract or by contact with the 
skin. 
Corrosive to all tissues. Permanent damage 
to the respiratory tract can result from 
prolonged contact. 
Highly corrosive. Severe lung damage can 
result from inhalation of the vapour. 
Prolonged exposure to low concentrations 
can cause inflammation of nasal and 
throat tissues. 
Narcotic agent. Its toxicity is considered 
to be associated with the benzene concen-
tration present as an impurity. 
Highly toxic. Do not inhale or allow this 
chemical to come in contact Avith the skin. 
Parts of gas or vapour per million parts of air by volume. 
No specific level adopted at this stage by the National Health and Medical Re-
search Council of Australia. 
84 LABORATORY REAGENTS 
c a n t e n d t o al low a " f a m i l i a r i t y b r e e d s c o n t e m p t " a t t i t u d e t o ar ise . T h e 
m a j o r i t y of chemica l s u s e d in s u g a r l abo ra to r i e s a re highly toxic substances, 
a n d for t h e sa fe ty o f all concerned , t h i s p o i n t c a n n o t be e m p h a s i z e d t o o 
s t rong ly . Some gene ra l i n fo rma t ion on t h e t ox i c p rope r t i e s of some of t h e 
m o r e c o m m o n l y u s e d chemica l s i n s u g a r l abo ra to r i e s i s l i s ted a b o v e in t a b u l a r 
form. T h e m a x i m u m permiss ib le levels i n t h i s t a b l e a re t h e t h r e s h o l d l imi t 
va lues w h i c h h a v e been p r o p o s e d by t h e A m e r i c a n Conference o f G o v e r n -
m e n t a l I n d u s t r i a l Hyg ien i s t s , a n d w h i c h h a v e also been r e c o m m e n d e d b y t h e 
N a t i o n a l H e a l t h a n d Medical R e s e a r c h Counci l o f Aus t r a l i a . H o w e v e r , t h e 
fact t h a t a chemica l i s n o t l i s ted in t h i s t a b l e does n o t necessar i ly m e a n t h a t 
i t i s n o t tox ic , a n d all l a b o r a t o r y chemica l s a n d r e a g e n t s shou ld be h a n d l e d 
as i f t h e y were po isonous . W h e n k n o w n tox i c o r corros ive chemica l s a r e 
be ing used t h e wear ing o f t h e a p p r o p r i a t e p r o t e c t i v e e q u i p m e n t , s u c h as 
goggles, gloves, a n d r e sp i r a to r s , i s s t r ong ly r e c o m m e n d e d . 
B o i l e r W a t e r A n a l y s i s 
A l k a l i n i t y 
Barium Chloride Solution—Dissolve 10 g of b a r i u m chlor ide BaCl 2 . 2 H 2 0 
in dis t i l led w a t e r a n d d i lu t e t o 100 m l . 
Methyl Orange Indicator—Dissolve 0.10 g of m e t h y l o r ange in 100 ml of 
h o t w a t e r , cool, f i l t e r i f necessa ry a n d a d j u s t to v o l u m e . 
Phenolphthalein Indicator—Dissolve 1.0 g of p h e n o l p h t h a l e i n in 60 ml 
of i n d u s t r i a l m e t h y l a t e d sp i r i t s . W h e n dissolved, a d d 40 ml of w a t e r , m i x 
well, filter i f necessa ry a n d ad jus t to v o l u m e . 
Sodium Sulphate Crystals—Reagent g r a d e N a 2 S 0 4 . 1 0 H 2 O . 
Sulphuric Acid 0 . 0 2 N — D i l u t e 10.0 ml of 1 . 0 0 N s t a n d a r d su lphu r i c ac id 
to 500 ml w i t h dis t i l led w a t e r . T h e p r e p a r a t i o n o f 1 . 0 0 N s t a n d a r d acid i s 
desc r ibed elsewhere in th i s c h a p t e r . 
P h o s p h a t e 
Acid Molybdate Solution—Dissolve w i t h o u t h e a t i n g , 8.8 g of a m m o n i u m 
m o l y b d a t e in 100 ml of w a t e r . In a s e p a r a t e con t a ine r , careful ly a d d 38 ml 
of c o n c e n t r a t e d su lphu r i c ac id to a p p r o x i m a t e l y 300 ml of w a t e r . Al low t h e 
d i l u t ed acid t o cool t o r o o m t e m p e r a t u r e a n d t h e n t r ans fe r t h i s so lu t ion a n d 
t h e a m m o n i u m m o l y b d a t e t o a 500 ml v o l u m e t r i c flask. D i l u t e t o v o l u m e 
w i t h dist i l led w a t e r . 
Hydroquinone—Dissolve 0.5 g of h y d r o q u i n o n e in 50 ml of 0 . 0 2 N sul-
p h u r i c acid. S to r e in a d a r k or a m b e r co loured b o t t l e . 
Carbonate—Sulphite Solution—Dissolve 130 g of a n h y d r o u s p o t a s s i u m 
c a r b o n a t e a n d 24 g of s o d i u m su lph i t e ( N a 2 S 0 3 . 7 H 2 0 ) in 500 ml of w a t e r . 
H a r d n e s s 
Wanklyns Soap Solution—This is u sua l ly p u r c h a s e d as a p r e p a r e d r e a g e n t 
f rom a chemica l suppl ier . 
S o d i u m S u l p h i t e 
Potassium Iodate—Iodide Solution—Dissolve 0.713 g of p o t a s s i u m i o d a t e 
in 200 ml of w a t e r a n d t h e n a d d 7 g of p o t a s s i u m iodide a n d 0.5 g of s o d i u m 
b i c a r b o n a t e . W h e n dissolved, t r ans fe r to a one l i t re v o l u m e t r i c flask a n d 
d i lu t e t o v o l u m e . 
Starch Indicator Solution—Mix 0.5 g of soluble s t a r c h w i t h 5 ml of cold 
w a t e r , a n d t h e n a d d 100 ml o f boi l ing w a t e r . H e a t on a bo i l ing w a t e r b a t h 
LABORATORY REAGENTS 85 
for 5 m i n u t e s , cool a n d s to re in a refr igera tor . (A commerc i a l solid i n d i c a t o r 
p r e p a r a t i o n c a n also be used) . 
Sulphuric Acid, 6.5 per cent v/v.—Carefully a d d 65 ml of c o n c e n t r a t e d 
su lphur i c ac id to a p p r o x i m a t e l y 900 ml o f dis t i l led w a t e r . Cool to r o o m 
t e m p e r a t u r e a n d d i lu t e to a v o l u m e of one l i t re . 
S u l p h a t e 
Barium Chloride, 0 . 0 4 N — D i s s o l v e 4.886 g of b a r i u m chlor ide (BaCl 2 . 
2 H 2 0 ) in dis t i l led w a t e r a n d d i lu t e to a vo lume of one l i t re . 
EDTA—(Diaminoethanetetra—acetic acid, disodium salt), 0 . 0 2 N . — D i s -
solve 3.72 g of E D T A in dis t i l led w a t e r a n d d i lu t e to a vo lume of one l i t re . 
Hydrochloric Acid, 0 . 5 N approximately—Measure o u t 45 ml of concen-
t r a t e d hydroch lo r i c ac id (d 1.18) a n d p o u r i n t o a p p r o x i m a t e l y 500 ml of 
w a t e r . Mix a n d t h e n d i lu t e to a v o l u m e of one l i t re . 
Solochrome Black Indicator—Weigh o u t 0.5 g of so lochrome b lack 
W . D . F . A . a n d dissolve in a b o u t 2 ml of h o t w a t e r . A d d 10 g of s o d i u m chlor-
ide, m i x t h o r o u g h l y a n d d r y a t 105 °C. W h e n d r y , a d d 90 g of s o d i u m chlor ide 
a n d g r ind t ho rough ly . Th i s i nd i ca to r can also be p u r c h a s e d in t a b l e t form. 
Sulphate Buffer Solution—To 56.5 ml of a m m o n i a (d = 0.880) a d d 4.125 
g of a m m o n i u m chlor ide a n d m a k e up to 500 ml w i t h wa te r . A d d 3.72 g of 
E D T A , m i x a n d t h e n a d d 2.03 g of m a g n e s i u m chlor ide ( M g C l 2 - 6 H 2 0 ) . 
Buffer S o l u t i o n s 
pH 4 .00 Potassium Hydrogen Phthalate Buffer—Dissolve 10.21 g of d r y 
p o t a s s i u m h y d r o g e n p h t h a l a t e A .R . in freshly dis t i l led wa te r . D i lu t e to one 
l i t re . T h e pH of th i s so lu t ion is defined as be ing 4.00 a t 15 °C a n d 4.01 a t 30 °C. 
pH 6.85 Mixed Phosphate Buffer—Dissolve 3.402 g of p o t a s s i u m di-
h y d r o g e n p h o s p h a t e K H 2 P 0 4 a n d 4.45 g o f d i s o d i u m h y d r o g e n p h o s p h a t e 
N a 2 H P 0 4 . 2 H 2 0 in freshly dis t i l led w a t e r a n d d i lu t e t o one l i t re . The pH o f 
th i s buffer i s 6.85 a t 25 °C a n d i t h a s a negligible pH c h a n g e ove r t h e r a n g e 
of o r d i n a r y r o o m t e m p e r a t u r e . 
pH 9.18 Borax Buffer—Dissolve 19.071 g of s o d i u m b o r a t e N a 2 B 4 0 7 . 
1 0 H 2 O in f reshly dis t i l led w a t e r a n d d i lu te to one l i t re . T h e solut ion has a 
p H of 9.18 a t 25 °C a n d 9.07 a t 38 °C. 
C l a r i f i a b i l i t y T e s t 
Lime-Sucrose Reagent 
T w o solu t ions a re in i t ia l ly r e q u i r e d : 
Solu t ion A: Dissolve 150 g of refined s u g a r in a p p r o x i m a t e l y 60 ml of 
h o t w a t e r . 
So lu t ion B: Slowly add , w i t h s t i r r ing , 15 g of A . R . ca l c ium oxide to 
100 ml of a lmos t boi l ing w a t e r . 
Careful ly m i x so lu t ion B in to so lu t ion A. F i l t e r t h e h o t so lu t ion t h r o u g h 
a 633A or s imi la r t y p e of filter p a p e r u n d e r v a c u u m , us ing Superce l f i l ter a id. 
T h e filtered solut ion m u s t be s to red in a refr igerator , whe re i t will k e e p for 
a p p r o x i m a t e l y t h r e e weeks . 
F i l t e r a b i l i t y D e t e r m i n a t i o n 
Triethanolamine Buffer Solution—Two so lu t ions a r e p r e p a r e d s e p a r a t e l y 
in 50 p e r c e n t w / w glycerol so lu t ion . 
86 LABORATORY REAGENTS 
Solution A: Dissolve 15.0 g of A.R. calcium acetate in approximately 
300 ml of 50 per cent glycerol solution in a beaker. Mild heating may be used. 
Solution B: In a second beaker, dissolve 400 g of triethanolamine with 
approximately 200 ml of 50 per cent glycerol. 
N.B.—Triethanolamine can cause severe skin irritation. Avoid direct contact. 
Transfer solutions A and B to a one litre volumetric flask and use 
50 per cent glycerol to rinse both beakers and to dilute to volume. Mix well 
and allow to stand overnight. 
Add a small quantity of filter aid and filter. Store in a stoppered clear 
glass bottle. 
Celite—This is a standard filter aid No. 505, wrhich has been standardized 
by the C.S.R. Company. No other type of filter aid is directly applicable to 
this test. 
Glass Cleaning Solution 
Dissolve 80 g of potassium bichromate (K2Cr207) in 300 ml of water in a 
litre pyrex beaker and cool to room temperature. Carefully add 460 ml of 
concentrated sulphuric acid with stirring. The addition of the acid precipitates 
chromic acid, and the solution will act as an effective cleaning agent while 
red crystals of this compound are present. 
Glass cleaning solution is extremely toxic and highly corrosive. All 
necessary precautions should be observed and it is advisable to stand the 
bottle in a lead tray so that damage to bench surfaces can be minimized. 
Indicators 
The preparation and characteristics of indicators for selected pH ranges 
are listed below: 
Indicator 
Methyl Violet 
Ouinaldine Red 
Methyl Orange 
Bromphenol Blue 
Bromcresol Green 
Methyl Red 
Bromphenol Red 
Bromthymol Blue 
Phenol Red 
Cresol Red 
Phenolphthalein 
Thymolphthalein 
Alizarin Yellow 
Preparation 
0.25 g per 100 ml of water 
0.10 gin 100 ml of ethyl alcohol 
0.10 g per 100 ml of water 
0.10 g in 8.6 ml of 0.02 x. 
NaOH. Dilute to 250 ml with 
water. 
0.10 g in 7.15 ml of 0.02 N. 
NaOH. Dilute to 250 ml with 
water. 
0.10 g in 18.6 ml of 0.02 x. 
NaOH. Dilute to 250 ml with 
water. 
0.10 g in 9.75 ml of 0.02 x. 
NaOH. Dilute to 250 ml with 
water. 
0.10 g in 8.0 ml of 0.02 x. 
NaOH. Dilute to 250 ml with 
water. 
0.10 g in 14.2 ml of 0.02 N. 
NaOH. Dilute to 250 ml with 
water. 
0.10 g in 13.1 ml of 0.02 x. 
NaOH. Dilute to 250 ml with 
water. 
1.0 g in 60 ml of ethyl alcohol. 
Dilute to 100 ml with distilled 
water. 
0.10 g in 100 ml of ethyl 
alcohol. 
0.10 g in 100 ml of 50% ethyl 
alcohol. 
pH Range 
0.1—1.5 
1.4—3.2 
3.1—4.4 
3.0—4.6 
3.8—5.4 
4.2—6.2 
5.2—7.0 
6.0—7.6 
6.8—8.4 
7.2—8.8 
8.2—10.0 
9.3—10.5 
10.0—12.0 
Colour Change 
Yellow to blue 
Colourless to red 
Red to orange 
Red to orange 
Yellow to blue 
Red to yellow 
Yellow to red 
Yellow to blue 
Yellow to red 
Yellow to red 
Colourless to red 
Colourless to blue 
Yellow to lilac 
LABORATORY REAGENTS 87 
Phosphate Analysis 
Acid Molybdate Solution—Dissolve 16.6 g of ammonium molybdate in 
600 ml of distilled water. Gentle heating may be used, but the temperature 
must not rise above 60 °C. 
Carefully add 96 ml of concentrated sulphuric acid and cool. Dilute to 
one litre with distilled water. Store in a dark bottle in a cool place. 
Acid Reagent—Carefully add 96 ml of concentrated sulphuric acid to 600 
ml of distilled water. Cool and dilute to one litre. 
Acid Washed Supercel—Add 50 g of supercel to one litre of distilled 
water. Add 50 ml of concentrated hydrochloric acid and stir for 5 minutes. 
Vacuum filter the slurry and wash with distilled water until no trace of acid 
remains (silver nitrate test). Dry the supercel at 100 °C for 6 hours and 
store in a screw top jar. 
Amidol Reagent—Dissolve 1.0 g of amidol and 20 g of sodium metabi-
sulphite in distilled water. Dilute to a volume of 100 ml. Add a level teaspoon 
of acid washed supercel and filter under vacuum through two Whatman No. 5 
filter papers. Store in a dark bottle and hold under refrigeration. Prepare 
freshly each week. 
Standard Phosphate Stock Reagent—Dry approximately 2 g of A.R. potas-
sium dihydrogen phosphate (KH2P04) for 1 hour at 110 °C. Weigh out 
1.0984 g of the dried salt, dissolve in distilled water and dilute to 250 ml in 
a volumetric flask. This reagent contains 1.00 mg/ml of P and should keep 
for about two years if a few ml of chloroform are added and it is stored in a 
refrigerator. 
Standard Phosphate Solution—Pipette 10.0 ml of the stock reagent into 
a one litre volumetric flask and dilute to volume. This solution contains 
0.01 mg/ml of P and is used for the preparation of the standard phosphate 
graph as described in Chapter IX. 
Pol Determination 
Acetic Acid 1 + 4—This solution is usually prepared in relatively large 
quantities. Apart from its use in pol determinations, the solution is effective 
for removing precipitated lead salts from volumetric glassware. 
To prepare a litre of 1 + 4 solution, add 200 ml of glacial acetic acid 
to distilled water in a litre measuring cylinder and dilute to volume. 
Herles' Reagents—Two separate stock solutions are prepared in the 
following manner : 
Solution A—Dissolve 50 g of A.R. sodium hydroxide pellets with 
distilled water in a litre volumetric flask. Dilute to volume after cooling. 
Solution B—Dissolve 500 g of lead nitrate with distilled water in a litre 
volumetric flask. Dilute to volume. 
Reagent Check—Dispense an equal volume of solution A and solution B 
into a beaker. Determine the pH of the resultant mixture. If the value 
obtained is not below 7 pH, solution A must be diluted until the resultant 
mixture gives an acid reading. 
N.B.—Sodium hydroxide and lead nitrate are dangerous solutions when 
prepared to the above concentrations. They should not be dispensed with 
mouth aspirated pipettes. 
88 LABORATORY REAGENTS 
Lead Acetate 
Safety Precautions with Lead Compounds:—Lead sa l t s a re c u m u l a t i v e 
poisons a n d t h e following ru les shou ld b e obse rved w h e n a n y lead c o m p o u n d s 
o r so lu t ions con t a in ing l e a d a r e be ing used . 
1 . Vessels c o n t a i n i n g lead so lu t ions m u s t be label led " P o i s o n " . 
2 . Do n o t open con t a ine r s o f d r y lead a c e t a t e in an enclosed r o o m . 
Avo id b r e a t h i n g t h e fine d u s t o f th i s s u b s t a n c e , especia l ly w h e n 
t rans fe r r ing i t f rom one c o n t a i n e r t o a n o t h e r . 
3 . A l w a y s w a s h t h e h a n d s t h o r o u g h l y af ter h a n d l i n g d r y l ead a n d 
polar iz ing so lu t ions . 
4 . A v o i d wip ing t h e face or eyes w i t h a l a b o r a t o r y glass towe l a n d do 
n o t use these towels for w ip ing e a t i n g u tens i l s . 
5 . K e e p t h e r e a g e n t s a n d polar iz ing so lu t ions a w a y from c u t s o r a b r a -
sions. 
6 . Do n o t use po la r i za t ion filter-glasses for d r i n k i n g pu rposes . 
7 . T h e a p p a r a t u s a n d p rocedure s u s e d for p r e p a r i n g o r t r ans fe r r ing w e t 
o r d r y l ead shou ld b e such t h a t t h e r e i s n o r i sk t h a t a n a n a l y s t m a y 
inges t or a b s o r b a n y of t h e r e a g e n t . 
8. A s u p p l y of a n t i d o t e s shou ld be p r o v i d e d in a c e n t r a l p lace in a 
l a b o r a t o r y , t o g e t h e r w i t h i n s t r u c t i o n s a s t o h o w t h e y shou ld b e used , 
viz. 10 pe r cen t a q u e o u s m a g n e s i u m s u l p h a t e , followed by mi lk o r 
a l b u m e n in cold w a t e r . 
9 . A no t i ce c o n t a i n i n g t h e a b o v e p r e c a u t i o n s shal l be p o s t e d in a p r o m i -
n e n t p lace i n t h e l a b o r a t o r y . 
Basic Lead Acetate Powder—The m o r e i m p o r t a n t specif icat ions p e r t a i n -
ing to t h e q u a l i t y o f bas ic lead a c e t a t e p o w d e r a re shown b e l o w : 
T o t a l L e a d (as P b O ) * * : N o t less t h a n 75.0 pe r c e n t 
Bas ic L e a d (as P b O ) * * : N o t less t h a n 33.0 p e r c e n t 
Moi s tu re* : N o t m o r e t h a n 1.5 pe r cen t 
Inso lub le i n w a t e r : N o t m o r e t h a n 2.0 pe r cen t 
Inso lub le i n ace t ic a c i d : N o t m o r e t h a n 0.05 p e r cen t 
A n a d d i t i o n a l specification t o m e e t A u s t r a l i a n r e q u i r e m e n t s i s t h a t 
75 p e r cen t m u s t pass t h r o u g h a 115 m e s h T y l e r s ieve a n d 100 p e r cen t m u s t 
pass t h r o u g h a 35 m e s h T y l e r s ieve. 
*Mois ture is d e t e r m i n e d by d r y i n g 1 g of s a m p l e at 100 °C for 2 h o u r s . 
**Tota l a n d Bas ic L e a d are d e t e r m i n e d b y t h e N a t i o n a l B u r e a u o f S t a n d a r d s 
M e t h o d (based on Circular C.440p.p . 120-122). 
Basic Lead Acetate Solution (Wet Lead)— Dissolve 560 g of bas i c l ead 
a c e t a t e p o w d e r (conforming to t h e a b o v e r e q u i r e m e n t s ) in one l i t re o f f reshly 
boiled dis t i l led wa t e r , wh ich h a s p rev ious ly been cooled, in a sealed con ta ine r . 
Boi l for 30 m i n u t e s a n d al low to se t t l e ove rn igh t in a sealed con t a ine r . 
S t a n d a r d i z a t i o n : D e c a n t t h e s u p e r n a t a n t l iquid . D i l u t e w i t h freshly boi led 
dis t i l led w a t e r to 1.25 specific g r a v i t y (54 Br ix ) . 
T h e m e t h o d s of ana lyses p rev ious ly specified for bas i c l ead a c e t a t e 
p o w d e r a re aga in employed , w i th t h e v a r i a t i o n t h a t 25 ml o f we t l ead solut ion 
are s u b s t i t u t e d for t h e or iginal 5 g s ample we igh t . I C U M S A specifies t h a t w e t 
lead m u s t c o n t a i n b e t w e e n 9.6 a n d 10.5 g of bas ic lead (expressed as P b O ) 
pe r 100 ml of so lu t ion . I f t h e q u a n t i t y d e t e r m i n e d i s a b o v e th i s r a n g e , t h e 
ca lcu la t ed vo lume of glacia l ace t ic ac id shou ld be a d d e d a n d t h e ana lys i s 
r e p e a t e d . 
LABORATORY REAGENTS 89 
N.B.—The basic lead acetate solution should be stored in a stoppered con-
tainer and labelled "Poison". 
Neutral Lead Acetate Solution—A 10 per cent solution is used i.e. dissolve 
100 g of lead acetate Pb(C2H302)2 in distilled water and dilute to one litre. 
The pH of the solution is then determined and adjusted to 7.0 with either 
acetic acid or sodium hydroxide. 
Preservatives 
Mercuric Chloride—Highly toxic. Prepare a saturated solution of the salt 
in alcohol. Store in a suitable automatic dispenser and use at the rate of 
0.5 ml per litre of juice. 
N.B.—Mercuric chloride cannot be used in samples taken for reducing sugar 
analysis. 
Phenyl Mercuric Acetate {P.M.A.)—Prepare a solution containing 1 g of 
the salt per litre. Label "Poison" and store in a suitable automatic dispenser. 
The following table is presented as a rough guide for the preservation 
and storage of samples for routine mill analysis. The recommendations are of 
a general nature but should provide effective preservation of normal samples 
under average factory conditions. 
Preservation of Samples 
*The calculated amount of lead acetate should be added with each aliquot in order 
to avoid overleading of initial portions of the sample. 
90 LABORATORY REAGENTS 
Reducing Sugar Analysis 
Methylene Blue Solution—Dissolve 1 g of methylene blue powder in 100 
ml of distilled water. This reagent must be freshly prepared at least every six 
months. 
Phosphate-Oxalate, Deleading Solution—Dissolve 30 g of C.P. potassium 
oxalate (K2C004) in 400 ml of distilled water, and 70 g of disodium phosphate (Na2HP04 .12H20) in another 400 ml portion of distilled water. Pour the 
two solutions into a one litre volumetric flask, mix and dilute to volume. 
Fehling's Solution—Two reagents are separately prepared and mixed in 
equal volumes just prior to use: 
Fehling's A—Dissolve 34.639 g of C.P. copper sulphate (CuS04 .5H,0) 
in a 500 ml flask and dilute to volume. Filter through prepared asbestos. 
Fehling's B—Dissolve 173 g of Rochelle salt (sodium-potassium tartrate) 
in about 250 ml of water, mix with 100 ml of solution containing 50 g of 
sodium hydroxide, in a 500 ml volumetric flask. Allow to stand for two days. 
Dilute to volume and filter through prepared asbestos. 
Standard Invert Sugar Solution—Weigh out 9.500 g of A.R. sucrose and 
wash with approximately 100 ml of distilled water into a one litre volumetric 
flask. Dissolve by gently swirling the flask. 
Transfer 5.0 ml of concentrated hydrochloric acid into the volumetric 
flask. Stopper with a cotton wool plug. Allow the flask and contents to stand 
at room temperature from three to seven days, according to the prevailing 
temperature. 
In a separate operation, determine the volume of a prepared sodium 
hydroxide solution required to adjust 5.0 ml of concentrated hydrochloric-
acid to 3.0 pH. Use methyl orange as an indicator. Add the determined 
quantity of sodium hydroxide to the semi-prepared invert solution. 
Dissolve 2.0 g of benzoic acid in a beaker. Gentle heating may be used. 
Add the benzoic acid to the invert solution, cool and carefully dilute to a 
volume of one litre. The prepared invert solution now contains 1 gramme 
of invert sugar per 100 ml of solution. 
Standardization of Fehling' s Solution—Pipette 50.0 ml of standard invert sugar 
solution into a 250 ml volumetric flask. Add one drop of phenolphthalein 
indicator and carefully neutralize with 5 N sodium hydroxide solution. 
Dilute to volume with distilled water. Rinse and fill an offset burette with 
this solution. 
Pipette 5.0 ml of each of the Fehling's A and B solutions into a 200 ml 
conical boiling flask. Add approximately 24.5 ml of the neutralized standard 
invert. Heat to boiling and titrate in the manner described in Analytical 
Methods, Chapter IX. Repeat the determination until two successive titres 
agree to within 0.1 ml. 
The calculated titration value is 25.64 ml. If the actual result varies by 
more than 0.5 ml from this value, the strength of the Fehling's A must be 
adjusted. If the actual value is within the 0.5 ml range, but different from the 
calculated value of 25.64 ml, a correction factor must be calculated and 
applied to all determinations involving that batch of Fehling's solution. 
LABORATORY REAGENTS 91 
Standard Acids and Alkalis 
Sulphuric Acid 1.00 Normal (0.5 M)—Cautiously add 28 ml of concen-
trated sulphuric acid (Sp.Gr. 1.84) via a measuring cylinder to approximately 
900 ml of distilled water. Cool, transfer to a one litre volumetric flask and 
dilute to volume. 
Standardize as follows: Transfer 1.0599 g of predried A.R. sodium 
carbonate to a 300 ml Erlenmeyer flask. Add 100 ml of distilled water, dis-
solve and add 2 drops of methyl orange indicator. Titrate against the un-
standardized acid. The titration should require exactly 20.0 ml of 1.00 N 
sulphuric acid. Adjust the strength of the solution until this is obtained. 
Hydrochloric Acid 0.20 Normal (0.2 M)—Measure out 18 ml of concen-
trated hydrochloric acid (Sp.Gr. 1.18). Pour this into approximately 500 ml of 
water and then dilute to a volume of one litre in a measuring cylinder. Agitate 
to obtain thorough mixing. 
Standardize as follows: Weigh accurately two portions, each between 
0.240 and 0.280 g, of pre-dried A.R. sodium carbonate. Carefully transfer 
each to wide necked 250 ml conical flasks containing about 50 ml of distilled 
water. Swirl gently until dissolved. Add 3 drops of methyl orange indicator 
and titrate against the unstandardized acid until the colour changes from 
yellow to orange. 
If V ml of acid are used for titrating W g of sodium carbonate, then 
W Strength of acid (factor) F = 
° 0.010b x V 
From the two portions of sodium carbonate originally weighed out, two 
independent factors will be obtained. These should be in close agreement 
before the mean value of F is accepted. 
Adjustment—Note the volume of 0.2 N acid left in the one litre measuring 
cylinder (V ml). Add Y(F — 1) ml of water to it, mix well and repeat the 
standardization. The final factor (F) should be 1.00+0.005. 
Sodium Hydroxide, 0.20 Normal (0.2 M).—The water used for the prepa-
ration of this reagent must be free from dissolved carbon dioxide. If in doubt, 
boil the water just before use and cool to room temperature in a sealed vessel. 
Prepare a stock solution of sodium hydroxide by dissolving 53 g of the 
chemical in 50 ml of distilled water. Store in a polythene bottle for three days. 
Decant off 12 ml of the stock solution and transfer to a one litre meas-
uring cylinder. Dilute to volume and thoroughly mix. The solution is then 
standardized as follows: Pipette 25.0 ml of the diluted solution into a 250 ml 
conical flask and add 3 drops of methyl orange indicator. Titrate with 0.2 N 
hydrochloric acid until the colour changes from yellow to orange. Repeat the 
standardization. If V ml of acid (mean of the two determinations) are re-
quired, then 
Adjustment—Note the volume of 0.2 N sodium hydroxide left in the litre 
measuring cylinder (V ml). Add V(F — 1) ml of water to it, mix well and 
repeat the standardization. The final factor (F) should be 1.00^0.005. 
Sodium Carbonate 1.00 Normal (0.5 M)—The water for the preparation 
of this reagent must be free from dissolved carbon dioxide. If in doubt, boil 
the water just before use and cool to room temperature in a sealed vessel. 
92 LABORATORY REAGENTS 
W e i g h o u t 2.650 g of a n h y d r o u s s o d i u m c a r b o n a t e a n d dissolve in 
a p p r o x i m a t e l y 50 ml o f w a t e r . T rans fe r t h e so lu t ion to a 500 ml v o l u m e t r i c 
f l ask a n d d i l u t e to v o l u m e . Mix well a n d s to re in a g r o u n d glass s t o p p e r e d 
b o t t l e . 
S t a r c h A n a l y s i s — S u g a r 
Calcium Chloride Dihydrate Solution—To 530 g of U n i v a r ca l c ium chlor-
ide d i h y d r a t e , a d d 470 g of dis t i l led w a t e r . A d j u s t to 8.2 pH w i t h 1 N s o d i u m 
h y d r o x i d e . S to re in a sealed con ta ine r . 
Acetic Acid 1 N . — D i l u t e 57 ml of g lac ia l ace t ic ac id to a v o l u m e of 
one l i t re . 
Calcium Chloride—Acetic Acid Reagent—Add 11 ml of 1 N ace t ic ac id 
to one l i t re of ca lc ium chlor ide d i h y d r a t e so lu t ion . 
Potassium Iodate Solution 0.01 N . — W e i g h a c c u r a t e l y 0.3566 g of A . R . 
p o t a s s i u m i o d a t e a n d dissolve in a l i t re v o l u m e t r i c flask. D i lu t e to v o l u m e 
a n d p o u r i n t o a b r o w n glass s t o p p e r e d b o t t l e . S to re in a d a r k c u p b o a r d . 
Concentrated Potassium Iodide—10% W/V—Dissolve 10 g of A . R . p o t a s -
s i u m iodide in a 100 ml v o l u m e t r i c flask. S to r e in a p lace a w a y f rom l ight in a 
b r o w n glass s t o p p e r e d b o t t l e . Th i s r e a g e n t m u s t b e d i s ca rded w h e n t h e solu-
t ion becomes yel low. 
Potassium Iodide—Iodate Reagent—This r e a g e n t m u s t be p r e p a r e d on 
t h e d a y i t i s to be used . To one p a r t o f c o n c e n t r a t e d p o t a s s i u m iodide 10 pe r 
cen t so lu t ion a d d 9 p a r t s o f dis t i l led w a t e r a n d m i x . To t h i s so lu t ion a d d an 
e q u a l v o l u m e of 0.01 N p o t a s s i u m i o d a t e r e a g e n t . Mix a n d s to re in a b r o w n 
s t o p p e r e d b o t t l e for n o longer t h a n one d a y . 
Standard Starch Solution—Determine t h e m o i s t u r e c o n t e n t of t h e s t a r c h 
by d r y i n g 2 g at 105 °C for t w o h o u r s ; d i sca rd t h i s p o r t i o n . W e i g h i n t o a 30 
ml b e a k e r t h e q u a n t i t y of u n d r i e d s t a r c h e q u i v a l e n t to a d r y we igh t of 0 .400 
g . A d d 500 ml of d is t i l led w a t e r i n t o a conica l f lask a n d boi l gen t ly . A d d 5 ml 
of cold dis t i l led w a t e r to t h e we ighed q u a n t i t y of s t a r c h a n d m i x to a t h i n 
s lu r ry cons i s tency . T rans fe r t o t h e boi l ing w a t e r a s r a p i d l y a s possible . 
R e m o v e a n y res idua l s t a r c h f rom t h e beake r w i t h a d d i t i o n a l 5 ml a l i quo t s o f 
cold w a t e r . Boi l t h e so lu t ion for t h r e e m i n u t e s . T i m i n g shou ld c o m m e n c e 
f rom t h e first a d d i t i o n of s t a r c h to t h e boi l ing f lask . T rans fe r t h e ho t so lu t ion 
q u a n t i t a t i v e l y , v i a a funnel , to a one l i t re v o l u m e t r i c f lask, wh ich h a s p r e -
v ious ly been r insed w i t h h o t w a t e r . By w a y o f t h e or ig inal 30 ml b e a k e r , 
w a s h t h e boi l ing f l a s k w i t h h o t dis t i l led w a t e r a n d t r ans fe r t o t h e v o l u m e t r i c 
f l a sk . Con t inue t h i s o p e r a t i o n u n t i l t h e t o t a l v o l u m e in t h e f l a sk i s a p p r o x i -
m a t e l y 900 m l . Mix, cool i n r u n n i n g w a t e r a n d d i lu t e t o v o l u m e . S to re u n d e r 
ref r igera t ion. T h i s so lu t ion shou ld k e e p for one week . 
S u c r o s e A n a l y s i s 
Jackson and Gillis Hydrochloric Acid Solution—Dilute chemica l ly p u r e 
hydroch lo r i c acid to a specific g r a v i t y of 1.1029. Th i s is e q u i v a l e n t to 24.85 
B r i x a t 20 °C. 
Jackson and Gillis Sodium Chloride Solution—Dissolve 231.5 g of chemic -
a l ly p u r e s o d i u m ch lo i ide in dis t i l led w a t e r . D i l u t e to one l i t re in a v o l u m e t r i c 
flask. 
S u g a r D e t e c t i o n 
Alpha Naphthol—This so lu t ion d a r k e n s r a p i d l y on e x p o s u r e to l ight a n d 
shou ld be p r e p a r e d freshly each week. T h e so lu t ion is u sed at a r a t e of 5 d r o p s 
alcohol and dilute to volume with ethyl alcohol. 
Phenol Reagent—Dissolve 50 g of A.R. phenol in distilled water and 
dilute to one litre. 
N.B.—A.R. grade phenol is stipulated. If this is not available, redistillation 
of other grades of phenol should be carried out before it is used. 
This reagent is also used for the determination of alcohol precipitated 
gums. 
Water Analysis—Chlorides 
Potassium Chromate Indicator—Dissolve 5.0 g of potassium chromate 
(K2Cr04), in approximately 75 ml of distilled water. Add silver nitrate solu-
tion by drops, until a permanent brick-red precipitate is established. Cover 
the container and allow to stand overnight. Filter into a 100 ml volumetric 
flask and dilute to volume with distilled water. 
LABORATORY REAGENTS 93 
per sample. On this basis the quantity required can be estimated before 
the preparation of this reagent. It is also advisable to visually check that no 
haze forms when a crystal of silver nitrate is added to a sample of this water. 
Dry approximately 5 g of silver nitrate on a watch glass at 100 °C for 
15 minutes. Transfer to a desiccator and cool to room temperature. 
Weigh out 4.786 g of the dried chemical and transfer to a 1000 ml 
volumetric flask. Dissolve and dilute to volume. Store in a dark bottle away 
from light. 
Subject 
Brix 
P o l 
Dry Substance 
Bagasse Analysis 
Cane Analysis 
Sucrose-High Purity 
Materials 
Sucrose-Low Purity 
Materials 
ReducingJSugars 
A s h 
Sugar Analysis 
Mud Analysis 
Gums 
Phosphates 
Sugar in Effluents 
Quality of Mill Lime 
Caustic Cleaning Solution 
Laboratory SettlinglTest 
Cyclone Sampling and 
Supersaturation 
Boiler Water Analysis 
Water Analysis 
Contents 
Mill Products 
Dry Lead Method 
Normal Weight Method 
Herles' Method 
Notes on Pol Determination 
Pan Products 
Sand Method 
Josse Filter Paper Method 
Moisture 
P o l 
Pol by Disintegrator Method 
Brix by Disintegrator Method 
Pol in Open Cells 
Fibre 
Optical Invertase Method 
Jackson and Gillis Modification No. IV 
Chemical Method 
Dane and Eynon Method 
Gravimetric Method 
Conductometric Method 
Polarization 
Moisture 
Filtcrability 
Grain Size 
Starch 
Total Colour Attenuation 
Insoluble Solids—Vacuum Filtration Method 
Insoluble Solids—Aluminium Dish Method 
Moisture 
P o l 
Fibre 
Determination of Gums in Juice 
Total Phosphate in Raw Sugar 
Total Phosphate in Syrups and Clarified Juice 
Total Phosphates in Juices 
Soluble and Insoluble Phosphate 
Phenol-Sulphuric Acid Method 
Bartholomae Method 
Alpha-Naphthol Test 
Neutralizing Value 
Available CaO 
Determination of Concentration 
C.S.R. Procedure 
Pressure Filtering Device 
Theory of Supersaturation 
Saturation Cell 
Alkalinity 
Phosphate 
Sulphite 
Hardness 
Total Dissolved Solids 
Sulphate 
Chlorides 
Page 
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CHAPTER IX 
ANALYTICAL METHODS 
The various methods of analysis have been grouped under headings, 
for ease of reference and are located as follows: — 
ANALYTICAL METHODS 95 
T h e p rev ious E d i t i o n l is ted t h e va r ious ana lyses wh ich wou ld be r equ i r ed 
for e ach p r o d u c t "if a c o m p l e t e chemica l con t ro l on all f ac to ry ope ra t i ons 
were t o b e o b t a i n e d . . . " T h e a d v a n c e s o f t he las t decade i n m a t t e r s p e r t a i n -
ing t o f ac to ry efficiency a n d suga r q u a l i t y h a v e however , r e su l t ed i n t h e 
i n t r o d u c t i o n of m a n y n e w m e t h o d s of ana lys i s to our I n d u s t r y . As far as 
possible t h e l a t e s t m e t h o d s o f ana lys i s h a v e b e e n i nc luded in t h i s c h a p t e r . 
I t i s real ized t h a t local cond i t ions m a y necess i t a te smal l dev i a t i ons f rom 
r e c o m m e n d e d m e t h o d s , a n d t h a t t h e f r equency w i t h wh ich ana lyses for 
r o u t i n e con t ro l pu rposes a re car r ied o u t is a ques t i on wh ich should be left 
to t h e d i sc re t ion of t h e chemis t in cha rge of each fac to ry . A fac tor for con-
s idera t ion in th i s r ega rd however , i s t h a t whi le t h e f requen t ana lys i s of ce r ta in 
p r o d u c t s i s essent ia l for b o t h r o u t i n e con t ro l a n d record keep ing pu rposes , 
t h e p r ac t i c a l va lue of each ana lys is shou ld be cons idered a n d t h e genera l 
l a b o r a t o r y r o u t i n e rev iewed from t i m e to t i m e . I f p rocedu re s a re no t reviewed, 
t h e s i t ua t i on c a n arise where a la rge n u m b e r of ana ly t i ca l d a t a is compi led 
on samples wh ich m a y b e a r l i t t le o r no re l a t ionsh ip t o t h e a c t u a l m a t e r i a l i n 
process . T h e m o r e p rac t i ca l s y s t e m is one which p e r m i t s sufficient ana lyses 
for bas ic cont ro l , a n d wh ich still l eaves some t i m e for t h e a n a l y s t s to s t u d y 
va r ious a spec t s o f t h e process which m a y w a r r a n t inves t iga t ion . 
T h e form of p r e s e n t a t i o n h a s been rev iewed whe reve r possible in th i s 
C h a p t e r i n a n e n d e a v o u r t o assist b o t h t h e a n a l y s t a n d t h e s t u d e n t t o o b t a i n 
a brief r e s u m e of t h e genera l pr inc ip les of each m e t h o d , m e r e l y by reference 
t o t h e a p p r o p r i a t e sub -head ings . Some m e t h o d s h a v e been condensed for 
sake of b r e v i t y , a n d a l t h o u g h t h e essent ia l de ta i l s a n d p rocedures h a v e been 
r e t a ined , a n a l y s t s en t i r e ly unfami l i a r w i t h a specific ana lys i s a re adv i sed to 
resor t to or iginal pub l i ca t ions to o b t a i n a m o r e comprehens ive b a c k g r o u n d 
of t h e f u n d a m e n t a l s of t h e p a r t i c u l a r m e t h o d . 
A d d i t i o n s t o th i s C h a p t e r s ince t h e F o u r t h E d i t i o n h a v e been o b t a i n e d 
f rom t h e Colonial Suga r Ref ining C o m p a n y L imi t ed , t h e Suga r R e s e a r c h 
I n s t i t u t e a n d va r ious o t h e r sources . The i r permiss ion t o pub l i sh these 
m e t h o d s is gra te fu l ly acknowledged . T h e l ibera l use of t h e 1964 E d i t i o n of 
t h e I C U M S A M e t h o d s of Suga r Analys is , a n d t h e R e p o r t of t h e P roceed ings 
of t h e F o u r t e e n t h Session of I C U M S A 1966, as reference s t a n d a r d s is also 
acknowledged . 
B r i x 
T h e m e t h o d of Br ix d e t e r m i n a t i o n is d e p e n d e n t u p o n the t y p e of ana lys i s 
to be per fo rmed . T h e m a j o r i t y o f B r i x d e t e r m i n a t i o n s a re usua l ly car r ied o u t 
by m e a n s of a B r i x h y d r o m e t e r , b u t in d i rec t c ane analys is , for example , 
B r i x i s d e t e r m i n e d b y precision re f rac tomete r , o r b y p y c n o m e t e r . 
B r i x b y H y d r o m e t e r 
M a n y samples such a s juice, m a c e r a t i o n f lu id a n d s y r u p are sufficiently 
low in v iscos i ty for a d i rec t h y d r o m e t e r d e t e r m i n a t i o n to be car r ied ou t . 
Samples of r e l a t ive ly h igh viscosi ty , such as massecu i t e s a n d molasses , re -
qu i re pr ior d i lu t ion w i t h w a t e r in a k n o w n w reight to weigh t r a t i o . F o r 
pu rposes of u n i f o r m i t y t h e s t a n d a r d degree of d i lu t ion in Queens land is one 
p a r t of w a t e r to one p a r t of s ample i.e. a 1:1 d i lu t ion , a n d th i s is accompl i shed 
as fo l lows:— 
T a r e a c o n t a i n e r of a c a p a c i t y in excess of one l i t re on a su i t ab le ba l ance . 
Mix t h e s a m p l e a n d a d d 500.0 g t o t h e t a r e d con ta ine r . A d d a p p r o x i m a t e l y 
300 ml of h o t w a t e r a n d s t i r u n t i l d i sso lu t ion i s c o m p l e t e . Cool a n d fu r the r 
d i l u t e t h e c o n t e n t s w i t h cold w a t e r to a t o t a l we igh t of 1000.0 g . T h o r o u g h l y 
96 ANALYTICAL METHODS 
m i x t h e so lu t ion . W h e n t h e B r i x r e a d i n g i s f i n a l l y t a k e n , t h e r e a d i n g o f t h e 
d i l u t ed s a m p l e m u s t b e co r r ec t ed for t e m p e r a t u r e . Th i s t e m p e r a t u r e -
co r rec t ed B r i x i s t h e n mu l t i p l i ed by a fac tor of t w o to o b t a i n t h e B r i x of 
t h e or iginal s amp le . 
Preparation—The p r o c e d u r e defined in R e g u l a t i o n 57 of t h e S u g a r Cane 
Pr ices A c t for t h e d e t e r m i n a t i o n of B r i x for cane p a y m e n t pu rposes appl ies 
i n pr inc ip le t o all B r ix d e t e r m i n a t i o n s b y h y d r o m e t e r , n a m e l y : — 
"A b r ix ing cyl inder , d r y o r wel l -dra ined , i s se t up a n d , w i t h o u t s t i r r ing , 
sufficient of t h e s ample ju ice is p o u r e d in to f i l l t h e cy l inder . I f a n y app rec i ab l e 
q u a n t i t y of bagasse , t r a s h , or o the r foreign m a t t e r i s s u s p e n d e d in t h e ju ice , 
t h e ju ice shou ld be d e c a n t e d t h r o u g h a s t r a ine r i n t o t h e cy l inder . 
T h e cy l inder a n d c o n t e n t s a re a l lowed to r e m a i n u n d i s t u r b e d for 20 
m i n u t e s o r t h e c o n t e n t s m a y be p laced u n d e r a p ressure n o t exceed ing 10 in. 
Hg abs . for a per iod of 5 m i n u t e s . In t h e l a t t e r case t h e ju ice m u s t be a l lowed 
to s t a n d u n t i l a t least 20 m i n u t e s h a v e e lapsed since t h e ju ice w a s las t 
s t i r r ed . . . " 
T h r e e i m p o r t a n t facets o f t h e d e t e r m i n a t i o n a re as fo l lows :— 
Temperature—The t e m p e r a t u r e of t h e so lu t ion m u s t be a p p r o x i m a t e l y 
t h a t of t h e s u r r o u n d i n g s . I f i t i s too h igh , t h e so lu t ion m u s t be cooled, a n d 
ca re shou ld be t a k e n to ensu re t h a t t h e en t i re s a m p l e i s cooled un i fo rmly . 
P re fe rab ly t h e c o n t e n t s o f t h e cy l inder shou ld be t h o r o u g h l y m i x e d af ter 
cooling. 
Suspended Matter—Coarse par t ic les in t h e s ample a re r e m o v e d by s t r a in -
ing t h r o u g h a f ine m e s h gauze as t h e s ample i s be ing p o u r e d i n t o t h e cy l inder . 
T h e h e a v y par t ic les o f smal le r size t h a t pass t h r o u g h t h e s t r a ine r will u sua l ly 
se t t le in t h e b o t t o m of t h e cy l inder d u r i n g t h e ob l iga to ry 20 m i n u t e s s t a n d i n g 
per iod. Some par t ic les h o w e v e r will still r e m a i n in suspens ion . These can 
h a v e a signif icant effect on t h e h y d r o m e t e r r e a d i n g a n d s hou ld be r e m o v e d 
by e i the r f i l t ra t ion or cent r i fuging i f precise r e su l t s a re r equ i r ed . 
Air Bubbles—Samples of b o t h low a n d high Br ix fluids f r equen t ly c o n t a i n 
a cons iderab le q u a n t i t y of air b u b b l e s at t h e t i m e of s ampl ing . F u r t h e r a i r 
can also be e n t r a p p e d in t h e process of p o u r i n g t h e l iquid i n t o t h e cy l inder . 
R e m o v a l of th i s a i r is accompl i shed e i ther by t h e app l i ca t ion of v a c u u m or 
by a l lowing t h e s ample to s t a n d for 20 m i n u t e s a s se t o u t in t h e R e g u l a t i o n . 
Procedure—The c leaned, d r ied h y d r o m e t e r shou ld be lowered i n t o t h e cyl in-
der , caus ing t h e l iqu id to overflow a n d c a r r y a w a y w i t h i t a n y f ro th f loat ing 
on t h e surface. T h e h y d r o m e t e r i s lowered u n t i l i t f loa t s freely, a n d ca re 
should be t a k e n to see t h a t t h e s t e m is w e t t e d for o n l y a few t e n t h s of a u n i t 
above t h e p o i n t a t wh ich t h e h y d r o m e t e r comes to res t . I f i n t h e a b o v e 
ope ra t ion t h e h y d r o m e t e r s t e m is w e t t e d m o r e t h a n a few t e n t h s of a u n i t 
a b o v e t h e men i scus , t h e r e a d i n g shou ld b e n o t e d , t h e h y d r o m e t e r lifted, a n d 
t h e e m e r g e n t po r t i on o f t h e s t e m wiped d r y . T h e h y d r o m e t e r i s t h e n careful ly 
lowered to t h e r e a d i n g f i r s t obse rved . 
I f t h e r e i s a n y apprec iab le difference in t e m p e r a t u r e b e t w e e n t h e so lu t ion 
a n d t h e h y d r o m e t e r , t h e l a t t e r should b e a l lowed t o f l o a t freely u n t i l t e m p e r -
a t u r e equ i l ib r ium is es tab l i shed . 
I f t h e so lu t ion i s c lear a n d l ight co loured t h e po in t a t wh ich t h e p l ane 
of t h e l iqu id surface would in te r sec t t h e scale i s r e ad i l y obse rved . F r e q u e n t l y 
t h e r e a d i n g of t h e u p p e r edge of t h e men i scus m u s t be t a k e n a n d a co r rec t ion 
appl ied . F o r t h e class o f h y d r o m e t e r genera l ly used in Q u e e n s l a n d t h e men i s -
cus cor rec t ion i s close to + 0 . 1 5 ° Br ix , so t h a t i f r e ad ings a re to be m a d e to 
t h e nea re s t 0.1° i t i s just i f iable to a d d e i the r 0.1° or 0.2° accord ing to t h e 
Significance of the Brix Determination—The d e t e r m i n a t i o n of B r i x as a sepa-
r a t e e n t i t y can be of i m p o r t a n c e in m e a s u r i n g such fac tors as B r i x of masse -
cui te , Br ix of m a c e r a t i o n fluid e tc . B r i x m e a s u r e m e n t however , i s n o r m a l l y 
assoc ia ted w i t h t h e d e t e r m i n a t i o n of po l in o rde r to o b t a i n a m e a s u r e of t h e 
q u a n t i t y of impur i t i e s p resen t in a so lu t ion . In th i s regard , t h e associa t ion of 
a B r i x t e s t w i th t h e d e t e r m i n a t i o n of pol by t h e d r y lead m e t h o d h a s a d u a l 
pu rpose . T h e Br ix o f t h e so lu t ion i s o b t a i n e d , a n d , in add i t i on , t h e B r i x 
r e a d i n g is used to give a m e a s u r e of t h e d e n s i t y of t h e solut ion, a n d hence t h e 
we igh t of 100 ml of t h e so lu t ion in air . 
A Br ix h y d r o m e t e r is, of course , c a l i b r a t ed in degrees Br ix , b u t e v e r y 
g r a d u a t i o n cor responds to a p a r t i c u l a r dens i ty . W h e n a h y d r o m e t e r ca l i b r a t ed 
at 20 °C i m m e r s e d in a l iquid at 20 °C r eads , for e x a m p l e , 25.0 °Brix , i t is 
e s tab l i shed t h a t t h e d e n s i t y of t h e so lu t ion is 1.103557 g p e r m l . If t h e 
h y d r o m e t e r itself were no t affected by t e m p e r a t u r e , t h e n i r respec t ive o f t h e 
t e m p e r a t u r e of t h e so lu t ion , a r e a d i n g of 25.0° would ind ica t e a d e n s i t y of 
1.103557 g pe r ml . In a c t u a l fact , t h e h y d r o m e t e r itself is affected v e r y l i t t le 
b y t e m p e r a t u r e ; t h e s u b s t a n t i a l t e m p e r a t u r e cor rec t ions wh ich a r e app l i ed 
to obse rved Br ix r ead ings (for t e m p e r a t u r e s o the r t h a n 20 °C), a re d u e a l m o s t 
en t i r e ly to t h e effect of t e m p e r a t u r e on t h e suga r so lu t ion and , for p rac t i ca l 
purposes , t h e t e m p e r a t u r e coefficient of v o l u m e of t h e h y d r o m e t e r is ignored, 
a n d a r e a d i n g at t °C is t a k e n as an i n d e x of t h e d e n s i t y of t h e so lu t ion 
a t t °C. 
P o l 
T h r e e m e t h o d s for t h e d e t e r m i n a t i o n of pol in ju ices a n d s imi lar l iqu ids 
con ta in ing up to 25 pe r cen t sucrose a re l is ted in th i s E d i t i o n . In t h e first 
m e t h o d a n d one vers ion o f t h e t h i r d m e t h o d , t h e B r i x o f t h e s ample m u s t 
also be d e t e r m i n e d . 
T h e use of t h e d r y lead m e t h o d i s ob l i ga to ry for f i r s t expressed ju ice 
ana lyses for cane p a y m e n t purposes . O n l y i f unsa t i s f ac to ry clarif ication is 
o b t a i n e d b y t h e d r y lead m e t h o d m a y t h e o the r m e t h o d s b e used . 
T h e specification of lead a c e t a t e p u r i t y a n d t h e p r e p a r a t i o n of He r l e s ' 
r e a g e n t s a re l is ted i n C h a p t e r V I I I . 
D r y L e a d M e t h o d 
In o rde r to o b t a i n t h e po l p e r cen t of a so lu t ion , a s e p a r a t e B r i x de te r -
m i n a t i o n i s r equ i r ed w i t h th i s m e t h o d . In t h e p r o c e d u r e ou t l ined below, 
a t t e n t i o n i s d r a w n to t w o aspec t s , t h e add i t i on o f lead a c e t a t e p o w d e r a n d 
t h e choice o f con ta ine r . T h e q u a n t i t y o f lead a c e t a t e a d d e d shou ld be j u s t 
ANALYTICAL METHODS 97 
r e a d i n g a t t h e t o p of t h e men i scus . W h e n e v e r possible an effort shou ld be 
m a d e t o e s t i m a t e t h e t r u e po in t a t wh ich t h e surface p l a n e wou ld in t e r sec t 
t h e scale. Th i s e l imina tes a n y d o u b t s a s t o w h e t h e r t h e men i scus cor rec t ion 
shou ld be 0.1 o r 0.2. In a n y case, t h e r e a d i n g a t t h e t o p o f t h e men i scus shou ld 
n e v e r be se t d o w n as a resu l t , b u t shou ld be cor rec ted m e n t a l l y before be ing 
e n t e r e d on t h e records a s obse rved Br ix . 
The t e m p e r a t u r e o f t h e so lu t ion shou ld be d e t e r m i n e d i m m e d i a t e l y t h e 
h y d r o m e t e r r e a d i n g h a s been m a d e a n d t h e necessa ry cor rec t ion app l i ed t o 
give t h e t r u e Br ix va lue . E x a m p l e : — 
Values of apparent density at 20 °C for corresponding Brix values are avail-
able from Table XV. 
Normal Weight Method 
This method is not recommended for general use, but it occasionally has 
some application where, for example, the pol per cent of a juice is required 
without an accompanying Brix determination. 
Unlike the previous method, the normal weight method is affected by 
the presence of insoluble matter in the juice, and also by the volume of 
precipitate formed when wet lead clarification is used. 
Procedure—Transfer three normal weights of juice (78.00 g) to a 100 ml 
volumetric flask. Wash in any residual juice with a small quantity of distilled 
water. 
Addition of Lead Acetate—Two alternatives are available: 
A. Dry Lead—Dilute the flask contents to 100 ml with distilled water 
and then add approximately 0.8 g of dry lead acetate. 
Shake thoroughly, allow to stand and filter as in the previous method. 
Read in a 200 mm tube. 
B. Wet Lead—Add 2 ml of wet lead solution and then dilute to the 
100 ml mark. Shake, allow to stand and filter. Read in a 200 mm tube. 
98 ANALYTICAL METHODS 
sufficient to achieve satisfactory clarification, and overleading must be 
avoided. 
The most suitable container for this determination is a flat-bottom 
conical flask of approximately 150 ml capacity, with a neck opening just wide 
enough to permit easy addition of the lead powder, but narrow enough to be 
easily stoppered for the purpose of shaking the contents. 
Procedure—Transfer approximately 100 ml of juice to a flask. Add 1 g 
of dry lead acetate, stopper and shake vigorously. Allow a reaction time of 
several minutes. A further mixing of the contents at this stage is re-
commended. 
Filter. Add the juice to a maximum safe level and cover the top of the 
filter to minimize evaporation. Discard the first 10 ml of filtrate, and read the 
optical rotation of the solution in a 200 mm tube. 
Calculation—This is simplified by the use of Schmitz's Table for undiluted 
solutions (Table II), which has been derived from the formula— 
The table is used in the following manner:— 
Suppose the uncorrected Brix = 18.1 (without temperature correction) 
and the polariscope reading = 60.5 CS. Under the column headed 18 (the 
closest approximation provided) and opposite 60 (the whole number of the 
polariscope reading), the value of 14.57 is found. Add to this the amount of 
0.12 (equivalent to 0.5 pol reading found in the inset table for tenths of a 
degree pol reading). The pol of juice then = 14.57 + 0.12 = 14.69. 
If it is desired to work out results for cases not shown in Schmitz's 
Tables, the pol may be derived from the formula— 
B. Volumetric Method—A separate Brix measurement is required in 
this case. 
Procedure—Add 50 ml of juice into a 100 ml volumetric flask. Proceed as 
above to the stage where a polariscope reading is obtained. 
Calculation—Multiply polariscope reading by 2. 
Refer to Schmitz's table (Table II) and derive pol per cent juice from 
the undiluted polariscope reading and the uncorrected Brix of the sample. 
Notes on Pol Determination 
Of the three methods described, the dry lead method is preferred and 
is used almost exclusively throughout the Industry. The notable exception 
to this is when juices from canes in an advanced stage of deterioration are 
encountered. In this instance, Herles' method will generally prove to be the 
most effective. 
The formula on which Schmitz's Table is based, namely— 
ANALYTICAL METHODS 99 
Herles' Method 
This method has been found to be of considerable benefit for clarifying 
juices that will not respond satisfactorily to lead acetate addition. 
Two variations of the method are presented: 
A. Gravimetric Method— 
Procedure—Weigh out 2 normal weights of juice into a 100 ml volumetric 
flask. 
Add 5 ml of reagent B, followed by 5 ml of reagent A. (Chapter VIII : 
Herles' reagents). Add distilled water short of the mark and mix well by 
swirling. Dilute to 100 ml. 
Mix, filter and polarize in a 200 mm tube. 
should theoretically be applied only when solutions are analysed at 20 °C. 
At temperatures other than 20 °C however, the influences of polariscope and 
tube coefficients are very minor items in practice, and the formula is used as 
if it were independent of temperature, with the one qualification that the 
polariscope reading and Brix determination are carried out at the same 
temperature. 
However, while the use of the observed Brix compensates adequately for 
the changes in density of undiluted juice at different temperatures, the effects 
of temperature on the optical rotation of sucrose, reducing sugars, etc., must 
also be considered. Sucrose solutions display a rotation which decreases with 
temperature. Invert sugar solutions display a much higher change of rotation 
in the reverse direction. When the reducing sugars (considered as invert sugar) 
constitute 6f per cent of the sucrose, the temperature coefficient of the 
mixture vanishes. 
An empirical formula suggested for the correction of the observed polar-
ization of juices as read in a quartz wedge compensated saccharimeter is 
100 ANALYTICAL METHODS 
N o t e t h a t w h e n t h e po la r i scope r e a d i n g i s 80, t h e co r rec t ion i s zero. T h e 
polar i scope r ead ings o f u n d i l u t e d ju ices a p p r o x i m a t e to 80 so t h a t , a cco rd ing 
to t h i s formula , t h e omiss ion of a t e m p e r a t u r e co r r ec t ion is just i f ied. H o w e v e r , 
i n d i v i d u a l s amp le s o f ju ices h a v e b e e n found to d i s p l a y signif icant t e m p e r -
a t u r e coefficients a n d t h e p r a c t i c e o f c o n d u c t i n g ju ice ana ly se s a t o r n e a r 
20 °C is r e c o m m e n d e d . 
T h e d e t e r m i n a t i o n of t h e po l of o t h e r m a t e r i a l s i s bes t d i scussed in 
re la t ion to specific p r o d u c t s as follows:—• 
P a n P r o d u c t s * 
F o r t h e d e t e r m i n a t i o n of pol in p a n p r o d u c t s , b o t h t h e c o n c e n t r a t i o n of 
so lu t ion a n d t h e a m o u n t o f clar ifying a g e n t m u s t be v a r i e d t o su i t t h e n a t u r e 
of t h e p r o d u c t . F o r p u r p o s e s of un i fo rmi ty , t h e following d i lu t ions a n d 
a m o u n t s o f d r y lead a r e sugges ted . These s hou ld be a d e q u a t e for t h e m a j o r i t y 
of samples e n c o u n t e r e d in each ca t ego ry . 
Product 
Syrup 
A and B Massecuite 
A and B Molasses 
Magma 
C Massecuite 
Final Molasses 
Aliquot 
1 normal weight of straight syrup/100 ml 
1 normal weight of 1:1 dilution/100 nil 
1 normal weight of 1:1 dilution/100 ml 
1 normal weight of 1:1 dilution/100 ml 
2 normal weights of 1:1 dilution/300 ml 
2 normal weights of 1:1 dilution/300 ml 
Weight of 
Dry Lead 
1 g 
3 g 
2 g 
5 g 
8 g 
T h e effects of ove r l ead ing a re m o r e p r o n o u n c e d in C massecu i t e a n d 
final molasses ana lyses a n d a cons iderab le inflat ion of t h e pol r e a d i n g s can 
resul t . F o r C m a s s e c u i t e a n d final molasses an a d d i t i o n a l s t e p shou ld be 
emp loyed in t h e d e t e r m i n a t i o n as follows: — 
After n o r m a l l ead ing a n d f i l t ra t ion, a d d 50 ml of t h e f i l t ra te to a 50-55 ml 
vo lume t r i c flask. T h e n a d d 2 ml of 1 + 4 ace t i c ac id r e a g e n t a n d d i l u t e to 
55 ml w i t h dis t i l led w a t e r . Mix t h o r o u g h l y a n d polar ize in a 200 mm t u b e . 
T h e ca lcu la t ion for t w o n o r m a l we igh t s in 300 ml of 1:1 d i l u t e d s a m p l e 
a n d f i l t ra te d i lu t ion f rom 50 to 55 ml t h e n b e c o m e s 
P o l p e r cen t = pol r e a d i n g X 3.3 
T h i s a d d i t i o n a l s t e p i s necessa ry d u e to t h e r e l a t i ve ly h igh c o n c e n t r a t i o n 
of laevulose in t he se p r o d u c t s . L e a d in so lu t ion c o m b i n e s w i t h laevulose to 
give a soluble c o m p o u n d of low o p t i c a l r o t a t i o n . Ace t i c ac id sp l i t s up t h i s 
c o m p o u n d , t h e r e b y r e s to r ing t h e r o t a t i o n o f t h e laevulose . 
D r y S u b s t a n c e 
T h r e e m e t h o d s a re ava i l ab le for t h e d e t e r m i n a t i o n o f d r y s u b s t a n c e by 
d r y i n g u n d e r con t ro l l ed cond i t ions , t h e S a n d m e t h o d , t h e T a t e a n d Ly le 
V a c u u m O v e n M e t h o d , (De W h a l l e y 1964), a n d t h e J o s s e F i l t e r P a p e r m e t h o d . 
O f t h e t h r e e , t h e Josse F i l t e r P a p e r m e t h o d w i t h v a c u u m d r y i n g i s cons idered 
t o be t h e m o s t su i t ab l e for Q u e e n s l a n d cond i t i ons . T h e S a n d m e t h o d i s st i l l 
u sed b y some factor ies , b u t i t s r e p l a c e m e n t b y t h e Josse F i l t e r P a p e r m e t h o d 
i s r e c o m m e n d e d . 
S a n d M e t h o d 
Sand Preparation—A s u p p l y of fine p r e p a r e d s a n d is r e q u i r e d . T h e re -
c o m m e n d e d m e t h o d of p r e p a r a t i o n is as fo l lows:— 
ANALYTICAL METHODS 101 
Use only sand that will pass through a 40 mesh and be retained on a 60 
mesh screen. Digest the sand in hot hydrochloric acid, and then wash in 
running water until the tailings will not give a positive reaction with silver 
nitrate. Oven dry and then ignite in a muffle furnace at a temperature in 
excess of 600 °C. 
Special Apparatus—Flat bottomed aluminium dishes, approximately 
three inches in diameter with 3/4 inch vertical walls and close fitting lids, are 
used for the determination. A glass stirring rod of such a length that it will 
just fit inside the dish on a slope is also required. 
Procedure—Pre-dry approximately 50 g of sand in the aluminium dish. 
Allow to cool in a desiccator just prior to use. Weigh dish plus sand and stirrer. 
Add a known weight of sample. This varies from 10 g for juices to 6 to 10 g 
of 1:1 dilution for massecuites and molasses. Mix sand and sample thoroughly 
with the glass stirring rod. Great care must be taken during this operation 
to avoid any loss of sand. 
Dry, either in a hot air oven at 103-105 °C for four hours, or preferably, 
under a vacuum of 28 inches Hg at 70 °C until successive weighings at two 
hourly intervals do not differ by more than 0.5 mg. This usually takes about 
16 hours. The air bleed into the oven should be fitted with a double calcium 
chloride drying tower. After completion of drying, replace the lid and allow 
to cool to room temperature in a desiccator. Complete the final weighing with 
a minimum of delay. Calculate the weight of dry solids and express as a 
percentage of the weight of the original undiluted sample. 
Josse Filter Paper Method 
The determination of dry substance by this or any other drying method 
can be subject to errors from various sources, unless analytical procedure, 
drying conditions and timing between operations are rigidly controlled. 
Two of the main sources of error in this regard are evaporation effects be-
tween addition and weighing of sample, and re-absorption after drying. 
Special Apparatus—Glass weighing bottles approximately 3 cm diameter 
and 7 cm in height with ground glass stoppers are required. Strips of filter 
paper 60 x 4.5 cm are rolled in loose coils and placed inside the bottles. 
Procedure—Pre-dry the bottle and paper in a vacuum oven at 63 °C for 
a minimum of 6 hours. Stopper immediately after removal from the oven and 
cool in a desiccator for 20 minutes. Weigh the sealed bottle plus paper. The 
sample, undiluted in the case of juices, or diluted 1:1 in the case of massecuites 
or molasses, is then added in the following manner. 
Remove the paper, introduce approximately 2 g of sample and weigh. 
Then add 1 ml of distilled water, mix by swirling, insert the paper coil and 
allow to stand for 30 minutes before commencement of drying. 
The sample is then dried at 63 °C for 16 hours under a vacuum of from 
26 to 29 inches Hg. A slight bleed of air, which is dried in double calcium 
chloride towers, is allowed to pass into the oven during the drying period. 
At the end of the drying period the vacuum is released slowly, the air entering 
through the drying towers. The bottles are then closed and cooled in a 
desiccator for 20 minutes before weighing. The weight of dry solids is calcu-
lated and expressed as a percentage of the weight of the original undiluted 
material. 
102 ANALYTICAL METHODS 
Bagasse Analysis 
Preparation of Sample 
The method of collecting and compositing bagasse has been described 
in Chapter VII. The sub-sampling of a large quantity of bagasse is facilitated 
by hammer-milling, which comminutes and mixes the bagasse. This is 
particularly useful for first mill bagasse where large pieces are usually present. 
Drying of the sample will also be facilitated by the finer subdivision. When 
hammer milling is carried out, care must be taken to avoid contamination 
of the samples, and care should be exercised during any bagasse sampling to 
minimize loss of moisture. 
Moisture 
Large capacity drying ovens based on the principle of the old Spencer 
type oven are now standard equipment in most mill laboratories. Bagasse is 
placed in a cylindrical container measuring approximately 11 inches by 7 
inches in diameter, the base of which is covered by a layer of 22 mesh gauze 
supporting a layer of 100 mesh gauze. Hot air is then passed through the 
sample. When a number of drying containers are to be used continuously, 
it is convenient to adjust all the containers to the same tare weight. 
ANALYTICAL METHODS 103 
Procedure—Add 1000 g of bagasse sample to the container and dry at a 
temperature of from 105 to 115 °C until the weight loss is less than 2 g in 
30 minutes. This usually takes from three to four hours. Weighings are made 
while the container is still hot. 
Pol 
The wet disintegrator method of pol determination has now almost 
completely replaced the old hot digestion method. Several minor changes 
have been made to the machine described by Foster (1955), but the same 
Fig. 39—Wet-Disintegrator. 
basic principle is still employed. The procedures described in this Manua are, 
however, designed for use with the modified type of wet disintegrator i.e. a 
machine fitted with three six inch blades at half inch intervals up the shaft, 
shaft end one eighth inch from the bottom of the can, and a water-cooled 
baffled can. The blades on these machines must be kept sharp. 
Procedure—Weigh out 1200 g of first mill bagasse or 1000 g of bagasse 
from subsequent mills. Transfer to the disintegrator can and add 10 kg of 
104 ANALYTICAL METHODS 
water. Disintegrate for 30 minutes at approximately 5600 rev/min and ensure 
that an adequate flow of cooling water is applied to the waterjacketed dis-
integrator can. Remove approximately 200 ml of extract for pol analysis, 
strain through a 40 mesh gauze into a 250 ml conical flask, stopper and cool 
to room temperature. 
Clarify with a minimum amount of dry lead acetate, shake, and allow 
to stand for at least five minutes. Filter, discard the first 10 to 15 ml of 
filtrate and polarize in a 400 mm tube. 
Calculation—It is assumed in the following formula that the specific 
gravity of the extract is 1.000 and that the fibre contains 25 per cent hygro-
scopic water. 
where w = moisture per cent bagasse 
Q = purity of residual juice. 
The purity of residual juice is frequently assumed to be 70, and a table, based 
on this assumption, and on the simplified formula given above, mav be found 
in Table III. 
Cane Analysis 
The present Queensland cane payment system evaluates cane for pay-
ment purposes in terms of c.c.s. or commercial cane sugar. The c.c.s. is 
calculated from the pol and Brix of cane, which are determined by means of 
an empirical formula involving the pol and Brix of first expressed juice and 
the fibre per cent cane. 
The need for a more exact method of cane analysis has resulted in the 
development of a system for direct cane analysis. In direct analysis, pol and 
Brix of cane are determined by use of the wet disintegrator on a sample of 
prepared cane. Moisture is also determined on the prepared cane sample and 
fibre calculated using the formula: Fibre per cent cane = 100 — Brix per cent 
cane — water per cent cane. 
The method of sampling cane for direct analysis is described in Chapter 
VII. 
where R = pol reading of extract 
W = weight of water added 
B = weight of bagasse 
M = moisture in total bagasse (B) 
Q — purity of residual juice 
neglected. 
For the routine analysis of final bagasse, where a 10:1 ratio of water to 
bagasse is used, a simplified formula, which neglects the influence of hygro-
scopic water, is frequently employed, and the formula reads as follows:— 
ANALYTICAL METHODS 105 
Sample Preparation 
Thoroughly mix the sample of prepared cane. If cane preparation is 
considered inadequate, the sample may be given additional preparation by 
passing the cane through a hammer mill or cutter-grinder. Care must be taken 
to minimize loss of moisture if comminution of the sample is carried out 
and if a cutter-grinder is used, the blades must be kept sharp. Transfer the 
sample to a sealed container and commence the following analyses with a 
minimum of time delay. 
Moisture 
This is determined in the manner described for moisture per cent bagasse. 
Brix and Pol 
Procedure—Weigh out accurately 2000 g of prepared cane and transfer 
to the water jacketed disintegrator can. Add 6000 g of water from a suitable 
dispenser. 
Disintegrate the material as described in the procedure for pol per cent 
bagasse. 
Brix of Extract—To a separate portion of extract, add approximately 
2 g of filter aid per 100 ml and filter. Discard the first runnings. Take all 
necessary precautions to minimize evaporation. 
Determine the Brix of extract by a precision refractometer after having 
previously checked the zero point of the instrument with distilled water, or 
by means of a pycnometer. 
Calculations (Deicke 1959)— 
Pol of Extract—For dry lead clarification and polarization of the extract 
in a 400 mm tube. 
Pol per cent cane = 
and y = weight of cane 
x = weight of water 
z = per cent hygroscopic water 
w = moisture per cent cane 
For 2000 g of cane, 6000 g of water and an assumed hygroscopic water 
content of 25 per cent, the formula is simplified to 
Pol in Open Cells 
An estimate of the percentage of broken and unbroken cells in cane 
can be obtained from the determination of pol in open cells as opposed to pol 
of the total sample; The determination is seldom used for routine control 
purposes, but it is of value in establishing the degree of cane preparation 
obtained prior to crushing. 
The basis of the method is that sugar can be rapidly leached from broken 
cells under conditions which do not induce diffusion of sugar from unbroken 
cells. It must also be assumed that the pol content of broken cells is the same 
as the pol content of unbroken cells. The forementioned must be viewed with 
some reservation and results should be considered more on a comparative 
than an absolute basis. 
A version of the method of Aldrich and Rayner (1962) as modified by 
the Sugar Research Institute, is listed below. 
Special Apparatus—A 3 gallon 
bottle neck container of the type and 
dimensions shown in Fig. 40 is re-
quired. 
Procedure—The prepared cane 
should be thoroughly mixed before 
subsampling. 
Pol in open cells—Weigh out 
1000 g of prepared cane and transfer 
into the special container. Add 
10,000 g of water, seal and rotate on 
a jar mill for 10 minutes at 70 rev/ 
min. 
Determine the pol reading of 
the extract in a 400 mm tube. 
Pol in total sample—Transfer 
2000 g of prepared cane and 6000 g 
of water to a wet disintegrator and 
disintegrate for 30 minutes. Deter-
mine the pol reading of the extract 
in a 400 mm tube. 
Pol in total sample—Transfer 2000 g of prepared cane and 6000 g of water 
to a wet disintegrator and disintegrate for 30 minutes. Determine the pol 
reading of the extract in a 400 mm tube. 
for percentage of pol in open cells reduces to 
106 ANALYTICAL METHODS 
ratio of the pols of the extracts, and if this ratio is designated r, the formula 
ANALYTICAL METHODS 107 
Fibre 
The direct determination of fibre for cane payment purposes is carried 
out by either of the two methods described below. It should be emphasized 
however that the form of presentation of these methods does not constitute 
an official interpretation of the Cane Prices Regulations. 
Whole Stalk Method -The use of this method has been superseded in most 
factories by the prepared cane method, but whole stalk selection and analysis 
is still required for certain milling and agricultural experiments. 
Procedure—Sticks should be selected in a manner which will ensure that 
they are a representative selection of the original parcel of cane. A group of 
12 sticks constitutes a suitable unit for fibre analysis, and if the amount of 
cane to be sampled cannot be adequately represented by this number, it is 
preferable to take as many groups of 12 as required and to analyse each group 
separately. 
Sub Sampling—Lay the 12 sticks on the ground in descending order of 
length and with all tops in the same direction. Cut each stalk into three equal 
sections, top, middle and butt. Sections are then selected and laid out as 
follows:— 
Stalk 
1 
2 
3 
4 
5 
6 
Section 
Top 
Middle 
Butt 
Top 
Middle 
Butt 
Direction 
Unchanged 
Unchanged 
Unchanged 
Reversed 
Reversed 
Reversed 
This sequence is repeated for the second group of six sticks. 
Preparation—When the old Queensland type fibrator is employed the 
12 sections are fibrated, without reversal, to the extent of half the length of 
each section. The resultant fibrated material should represent two complete 
stalks of cane. It is important that the fibrator should be sharp and in good 
order. The fibrated material should be mixed thoroughly and quickly on a 
shallow tray and a representative portion selected and placed in an airtight 
container. The actual analysis is then carried out in a similar manner to that 
described for the prepared cane method. 
An alternative and more efficient preparatory device is the Jeffco type 
cutter-grinder. When this is employed however, the full sections are fibrated. 
Prepared Cane Method—The method previously described has several 
limitations, the more important being that it is extremely difficult to obtain 
a representative sample of cane. The lengthy procedure of stick selection and 
preparation also limit the number of determinations that may be carried out 
in any one period. 
The need for an improved method of fibre determination resulted in the 
development of a technique which permits the sampling and analysis of 
prepared cane just prior to milling. A more detailed discussion of this subject 
may be found in a paper by Anderson and Petersen, (1959). 
Sample Preparation—A sample of prepared cane is removed from the 
carrier to a table by the method as described in Chapter VII. After rapid but 
thorough mixing, a sub-sample is transferred to a Waddell type hammer mill 
which has previously been conditioned with a discarded portion of the sample. 
N.B.—The determination should be carried out in duplicate whenever 
practicable. 
Sucrose in High Purity Materials 
The present methods for the determination of sucrose in relatively high 
purity materials e.g. first expressed juice, clarified juice and syrup, are based 
on the original Clerget method whereby the polarization of the sucrose solu-
tion is determined both before and after inversion. The method is based on 
the assumption that optically active materials other than sucrose are not 
affected by the inversion. 
The inverting agents employed are either the enzyme invertase or hydro-
chloric acid. The former is considered to yield more correct results, due to the 
fact that it is an enzyme specific to sucrose, but because of the necessity of 
maintaining and storing a supply of suitable invertase, this method has in the 
past received only partial acceptance for factory control analysis. 
Attempts to eliminate the defects of hydrochloric acid as an inverting 
agent have led to the development of numerous modifications of Clerget's 
method. The method most widely accepted is the Jackson and Gillis Modifica-
tion No. IV, in which sodium chloride is added to the solution used for the 
direct polarization, to offset the effect of the chloride ions in the acid added 
to the inverted solution. 
Two methods of analysis are presented. Both require a high degree of 
analytical precision to obtain reproducibility, and it is recommended that for 
reliable results the determination of sucrose on any one sample be carried out 
at least in duplicate. 
Optical Invertase Method 
Preparation—Dissolve t w o a n d a half t i m e s t h e n o r m a l we igh t of t h e 
s u b s t a n c e in w a t e r in a 250 ml v o l u m e t r i c f l ask . ( D e p e n d i n g on t h e colour , 
mu l t i p l e s o r f rac t ions o f th i s we igh t m a y be used a n d t h e we igh t s ca l cu l a t ed 
to a bas i s of 26 g pe r 100 ml.) 
108 ANALYTICAL METHODS 
Procedure—Hammer mi l l t h e cane for a p p r o x i m a t e l y 15 seconds a n d 
aga in r a p i d l y b u t t h o r o u g h l y m i x t h e p r e p a r e d s a m p l e . T rans fe r a r e p r e s e n t -
a t ive s u b - s a m p l e to a closed con ta ine r . W e i g h a p r e d r i e d f ibre b a g in an air-
t i g h t c o n t a i n e r a n d r eco rd t h e we igh t of b a g + c o n t a i n e r (Wl). R a p i d l y 
t ransfe r a p p r o x i m a t e l y 150 g of t h e h a m m e r mi l led s a m p l e to t h e b a g . F a s t e n 
t h e t o p o f t h e b a g a n d t r ans fe r to t h e a i r t i gh t c o n t a i n e r . W e i g h t h e b a g + 
con t a ine r a n d r eco rd as (W2). 
Washing—Immerse t h e b a g in cold r u n n i n g w a t e r a n d squeeze a t t h e 
c o m m e n c e m e n t of w a s h i n g a n d at 15 m i n u t e i n t e r v a l s for a per iod of one 
hou r . R e m o v e t h e b a g , squeeze o r spin d r y t o r e m o v e s u r p l u s w a t e r a n d 
t rans fe r to boi l ing wa te r , r e p e a t i n g t h e p r o c e d u r e for a fu r the r hour . 
Drying—Remove su rp lus w a t e r by squeez ing o r sp in d r y i n g a n d t r ans fe r 
to an air oven . D r y to c o n s t a n t we igh t a t 100 to 105 °C. W h e n r e m o v e d f rom 
t h e oven for we igh ing t h e b a g s a re p l aced in t h e a i r t i g h t con t a ine r . R e c o r d 
t h e we igh t o f c o n t a i n e r + b a g + f ib re (W3). E m p t y t h e b a g s a n d r e m o v e all 
adhe r ing fibre. R e - d r y in t h e oven for one h o u r a t 100 to 105 oC. Cool in t h e 
a i r t i gh t c o n t a i n e r a n d re-weigh (W4). 
ANALYTICAL METHODS 109 
Add sufficient dry lead to just clarify the solution, mix by swirling and 
dilute to volume. Mix by shaking and filter, keeping the funnel covered with 
a watch glass. Reject the first 25 ml of nitrate. If the filtration rate is slow, 
it is advisable to use two filters in parallel. 
Delead the filtrate by adding ammonium dihydrogen phosphate in as 
small an excess as possible. Mix well, filter and again reject the first 25 ml of 
filtrate. 
Direct Reading—Pipette 50.0 ml of lead-free filtrate into a 100 ml 
volumetric flask. Dilute to volume, mix well and transfer to a 200 mm water 
jacketed tube. Allow to stand for approximately 10 minutes, record the 
temperature and polarize. 
The polariscope reading multiplied by 2 is taken as the direct reading, 
designated P. 
Invert Reading—Two alternatives are available, either a 24 hour inver-
sion using 5 ml of invertase for the actual inversion, or a rapid inversion at 
elevated temperatures using 10 ml of invertase. 
24 Hour Inversion—In a separate operation accurately determine the 
quantity of acetic acid required to reduce 50 ml of the filtrate to a pH of 4.4. 
To another 50.0 ml portion in a 100 ml volumetric flask add the requisite 
quantity of acid and 5 ml of invertase solution. Dilute almost to volume 
and allow to stand overnight, preferably at a temperature of not less than 
20 °C. 
Dilute to volume, mix well and polarize in a water jacketed tube at 20 °C. 
Determine the optical activity of a similar portion of the invertase previously 
used by diluting this portion to 100 ml and polarizing. Correct the invert 
polarization for the effect of the optical activity of the invertase solution, and 
multiply by 2 to obtain the corrected invert reading for a normal solution, 
designated P1 . 
Determine the total solids of the original sample by refractometer, mul-
tiply this figure by the density at 20 °C and use the result to calculate total 
solids from the original solution in 100 ml of the invert solution, designated g. 
Rapid Inversion—If this procedure is used, add 10 ml of invertase solu-
tion to 50.0 ml of nitrate in a 100 ml volumetric flask. Transfer to a water 
bath and hold at 55-60 °C for 15 minutes with occasional swirling. Cool the 
flask and contents, add soduim carbonate until distinctly alkaline to litmus 
paper, adjust to volume and polarize in a water jacketed 200 mm tube. 
Record the temperature to the nearest 0.1 °C. Allow the solution to remain 
in the tube for approximately 15 minutes and again determine the polariza-
tion. If there is no change from the previous reading, mutarotation is com-
plete. 
If it is necessary to work at a temperature other than 20 °C, both the 
direct and invert polarizations should be made at the same temperature, 
which should be as near as possible to 20 °C. 
Calculation—The percentage sucrose, S, in the original sample is derived 
from the formula 
N.B.—The strength of each batch of invertase should be periodically 
checked to ensure that it complies with the A.O.A.C. specification. This is 
If the activity is unity or greater, the invertase complies with the 
A.O.A.C. specification. 
Jackson and Gillis Modification No. IV 
This method is applicable in the presence of invert sugar, as the effect 
of hydrochloric acid inversion on this substance is balanced by the addition 
of sodium chloride ions to the solution used for the direct polarization. As 
previously mentioned, the method is not recommended for low purity 
materials or materials containing appreciable quantities of optically 
active non sugars, the specific rotations of which can be subject to significant 
changes during acid inversion. 
Preparation—Juices are taken undiluted, while sugar, syrup and high 
grade pan products are prepared at a concentration of 2 normal weights in 
200 ml. 
Clarify the appropriate preparation with dry lead (as for pol determina-
tion) and filter. Delead the filtrate with anhydrous potassium oxalate. The 
quantity required is determined by a potassium iodide test on small portions 
of the filtrate. 
Direct Polarization—Pipette 50.0 ml of filtrate into a 100 ml volumetric 
flask. Add 10.0 ml of Jackson and Gillis sodium chloride solution. Dilute to 
volume with distilled water and filter only if necessary. Stopper and retain 
so that this solution and the one from the next stage are read at approximately 
the same time and at the same temperature. 
Polarize in a water jacketed 200 mm tube and multiply the result by 2. 
Designate as P. 
Invert Polarization—Pipette 50.0 ml of filtrate into a 100 ml volumetric 
flask. Either of the following procedures may be adopted for inversion but the 
U.S. Customs method is considered to be more precise and is preferred. 
A. Walker Method—Insert a thermometer in the flask and heat in a 
water bath until a temperature of 65 °C is attained. Remove the flask and 
add 10.0 ml of Jackson and Gillis hydrochloric acid solution. Mix by swirling 
and set aside for 30 minutes. 
Cool to room temperature, wash any adhering liquid from the thermo-
meter and dilute to volume. Polarize in a water jacketed 200 mm tube at the 
same temperature at which the direct reading is determined and multiply 
the reading by 2. Designate as P1. Record the temperature of the polarization 
to the nearest 0.1 °C. 
110 ANALYTICAL METHODS 
defined as invertase which under the specified conditions of the test will 
produce a drop in polarization of 3.96 in a solution of 10 g of sucrose in 110 ml. 
The test is carried out as follows:— 
Dilute 1 ml of invertase concentrate to 200 ml with distilled water. 
Dissolve 10.00 g of pure sucrose in a 100-110 ml volumetric flask, using 
approximately 60 ml of distilled water. Add two drops of glacial acetic acid 
and make up to a volume of 100 ml. 
Add 10 ml of the diluted invertase to the sugar solution, mix thoroughly 
and allow to stand for exactly 60 minutes at 20 CC. 
Render alkaline to litmus by the addition of solid sodium carbonate. 
Polarize in a 200 mm tube to obtain a reading P. 
In the case of an undiluted solution this formula gives an apparent sucrose 
reading which is used in conjunction with Schmitz's Table as if it were a pol 
reading. 
A separate Clerget divisor is required for each method. 
Walker Method Divisor = 132.63 + 0.0794 (m —13) —0.53 (t — 20) 
U.S. Customs Method. Divisor = 132.56 + 0.0794 (m —13) —0.53 (t — 20) 
where t = temperature of polarization °C 
and m = total solids, g per 100 ml, in the actual 
invert solution 
N.B.—The divisors for the Walker Method for solutions ranging from 
8 to 26 Brix are shown in Table IX, while the temperature corrections are 
shown in Table X. 
The divisors for the U.S. Customs Method may be obtained by deducting 
0.07 from those listed in this table. 
Brix 
P at 25.7 °C 
P1 at 25.7 °C 
P—P1 
Divisor for 18 Brix 
Temperature correction 
Corrected divisor 
= 18.1° 
= 60.2 
= —18.3 
= 78.5 
= 132.31 
= —3.02 
= 129.29 
In the case of solutions of normal strength, or related thereto by a simple 
ratio, the values of P and P1 must be expressed as for a normal solution. 
Hence, if the original solution were of half normal strength the direct and 
invert readings would be made at quarter normal strength and the readings 
must be multiplied by four to give P and P1. 
ANALYTICAL METHODS 111 
Or B. U.S. Customs Method—Transfer 10 ml of Jackson and Gillis 
hydrochloric acid solution to the cold 50 ml of nitrate. Insert a thermometer 
and transfer to a water bath. Heat to 60 °C and hold for 10 minutes. Agitate 
the flask during the first 3 minutes. Rapidly cool to room temperature, wash 
adhering liquid from the thermometer and dilute to volume. Polarize as 
described in the previous alternative. 
Calculation— 
The concentration of sucrose is calculated from P and P1 using the 
formula 
112 ANALYTICAL METHODS 
The Clerget divisors may be calculated from the formulae given above. 
For sugars (1 N.W. in 100 ml) the value 132.63 at 20 °C may be taken, and 
for final molasses (1 N.W. in 300 ml) 131.88 at 20 °C. These apply to the 
Walker method of inversion, and must, of course, be corrected to the temper-
ature of the operation. The formula shown above 
S = (P — Pl) X 100 
Clerget divisor 
then gives the percentage of sucrose S directly, when P and P1 are expressed 
in terms of a normal solution. 
Sucrose in Low Purity Materials 
Optical methods are not recommended for the determination of sucrose 
in low purity materials. A more suitable technique is that known as the Chemi-
cal Method. Basically the chemical method involves the determination of the 
original reducing sugar content of the sample, followed by another reducing 
sugar determination after the sucrose present has been inverted to reducing 
sugar. Two methods for carrying out the inversion are given. 
Chemical Method 
The weights and suggested dilutions shown below are normally suitable 
for final molasses samples. They may have to be varied to suit local condi-
tions. (If B molasses is to be analysed, a concentration 10 g of sample in 250 
ml, and titration of the undiluted filtrate should suffice). 
Procedure—Accurately weigh out approximately 4 g of final molasses. 
Transfer to a 250 ml volumetric flask. Dissolve and dilute to volume. Warm 
the flask and contents to 40 °C. Add 1 g of powdered potassium oxalate. 
(This precipitates the calcium from the solution.) Shake well and cool. Filter 
through a No. 1 Whatman paper after having added a small amount of 
kieselguhr to assist filtration. 
Direct Reducing Sugar Determination—Pipette 50.0 ml of filtrate into a 
100 ml flask. Dilute to volume and shake. 
Prepare Fehling's solution by adding 5.0 ml of No. 1 and 5.0 ml of No. 2. 
Fehling's into a 250 ml boiling flask. Add four drops of methylene blue 
indicator and titrate as described in the section on reducing sugars determina-
tion. 
Estimation of Total Sugars 
A. Invertase Method—Pipette 50.0 ml of filtrate into a 250 ml volumetric 
flask. Add two drops of glacial acetic acid followed by 10 ml of invertase. 
Heat in a water bath to 57.5 °C for 25 minutes. Agitate continuously 
for the first three minutes and then intermittently for the remainder. Cool 
to 20 °C and make to volume with distilled water. Titrate against 10.0 ml 
of mixed Fehling's solution using methylene blue as an indicator. 
B. Acid Inversion Method—Pipette 50.0 ml of filtrate into a 200 ml 
volumetric flask. Add 10.0 ml of Jackson and Gillis hydrochloric acid solution. 
Insert a thermometer and heat the flask and contents to 60 °C in a water 
bath. Agitate the flask during the initial three minutes of heating. After a 
total heating time of ten minutes, remove the flask, cool in water and dilute 
to volume. 
Add one drop of phenolphthalein indicator and neutralize with 4 N 
sodium hydroxide to the first darkening of the solution. Dilute to 
Per cent sucrose = (total sugars — reducing sugars) X 0.95 
Note 1. In this calculation the 0.5 g sucrose column in Table V is used. 
Note 2. In this calculation the 0.0 g sucrose column in Table V is used. 
Reducing Sugars 
Of the numerous methods available for the determination of reducing 
sugars, only one is listed in this Edition, namely the Lane and Eynon method, 
as this has now received almost universal acceptance by the Queensland 
Sugar Industry. Briefly, this method consists of the titration of a sugar 
solution of unknown reducing capacity against standard strength Fehling's 
solution. 
For accurate results the level of reducing sugars in the test sample should 
be approximately 0.2 g per 100 ml of solution. If the test solution has a 
concentration greater than this it must be diluted. If the test solution has a 
reducing sugar concentration less than 0.1 g per 100 ml, a known quantity 
of standard invert solution should be added to the test solution to laise the 
reducing sugar concentration to a level of approximately 0.2 g per 100 ml. 
The amount of added invert is later subtracted from the final result. In the 
case of high polarization sugars, this can normally be obtained by adding 
20 ml of standard invert solution to a 200 ml flask. One drop of phenolphtha-
lein indicator is added, and the excess acidity is then neutralized with caustic 
soda solution. The weighed quantity of sugar (usually 50 g) is then added to 
the flask, dissolved and diluted to volume. 
For other sugar mill products the dilution required must be ascertained 
by a process of trial and error. Clarification of samples is not usually carried 
out, but when any appreciable quantity of calcium is present this is precipi-
tated by adding 0.1 g of potassium oxalate per 100 ml, and filtering off the 
precipitate. 
Method of Lane and Eynon 
Incremental Method of Titration—Prepare the Fehling's solution just 
prior to the titration, by pipetting 5 ml of Fehling's A solution and 5 ml of 
Fehling's B solution into a 250 ml boiling flask. 
N.B.—If water is added at this point to obtain a more workable volume, 
the quantity added must be standardized. This same volume must also be 
used in the initial standardization of the Fehling's solution. 
Exploratory Titration—Add approximately 15 ml of the test solution 
from an offset burette to the prepared Fehling's. Heat to boiling. The colour 
of the boiling solution will give an indication of the additional quantity of test 
liquid required to reduce the remaining copper. If the end point appears to 
be reasonably close, continue boiling for two minutes and add four drops of 
methylene blue indicator. Continue the titration in aliquots of 1 ml or less 
until the colour is completely discharged. 
ANALYTICAL METHODS 113 
volume. Titrate against 10.0 ml of mixed Fehling's solution using methylene 
blue as an indicator. 
Calculation—(Example for the Acid Inversion method using the weights 
and dilutions as stipulated). 
Example {A) Undiluted Juice 
Uncorrected Brix of juice 
Pol of juice 
Approximate density of juice (Table 
Grammes sucrose per 100 ml (pol x 
Titration (ml) 
mg R.S. per 100 ml (Table IV) 
Per cent R.S. in sample 
Example (B) Sugar with Added Invert 
Added invert 
Sucrose concentration 
Titration (ml) 
mg R.S. per 100 ml (Table IV) 
After deduction for added invert 
Per cent R.S. in sample 
A s h 
XIV) 
density) 
= 19.7 
= 17.8 
= 1.08 grammes per ml 
= 19.0 approx. 
= 20.0 
= 222 
222 x 100 
= 1000 x 108 
= 0.21 per cent 
= 100 mg per 100 ml 
= 25 g per 100 ml 
= 27.5 
= 155 
= 55 
55 x 100 
= 1000 x 25 
= 0.22 per cent 
Theoretically, ash is defined as the residue remaining after burning off 
all organic matter. In practice however, the position is more complicated, 
as the total removal of "ash" from all sugar products is not always possible. 
A further complication arises from the fact that the chemical form in which 
the ash is determined is normally not the form in which the ash is present in 
a sugar product. 
Furthermore, a diversity of opinion still exists on such points as whether 
single or double sulphation should be used and whether or not a ten per cent 
deduction should be applied. The overall quantity of sulphuric acid to be 
used for the determination is also a matter of debate. Apart from the varia-
tions in registered quantities that result from changes in technique, the in-
fluence of these changes on working formulae such as R.S./Ash ratio, and the 
effect on the difference between actual and expected purity when considering 
final molasses exhaustion criteria, should also be borne in mind. 
In an endeavour to remedy this situation and to obtain some uniformity 
in reporting results for Mutual Control purposes, we strongly recommend that 
the following be adopted for control analysis—double sulphation, no deduc-
tion, concentrated acid addition of 0.5 ml before the first incineration followed 
114 ANALYTICAL METHODS 
N.B.—The liquid must be kept boiling during all stages of the titration. 
Final Titration—Repeat the above in a modified form i.e. To 10 ml of 
mixed Fehling's solution, add the volume determined from the rough titration 
less approximately 0.5 ml. 
Heat to boiling, and boil for exactly two minutes. Add four drops of 
methylene blue indicator, and recommence the titration 15 seconds after the 
commencement of indicator addition. 
Complete the titration within a total boiling time of three minutes. 
Calculation of Results—The reducing power of an invert sugar solution 
is affected by both the volume of the final solution and the concentration of 
sucrose present in the solution. Allowances for these factors have been 
calculated in Table IV and the expanded version in Table V. 
ANALYTICAL METHODS 115 
by five drops before the second incineration. For the analysis of sugar for 
payment purposes, the practice of single sulphation, using 2 ml of concentrated 
acid and the application of 10 per cent deduction to the result, is still followed 
in Queensland. 
Gravimetric Ash Determination 
Three items of importance that are associated with the ash determination 
are listed below:— 
Quality of Sulphuric Acid—Check each bottle of sulphuric acid to be 
used for ash determination as follows:— 
Transfer 25 ml of the acid from a measuring cylinder to a prepared 
platinum crucible. Evaporate cautiously in a fume cupboard. Transfer to a 
muffle oven and ignite at 500 °C. Cool in a desiccator. The weight of residual 
ash from the 25 ml aliquot should not exceed 0.001 g. Acids with a residue in 
excess of this figure should not be used for this work. 
Preparation of the Platinum Crucible—Wash the crucible and polish both 
inside and out with moistened keiselguhr. Rinse with distilled water and 
remove excess droplets with filter paper. Heat to 800 °C for approximately 
30 minutes and allow to cool in a desiccator. 
Health Hazard—It is important that the preparatory stages of heating 
should be carried out in a fume cupboard effectively vented to the atmosphere. 
Sulphuric acid vapour can cause severe damage to the respiratory tract. 
The vapour also has a highly corrosive action on metallic laboratory fittings. 
Procedure—The following sample weights for the various sugar products 
are recommended. 
Sugar 5 g 
First Expressed and Clarified Juices 20 g 
Syrup and A Massecuite 3 g 
Products of lower purity 2 g 
Weigh out the recommended weight of sample into a prepared platinum 
crucible. Add 0.5 ml of concentrated sulphuric acid by drops over the surface 
of the sample. Heat the crucible gently on a hot plate to carbonise the sample. 
(Dilute solutions should be evaporated to syrup consistency in a water bath 
to avoid loss of solids.) Continue heating on a hot plate until frothing has 
ceased. Incinerate in a muffle oven at 550 °C until no trace of unburnt carbon 
is visible. 
Remove the crucible, cool and add five drops of concentrated sulphuric 
acid to wet the residue. Transfer to a muffle oven and again incinerate until 
a temperature of 800 °C is attained. Remove after 15 minutes at 800 °C and 
transfer to a desiccator. Weigh when cool and express the weight of residue 
as a percentage of the original sample. 
Conductometric Ash 
An approximation of the ash content of raw sugar products can be 
obtained rapidly by the conductometric method. When sugar is dissolved in 
water, the soluble impurities disperse into electrically charged particles called 
ions. As the passage of an electric current through a solution is dependent 
upon the concentration of ions present, a measure of the concentration of 
soluble impurities can be obtained from a simple conductivity measurement. 
One shortcoming of the conductometric method is that the relationship 
between gravimetric and conductometric ash must be known for each grade 
116 ANALYTICAL METHODS 
of sugar product. This relationship is then assumed to be valid for all samples 
tested in each category. Significant departures from these standards can occur 
in actual practice however, but the method is a useful adjunct to routine 
factory control purposes. 
Apparatus—A special elec-
trolytic conductivity meter 
known as an "ash bridge" is 
used. A suitable conductivity 
meter is illustrated in Fig. 41. 
Procedure—Weigh out 10 g 
of sample (if below one per 
cent ash) and transfer to a 
200 ml volumetric flask. Dis-
solve and dilute to volume. 
N.B.—If the sample has 
an ash content above one per 
cent, a mixture of sample and 
pure sucrose should be substi-
tuted to give a 10 g sample 
with an ash content equal to 
approximately 0.5 per cent. 
Determine the conductivity of the solution, making corrections for the 
temperature at which the determination is carried out. 
Calculation— 
where C = the predetermined relationship between gravi-
metric and conductometric ash for the particular 
grade of product. 
Sugar Analysis 
The majority of methods for the routine analysis of raw sugar are 
presented under this sub-heading. The procedures for reducing sugars, ash 
and phosphates however, may be located under their specific sub-headings 
as their procedures have a general application to other types of sugar products. 
Polarization 
The procedure for raw sugar polarization has been the subject of much 
debate for a number of years. Investigations into this analysis are still being 
carried out, and, no doubt, the pending introduction of automatic polari-
meters into the industry will result in considerable changes in this section. 
The polarization of a sugar is one of the most exacting analyses carried out 
by a sugar chemist, and rigorous adherence to a standard procedure is 
essential if reproducible results are to be obtained. 
At the 14th Session of ICUMSA in 1966, a recommendation was duly 
adopted for a method to be referred to as ICUMSA polarization Method 1. 
This method is based on the use of the International Sugar Scale, clarification 
by the standard wet lead solution, a standard specification for apparatus, 
and for the procedures to be followed during preparation of the solution, 
filtration, polarization of the filtrate and the corrections to be applied to the 
observed polarization. The following procedure is based in principle on 
ICUMSA polarization Method 1. 
capsule, on a balance with a sensitivity reciprocal of 0.1 milligrammes per 
scale division. Transfer by washing with about 60 ml of distilled water into 
a 100 ml flask conforming to B.S. 675 Type 2 specification. 
Dissolve the sugar, without any loss from the flask, and add 1.0 ml of 
basic lead acetate solution, (made to the specification as detailed in Chapter 
VIII) from a reservoir protected from atmospheric carbon dioxide. Mix in the 
added lead solution by swirling gently, then add further distilled water until 
the bulb of the flask is filled. Allow to stand at least 10 minutes making sure 
that no air bubbles are entrapped in the flask. 
Dilution to Volume 
Add distilled water to bring the meniscus level to about five mm below 
the graduation line. If necessary, ether or alcohol vapour from a blower may 
be used to clear the meniscus before finally making to volume with distilled 
water. For setting of the meniscus to the graduation line it is recommended 
that a strip of black paper be secured around the neck of the flask with a 
clip, at about 1 mm below the graduation mark. Place the flask on a stand at 
eye level and add the distilled water from a fine jet until the lowest point of 
the meniscus is at the top edge of the graduation line. 
Remove any drops of water adhering to the neck of the flask by means 
of a rolled strip of filter paper. Stopper and thoroughly mix the solution. 
Allow it to stand for at least five minutes to permit settling of the precipitate. 
Filtration 
Filter the solution through a single paper (the moisture content of which 
is in the range 6-8 per cent when dried for 3 hours at 100 °C), fitted neatly 
without any overlap in a stemless funnel made of non-corrosive material. 
Cover the filter with a suitable cover of non-corrosive material to minimize 
evaporation during filtration. Discard the first 5 to 10 ml of filtrate and do 
not return any of the filtrate to the filter. 
N.B.—The nitration should be carried out as rapidly as possible and the 
funnel must be seated firmly in the mouth of the filter glass and not in a 
filter stand. 
Rinse a clean dry glass pol tube of 200 i 0.03 mm length (previously 
tested so that no detectable change in reading is observed on rotating the tube 
ANALYTICAL METHODS 117 
Apparatus 
This should conform to the standards laid down by ICUMSA (1966). 
Included in the apparatus are saccharimeters or sugar polarimeters, quartz 
plates, balances, flasks, polarimeter tubes or cells, cover glasses, funnels, 
filter paper and basic lead acetate. 
Although the specification for flasks includes various types, it is re-
commended that the flask made to the British Standard 675 Type 2, be the 
only flask used for the polarization of raw sugar. This flask has been specific-
ally designed for this purpose not only in its dimensions, but also for ease of 
mixing after completion to volume. 
All sugar polarizations should be conducted in a room maintained at a 
constant temperature and relative humidity (20° ± 0.5 °C and 65-70 R.H.). 
If this temperature is not attainable the range 15 to 25 °C should not be 
exceeded, if possible. 
Preparation of Solution 
Thoroughly mix the sugar samples received for analysis prior to weighing 
118 ANALYTICAL METHODS 
in the trough of the saccharimeter), at least twice with filtrate. This rinsing 
assists in wetting the walls of the tube and washes out any unobserved foreign 
matter. When the tube is finally filled with the filtrate, close off with a cover 
glass made of good optical glass with plane parallel faces free from defects. 
The cover glasses are held in position with the threaded cap ends complete 
with good quality rubber washers of the correct size. Do not overtighten the 
caps as this could cause strain to the cover glasses, resulting in their becoming 
optically active. With enlarged end tubes any air bubbles in the tube are 
collected in the enlarged end by inverting the tube a few times, so that on 
placing the tube in the trough of the saccharimeter a continuous path of solu-
tion is presented to the polarized light. To avoid undue temperature rise in 
the filtrate, the tube must be handled as little as possible before being placed 
in the trough of the saccharimeter. 
The saccharimeter used shall be fitted with the International Sugar Scale 
in compliance with the ICUMSA (1966) standards. 
Reading of the Filtrate 
The saccharimeter shall be standardized at the time of reading, by means 
of a standard quartz plate of the value close to the observed polarization. 
The value of the quartz plate shall have been checked by an authorized 
authority. 
Determine the reading of the filtrate, making at least five settings of the 
instrument and averaging the result. Each setting should be read to the 
accuracy of the instrument. 
A scale correction based on the reading of the standard quartz plate is 
then applied to the observed reading. 
Determine the temperature of the filtrate as soon as practicable after the 
saccharimeter readings, by immersing a thermometer graduated in tenths of 
a degree in the tube after a little of the solution has been removed. To mini-
mize handling, it is recommended that the tube be placed upright in a clean 
dry container whilst the temperature is being determined. 
After the temperature of reading has been measured, the correction to be 
applied to adjust the observed polarization to 20 °C is made as follows: — 
When the reading is obtained in a quartz wedge saccharimeter 
P20 = pt +. 0.00033 S (ty — 20) — 0.0047R (tv — 20) 
where P20 = polarization at 20 °C 
Pt = polarization at t °C 
S = per cent sucrose in sample 
R = per cent reducing sugars in sample 
tr = temperature of solution as read °C. 
When a sugar polarimeter is used the coefficient 0.00033 S is smaller and 
may be taken as 0.00019 5. 
The temperature used in the above formulae for correcting polarizations 
to 20 °C is the actual temperature of reading, and the assumption is made 
that this temperature is the same as that at which the solution was made to 
the mark. Even if all operations are carried out in a constant temperature 
room, this assumption will not necessarily be correct. Any change in concen-
tration of the solution caused by a change in temperature between making 
to the mark and polarizing should be allowed for. For this reason if it is not 
possible to carry out the preparation of solutions, the nitrations, and the 
ANALYTICAL METHODS 119 
readings in a constant temperature room, it is important that the temperature 
should vary as little as possible from the start to finish of the operations i.e., 
by not more than 0.5 degree C. If however, there is reason to suspect that the 
temperature of reading the filtrate differs from the temperature of making 
to the mark by more than 0.5 degree C, the temperature of making to the 
mark shall be determined. This shall be done by placing a clean dry thermo-
meter, graduated in tenths of a degree C, in the flask immediately after 
shaking and before the solution is poured on the filter. This temperature 
should be noted and recorded to the nearest tenth of a degree, and if necessary 
the quantity 0.027 (tr —• tm) should be added to the observed polarization, 
where tr is the temperature of reading the filtrate in the saccharimeter, and 
tm is the temperature of making the solution to the mark. 
The pol of the sugar reported will be the observed reading, corrected 
for scale error, corrected if necessary for errors in flask and tube, and corrected 
for temperature when observations are made at temperatures other than 20°C. 
Moisture 
For routine control purposes, the moisture content of raw sugar is taken 
as the loss of weight resulting from the air drying of a 5 g sample at 103 to 
105 °C for a period of three hours. The value recorded should be regarded as 
relative rather than absolute, as some thermal degradation of the sample 
occurs under these test conditions. 
Although a simple procedure, the moisture determination can give vary-
ing results unless both technique and test conditions are adequately stan-
dardized. Determinations should be carried out in duplicate and repeat deter-
minations carried out if the duplicates differ by more than 0.05 per cent. 
Drying Dishes- -These are approximately two inches in diameter, half 
an inch deep and should be fitted with close fitting lids. 
Procedure—Prepare the requisite number of dishes by drying overnight 
in an air oven. Transfer the covered dishes to a desiccator and allow to cool 
to room temperature. Weigh the dish plus lid to ^O.OOOl g. 
Rapidly add approximately 5 g of sample evenly over the dish surface 
and replace the lid. Determine the weight accurately. The sample addition 
and weighings should be carried out as rapidly as possible. Transfer the dish 
and contents to an air oven and dry for three hours at 103 to 105 °C. 
At the completion of drying, replace the lid and allow to cool to room 
temperature in a desiccator. Weigh the dish plus dried sample again to 
±0.0001 g. Express the loss of weight as a percentage of the original sample 
weight. 
Filterability 
The test involves the constant pressure filtration of a raw sugar solution 
under standard conditions. The filtration rate of the test solution is compared 
with the filtration rate of a pure sugar solution which has been filtered under 
identical conditions. 
Strictly speaking, the per cent filterability is defined at 20 ±1 °C, and 
the procedure and calculation tables are designated for temperature controlled 
laboratories. Temperature control of ±1 °C is difficult to maintain however, 
and if the test is performed at a temperature outside this range, the result 
can only be validly expressed as "filterability at t°C". 
Table XXXVII will permit the calculation of "filterability at t °C" 
between the ranges of 12 and 32 °C. As temperature changes are likely to 
ANALYTICAL METHODS 
occur during the test, the average of the temperatures taken before and after 
the test should be used. 
Special Apparatus—Pressure Filter. The C.S.R. type filter shown in 
Fig. 42 is assembled in the following order:— rubber gasket, filter disc, 
Whatman No. 54 filter paper, retaining ring and second rubber gasket. 
Air Pressure. A supply of compressed air or nitrogen at 50 pounds per 
square inch is required. 
Stirrer. This should have a running 
speed between 1000 and 1200 rev/min. 
Excessive and prolonged stirring should 
be avoided so that damage to filter aid 
particles is minimized. 
Procedure—Mix the sample thor-
oughly and weigh out the appropriate 
amount of sugar (listed in the following 
table) into a 400 ml beaker. 
Add 99.4 ml (equivalent to 99.1 g 
in air) of distilled water. Then add 
0.720 g (equivalent to 0.48 per cent on 
solids) of standard filter aid, and dis-
solve the sugar using the stirrer. This 
usually requires 25 to 35 minutes of 
stirring. Minimize evaporation by keep-
ing the solution away from draughts 
and covering it when not being stirred. 
Add 2.0 ml of standard buffer 
solution (Chapter VIII), and stir for 
two minutes ±lO seconds. Cover the 
solution and allow to stand for 15 min-
utes ±0.5 minutes. 
Assemble the filter, stir for a fur-
ther 60 seconds and pour the liquid into 
the filter body. Read the temperature 
of the solution to ±0.1 °C. 
Per cent Moisture of Sugar 
0.0 — 0.2 
0.2 — 0.5 
0.5 — 0.8 
0.8 — 1.0 
Sample Weight g ±0.05 
149.0 
150.0 
151.6 
152.6 
Close filter, apply air pressure of 50 lb/in2 gauge and commence timing 
of filtration immediately the pressure is applied. Discard the filtrate for the 
first two minutes and collect the filtrate for the next five minutes in a tared 
100 ml beaker. Release the air pressure and determine the temperature of 
the residual solution. 
Calculation—Average the initial and final temperatures to 0.1 °C. Re-
weigh the beaker to determine the amount of filtrate collected between two 
and seven minutes of filtering. Refer to Table XXXVII and find the corre-
Notes on the Determination 
(i) Keep the filter and gaskets thoroughly clean. 
(ii) Keep the filter disc, when not in use, in the lightly assembled filter. 
(iii) Make sure that the gaskets are not perished or damaged in any way. 
(iv) Check the pressure gauge at regular intervals. 
(v) The filter disc should be calibrated once every two months to check 
its performance. 
(vi) For affined or good filtering sugars, twice the amount of solution 
may be required. In these cases, twice the amount of buffer solution 
and filter aid will have to be added. 
Calibration of Pressure Filter Discs—The performance of a filter disc 
must be checked at regular intervals against the standard flow rates in 
Table XXXVII, before any routine filterability determinations are carried 
out. If the discrepancy is greater than four per cent, a replacement filter is 
required. 
The calibration is carried out as follows:— 
Prepare about 500 g of 60° Brix syrup using A.R. sucrose and distilled 
water. Add a weight of standard filter aid equal to 2 1/2 per cent of the weight 
of the solids in the syrup. Mix and pressure filter in two separate portions 
through Whatman No. 54 filter papers. Discard the first 20 ml of filtrate 
from each filtration. Mix both portions of clear filtrate, weigh, and adjust 
the Brix to 60.0 ± 0 . 1 ° Brix. 
Determine the amount of filter aid equal to 0.48 per cent of the solids in 
the syrup. Add about 50 ml of syrup to the weighed amount of filter aid in a 
separate beaker and mix to a smooth slurry consistency by means of a rubber 
tipped stirring rod. Avoid grinding of the filter aid. Transfer the slurry to the 
bulk of the syrup and recover any residual slurry with original syrup. 
Add 1.4 ml of standard buffer solution. Mix for two minutes using the 
electric stirrer, cover and allow to stand for 15 minutes as before. Filter the 
syrup as previously described. 
N.B.—(i) The quantity of syrup collected should be within 4 per cent of 
the corresponding quantity shown in the table. 
(ii) If a check reveals faults, and the pressure gauge is correct, renew the 
filter disc. Calibrate the new disc before use. 
Grain Size Distribution: Grist Analysis 
The results obtained from previous routine methods for grist determina-
tion were often influenced by the amount of syrup film surrounding the 
crystals, and by the conditions of humidity and temperature prevailing at the 
time of the determination. The C.S.R. method presented below, however, 
minimizes the tendency of crystals to adhere to each other, by removal of 
most of the syrup film with successive washings of methyl and isopropyl 
alcohol. 
ANALYTICAL METHODS 121 
sponding weight of pure sugar syrup equivalent to the weight obtained at the 
temperature of the determination. Calculate per cent filterability as 
122 ANALYTICAL METHODS 
Special Apparatus— 
Drying Oven—This should have an explosion proof rating and should be 
so situated that any emerging alcohol vapours can be directly removed to 
outside atmosphere. 
Sieves—Three British Standard screens or their equivalents in the Tyler 
rating are employed. The recommended screens are as shown:— 
! British Standard Screen 
Mesh 
i 
18 
25 
36 
Size of Opening 
mm 
0.853 
0.599 
0.422 
Mesh 
20 
28 
35 
Tyler Screen 
Size of Opening 
mm 
0.833 
0.589 
0.417 ! 
Jar Mill—A jar mill with a speed of approximately 75rev/min is required 
for the mixing process. Several commercial units are available, but some 
items of laboratory machinery can be modified for this purpose. 
A two pint Agee jar with the normal sealer cap is required for mixing. 
The outer surface of the jar should be covered wdth one thickness of bandage 
impregnated with Araldite. Also required are an Agee lid ring covered with 
100 mesh gauze, and an outer rubber sealing ring, which will form a seal when 
the jar is inverted over a Buchner funnel. 
Sample Preparation—Thoroughly mix the sugar sample and transfer 
approximately 11.0 g to the Agee jar. Add 250 ml of 99 per cent methyl 
alcohol, seal and rotate for three minutes at 75 rev/min on the jar mill. 
Substitute the gauze covered cap, invert the jar over a Buchner funnel and 
draw off the alcohol under vacuum. Add 250 ml of 99 per cent isopropyl 
alcohol, rotate for three minutes and again remove the alcohol under vacuum. 
N.B.—The preceding alcohol washings should be repeated at this stage, 
if the sugar sample is below 98 polarization. 
Oven dry the sugar on a flat tray at 80 to 90 °C. Occasionally disturb the 
sugar with a spatula to prevent caking. Allow the sugar to cool in a desiccator. 
Sieve Separation—Weigh out 100.00 g of prepared sample and sieve for 
10 minutes on a Ro-tap shaker or Pascall sieve vibrator. Empty the sugar 
crystals caught on each sieve onto sheets of glazed paper, brushing out the 
sieve with a firm tapping brush, taking care not to damage the screens. 
Transfer the sugar from each section to a tared container and weigh the 
fractions to 0.01 g. 
Round off weights so that the weights of the four fractions add up to 
100.0 g. Report the results as a percentage. The percentage of fines is defined 
as the percentage passing through the B.S.25 mesh screen, and by plotting 
cumulative weight fraction against sieve aperture (linear axis) on arithmetic 
probability paper, mean aperture and coefficient of variation can be obtained 
in the following manner. 
Mean aperture == sieve aperture corresponding to 50 per cent weight fraction. 
ANALYTICAL METHODS 123 
Starch 
The C.S.R. method for the determination of starch in raw sugar is 
presented below in a slightly abbreviated form. The method involves hot, 
mild digestion of an aqueous solution of raw sugar in calcium chloride/acetic 
acid to ensure that any starch present is in a form suitable for subsequent 
reaction with iodine. The starch/iodide complex is then determined colori-
metrically at 700 nm. This complex is essentially a colloidal suspension which 
is stable for at least five minutes. 
Standardization—A standard graph is prepared using B.D.H. Laboratory 
Reagent Potato Starch Batch No. 2499440. Refer to Chapter VIII for 
preparation of the standard starch and other starch reagents. 
Prepare aliquots of the standard starch solution, increasing in concentra-
tion from 0 to 500 p.p.m. starch on solids. These are obtained by adding 40 g 
of standard starch-free sugar to each of eight 100 ml volumetric flasks and 
then adding 0, 5, 10, 15, 20, 25, 30 and 50 ml aliquots of standard starch solu-
tion. Add distilled water to each flask to make a total volume of approximate-
ly 75 ml, and dissolve. Dilute to volume, stopper and mix. Pipette 15 ml of 
each solution into separate 50 ml volumetric flasks and then add 25 ml of 
calcium chloride/acetic acid reagent from an automatic burette or graduated 
cylinder. Mix thoroughly. 
Hold each flask in boiling water for 15 minutes and swirl at five minute 
intervals to facilitate the escape of gaseous materials. After exactly 15 minutes 
of heating, cool the flasks in running water, dilute to volume, stopper and mix. 
From each 50 ml flask, pipette 15 ml aliquots into each of two 25 ml 
volumetric flasks designated (a) blank sample and (b) test sample. Then add 
2.5 ml of 1 N acetic acid reagent to each 25 ml flask. Flask (a) from each set 
is then diluted to volume, stoppered, mixed and later used as a separate blank 
for each test sample. 
Prepare and analyse each of the flask (b) test samples as a separate entity 
in the following manner:— Add 5 ml of freshly prepared potassium iodide-
iodate solution (Chapter VIII). Swirl during the addition of this reagent and 
then make to the mark, stopper and mix. Transfer to a 1 cm cuvette. Deter-
mine the optical density at 700 nm against the corresponding blank. The 
determination should be completed as rapidly as practicable after the iodide-
iodate solution has been added. 
Plot p.p.m. starch on solids against optical density. 
Procedure—-The procedure used for raw sugar is basically the same as 
that used to obtain the standardization curve. 
Dissolve 40.0 g of sugar in 50 ml of distilled water in a 100 ml volumetric 
flask. Make up to the mark and mix. Pipette 15 ml of this solution into a 50 
ml volumetric flask, add calcium chloride/acetic acid reagent, mix, digest in 
a boiling water bath, cool and make up to the mark as previously described. 
Pipette 15 ml aliquots into each of two 25 ml volumetric flasks. Add 
2.5 ml of 1 N acetic acid to each flask, mix well and make one flask up to the 
mark, stopper and mix. This is the sample blank solution. 
Fill a 1 cm cuvette with this solution and use it to adjust the spectro-
photometer for infinity and zero optical densities at a wavelength setting of 
700 nm. 
Add 5 ml of potassium iodide-iodate reagent to the other flask, make up 
to the mark, stopper and mix. Transfer this solution to a 1 cm cuvette and 
read the optical density at a wavelength of 700 nm, within five minutes. 
124 ANALYTICAL METHODS 
Read the concentration of starch as p.p.m. on raw sugar solids from the 
standard graph. 
Total Colour Attenuation 
Two methods of colour attenuation have been issued by the C.S.R. 
Company. The more precise of these is not included in this Edition as it 
requires the use of a precision spectrophotometer of a type which is not 
generally available in mill laboratories. 
The procedure for the routine method for colour measurement of raw 
sugar is given below. The method is also applicable to low polarization sugars, 
but in this case, the initial sample weight should be reduced to maintain 
maximum sensitivity on the spectrophotometer scale. 
Special Apparatus—A millipore vacuum filtering apparatus or a C.S.R. 
type pressure filter may be used. Filtration is affected through Millipore type 
A.P.30 prefilter discs and type PH (0.3 micron) filter membranes. 
Sample Preparation—Weigh out 12.50 g of raw sugar and transfer to a 
100 ml volumetric flask. Dissolve in approximately 40 ml of distilled water 
and dilute to volume. Mix thoroughly. 
pH Adjustment—By means of a graduated measuring cylinder, transfer 
50 ml of the solution to a beaker and determine the pH. Adjust the pH of the 
solution to 7.00 ± 0.05 pH by drops of either 0.1 N NaOH or 0.1 N HC1, 
stirring vigorously during the addition. 
Filtration—Filter the solution through a Millipore prefilter disc and 0.3 
micron filter membrane. If insufficient sample is collected before the filtration 
rate slows appreciably, the filter and prefilter should be renewed. 
Reading—Determine the optical density at 420 nm in a 1 cm cuvette 
against a distilled water blank. 
Calculation— 
Total colour attenuation @ 420 nm = 
1000 x optical density 
(concentration of solution g/ml) x (cell size in cm) 
N.B.—If less than ten drops of alkali or acid are used for neutralization, 
the calculation, for an original sample weight of 12.50 g per 100 ml, may be 
abbreviated to— 
Total colour attenuation = 8000 x optical density 
If more than ten drops are used for neutralization, the refractometer 
Brix should be accurately determined and converted to g/ml concentration, 
using Table VII of the Manual. 
Mud Analysis 
Insoluble Solids 
The measurement of insoluble solids in clarifier feed and primary mud 
is usually carried out in conjunction with the laboratory settling test for the 
assessment of clarifier performance, while the determinations on filter feed and 
filter cake are carried out to assess rotary filter performance. Two methods 
are given below. 
Vacuum Filtration Method—Weigh out 200 g of well mixed sample 
and filter through a Buchner funnel. Do not wash the cake with water. 
Aluminium Dish Method—This method has been used extensively by 
the Bureau in clarifier investigations and is useful where a large number of 
samples have to be analysed. Its accuracy is mainly dependent upon accurate 
subsampling of a relatively small quantity of material, and the minimizing 
of evaporation effects. When samples with a relatively low insoluble solids 
content are encountered, the accuracy of the determination may be improved 
by prethickening before subsampling. If this is carried out the formula must 
be modified accordingly. 
Equipment—Flat bottomed aluminium dishes with close-fitting lids. 
A deep welled measuring spoon to contain approximately 3 g of sample. 
Procedure—Prepare the aluminium dishes by pre-drying and cooling in 
a desiccator. Weigh . . .. .. . . . . . . . . .. W1 
Thoroughly but rapidly mix the sample and transfer approximately 3 g 
to the aluminium dish. Immediately seal the dish and weigh dish plus 
contents . . .. . . . . . . . . . . . .. W2 
Remove the lid and rotate the capsule to spread the sample in an even film 
over the bottom of the container. 
Oven dry for 16 hours at a temperature of 70 °C. Seal the container and 
allow to cool in a desiccator for 30 minutes. Weigh and record as ..W3 
Soluble Solids Correction—Filter a separate portion of the original sample, 
taking care to minimize evaporation effects. Determine the Brix to an 
accuracy of ±0.03 units by means of a precision refractometer. 
Calculation— 
ANALYTICAL METHODS 125 
Peel off the cake from the filter paper and weigh the wet cake. Dry to 
constant weight at 96 to 100 °C. 
Determine the soluble solids content of a separate quantity of gravity 
filtered filtrate. This is required to correct for the weight of soluble solids 
contained in the cake. 
Calculation— 
Per cent insoluble solids = 
N.B.—In the case of materials containing an appreciable amount of 
fibre, the fibre content must be determined as described below, and sub-
tracted from the insoluble solids content to obtain the actual percentage of 
mud solids. 
In the case of filter cake, it may be necessary to apply some compression 
to the sample in order to obtain a juice sample for the determination of 
refractometer Brix. 
126 ANALYTICAL METHODS 
Moisture 
Low temperature drying of mud is recommended for experimental pur-
poses. For comparative routine determinations on filter cake however, drying 
at 100 °C will not introduce serious errors. 
Procedure—Weigh out 5.0 g of well mixed sample into a tared aluminium 
container. 
Dry at 70 °C for 16 hours or for four hours at 100 °C. Cool in a desiccator 
and reweigh. 
Calculate moisture per cent original sample. 
Pol 
In the determination of per cent pol in mud by wet lead clarification an 
arbitrary adjustment is made to the weight of sample taken, to correct for the 
error introduced by the presence of insoluble solids. 
Procedure—Thoroughly mix the sample and weigh out 50 g into a nickel 
weighing dish. Add a small quantity of water to promote mobility and trans-
fer into a wide mouthed (Kohlrausch type) 200 ml volumetric flask. Add 
sufficient wet lead to clarify. This usually requires from 2 to 5 ml. Dilute to 
volume with distilled water, shake and allow to stand for at least 5 minutes. 
Filter and then polarize in a 400 mm tube. 
Calculate pol per cent mud by halving the polariscope reading. 
Fibre 
For the determination of fibre in mud, a 3 inch diameter 3 inch high cylin-
drical container fitted with a 100 mesh gauze base is employed. An old style 
Spencer over drying capsule is ideal for this purpose. 
Procedure—Transfer 50 g of the premixed mud sample into the drying 
capsule. Hold over a sink and wash with a steady stream of water until the 
runnings are clear. Allow surplus water to drain off and then dry to constant 
weight in a Spencer-type oven. 
The fibre per cent mud will equal double the dry weight of the fibre 
(in g), weighing to an accuracy of ± 0.C1 g. 
Gum Analysis 
The following is a revised version of the U.S.D.A. method for the deter-
mination of gums in cane juices by alcohol precipitation. The method has 
been used extensively in cane deterioration studies as it provides a quantita-
tive index of changes that occur in gum content during cane storage. Other 
methods of gum determination are available, and although the results of the 
method described below may not agree precisely with these, the alcohol 
precipitation method is considered to be the most suitable for routine analyses. 
Preparation of Standard Graph—Prepare aqueous solutions of A.R. dex-
trose (C6H1206) to the following concentrations:—0.001 per cent, 0.05 per 
cent and 0.01 per cent. 
To a separate test tube for each concentration, add 2.0 ml of dextrose 
solution and 1 ml of phenol reagent. (See Chapter VIII under Sugar Detec-
tion). Rapidly add 10 ml of concentrated sulphuric acid to each test tube, 
holding the tip of the safety pipette about two inches above the liquid 
surface. Take care in case the mixture boils and ejects from the tube. Swirl 
to mix and allow to stand for ten minutes. 
ANALYTICAL METHODS 127 
After t h e r eac t i on t i m e h a s e lapsed, cool in w a t e r for t e n m i n u t e s a n d 
d e t e r m i n e op t ica l d e n s i t y a t 485 nm aga ins t a b l a n k p r e p a r e d a s a b o v e us ing 
dis t i l led w a t e r in p lace of t h e d e x t r o s e so lu t ion . 
N.B.—The pheno l - su lphur ic acid m e t h o d requi res an e l eva ted r eac t ion 
t e m p e r a t u r e t o conve r t t h e po lysacchar ides p r e sen t t o dex t ro se a n d o t h e r 
m o n o s a c c h a r i d e s . 
F r o m t h e op t ica l d e n s i t y resu l t s a s t a n d a r d g r a p h of po lysaccha r ide 
c o n c e n t r a t i o n (expressed as anhydroglucose) ve r sus op t i ca l d e n s i t y i s o b -
t a i n e d . 
T h e c o n c e n t r a t i o n of anhydrog lucose i s ca lcu la ted by d e d u c t i n g t e n 
per cent f rom t h e c o n c e n t r a t i o n of t h e d e x t r o s e so lu t ions or iginal ly used . 
T h e r ea son for t h i s deduc t i on c a n be seen f rom t h e following f o r m u l a e : — 
D e x t r o s e C 6 H 1 2 0 6 , Molecular W e i g h t 180.156 
P o l y - D e x t r o s e (C 6 H 1 0 O 5 ) n , Molecular W e i g h t 162.141 
A difference of 18.015 or 9.9997 per cen t . 
D e t e r m i n a t i o n o f G u m s i n J u i c e 
Sample Preparation—Sieve a p o r t i o n of t h e ju ice s a m p l e t h r o u g h a 325 
m e s h screen. Centr i fuge for six m i n u t e s a t no less t h a n 2000 g . P r o v i d e d t h e 
ju ice i s u n h e a t e d , t h e a b o v e p r o c e d u r e will r e m o v e s t a r c h in te r ference . I f t h e 
ju ice o r p r o d u c t h a s b e e n h e a t e d , t h e s t a r c h c a n n o t b e i so la ted , a n d " t o t a l 
g u m s " will b e d e t e r m i n e d . 
Alcohol Precipitation—Pipette 10 ml of t h e s u p e r n a t a n t l iqu id i n t o a 
s e p a r a t e centr i fuge t u b e con t a in ing 30 ml of abso lu t e alcohol , m i x a n d al low 
t h e p r ec ip i t a t e to fo rm by s t a n d i n g for a t leas t five m i n u t e s . 
Recen t r i fuge for six m i n u t e s t o c o n c e n t r a t e t h e g u m s in t h e b o t t o m 
of t h e cent r i fuge t u b e . D e c a n t t h e s u p e r n a t a n t l iqu id as qu ick ly as possible 
to avo id loss of g u m s . I n v e r t t h e t u b e s over a t owe l a n d al low excess alcohol 
to d r a i n off. 
Purification of Gums—Add a few d r o p s of 80 pe r cen t alcohol in i t ia l ly 
t o assist i n r e suspend ing t h e g u m s , a n d s t i r w i t h a glass rod . W a s h t h e t u b e 
w i t h m o r e alcohol us ing a t o t a l of 30 ml of 80 pe r cen t alcohol . Allow to s t a n d 
for five m i n u t e s . 
Centr i fuge for s ix m i n u t e s a t no less t h a n 2000 g . D e c a n t t h e s u p e r n a t a n t 
l iquid a n d aga in al low to d ra in over a towel . Dissolve t h e g u m s in dis t i l led 
w a t e r a n d d i lu t e to a v o l u m e of 100 ml in a vo lume t r i c flask. 
Blank and Test Solution—Pipette 2.0 ml of g u m solu t ion i n t o a t e s t t u b e 
a n d proceed w i t h t h e add i t i on of 1 ml of pheno l r e a ge n t a n d 10 ml of su lphur ic 
ac id as descr ibed in t h e sect ion on p r e p a r a t i o n of t h e s t a n d a r d g r a p h . 
T h e b l a n k so lu t ion i s p r e p a r e d in a s imilar m a n n e r , w i t h t h e excep t ion 
t h a t 2.0 ml o f dis t i l led w a t e r i s s u b s t i t u t e d for t h e g u m so lu t ion . 
D e t e r m i n e t h e op t i ca l d e n s i t y o f t h e t e s t aga ins t t h e b l a n k so lu t ion a t 
485 n m . 
Calculation—Read off t h e p e r cen t g u m s in ju ice for t h e co r respond ing 
op t ica l d e n s i t y on t h e s t a n d a r d g r a p h . (If t h e op t i ca l d e n s i t y i s ou t s ide t h e 
l imi t s o f t h e g r a p h , t h e g u m so lu t ion m u s t be r ed i lu t ed ) . A B r i x d e t e r m i n a t i o n 
i s ca r r i ed out on t h e or iginal ju ice a n d t h e resu l t s expressed as g u m s per cen t 
solids. 
128 ANALYTICAL METHODS 
P h o s p h a t e A n a l y s i s 
T h e C.S.R. a m i d o l m e t h o d i s r e c o m m e n d e d for t h e d e t e r m i n a t i o n o f 
p h o s p h a t e i n r a w sugars , s y r u p s a n d ju ices . P h o s p h a t e i s d e t e r m i n e d b y 
m e a s u r i n g t h e i n t e n s i t y of t h e b lue co lora t ion deve loped in t h e p resence of 
ac id m o l y b d a t e a n d amido l a t a w a v e l e n g t h of 660 n m . F o r p u r p o s e s of 
un i fo rmi ty , i t i s sugges ted t h a t all p h o s p h a t e r e su l t s be expres sed as p a r t s 
pe r mil l ion p h o s p h o r u s i.e. p . p . m . P . 
W h e n us ing th i s m e t h o d o f ana lys i s t h e following p o i n t s shou ld be b o r n e 
i n m i n d : 
(a) I n h a l a t i o n of t h e v a p o u r f rom amido l so lu t ions s hou ld be careful ly 
avo ided a t all t imes . Th i s s u b s t a n c e i s v e r y tox ic . 
(b) T h e m e t h o d specifies acid w a s h e d superce l as some b a t c h e s of super -
cel, as rece ived , h a v e been found to c o n t a i n app rec i ab l e q u a n t i t i e s o f p h o s -
p h o r u s . E a c h b a t c h o f filter p a p e r s shou ld also be checked to ensu re t h a t 
p h o s p h o r u s c a n n o t b e e x t r a c t e d f rom t h e p a p e r i n t o t h e s amp le . 
(c) I t is adv i sab le to h a v e a se t of flasks a n d c u v e t t e s wh ich a re k e p t 
solely for p h o s p h a t e ana lys i s as m i n u t e t r a ce s of t h e r e d u c i n g a g e n t u s e d in 
t h i s d e t e r m i n a t i o n c a n affect t h e resu l t s of o t h e r ana lyses . 
Preparation of Standard Graph—The p r e p a r a t i o n of t h e s t a n d a r d p h o s -
p h a t e so lu t ion (con ta in ing 0.01 mg P per ml) a n d t h e assoc ia ted r e a g e n t s a r e 
descr ibed in C h a p t e r V I I I . T h e following a l iquo t s o f t h e s t a n d a r d p h o s p h a t e 
so lu t ion are t r ans fe r r ed i n t o 50 ml v o l u m e t r i c f lasks: 0 , 1 , 2 , 3 , 4 , 7.5 a n d 
10 m l . 
Colour Development—To e a c h flask a d d t w o d r o p s of c o n c e n t r a t e d h y d r o -
chloric ac id followed by dis t i l led w a t e r to m a k e to a t o t a l v o l u m e of 30 ml . 
T h e n a d d 10 ml of ac id m o l y b d a t e followed by 4 ml of a m i d o l r e a g e n t by 
m e a n s o f a u t o m a t i c d i spensers . D i lu t e to v o l u m e w i t h dis t i l led w a t e r , s h a k e 
a n d let s t a n d for a t leas t 10 m i n u t e s to a l low a s t a b l e co lour to deve lop . 
Blank Preparation—Prepare a b l a n k so lu t ion in a 50 ml flask us ing t w o 
d r o p s of c o n c e n t r a t e d hydroch lo r i c acid, 10 ml of acid r e a g e n t a n d dis t i l led 
w a t e r . A d j u s t t h e s p e c t r o p h o t o m e t e r w i t h t h e b l a n k so lu t ion t o r e a d zero 
op t i ca l d e n s i t y in a 1 cm cell a t 660 nm w a v e l e n g t h . 
Colour Measurement—Determine t h e op t i ca l d e n s i t y of t h e co loured 
so lu t ion af ter t h e s p e c t r o p h o t o m e t e r h a s been s t a n d a r d i z e d w i t h t h e b l a n k 
solu t ion . T h i s o p e r a t i o n shou ld be car r ied o u t b e t w e e n 10 a n d 30 m i n u t e s 
af ter t h e a d d i t i o n of amido l r e agen t . 
P r e p a r e a s t a n d a r d g r a p h by p l o t t i n g op t i ca l d e n s i t y aga in s t mg of P 
used f rom t h e s t a n d a r d so lu t ion . 
T o t a l P h o s p h a t e i n R a w S u g a r s 
Preparation—Weigh o u t 40 .0 g of s a m p l e a n d t r ans f e r to a 200 ml 
vo lume t r i c flask. A d d sufficient w a t e r t o dissolve t h e c rys t a l s . 
pH Adjustment—Reduce t h e pH of t h e so lu t ion to a p p r o x i m a t e l y 4 .0 . 
Th i s u s u a l l y r equ i res on ly t w o d r o p s o f c o n c e n t r a t e d hyd roch lo r i c ac id . 
D i lu t e t o v o l u m e w i t h dis t i l led w a t e r a n d m i x . 
Filtration—Prepare a s l u r r y by m i x i n g a p p r o x i m a t e l y 20 ml of t h e solu-
t i on w i t h a level t e a s p o o n of ac id w a s h e d superce l . Use t h i s s l u r r y to p r e c o a t 
t w o W h a t m a n N o . 5 p a p e r s in a B u c h n e r funnel . R i n s e t h e B u c h n e r flask 
Total Phosphate in Clarified Juice and Syrup 
Sample Preparation—Determine the Brix of the material by refracto-
meter, and calculate the weight of material which contains 10 g of soluble 
solids. Transfer this amount into a 200 ml volumetric flask, adjust the pH 
to 4.0, dilute to volume and mix. 
The solution is then filtered and analysed in the same manner as de-
scribed for the determination of phosphate in raw sugars. 
Convert optical density to mg P from the standard graph. Then p.p.m. P 
on solids = mg P x 1000. 
Total Phosphate in Raw Juices 
The same procedure as described for syrups is applied, with the exception 
that a smaller aliquot of filtered sample is taken for colour development. 
A 5 ml aliquot should be sufficient for normal juices, and the calculation in 
this instance would then become:— p.p.m. P on solids = mg P x 4000. 
Soluble and Insoluble Phosphate 
The form in which phosphate is originally present, and the efficiency of 
phosphate removal during clarification, bear an important relationship to the 
filtering qualities of the raw sugar produced. While on one hand it is desirable 
to have a relatively high concentration of phosphate present in raw juice, the 
presence of phosphate in raw sugar is considered to be undesirable. A com-
plication also arises by virtue of the fact that some phosphates are present in 
cane juice in a form that does not favour their precipitation and subsequent 
removal during clarification. These are commonly referred to as insoluble 
phosphates, although the term "organically bound phosphate" is more 
precise. 
Soluble phosphate is determined after filtration of the undiluted 
product at its existing pH value. The level of soluble phosphate in clarified 
juice is of value as an index of the efficiency of juice clarification, but 
the figure should always be examined in conjunction with the level of phos-
phate in unlimed juice, as a marked decline in the latter can result in an in-
crease in the residual phosphate present after clarification. 
ANALYTICAL METHODS 129 
with this filtrate and discard. Filter approximately 50 ml of the test solution 
through the pre-coated papers. 
Colour Development—Pipette 20 ml of the filtered solution into a 50 ml 
flask. Add 10 ml of acid molybdate and 4 ml of amidol by means of automatic 
dispensers. Dilute to volume, shake and allow to stand for 10 minutes. 
Blank Preparation— Pipette 20 ml of filtered test solution into a separate 
50 ml volumetric flask. Add 10 ml of acid reagent, dilute to volume and shake. 
Use this solution to adjust the spectrophotometer to zero optical density at 
660 nm in a 1 cm cell. 
Determine the optical density of the coloured solution against the blank. 
This should be carried out between 10 and 30 minutes after the addition of 
amidol reagent. 
Convert optical density to mg P from the standard graph. Then p.p.m. P 
132 ANALYTICAL METHODS 
t h e presence of suga r in a s amp le . T h e a l p h a - n a p h t h o l t e s t i s n o t r e c o m m e n d e d 
for c o n t r o l p u r p o s e s w h e n facili t ies a r e ava i l ab l e for u s ing t h e pheno l -
su lphur i c ac id m e t h o d . 
Procedure—Pipette 5 ml of cooled s a m p l e i n t o a c lean t e s t t u b e a n d a d d 
five d r o p s of a l p h a - n a p h t h o l so lu t ion . Swir l to m i x . Careful ly a d d 5 ml of 
c o n c e n t r a t e d s u l p h u r i c ac id t o t h e inc l ined t e s t t u b e s o t h a t t w o c lear ly 
defined l iqu id l aye r s a r e formed. 
I f sucrose is p r e sen t , a v io le t r i n g will f o r m at t h e j u n c t i o n of t h e t w o 
l iqu ids a n d t h e i n t e n s i t y of t h e co lour of t h i s r i n g i s an i n d i c a t i o n of t h e 
q u a n t i t y of sucrose p r e s e n t . T h e t e s t i s e x t r e m e l y de l i ca te in t h a t 1 p . p . m . 
of sucrose will g ive a s l ight co lo ra t ion . An i n t e n s e b l a c k r ing will fo rm at a 
c o n c e n t r a t i o n of a p p r o x i m a t e l y 100 p . p . m . 
Q u a l i t y o f M i l l L i m e 
T h e q u a l i t y o f l ime supp l ied to s u g a r fac tor ies i s an i m p o r t a n t b u t of ten 
neg lec ted fac tor i n t h e ju ice clarif icat ion process . A p a r t f rom t h e economic 
aspec t , t h e use of inferior q u a l i t y l ime c a n i n t r o d u c e signif icant q u a n t i t i e s of 
undes i r ab l e impur i t i e s i n t o process . T h e compos i t e s a m p l i n g a n d ana lys i s o f 
all i ncoming l ime c o n s i g n m e n t s a r e fac tors w o r t h y of ser ious cons ide ra t ion . 
T w o d e t e r m i n a t i o n s a re r e q u i r e d to assess t h e su i t ab i l i t y of a mil l l ime. 
These a re t h e Neu t r a l i s ing V a l u e — e x p r e s s e d a s p e r c e n t CaO, a n d Ava i l ab le 
CaO. 
Sampling Procedure—An in i t ia l b u l k s amp le , r e p r e s e n t i n g a p p r o x i m a t e l y 
one p o u n d pe r t o n o f l ime rece ived , i s s u b s a m p l e d d o w n to a p p r o x i m a t e l y 
one p o u n d . T h i s i s t h e n g r o u n d i n a m o r t a r a n d pas sed t h r o u g h a n 0.5 m m 
sieve. I t i s i m p o r t a n t t h a t t h i s o p e r a t i o n b e ca r r i ed o u t a s r a p i d l y a s possible 
s o t h a t r e c a r b o n a t i o n i s k e p t t o a n a b s o l u t e m i n i m u m . 
Sample Preparation—Two ounces of t h e s ieved m a t e r i a l a r e o v e n d r i ed 
for four h o u r s a t 100 °C. T h e s a m p l e is t h e n s t o r e d in a sma l l a i r t i g h t 
con ta ine r . 
N e u t r a l i z i n g V a l u e 
Trans fe r an a c c u r a t e l y d e t e r m i n e d w e i g h t a p p r o x i m a t i n g 1 g of s a m p l e 
to a 600 ml E r l e n m e y e r flask a n d a d d 40.0 ml of 1.00 N HC1. Cover t h e m o u t h 
of t h e flask w i t h a w a t c h glass a n d h e a t on a s t e a m b a t h for 15 m i n u t e s . 
F i l t e r , a n d w a s h t h e r e s idue w i t h h o t d is t i l led w a t e r . D i l u t e t h e n i t r a t e a n d 
t o t a l wash ings to a v o l u m e of 100 ml a n d boi l v e r y g e n t l y for five m i n u t e s . 
Al low to cool in a w a t e r b a t h . A d d five d r o p s of p h e n o l p h t h a l e i n ind ica -
t o r a n d t i t r a t e t o t h e e n d p o i n t w i t h 1.00 N N a O H . 
Calculation— 
Neut ra l i z ing Va lue ml of 1.00 N HC1 u s e d X 2.80 
(expressed as p e r cen t CaO) = we igh t of s a m p l e 
A v a i l a b l e C a l c i u m O x i d e 
T h e following m e t h o d i s p r e s e n t e d for o b t a i n i n g an a p p r o x i m a t e e s t i m a -
t ion o f t h e p e r c e n t a g e c a l c i u m ox ide t h a t wil l c o m b i n e w i t h sucrose t o fo rm 
a soluble ca l c ium s a c c h a r a t e . I t i s i m p o r t a n t t h a t t h e s a m e s t a n d a r d sucrose 
be u s e d for al l t e s t s , a n d for t h e p u r p o s e o f u n i f o r m i t y , i t i s r e c o m m e n d e d 
t h a t B . D . H . A . R . sucrose o n l y b e u sed . 
Procedure—Transfer 1.60 g of s a m p l e to a d r y s t o p p e r e d 200 ml E r l e n -
m e y e r flask. A d d 2 .0 ml o f e t h y l a lcohol t o p r e v e n t t h e f o r m a t i o n o f agg lomer -
C a u s t i c C l e a n i n g S o l u t i o n 
D e t e r m i n a t i o n o f C o n c e n t r a t i o n 
Care shou ld be t a k e n to ensure t h a t t h e s ample of c leaning solut ion i s 
r e p r e s e n t a t i v e of t h e c o n t e n t s of t h e ho ld ing vessel. P a r t i c u l a r emphas i s 
shou ld be p laced on th i s po in t , especial ly after m o r e solid caus t ic soda has 
been a d d e d to increase t h e concen t r a t i on of t h e solut ion. 
T h e d e t e r m i n a t i o n of caus t ic s t r e n g t h by a s t r a i g h t ac id /base t i t r a t i o n 
can give e r roneous resu l t s i f significant a m o u n t s of s u l p h a t e are p resen t . Th i s 
in terference c a n be ove rcome by p rec ip i t a t i on o f t h e s u l p h a t e s w i t h b a r i u m 
chlor ide a n d r e m o v a l o f t h e p rec ip i t a t e by f i l t rat ion. 
Procedure—To 50 ml of t h e s a m p l e a d d 20 ml of 4 per cen t W / V b a r i u m 
chlor ide so lu t ion . Mix a n d filter. 
T i t r a t e a 25 ml a l iquo t of t h e f i l t rate aga ins t 0.50 N hydroch lo r i c acid , 
us ing m e t h y l r e d a s an ind ica to r . 
P e r cen t s o d i u m h y d r o x i d e = t i t r e x N of HCI x 0.224 
N.B.—The s t r e n g t h of t h e s t a n d a r d ac id c a n be va r i ed to su i t t h e caus t i c 
so lu t ion be ing ana lysed . 
C.S.R. L a b o r a t o r y S e t t l i n g T e s t 
T h e l a b o r a t o r y se t t l ing t e s t i s u sed to d e t e r m i n e t h e clarifying p roper t i e s 
o f i n d i v i d u a l ju ices a n d to p r e d i c t f ac to ry se t t l ing r a t e s . T h e mu l t i p l e t e s t ing 
of f ac to ry m i x e d ju ices also p e r m i t s t h e e s t a b l i s h m e n t of s t a n d a r d s to 
e v a l u a t e f ac to ry pe r fo rmance (Burgess et al., 1962). 
Special Apparatus—The following e q u i p m e n t is required:-— 
J u i c e H e a t i n g — H e c l a 450 w a t t A.C. pe rco la to r p lus a 
1500 w a t t immers ion hea t e r . 
S t i r r ing Mechan i sm — L a b o r a t o r y t y p e s t i r re r ope ra t i ng a t a p -
p r o x i m a t e l y 1200 r e v / m i n . 
L i m e A d d i t i o n — A 10 ml g r a d u a t e d p i p e t t e w i t h a p p r o x i -
m a t e l y 1 inch of flexible t u b i n g a t t a c h e d 
to t h e de l ivery end . A h y p o d e r m i c syr inge 
m a y be used as a su i t ab le s u b s t i t u t e . 
H e a t e d Se t t l i ng B a t h — As pe r C.S.R. specifications. 
Se t t l ing T u b e s — These shou ld be 1.50 inches i n t e r n a l d ia-
m e t e r , a n d g r a d u a t e d i n vo lume p e r cen t 
over a l e n g t h of 16 inches . 
Lime Requirement—The l ime r e q u i r e m e n t va r ies cons ide rab ly be tween in-
d iv idua l juices , b u t an a p p r o x i m a t e e s t i m a t e o f th i s q u a n t i t y can be o b t a i n e d 
in t h e following m a n n e r : — S e t up a s t i r re r a n d pH e lec t rodes in a b e a k e r con-
t a in ing 600 ml o f t h e s ample . Slowly a d d t h e l ime sucrose so lu t ion (Chap te r 
V I I I ) f rom a b u r e t t e un t i l t h e des i red pH i s o b t a i n e d . Th i s q u a n t i t y o f l ime 
ANALYTICAL METHODS 133 
a tes . T h e n a d d 100.0 ml of 10 p e r cen t sucrose so lu t ion p r e p a r e d f rom B . D . H . 
A .R . sucrose, to fo rm a soluble s a c c h a r a t e . Seal t h e flask a n d s h a k e for 30 
m i n u t e s . 
F i l te r . D i sca rd t h e first 5 ml of f i l t ra te . A d d t h r e e d r o p s of m e t h y l o range 
i nd i ca to r to a 50 ml a l iquo t of t h e n i t r a t e a n d t i t r a t e aga ins t 1.00 N HC1. 
Calculation — 
a n d d r a w a ho r i zon t a l l ine a t t h e under f low c o n c e n t r a t i o n level . 
P r o d u c e t h e in i t ia l s t r a i g h t l ine 
sect ion (free se t t l ing zone) of t h e 
c u r v e to c u t t h e under f low h line a t 
po in t A . Bisec t t h e o u t e r ang le 
fo rmed b y t h e e x t e n d e d free se t t l i ng 
line a t t h e i n t e r c e p t on t h e h 
l ine . 
D r a w a l ine pe rpend icu l a r to 
th i s b i sec tor a n d t a n g e n t i a l t o t h e 
se t t l ing c u r v e . P r o d u c e th i s t a n g e n t 
to c u t t h e h l ine a t p o i n t C. R e a d off 
t h e t i m e co r r e spond ing to p o i n t C . 
D e s i g n a t e t h i s t i m e a s T . 
T h e u n i t se t t l ing a r ea r e q u i r e -
m e n t of t h e ju ice t e s t e d i s t h e n g iven 
b y t h e e q u a t i o n : — 
U n i t A r e a = 0.002 x T 
s q u a r e foot /gal lon ju ice 
/ hou r 
134 ANALYTICAL METHODS 
s a c c h a r a t e i s t h e n used in t h e a c t u a l se t t l ing t e s t . A re f inement to t h i s 
p r o c e d u r e i s t h e use of a m a g n e t i c s t i r re r h o t p l a t e . T h i s a p p a r a t u s r e d u c e s 
t h e r i sk o f e l ec t rode d a m a g e a n d also p e r m i t s t h e d e t e r m i n a t i o n t o be ca r r i ed 
o u t a t e l eva t ed t e m p e r a t u r e s . 
Procedure—Subsample t w o 600 ml a l i quo t s of ju ice . D e t e r m i n e t h e l ime 
r e q u i r e m e n t on one po r t i on . 
Trans fe r t h e r e m a i n i n g 600 ml o f ju ice to t h e pe r co l a to r in wh ich t h e 
s t i r re r h a s a l r e a d y been pos i t ioned , a n d h e a t r a p i d l y t o boi l ing us ing t h e 
pe rco la to r e l emen t a n d t h e i m m e r s i o n h e a t e r . T h e t i m e b e t w e e n s a m p l i n g 
a n d boi l ing shou ld n o t exceed seven m i n u t e s . 
Af ter t h e ju ice h a s boi led for t w o m i n u t e s , t u r n t h e s t i r r e r o n a n d a d d 
t h e p r e d e t e r m i n e d a m o u n t of l ime a t a c o n s t a n t r a t e to t h e o u t e r edge of t h e 
r o t a t i n g s t i r re r b l a d e . T h e a d d i t i o n o f l ime shou ld t a k e a p p r o x i m a t e l y 15 
seconds . C o n t i n u e s t i r r ing a n d h e a t i n g for a f u r t he r 15 seconds . 
T u r n t h e h e a t e r a n d s t i r re r off a n d t rans fe r t h e ju ice to a p r e h e a t e d s e t t -
l ing t u b e i m m e r s e d i n boi l ing w a t e r . Fi l l t h e t u b e t o t h e 100 pe r cen t g r a d u a -
t i on m a r k , s t o p p e r a n d c o m m e n c e t i m i n g o f t h e se t t l i ng t e s t . R e c o r d per cen t 
m u d v o l u m e aga ins t t i m e a t one m i n u t e i n t e r v a l s for 1 5 m i n u t e s a n d t h e n a t 
2 0 a n d 2 5 m i n u t e s . Comple t e t h e t e s t a t 3 0 m i n u t e s a n d r e c o r d t h e final m u d 
v o l u m e . A s a m p l e of clarified ju ice is t h e n r e m o v e d , cooled a n d a n a l y s e d for 
p H , t u b i d i t y a n d p h o s p h a t e . 
Calculation of Settling Area Requirement—Plot a se t t l ing c u r v e of per c e n t 
m u d v o l u m e ve r sus se t t l ing t i m e in m i n u t e s . Use a scale such t h a t 10 pe r cen t 
in m u d v o l u m e is e q u i v a l e n t to a t i m e i n t e r v a l of five m i n u t e s . 
T h e "c r i t i ca l p o i n t " i.e. t h e p o i n t o f m i n i m u m f lux , i s l oca t ed by t h e 
following m e t h o d a s s h o w n in F ig . 4 3 . 
D e t e r m i n e under f low c o n c e n t r a t i o n h by t h e e q u a t i o n 
ANALYTICAL METHODS 135 
It should be noted that this formula applies only to settling tubes of 
the dimensions previously stated. 
This unit area has been used to calculate the area required in factory 
clarifiers by multiplying the unit area by the factory mixed juice flow, ex-
pressed in gallons per hour. However, while the concept has been a valuable 
guide in the past, with the present extensive use of flocculating agents and 
the consequent increase in settling rates obtained with these additives, the 
areas predicted from this test must now be considered with a good deal of 
reserve. The advent of flocculating agents has, however, introduced a further 
use for this settling test as it enables the performance of various flocculants 
to be compared under laboratory and factory conditions. 
Due to variations in juice composition, and slight differences in test 
procedure, a single test is of limited value, and the average of a number of 
tests is required to provide a valid comparison with factory results. 
As explained in Chapter I, a cyclone sample is a sample of the mother 
liquid extracted from a massecuite. For the separation process the laboratory 
Cyclone Sampling and Supersaturation 
Fig. 44—Illustrating a pressure filter for separation of molasses from massecuite. 
136 ANALYTICAL METHODS 
b a s k e t t y p e fugal w a s fo rmer ly r e c o m m e n d e d . T h e use of a fugal h a s t h e 
d i s a d v a n t a g e t h a t a s ignif icant p r o p o r t i o n of w a t e r i s e v a p o r a t e d f rom t h e 
molasses in t h e s e p a r a t i o n process . Th i s does n o t inf luence p u r i t y o f t h e 
molasses b u t i t does a l t e r t h e sucrose a n d t o t a l solids c o n c e n t r a t i o n s . Suc t ion 
filters h a v e been used for t h e s e p a r a t i o n , b u t t h e s e d i s p l a y t h e s a m e dis-
a d v a n t a g e s . 
T h e r e c o m m e n d e d dev ice for s e p a r a t i o n of cyc lone s a m p l e s is a p r e s su re 
filter, of wh ich one e x a m p l e is i l l u s t r a t ed in F i g u r e 44 . I t cons is t s s i m p l y of a 
w a t e r j a c k e t e d p res su re vessel w i t h r e m o v a b l e t o p a n d b o t t o m covers . T h e 
b o t t o m p l a t e i s p r o v i d e d w i t h d r a i n a g e channe l s l ead ing to a c e n t r a l ho le 
a n d s u p p o r t s a screen on wh ich t h e a c t u a l f i l t ra t ion i s ach ieved . W h e n m a s s e -
cu i t e i s p l aced in t h e sealed vessel a n d air p re s su re app l i ed a t t h e t o p , t h e 
molasses i s forced o u t t h r o u g h t h e screen. E x c e p t in t h e m o s t difficult cases , 
t h e s e p a r a t i o n is accompl i shed in a few m i n u t e s a n d t h e compos i t ion of t h e 
m o t h e r l iquor i s n o t adve r se ly affected in t h e process . Care m u s t be t a k e n , 
however , t o e n s u r e t h a t t h e s e p a r a t i o n i s ca r r i ed o u t a t t h e t e m p e r a t u r e o f 
s a m p l i n g of t h e m a s s e c u i t e a n d t h e first 5 to 10 ml of s a m p l e s hou l d be 
re jec ted . 
S u p e r s a t u r a t i o n 
T h e d e t e r m i n a t i o n of t h e degree of s u p e r s a t u r a t i o n of molasses is of 
cons iderab le i m p o r t a n c e in t h e s t u d y o f p a n boi l ing a n d c rys ta l l i za t ion . T h e 
e x p l a n a t i o n of t h e t h e o r y assoc ia ted w i t h t h e d e t e r m i n a t i o n of coefficient of 
s u p e r s a t u r a t i o n invo lves t h e u s e o f t e r m s w h i c h a r e defined as fo l lows :— 
(a) C o n c e n t r a t i o n . T h e p e r c e n t a g e r a t i o by we igh t o f so lu te to so lven t 
(unless o the rwise s t a t e d ) . 
(b) S a t u r a t i o n . T h a t cond i t ion in wh ich t h e q u a n t i t y of so lu te d issolved 
in a so lven t i s t h e m a x i m u m which c a n be c o n t a i n e d in s t a b l e equ i l i b r i um. 
(c) Solubi l i ty . T h e c o n c e n t r a t i o n of so lu te in t h e so lven t g iv ing a cond i -
t ion of s a t u r a t i o n . So lubi l i ty is r e spons ive to v a r i o u s influences, of w h i c h 
t e m p e r a t u r e a n d t h e p resence o f o t h e r so lu tes i n t h e so lven t a r e i m p o r t a n t 
i n t h e p r e sen t connec t ion . 
(d) So lub i l i ty Coefficient. T h e r a t i o of t h e so lub i l i ty of sucrose in t h e 
i m p u r e w a t e r o f t h e s a m p l e to t h e so lub i l i ty o f sucrose in p u r e w a t e r a t t h e 
s a m e t e m p e r a t u r e . Some i m p u r i t i e s ra i se t h e so lub i l i ty o f sucrose in w a t e r , 
o t h e r s lower i t . T h e c o m b i n e d effect of t h e i m p u r i t i e s p r e s e n t in c ane molasses 
i s u s u a l l y to lower t h e so lub i l i ty of sucrose . 
(e) Coefficient of S u p e r s a t u r a t i o n . T h e r a t i o of t h e a c t u a l c o n c e n t r a t i o n 
of sucrose p r e s e n t in a s a m p l e to t h e so lubi l i ty of sucrose in t h e w a t e r of t h e 
s a m p l e a t t h e s a m e t e m p e r a t u r e . S u p e r s a t u r a t i o n i s a n u n s t a b l e c o n d i t i o n ; 
t h o u g h , i n p rac t i ce , t h e t e n d e n c y t o r e v e r t t o t h e e q u i l i b r i u m cond i t i on i s 
s o m e t i m e s v e r y feeble. 
T h e m e t h o d of d e t e r m i n a t i o n of t h e coefficient of s u p e r s a t u r a t i o n , d e -
v i sed by H a r m a n , i s b a s e d on t h e fact t h a t , i f a s u p e r s a t u r a t e d so lu t ion i s 
h e a t e d , t h e s u p e r s a t u r a t i o n coefficient will fall, d u e to t h e r ise in t h e so lub i l i ty 
o f sucrose w i t h t e m p e r a t u r e . A t some t e m p e r a t u r e t h e so lu t ion will b e c o m e 
s a t u r a t e d , a n d i f t h i s t e m p e r a t u r e i s exceeded , u n d e r s a t u r a t i o n will r e su l t . 
A n y c rys ta l s o f sucrose p r e s e n t in t h e so lu t ion wil l t h e n c o m m e n c e to dis-
solve, a p h e n o m e n o n w h i c h m a y be o b s e r v e d v i sua l ly u n d e r s u i t a b l e 
cond i t ions . 
where solubi l i ty is t h a t of sucrose in wa t e r , i.e. g sucrose pe r 100 g of w a t e r 
(Table X I I I ) . 
T h e s t a t e m e n t t h a t k 1 m a y be t a k e n equa l to k 2 can g ive rise to v e r y 
ser ious er rors in some cases. 
W h e n cor rec t ions a re m a d e for chang ing solubi l i ty coefficient i t shou ld 
be n o t e d t h a t th i s defini t ion m u s t be s t a t e d a s be ing for c o n s t a n t p u r i t y . I n 
p rac t i ce a so lu t ion w h e n crys ta l l ized does n o t r e m a i n a t c o n s t a n t p u r i t y , a n d 
a m o r e f u n d a m e n t a l va lue of coefficient of s u p e r s a t u r a t i o n is o b t a i n e d by 
express ing i t as 
ANALYTICAL METHODS 137 
F o r a p u r e so lu t ion of sucrose in w a t e r , s u p e r s a t u r a t e d a t t e m p e r a t u r e t 1 
a n d found t o b e s a t u r a t e d a t t e m p e r a t u r e t 2 i t m a y b e c la imed t h a t t h e 
c o n c e n t r a t i o n of sucrose ac tua l l y p re sen t i s t h a t cor responding to t h e solubil-
i t y of sucrose at t2. T h e c o n c e n t r a t i o n of sucrose r equ i r ed to give a s a t u r a t e d 
solut ion a t t 1 i s t h e so lubi l i ty a t t 1 . B o t h so lubi l i ty figures m a y be a sce r t a ined 
for se lected t e m p e r a t u r e s f rom t ab le s such as t h a t of Charles (Table X I I I ) . 
T h e n if S be t h e coefficient of s u p e r s a t u r a t i o n at t e m p e r a t u r e t1 
F o r i m p u r e solut ions , t h e so lubi l i ty of sucrose i s a l t e red d u e to t h e 
presence of t h e impur i t i e s , and , a t s a t u r a t i o n , t h e a c t u a l c o n c e n t r a t i o n of 
sucrose will be e q u a l to t h e so lubi l i ty of sucrose in p u r e w a t e r mu l t ip l i ed by 
t h e so lubi l i ty coefficient. 
If k1 is t h e so lubi l i ty coefficient at t1 a n d k2 t h e solubi l i ty coefficient of 
t h e s ame sample a t t 2 t h e n 
H a r m a n po in t s o u t t h a t , over t h e r a n g e of t e m p e r a t u r e s invo lved , k 1 
m a y be t a k e n e q u a l to k 2 w i t h o u t apprec iab le error . H e n c e for i m p u r e solu-
t ions also 
No ga in or loss of w a t e r i s a l lowed d u r i n g t h e c rys ta l l i za t ion a n d so t h i s 
definit ion implies a c o n s t a n t i m p u r i t i e s / w a t e r r a t io . 
Special Apparatus—In t h e d e t e r m i n a t i o n of s a t u r a t i o n t e m p e r a t u r e , a 
" s a t u r a t i o n ce l l " i s used . T h e t y p e favoured , as shown in F ig . 45 , cons is ts of a 
sha l low cyl indr ica l cell of bake l i t e or s imilar m a t e r i a l . Ins ide t h e cell is 
m o u n t e d a m e t a l t a b l e wh ich s u p p o r t s t h e s ample a n d a c c o m m o d a t e s a 
t h e r m o m e t e r b u l b . A r o u n d t h e i n t e r n a l p e r i p h e r y o f t h e cell an electr ic 
h e a t i n g e l emen t is m o u n t e d . A glass w indow in t h e b o t t o m of t h e cell a n d a 
hole in t h e c e n t r e o f t h e t a b l e a l low l ight t o pa s s up t h r o u g h t h e cell. 
T h e cell i s set on a microscope s tage , t h e t h e r m o m e t e r inse r ted , t h e s a m -
ple m o u n t e d over t h e hole in t h e t ab le , a n d t h e cell covered w i t h a shee t of 
c lear glass . T h e sample , a smal l d r o p of molasses , is m o u n t e d on a smal l 
s q u a r e of mic roscope slide glass . I f no t i n y c rys ta l s a re l ikely to be p re sen t , 
a l i t t le f inely g r o u n d sugar is sp r ink led over t h e s ample a n d a t h i n cover sl ip 
i s t h e n p laced ove r t h e s a m p l e a n d pressed d o w n to give a t h i n f i lm. T h e 
mic roscope i s t h e n focused on t h e sample . (A c o m b i n a t i o n of 16 mm (2/3 
138 ANALYTICAL METHODS 
inch) objective and a X25 eyepiece has been found to be very satisfactory). 
The field is moved until several small sharp edged crystals are in view. 
Procedure—The electric heater is turned on, and adjusted so that the 
temperature rises about 3 °C per minute. Eventually erosion of the crystals 
will be observed, and at the first sign of this, the temperature should be noted. 
The experiment should then be repeated with the temperature rising 
more slowly—about 0.5 °C per minute—in the vicinity of the critical temper-
ature noted earlier. 
Hints on the Determination—Materials of high purity crystallize quickly 
and excessive chilling may even lead to spontaneous crystal formation which 
would spoil the sample. Such materials must be handled quickly, and before 
the determination is commenced, the cell should be heated to within a few 
degrees of the probable saturation temperature. 
A sample of molasses may be separated from a massecuite by enclosing 
a small ball of the massecuite in a pocket of a piece of cloth, and squeezing. 
If the cloth is of fairly open texture, sufficient fine crystals for observation 
purposes will nearly always be found in the sample. More satisfactory results 
appear to be achieved with crystals originally present in the sample. 
The observation is tedious and exacting. The use of a red filter improves 
the ease of observation; polarized light is even better. Several crystals should 
be studied in rotation, as there appears to be no means of predicting where 
the erosion will first be noticed. Beware of a false end point; always maintain 
the heating until erosion is obviously well advanced, thus verifying the 
suspected onset of erosion. 
The saturation cell may be checked for accuracy of temperature reading 
by using it as a melting point apparatus for various pure chemicals, the actual 
melting points of which may be established by a recognized method. 
Boiler Water Analysis 
The various constituents in both natural and make-up water can result 
in severe scale formation, boiler corrosion and carry-over unless an effective 
method of chemical treatment is adopted. Some of the common scale forming 
constituents encountered in sugar factories are silica, calcium and mag-
nesium, oil and residues from the thermal degradation of sugars. These 
ANALYTICAL METHODS 139 
deposits are undesirable because of their adverse effect on heat transfer, and 
because their presence can lead to localised overheating of the metal with 
consequent failure and risk of explosion. Corrosion is due to acid conditions 
in the boiler or the presence of dissolved oxygen. The prevention of carry-over 
by strict control on the level of total dissolved solids is also essential to prevent 
damage to the equipment in which steam is utilized. 
A detailed discussion on the application of recommended systems and 
methods of boiler water treatment is contained in Chapter XII . Chapter XII 
also permits the analyst to obtain an understanding of the functions of the 
various chemicals added for effective water treatment and it is suggested 
that the analyst should become familiar with its contents. The following 
simple methods of analysis, most of which are extracted from the relevant 
British Standard, are suitable for routine control of the boiler station. More 
sophisticated methods of analysis are available in some cases, and if the 
apparatus is available, these methods may be used at the discretion of the 
analyst. 
Alkalinity 
Three different types of alkalinity determinations are carried out on 
boiler waters. These are 
(a) Alkalinity to phenolphthalein, end point at pH 8.3 
(b) Alkalinity to methyl orange, end point at pH 4.5 
(c) Alkalinity to phenolphthalein after barium chloride addition. 
If organic matter is present in the sample, the alkalinity to methyl 
orange is unreliable, and determination of alkalinity to phenolphthalein, both 
before and after the addition of barium chloride, is carried out. Barium 
chloride addition also corrects for the presence of any residual trisodium 
phosphate which would register as alkalinity, unless precipitated. 
Procedure (a) Alkalinity to Phenolphthalein (P) 
Measure 100 ml of the sample and transfer to a white porcelain basin. 
Add 1 ml of phenolphthalein indicator. A pink colour will form if the solution 
is alkaline to phenolphthalein. 
Titrate with 0.02 N sulphuric acid until the pink colour just disappears. 
Retain the solution for procedure (b) 
Alkalinity to phenolphthalein (P) = 
Procedure (b) Alkalinity to Methyl Orange (M) 
To the solution treated as described above, add 3 drops of methyl orange 
indicator. Titrate slowly with 0.02 N sulphuric acid, while stirring continu-
ously, until the solution shows the first colour change from yellow to orange. 
Record the total number of ml of acid used, i.e. including those used in 
the previous titration with phenolphthalein. 
Alkalinity to methyl orange (M) = 
If the solution is so highly coloured that the indicator end points cannot 
be detected, a pH meter may be used. When this procedure is adopted, the 
P h o s p h a t e 
Severa l m e t h o d s a re ava i l ab le for t h e d e t e r m i n a t i o n of p h o s p h a t e in 
boi ler w a t e r s . T h e m a j o r i t y of t he se a re b a s e d on t h e f o r m a t i o n of a b l u e 
p h o s p o - m o l y b d a t e c o m p l e x , t h e i n t e n s i t y of w h i c h i s d i r ec t l y p r o p o r t i o n a l 
t o t h e a m o u n t o f P 0 4 ion p r e sen t i n t h e so lu t ion . F o r r o u t i n e con t ro l work , 
t h e chemis t a n d engineer n e e d on ly to k n o w t h a t a r e se rve of p h o s p h a t e i s 
p re sen t a n d t h a t t h e level i s w i t h i n a ce r t a in r a n g e . Th i s p e r m i t s a r e d u c t i o n 
i n t h e t i m e s p e n t on c a r r y i n g o u t t h e d e t e r m i n a t i o n . T h e colour fo rmed af ter 
reagen t a d d i t i o n i s c o m p a r e d e i the r in a L o v i b o n d t y p e c o m p a r a t o r or aga in s t 
s t a n d a r d colour p l a t e s . A su i t ab l e e x a m p l e of p h o s p h a t e colour p l a t e s is 
s h o w n on p a g e 49 of B r i t i s h S t a n d a r d s 1170:1957 . A s p e c t r o p h o t o m e t e r 
m a y be used , i f ava i l ab l e . 
Apparatus—Two tes t t u b e s a p p r o x i m a t e l y 6 inches in l e n g t h a n d half an 
i n c h in d i a m e t e r . T w o 250 ml bo t t l e s , e a c h f i t ted w i t h a r u b b e r t e a t p i p e t t e 
g r a d u a t e d at a 2 ml d i scha rge level. Use one b o t t l e for d i spens ing ac id 
m o l y b d a t e a n d t h e o t h e r for c a r b o n a t e - s u l p h i t e . O n e 250 ml b o t t l e f i t ted 
w i t h a r u b b e r t e a t p i p e t t e g r a d u a t e d at a 1 ml d i scharge level for d i spens ing 
h y d r o q u i n o n e . W h a t m a n N o . 5 filter p a p e r s . 
Procedure—The t e m p e r a t u r e o f t h e s a m p l e a n d r e a g e n t s m u s t be k e p t 
b e t w e e n 20 a n d 30 °C. 
F i l t e r a s a m p l e of t h e cooled boi ler w a t e r t h r o u g h t w o W h a t m a n N o . 5 
filter p a p e r s . D i s c a r d t h e first 10 ml a n d refilter t h e e x t r a c t i f a c lear l iqu id 
i s n o t o b t a i n e d f rom t h e first f i l t ra t ion. 
Trans fe r 5 ml of t h e s a m p l e to a t e s t t u b e , a d d 2 ml of ac id m o l y b d a t e 
a n d m i x t h o r o u g h l y . T h e n a d d 1 ml o f h y d r o q u i n o n e a n d aga in m i x t h o r o u g h -
ly. Allow t h e c o n t e n t s of t h e t u b e to s t a n d for 5 m i n u t e s . 
A d d 2 ml of c a r b o n a t e - s u l p h i t e so lu t ion to t h e o t h e r t e s t t u b e . Careful ly 
p o u r t h e c o n t e n t s o f t h e f i r s t t u b e i n t o t h e one c o n t a i n i n g t h e c a r b o n a t e -
su lph i t e so lu t ion . Mix b y c a u t i o u s l y t r ans fe r r ing severa l t i m e s t h e c o n t e n t s 
f rom one t u b e t o t h e o t h e r . 
H o l d t h e t e s t t u b e c o n t a i n i n g t h e s a m p l e a l i t t l e d i s t a n c e a w a y from t h e 
s ide o f t h e s t a n d a r d co lour p l a t e s , a n d e s t i m a t e t h e P 0 4 level i n t h e so lu t ion . 
I t i s adv i sab le t o use a t u n g s t e n f i lament l a m p w h e n m a k i n g t h e c o m p a r i s o n 
as i t i s n o t possible to o b t a i n a good c o m p a r i s o n by d a y l i g h t or f luorescent 
l ight . 
Interpretation of Results—A P 0 4 level b e t w e e n 30 a n d 70 p . p . m . is 
u s u a l l y cons ide red t o b e sa t i s fac to ry . R e s u l t s a re u s u a l l y r e c o r d e d a s " l o w " , 
" s a t i s f a c t o r y " o r " h i g h " . 
140 ANALYTICAL METHODS 
i n d i c a t o r so lu t ion i s n o t a d d e d a n d t h e t i t r a t i o n v a l u e s a t p H 8.3 a n d p H 4.5 
a re r eco rded for p h e n o l p h t h a l e i n a n d m e t h y l o r a n g e respec t ive ly . 
Procedure (c) Alkalinity to Phenolphthalein after Barium Chloride addition 
T h e p r o c e d u r e for t h e n o r m a l i n d i c a t o r t i t r a t i o n i s a s fo l lows :— 
Measure 100 ml of s a m p l e a n d t r ans fe r to a w h i t e porce la in b a s i n . A d d 1 ml 
of p h e n o l p h t h a l e i n ind ica to r , followed by a c ry s t a l of s o d i u m s u l p h a t e a n d 
10 ml of 10 pe r cen t b a r i u m chlor ide so lu t ion . S t i r wel l for t w o m i n u t e s a n d 
t h e n t i t r a t e w i t h 0.02 N su lphur i c ac id u n t i l t h e p i n k colour j u s t d i s a p p e a r s . 
D i s r ega rd a n y r e a p p e a r a n c e s o f t h e p i n k colour . 
A lka l i n i t y t o p h e n o l p h t h a l e i n af ter b a r i u m chlor ide a d d i t i o n 
ANALYTICAL METHODS 141 
Sulphite 
The presence of free sodium sulphite in a boiler water is an assurance 
that all dissolved oxygen in the feed water has been eliminated. Special 
attention must be given to the method of sampling for this determination, 
as sulphite can be rapidly destroyed when the sample is exposed to atmos-
phere. This is more pronounced at elevated temperatures, but the effect can 
be minimized if the following sampling procedure is carried out:— 
A stainless steel or nickel-copper cooling coil which will reduce the outlet 
temperature to below 30 °C is required. Position the outlet tube into the 
bottom of the sample container, and allow water to flow until at least five 
changes have occurred. Withdraw the outlet tube slowly so that the container 
is filled to maximum capacity, and stopper with an effective sealing device. 
Analyse the sample as soon as possible. 
Procedure—Transfer 4 ml of 6.5 per cent V/V sulphuric acid to a white 
porcelain basin. Add 100 ml of unfiltered boiler water sample and 1 ml of 
starch indicator. 
Titrate with potassium iodide-iodate solution and stir continuously 
during the titration until a faint permanent blue colour is obtained. 
Hardness 
Refined methods are available for the determination of hardness in 
boiler waters. The majority of these are time consuming, and for ordinary 
routine control purposes sufficient accuracy can be obtained by titrating a 
known volume of sample with standard soap solution. During this titration, 
the soap combines with calcium and magnesium salts in the water until they 
are precipitated as an insoluble curd, and when all these salts have been 
converted, the addition of an extra drop of soap solution will produce a 
permanent soap lather. Thus, the soap solution provides its own indicator, 
and the formation of this permanent lather corresponds to the point where 
colour changes occur when indicators are used for the more refined methods 
of hardness determination. 
Standardization of Soap Solution—Each batch of Wanklyn's reagent 
should be checked by titrating the reagent against 100 ml of distilled water. 
The amount of soap solution required to establish a permanent lather with 
distilled water is then regarded as the blank, and is subtracted from all other 
titrations carried out with that particular batch of reagent. 
Procedure—Measure out 100 ml of filtered boiler water sample and 
transfer into a glass stoppered bottle of approximately 250 ml capacity. 
Titrate with Wanklyn's soap solution from a burette, 0.2 ml at a time, 
replacing the stopper and shaking after each addition. Continue additions 
until a permanent lather, i.e. one that remains at least 5 minutes, is obtained. 
It is not necessary to wait 5 minutes between additions, as the immediate 
breakdown of individual bubbles is an indication that the lather will not be 
permanent. View the lather by laying the bottle on its side at eye level. It 
will be noted that the lather rapidly becomes more permanent as the end 
point is approached and additions of the reagent should then be made in 
smaller quantities. 
For a 100 ml sample aliquot, 
142 ANALYTICAL METHODS 
Total Dissolved Solids 
These may be determined either gravimetrically by weighing after dry-
ing, conductometrically, or by the determination of specific gravity using a 
special hydrometer of the type supplied with "Alfloc" testing equipment. 
The last method is recommended for routine control determinations because 
of the simplicity of the technique. 
Two factors which must receive special attention in the determination 
of T.D.S. by the hydrometer are, firstly, that special care is required when 
handling and cleaning the hydrometer, and, secondly, that the hydrometer 
must be restandardized against the gravimetric method at regular intervals 
to ensure its reliability. 
Effect of Temperature—Changes in temperature during the determination 
and a temperature difference between the instrument and surrounding solu-
tion can result in considerable discrepancies in the values determined. The 
analyst must therefore ensure that sufficient time is allowed for each sample 
to cool to near room temperature, and also for the hydrometer to attain the 
temperature of the solution. The temperature corrections to be applied 
to the standard 80 °F type hydrometer are listed in the following table. 
—• Temperature Corrections—80 °F Type Hydrometer 
Temp. 
° F 
44 
46 
48 
50 
52 
54 
56 
58 
60 
62 
Correction to 
observed 
(divisions 
Subtract 
reading 
2 6 
2 6 
26 
26 
26 
25.5 
24.5 
23.5 
22.5 
2 1 
Temp. 
° F 
64 
66 
68 
70 
72 
74 
76 
78 
80 
82 
Correction to 
observed reading 
(divisions) 
Subtract 
"Nil 
A d d 
19 
17 
15 
13 
10.5 
8 
5.5 
3 
2 
Temp. 
° F 
84 
86 
88 
90 
92 
94 
96 
98 
100 
Correction t o 
observed reading 
(divisions) 
A d d 5 
8 
11 
14 
18 
22 
26 
30 
34 
Procedure—Pour in a sufficient quantity of boiler water sample to fill the 
hydrometer jar to approximately one inch from the top. Add six drops of 
wetting agent and mix into the solution. 
Lower the hydrometer carefully into the solution. If air bubbles are 
observed to be adhering to the instrument, these can usually be removed 
by gently spinning the hydrometer. Record the temperature of the solution 
to the nearest °F. 
Read the hydrometer scale by looking slightly down on the surface of 
the liquid. Correct the scale reading for temperature by reference to the above 
table. 
Multiply the corrected reading by 100 and record as p.p.m. Total Dis-
solved Solids. 
Sulphate 
Sulphate is precipitated as barium sulphate by the addition of a known 
amount of barium chloride to the acidified solution. The excess barium chlor-
ide is then determined by titrating against EDTA, using either solochrome 
or eriochrome black as an indicator. 
ANALYTICAL METHODS 143 
The test for sulphate is not applicable to waters containing appreciable 
amounts of calcium and magnesium salts as these also react with EDTA. 
The test is generally applicable to boiler waters with a hardness value below 
20 p.p.m. CaC03. In these circumstances the errors caused by hardness salts 
can be ignored. 
Procedure—Pipette 10 ml of the sample into a porcelain basin and 
acidify with 1 ml of 0.5 N hydrochloric acid. Add exactly 10 ml of 0.04 N 
barium chloride solution from a suitable automatic dispenser. 
Pipette into a small beaker 3 ml of the sulphate buffer and add to it 
0.2 g of solochrome black indicator. Mix well and pour into the basin con-
taining the sample. 
Slowly titrate the contents of the basin with 0.02 N EDTA, stirring the 
sample with a glass rod until the colour begins to change to purple. Then add 
the EDTA solution, drop by drop, stirring continuously until all traces of red 
colour have disappeared. The final colour at the end point is usually blue, 
but with some waters a greyish coloured end point is obtained. 
Water Analysis 
Chlorides 
Chloride is determined by titrating a neutral or slightly alkaline solution 
against a standard silver nitrate solution in the presence of chromate indica-
tor. White silver chloride is precipitated, followed by reddish silver chromate 
when the chloride end point has been reached. The presence of sulphites in 
some waters can cause considerable interference to this determination. This 
effect may be overcome by the addition of 1 ml of hydrogen peroxide (10 vol.) 
prior to the commencement of the titration. 
Procedure—Pipette 50 ml of sample into a white porcelain basin. Add 
1 ml of potassium chromate indicator and commence titrating with 
silver nitrate solution. Stir continuously with a rubber-tipped glass 
stirring rod and continue the titration until the first permanent reddish colour 
change is established. Record the volume of silver nitrate used. 
Chloride = titre x 20 as p.p.m. CI. 
REFERENCES 
Aldrich, B. I. and Rayner, P. C, (1962), Cell-Breakage Determination in Prepared 
Cane and Bagasse. Proc. I.S.S.C.T., eleventh Conf., 1004-1013. 
Anderson, G. A. and Petersen, K. J., (1959), Operation of an Individual Fibre System. 
Proc. Q.S.S.C.T., twenty-sixth Conf., 15. 
Burgess , I. G., Beardmore, R. H., Fortescue, G. E„ and Davis, G. W. (1962), 
Development and Application of a Laboratory Clarification Test. Proc. 
I.S.S.C.T. eleventh Conf., 920-927. 
Deicke, R. (1959), Investigations with the Wet Disintegrator for Direct Analysis of 
Cane. Proc. I.S.S.C.T. tenth Conf., 168-174. 
De Whalley, H. C. S. (Editor) (1964), ICUMSA Methods of Sugar Analysis, Elsevier, 
41-44. 
Foster, D. H., (1955), The Determination of Pol in Bagasse, Proc. Q.S.S.C.T., twenty second Conf., 279-283. 
Since the degree of dissociation of water is so low, no appreciable error 
will be introduced if the concentration of undissociated molecules be regarded 
as constant, and therefore 
[H+] [OH-] = K [HOH] = Kw 
where Kw is known as the Dissociation Constant of Water. 
Careful measurements have demonstrated that at 22 °C, pure water 
possesses a concentration of hydrogen ions equal to 10-7 gramme ions per litre. 
It contains also a similar ionic concentration of hydroxyl ions. Thus at 22 °C 
the dissociation constant of water is equal to 10 - 7 x 10-7 or 10-14. It should 
be observed, also, that in dilute aqueous solution the product of the concentrations 
of H+ and O H - is for practical purposes a constant at constant temperature, 
and equals 10-14 at 22 °C. 
As the concentration of hydrogen ions often has a very low value, in 
order to avoid the nuisance of writing a long decimal expression to describe it, 
it has been found useful to use an exponential notation. The term pH, first 
proposed by Sorensen in 1909, is widely used today. It is defined as the 
negative exponent of 10 which gives the hydrogen ion concentration. 
CHAPTER X 
THE DETERMINATION OF pH 
Hydrogen Ion Concentration 
Pure water exhibits a very high resistance to the passage of an electric 
current, but its conductivity is markedly increased when substances known 
as electrolytes are dissolved in it; electrolytes include all acids, bases and salts, 
whereas substances such as sugars, alcohols and ketones are without influence 
on the conductivity of the solution and are known as non-electrolytes. An 
attempt to explain the effect of electrolytes led Arrhenius in 1887 to pro-
pound his Electrolytic Dissociation Theory. He postulated that when an 
electrolyte is dissolved in water, some of the molecules of the substance dis-
sociate into electrically charged particles, which are known as ions. Thus a 
molecule of hydrochloric acid gives in solution a positively charged hydrogen 
ion H+, and a negatively charged chlorine ion Cl~. In all cases, the sum of 
ionic charges must be zero, for the molecule is electrically neutral. 
The molecules of all electrolytes are not dissociated to the same degree. 
For example, a normal solution of hydrochloric acid is dissociated to the 
extent of 80 per cent, while a solution of acetic acid of similar concentration 
possesses but 0.43 per cent of its molecules in the ionised form. Electrolytes 
which are highly dissociated in solution are known as strong electrolytes, 
while those which are but slightly dissociated are called weak electrolytes. 
The degree of dissociation is a function of the concentration of the solution; 
the more dilute the solution the higher the percentage of dissociation. 
Pure water does conduct an electric current in a feeble degree, and is 
therefore itself a weak electrolyte. The equation for the electrolytic dis-
sociation of water may be represented:— 
F o r p u r e w a t e r a t 22 °C, [H+] equa l s 1 0 - 7 g r a m m e s p e r l i t re , therefore t h e 
p H is 7. 
An acid solut ion m a y be defined as one in which t h e concen t r a t i on of 
t h e H+ exceeds t h a t o f O H - ; a n d converse ly , an a lka l ine so lu t ion i s one 
which possesses an excess of O H - over H+. A solut ion of pH 7.0 is, therefore , 
r ega rded as a n e u t r a l so lu t ion ; pH va lues less t h a n 7.0 ind ica te an ac id solu-
t ion , while va lues above 7.0 a re charac te r i s t i c of a lkal ine solut ions . In 
employ ing th i s conven t ion , i t m u s t be r e m e m b e r e d a lways t h a t pH i s a 
logarithmic func t ion ; a n d therefore a solut ion of pH 6.0 h a s a H+ concen t r a -
t ion t en t imes t h a t of a solut ion of pH 7.0. 
I t will be obse rved t h a t t h e va lue of pH for w a t e r a t 22 °C is 7.0. Th i s 
va lue does v a r y w i t h t h e t e m p e r a t u r e in qu i t e a m a r k e d degree, as i s shown 
by t h e following t ab l e for pu re w a t e r : — 
T e m p e r a t u r e °C pH 
16 7.10 
20 7.03 
22 7.00 
25 6.95 
40 6.71 
100 6.12 
T h e i m p o r t a n c e o f t e m p e r a t u r e con t ro l m u s t be b o r n e in m i n d in ca r ry ing 
ou t all pH d e t e r m i n a t i o n s ; s t r ic t ly these should be m a d e a t a c o n s t a n t 
t e m p e r a t u r e , so as to be c o m p a r a b l e w i t h one ano the r . 
M e a s u r e m e n t o f p H 
T w o genera l m e t h o d s a re employed in t h e d e t e r m i n a t i o n o f p H , t h e 
color imetr ic m e t h o d a n d t h e e lec t romet r ic m e t h o d . E a c h possesses i t s 
a d v a n t a g e s a n d d i s a d v a n t a g e s ; t h e l a t t e r requi res a pH m e t e r a n d i s m o r e 
accura te , while t h e former requi res less sophis t ica ted a p p a r a t u s . 
C o l o r i m e t r i c m e t h o d 
Cer ta in chemica l c o m p o u n d s h a v e t h e ab i l i ty t o change colour w h e n t h e 
pH of t h e solut ion, in wh ich t h e y are dissolved, changes over cer ta in r anges . 
These c o m p o u n d s a re k n o w n a s ind ica tors . Os twa ld exp la ined th i s ab i l i t y t o 
change colour by a s suming t h a t c o m p o u n d s o f th i s n a t u r e b e h a v e a s w e a k 
acids or bases , t h e molecules of which a re ab le to abso rb l ight of a definite 
spec t ra l r ange , whi le the i r ions h a v e t h e ab i l i ty of absorb ing l ight of a n o t h e r 
spec t ra l b a n d . An acid ind ica to r a t low pH va lues will exh ib i t t h e colour 
charac te r i s t i c s of t h e und issoc ia ted molecules , whi le t h e neu t r a l i za t i on of t h e 
ac id by t h e add i t ion of a base resul t s in t h e p r o d u c t i o n of a h igh ly dissocia ted 
sa l t (since all sa l t s a re h igh ly dissociated) a n d t h e so lu t ion exh ib i t s t h e colour 
of t h e ions. I n d i c a t o r s a re usua l ly ut i l ized in t h e m e a s u r e m e n t of t h e pH of 
solut ions by m e a n s of t es t pape r s or a colour c o m p a r a t o r . 
Test papers: T h e r e a re n u m e r o u s different t y p e s of t e s t p a p e r s ava i l ab le 
commerc ia l ly for t h e e s t ima t ion o f p H . " U n i v e r s a l " t e s t p a p e r s cover t h e 
r a n g e 1.0 to 11.0 pH in s t e p s of 1.0 p H ; t h e co lour c h a n g e c h a r t for t h e s e 
p a p e r s i s p r i n t e d on t h e inside of t h e cover . A n o t h e r useful t y p e for suga r 
mi l l app l i ca t ion i s t h e " H y d r i o n " sho r t r a n g e p H t e s t p a p e r cover ing t h e 
r a n g e 6.0 to 8.0 in half u n i t s t eps . These t e s t p a p e r s a r e p o r t a b l e a n d speedy , 
b u t n o t e x t r e m e l y a c c u r a t e . 
THE DETERMINATION OF pH 145 
T h u s , 
146 THE DETERMINATION OF pH 
Comparator: The Lovibond or Hellige comparator comprises a plastic 
housing into which can be fitted a disc of permanent colour standards to-
gether with two glass containers, one for the specimen under test and the 
other for a blank (to compensate for inherent colour in the sample). 
Each particular test requires the use of the appropriate disc which 
contains a number of permanent glass colour standards (usually nine) re-
presenting the range of colours produced by different concentrations of the 
material which is the subject of the test. The discs for pH determinations are 
usually supplied complete with the appropriate indicator. A useful disc for 
sugar mill work is the Bromothymol blue disc, containing nine steps of 0.2 pH 
over the range 6.0 to 7.6. The comparator can only be used for fairly clear 
solutions. It is slower than the test papers but more accurate. 
Electrometric method 
Electrometric methods are based upon the principle of measuring the 
electromotive force generated, as a function of the hydrogen ion concentra-
tion (and temperature), between electrodes of various types immersed in a 
solution to be tested and in a solution of known and definite characteristics 
joined thereto by a liquid junction. The standard and classical electrometric 
method employs the hydrogen electrode and while, because of the many 
difficulties involved in its use, the hydrogen electrode has found no direct 
application in the sugar industry, an understanding of its operation is useful 
to give a clear picture of the method. 
Hydrogen electrode: The hydrogen electrode consists of a platinum or 
gold foil carefully plated with platinum, palladium, or iridium, and immersed 
in the solution being tested, which is saturated to equilibrium with purified 
hydrogen gas. The hydrogen is bubbled through the solution surrounding 
the electrode. In order to measure the electric potential of the solution in 
which the hydrogen electrode is placed, it is brought in contact by liquid 
junction with another electrode or half-cell, which may be a similar hydrogen 
electrode, or it may be one of the other types of standard half-cells, such as 
one of the calomel electrodes. Thus, if two hydrogen electrodes are placed in 
solutions containing different hydrogen ion concentrations, but joined by a 
liquid junction, then the potential difference is given by the equation— 
and therefore the potential difference is proportional to the difference in pH 
between the two solutions. If E is measured, and one pH is known, the 
unknown pH may be evaluated. 
THE DETERMINATION OF pH 147 
T h e e lec t rochemical effects of ions in solut ion a re influenced n o t on ly 
by t h e concen t r a t ion o f t h e ions b u t also by t h e " a c t i v i t y coefficient", a n d 
s t r i c t ly speak ing t h e p H i s n o t d i rec t ly r e la ted t o t h e h y d r o g e n ion concen t r a -
t ion . However , for p rac t ica l purposes t h e pH i s accep ted a n d i n t e r p r e t e d as 
be ing re la ted t o t h e h y d r o g e n ion concen t ra t ion . 
As prev ious ly men t ioned , i t i s no t p rac t i cab le to m e a s u r e t h e pH of a 
solut ion by m e a n s of h y d r o g e n electrodes, i t can, however , be m e a s u r e d by a 
combina t ion of two o the r e lectrodes (half-cells) such as t h e calomel e lec t rode 
a n d t h e glass e lectrode. 
Calomel electrode: T h e calomel e lect rode is composed of m e r c u r y a n d 
calomel (mercurous chloride) in a w a t e r solut ion of p o t a s s i u m chloride. These 
ma te r i a l s a re c o n t a i n e d in a glass vessel of a su i t ab le design. One such design 
is shown in Fig . 46 (b). Provis ion is m a d e in some m a n n e r to p ro t ec t t h e 
Fig. 46—(a) Glass electrode. (b) Calomel electrode. 
e lec t rode from c o n t a m i n a t i o n by diffusion of t h e so lu t ion be ing t e s t e d 
t h r o u g h t h e l iquid junc t ion . Th is i s n o r m a l l y achieved by m a i n t a i n i n g t h e 
so lu t ion ins ide t h e cell a t a h igher level t h a n t h e t e s t so lut ion, t h u s keep ing 
t h e l iquid j u n c t i o n flushed w i t h fresh p o t a s s i u m chlor ide solut ion. E lec t r ica l 
c o n t a c t to t h e ca lomel cell i s o b t a i n e d t h r o u g h t h e m e r c u r y by m e a n s of a 
p l a t i n u m wire, sealed t h r o u g h t h e b o t t o m of t h e ca lomel e lec t rode , or fed 
t h r o u g h t h e t o p open ing of t h e vessel i n t o t h e m e r c u r y . T h e p o t e n t i a l of a 
ca lomel e lec t rode i s d e p e n d e n t u p o n t h e concen t r a t i on of t h e p o t a s s i u m 
148 THE DETERMINATION OF pH 
chloride solution in contact with the calomel and mercury. One of three 
concentrations may be used, namely, 0.1 normal, normal, or saturated. The 
last is used most widely in practice because it is easily prepared; it has the 
same salt concentration as the salt bridge (liquid junction) and hence 
eliminates diffusion difficulties; and it has a high conductivity which increases 
the sensitivity of the system. 
Glass electrodes: Glass electrodes, as the name implies, are bulbs of thin-
walled glass of special composition blown on the end of a glass tube. Inside 
this tube is an electrode of some type, such as a silver-silver chloride electrode 
in a hydrochloric acid solution. A typical glass electrode is shown in Fig. 
46 (a). It is believed that an actual transfer of hydrogen ions takes place 
through the bulb, which makes it behave like a hydrogen electrode, and like 
the hydrogen electrode it needs a reference electrode and salt bridge to 
complete the hydrogen ion cell. 
In many respects the glass electrode is considered ideal, in that nothing 
has to be added to the solution which might alter its hydrogen ion concentra-
tion; also the electrode cannot become poisoned, and it can be used for 
measuring the pH of all kinds of materials, including those which are semi-
solid in consistency and those which contain active reducing or oxidizing 
substances. The range of application is normally from about 1 to 13 p H ; 
however, errors may be introduced in alkaline solutions containing appreci-
able amounts of sodium salts. With frequent and proper calibration a limit 
of error of about 0.02 pH is attainable with the glass electrode. 
Before use, all glass electrodes should be immersed in distilled water for 
at least 24 hours. When not in use, the glass electrode should be stored in 
distilled water, as repeated wetting and drying impairs the action of the glass 
membrane. Several makes of pH equipment using glass electrodes are on the 
market, all of which operate on more or less similar principles, the main 
differences between them being in structural detail. 
THE DETERMINATION OF pH 149 
pH Meters: Modern pH meters usually utilize the glass electrode, calomel 
electrode combination. A typical modern pH meter is illustrated in Fig. 47. 
Because the conductivity of glass is very low, even a thin membrane exhibits 
very high resistance (108 ohms), it is necessary to amplify the potential 
difference across the two electrodes, and to measure the voltage directly with 
a calibrated galvanometer. 
The overall potential developed by the complete electrode assembly is 
of the form— 
E = K pH + Eo 
where E = overall measured potential 
K = a thermodynamic constant varying with temperature 
Eo = the result of a group of fixed potentials—half cell poten-
tials, asymmetry potential, liquid junction potentials, 
etc. This also varies with temperature. 
Due to the fact that asymmetry potential will vary from electrode to 
electrode, and, even for the same electrode, from time to time, a pH meter 
must be standardized before being used to measure the pH of an unknown 
solution. This is carried out in the following manner. A standard buffer solu-
tion of known pH is used and the electrode assembly is immersed in the 
buffer. The temperature effect of the standard buffer solution must be 
compensated for either by the use of a platinum resistance thermometer 
connected directly to the pH meter, in which case the compensation is auto-
matic, or by measuring the temperature and manually compensating for it 
by adjusting the temperature compensating dial on the instrument. When 
this has been done the correct value of K in the above equation is established 
in the instrument. The meter is checked for zero reading and this is adjusted 
if necessary, and then switched to the appropriate scale to measure the pH 
of the standard buffer solution. By adjustment of a knob provided, the meter 
is made to read the pH of the buffer solution used and this operation serves 
to provide the correct value of Eo in the equation. The meter should then 
indicate correctly the pH of an unknown solution. For strict accuracy the 
buffer solution and any other solutions tested should be at the same temper-
ature, and the results obtained will then correspond to pH at this temperature. 
Values of pH at one temperature cannot be converted to the basis of another 
temperature unless the pH-temperature relationship of the solution is known. 
Determination of pH values of Sugar Mill Products: The most important 
aspect of pH measurement in a sugar mill is its use for the control of the 
clarification process. Almost all mills have now installed automatic equip-
ment for the addition of lime to mixed juice, and this addition of lime is 
controlled by pH measurements made on the limed juice. This pH measure-
ment is continuous and generally utilizes an industrial glass electrode, which 
will operate at high temperature and withstand erosion, together with an 
industrial calomel electrode, which maintains a slight pressure on the 
potassium chloride solution to ensure that the liquid junction is not fouled. 
The pH of the limed juice determines the final pH of clarified juice, and the 
set point of the pH controller is altered up or down according to the value 
determined on the clarified juice. The pH of clarified juice is the most im-
portant pH measurement in the factory, and for preference this quantity 
should be measured continuously using a pH recorder. Whether a recorder 
is used or not, periodic laboratory pH determinations should be carried out 
on clarified juice, to determine its pH value, or to check the accuracy of the 
recorder. 
These determinations should be carried out with an accurate laboratory 
pH meter, which is a most useful instrument for general laboratory work 
150 T H E DETERMINATION OF pH 
and for measurements of pH on other factory products. Laboratory pH 
measurements are carried out in the following manner:— 
Check and restandardize the instrument at least once per shift with 
standard buffer solution as described previously. 
Cool the solution to room temperature or to the temperature at which 
the instrument was restandardized. 
Rinse the electrodes with a portion of the test solution prior to carrying 
out the determination. 
Fill the beaker or receptacle with test solution to a level which will 
ensure that the electrodes and thermometer bulb are well covered. 
Read the temperature of the solution and adjust the instrument temper-
ature compensator to the desired setting. (Reference tables may have to be 
used on older model pH meters.) 
Allow sufficient time for the system to come to equilibrium, and 
determine the pH. 
After the determination is completed, thoroughly wash the electrodes 
with distilled water and keep them immersed in distilled water when not 
in use. 
N.B.—Glass electrodes are fragile and susceptible to breakage. Extreme 
care should be taken when handling these electrodes. 
CHAPTER XI 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
The chemical control of any process is divisible into two fairly distinct 
phases. One phase involves the study of a group of facts associated with the 
process—quantities of materials entering process, leaving process or in pro-
cess; the compositions of original, intermediate and final products; the 
necessary details of auxiliary materials used in the process; and the conditions 
under which the various stages are operated. The second phase deals with 
attempts to express in figures the merit of the results achieved. In industry 
generally the purely quantitative relationships provide an adequate index of 
performance, but this is not usually the case in sugar manufacture. For 
instance, pol extraction and recovery which are purely quantitative figures 
are not adequate measures of milling or manufacturing efficiency. Other 
things being equal, a recovery of 86 per cent is better than one of 85 per cent, 
but in practice other things are not equal and the lower recovery may re-
present the better performance. 
In the majority of Queensland sugar factories the analytical and quan-
titative data are only approximate. Actual weights are available for only a 
few of the materials involved, pol is used as an approximation for sucrose, 
Brix instead of total soluble solids, and various empirical formulae are 
introduced. This provides a set of figures which are substantially accurate 
and trustworthy for certain "normal" conditions. Should the existing condi-
tions not conform to those assumed the data are rendered incorrect; and the 
magnitude of the discrepancies which enter depends upon the extent of the 
divergence from normal. The shortcomings of this control are generally 
recognized by the mill chemist, but in the absence of means of securing 
accurate data, the magnitude of the discrepancies at any time cannot be 
gauged. 
These shortcomings of the present empirical system for cane analysis 
have been well known for many years, but there is no point in discarding an 
accepted system unless some improved method is available. Several years ago 
an intensive investigation into the juice weighing system of factory control 
was carried out. The results of this investigation showed the system to be less 
prone to the large seasonal variations of the empirical system, but it also 
brought to light several disturbing sources of inaccuracy in the method. 
Attention has now moved from juice weighing to the direct analysis of cane 
using a wet disintegrator for the determination of Brix and pol, and a Spencer 
or similar type of hot air circulating oven for the determination of moisture. 
At the time of writing this edition the matter is under investigation, and it 
may well be that the empirical method of analysis will be superseded by 
direct analysis of cane. 
Quantitative Data 
Materials Balances—A materials balance involves a statement of (1) the 
total quantity of a particular material entering a process from various 
sources, and (2) the total quantity of the same material leaving the process 
through various avenues. In the factory, materials balances may be drawn 
up to cover a single stage of processing, several stages, or the whole operation, 
and may deal with pol, Brix, impurities, fibre, crystal, etc. 
152 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
Pol Balance (Empirical System) 
The most important materials balance is the pol balance of the factory. 
Pol enters the factory only in the cane, and leaves mainly in bagasse, mud, 
molasses and sugar. The total of these quantities of pol leaving will normally 
be less than that of the pol entering, the discrepancy being due to mechanical 
losses, destruction of pol in the process and errors in the measurements, 
analyses and formulae. These losses are grouped under the title of "un-
determined" losses. For convenience, each quantity of pol leaving the factory 
is expressed as a percentage of the quantity of pol entering the factory. 
Stock—When a materials balance is taken out at an intermediate stage 
of operation of a process some of the material involved may be only partly 
treated and held in stock. Such material may be entered in the materials 
balance as "in stock", but for the purposes of the pol balance it is customary 
to presume that all the pol in stock will eventually leave the factory in sugar 
or final molasses, and to calculate how much of the pol in stock should pass 
into each of these channels. This involves the use of recovery formulae (see 
later) or recovery tables. A recovery formula or table will predict the 
percentage of the total pol in stock which may be expected later to pass out 
in the sugar. It follows that, if x is the percentage "recovered" as sugar, 
then 100 — x per cent will enter the molasses. 
Normally when taking out a pol balance over a period, account must be 
taken of stock at both the beginning and the end of the period. The quantities 
of recoverable and unrecoverable pol in each stock are calculated and those 
figures for the beginning of the period are subtracted algebraically from the 
respective figures for the end of the period. The balances may be positive or 
negative and are accordingly added to or subtracted from the respective 
figures for pol in sugar and in molasses actually made during the period. 
Hence the pol balance becomes:— 
Pol in sugar, made and estimated, per cent pol in cane 
Pol loss in bagasse per cent pol in cane 
Pol loss in mud per cent pol in cane 
Pol loss in molasses, made and estimated per cent pol in cane 
Undetermined loss 
100 
Pol in Cane—The quantity of pol entering the factory is not measured 
directly but determined from the weight of the cane and the analysis of the 
first expressed juice, with the aid of an empirical formula—thus:— 
Tons pol in cane = tons cane x pol per cent cane 
Pol Loss in Molasses—This is derived from the weight of molasses and 
the pol per cent molasses, with correction for stock. 
where F = fibre per cent cane 
Pol Loss in Bagasse—From the definition of pol extraction it follows that 
Pol loss in bagasse = 100 — pol extraction. 
Pol Loss in Mud—This is derived from the weight of mud and the pol 
per cent mud. 
Undetermined Loss—This is a residual, calculated by difference, either 
in tons or per cent pol in cane. 
Pol Balance (Direct Analysis) 
The only difference between this system and the empirical system just 
set out, is that pol per cent cane is determined directly, using the wet dis-
integrator. Thus the empirical formula for pol in cane is not used in this 
method and one possible source of error is avoided. 
The accuracy of the direct analysis system, as with all other analytical 
systems, depends of course, on the accuracy and adequacy of sampling 
techniques, plus strict adherence to good analytical procedures. 
Overall Recovery—Overall recovery, frequently simply called recovery 
is the tons of pol recovered in sugar expressed as a percentage of the tons of 
pol in cane. 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 153 
Pol loss in molasses = 
Pol in Sugar—This is derived from the weight of sugar and the pol of 
the sugar, with correction for stock. 
Pol in Sugar = 
and is identical with the figure for pol in sugar per cent pol in cane. 
Boiling House Recovery—In the boiling house recovery, the quantity 
of pol in sugar, made and estimated, is expressed as a percentage of the 
quantity of pol entering the boiling house, i.e., in the juice leaving the mills. 
It follows by simple reasoning that 
Extraction—This is an important figure from a commercial point of 
view, since it relates the quantity of pol extracted by the milling plant to the 
quantity of pol in the cane. It also provides an estimate of the percentage of 
the pol in cane which enters the boiling house, and thus forms a basis for the 
evaluation of boiling house recovery. The extraction is calculated from the 
analysis of bagasse and cane as follows:— 
Let— Pc = pol per cent cane 
Fc = fibre per cent cane 
Pb = pol per cent bagasse 
Bb = Brix per cent bagasse 
W = moisture per cent bagasse 
Fb = fibre per cent bagasse 
Then since bagasse consists of fibre, soluble solids and water— 
Fb = 100— Bb — W 
154 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
In p rac t i ce B b i s f r equen t ly ca lcu la t ed by a s s u m i n g t h a t t h e p u r i t y o f t h e 
ju ice in t h e bagasse i s e q u a l to t h e p u r i t y o f las t exp res sed juice , a n d f rom 
th i s a s s u m p t i o n : — 
T h e e x t r a c t i o n o b t a i n e d by each i nd iv idua l mil l expressed as a p e r c e n t a g e 
o f t h e po l in t h e feed to t h e mil l c a n be ca l cu l a t ed by c a r r y i n g o u t a m a t e r i a l s 
ba l ance over t h e mil l ing t r a i n . 
whe re en = pol e x t r a c t i o n at t h e wth mill expressed as a p e r c e n t a g e of 
pol in t h e bagasse from t h e p rev ious (n — 1) mill . 
En = pol e x t r a c t e d p e r cen t pol in cane for n mil ls of t h e t r a i n . 
En - i = pol e x t r a c t e d pe r cen t pol in c ane for n — I mil ls of t h e 
t r a in . 
For example:—Consider t h e fol lowing list of po l e x t r a c t i o n s p e r cen t 
pol in cane . 
N o . 1 mi l l—70.0 
N o . 2 mi l l—82.0 
N o . 3 mi l l—90 .0 
N o . 4 mi l l—95.0 
T h e n e x t r a c t i o n by n u m b e r t h r e e mil l , exp re s sed as a p e r c e n t a g e o f t h e pol 
i n n u m b e r t w o mi l l b a g a s s e : — 
T h e e x t r a c t i o n o b t a i n e d by ind iv idua l mil ls s u b s e q u e n t to No . 1 mill can 
also be ca lcu la t ed as a pe r cen t age of t h e pol in t h e bagasse from t h e p rev ious 
mill in t h e following m a n n e r : — 
where C = p u r i t y of las t expressed ju ice 
This a s s u m p t i o n i s n o t u sua l ly correct , t h e p u r i t y of ju ice in t h e bagasse 
be ing n o r m a l l y lower t h a n t h e p u r i t y o f las t expres sed juice , b u t t h e e r ror 
i n t r o d u c e d i s n o t large a n d i s f r equen t ly t o l e r a t ed . 
As no fibre is lost or ga ined in t h e process , t h e q u a n t i t y of fibre wh ich 
en te r s m u s t e v e n t u a l l y a p p e a r in t h e bagasse . Therefore , t h e r e a re F c p a r t s 
of fibre en te r ing a n d pass ing to t h e bagasse , per 100 p a r t s of cane , so t h a t — 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 155 
Maceration—The quantity of maceration is logically considered as a 
percentage of fibre. It is strongly recommended that the maceration water 
be weighed or measured, since this gives an accurate figure for the water used, 
which moreover is immediately available as a guide to the correct regulation 
of the added water. The maceration water per cent fibre for any period is 
then readily calculated from the weight of water, weight of cane and average 
fibre in cane for the period. 
The proportion of water added is often conveniently reported in terms 
of "dilution", i.e., the portion of the maceration water which passes into the 
mixed juice. This may be expressed as a percentage of undiluted juice or as 
a percentage of fibre in cane. 
Dilution per cent Undiluted Juice—This is calculated by a Brix balance, 
since the added water introduces no solids and the quantity of Brix in the 
diluted juice is identical with that in the undiluted juice. 
Let— 100 — weight of undiluted juice, 
B = Brix of undiluted juice, 
b = Brix of diluted juice, 
x = weight of maceration water in diluted juice, 
and 100 + x = weight of diluted juice (mixed or clarified 
juice). 
Dilution per cent Fibre—This is obtained by multiplying the dilution 
per cent undiluted juice by the weight of undiluted juice extracted from cane, 
expressed as per cent fibre, thus— 
Dilution % fibre = 
The expression for undiluted juice in cane is derived from the first part 
of the c.c.s. formula from which we have— 
Filter Washing Water—The water used in washing filter cake (or in 
diluting mud prior to filtering) should be metered and the quantity expressed 
as a percentage of the dry substance in filter cake. The weight of filter cake 
is determined for rotary niters as described under sampling. 
Pol Added to Filter Cake by Bagacillo—Some of the pol contained 
in rotary filter cake was present in the bagacillo added to assist nitration 
and theoretically had been accounted for as pol lost in bagasse. Hence a 
portion of the pol in the bagacillo is included in both the pol loss in bagasse 
and the pol loss in mud. 
In measuring retention, the values Mf and Mc, Ff and Fc are determined 
as described in Chapter IX. There are other methods of obtaining an estimate 
of retention, one of which was shown in the previous edition of this manual. 
However, the method listed above is the only mathematically correct one 
which can normally be carried out in practice, and it is recommended that 
this method be used in preference to the more approximate alternatives. 
Clarified Juice per cent Cane—This quantity is obtained by means 
of a pol balance, thus— 
Tons pol in clarified juice = tons pol in cane — tons pol in bagasse — tons 
pol in mud 
156 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
A method of correcting the observed pol loss in mud to the basis of 
original mud without added bagacillo was outlined in a previous edition of 
this Manual. Some of the reasoning involved in the calculation is open to 
question and the method is not recommended for adoption. The actual 
correction is of the order of ten per cent of the observed mud loss and there-
fore is a relatively small factor on the actual pol balance. 
Retention (Rotary Filters)—The calculation of retention is based on 
the assumption that all fibre (bagacillo) in the feed is retained in the cake. 
Let— Mf and Mc be the mud solids contents per cent, 
and Ff and Fc the fibre (bagacillo) contents per cent, 
in feed and cake respectively. 
Then— 
Concentration and Evaporation Formulae—These formulae are 
similar to those for Dilution, and are calculated as follows:— 
Let— 100 = weight of original juice, etc. 
b = Brix of original juice, etc. 
B = Brix of final product, 
x = water evaporated, as percentage by weight of 
original juice, 
Then— 100 b = (100— x)B 
Overall Evaporation Coefficient of Effets—This figure represents 
the weight of water, in pounds, evaporated per hour per square foot of 
heating surface, and is readily calculated with the aid of the two preceding 
formulae as follows:— 
N.B.:—The calculation of heating surface area for effets or other vessels 
must be clearly defined if comparisons between different installations are 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 157 
to be m a d e . T h e m e t h o d of ca lcula t ion of he a t i ng surface is la id down in t h e 
S.A.A. Boiler Code, AS. C B 1 , where a p p e n d i x A, sect ion R-9 s t a t e s : — 
" E v a p o r a t o r s , V a c u u m P a n s , E t c . — F o r evapo ra to r s , v a c u u m pans , 
h e a t e r s a n d o the r similar unfired vessels, t h e h e a t i n g surface shal l inc lude 
t h e t o t a l a rea of t ubes , inc lud ing c i rcu la t ing t u b e s (if any) , t h e t u b e p la te s 
exc lud ing t h e a rea of t h e t u b e holes, a n d in t h e case of b a s k e t ca landr ia s , 
t h e a rea of t h e shell. 
F o r th i s pu rpose t h e a rea of t h e t u b e s shall be based on t h e e x t e r n a l 
d i a m e t e r of t h e t u b e s a n d the i r l eng th be tween t h e ou te r surfaces of t h e t u b e 
p la tes . T h e n e t t u b e p l a t e a rea shall be t h e t o t a l a rea o f t h e t u b e p l a t e , 
ca lcu la ted on t h e ex t e rna l d i ame te r of t h e ca landr ia , m i n u s t h e a rea of t h e 
t u b e holes. In t h e case o f ba ske t ca landr ias t h e u p p e r t u b e p la te , m i n u s t h e 
t u b e holes, a n d t h e a rea of t he s t e a m inlet shall be measu red , a n d also, in 
t h e b a s k e t t y p e , t h e a rea of t h e shell shall be ba sed on t h e ou ts ide d i a m e t e r 
a n d t h e l eng th be tween t h e ou te r surfaces of t h e t u b e p la tes . In t h e case of 
e v a p o r a t o r s w i t h coils, h e a t i n g surface shall be based on t h e ex t e rna l d ia-
m e t e r of t h e coil a n d t h e coil l eng th be tween t h e inlet a n d ta i l p i p e . " 
R e c o v e r y F o r m u l a e — T w o recovery formulae are i n c o m m o n use ; t h e 
S.J .M. a n d t h e Win te r -Ca rp . E a c h i s t a k e n to represen t t h e pe rcen tage of 
t h e pol in t h e original m a t e r i a l recoverable as pol in sugar . The S.J .M. 
formula is der ived as fol lows:— 
L e t — 100 = weight of p r i m a r y p roduc t , 
J = p u r i t y of p r i m a r y p roduc t , 
P = pol of p r i m a r y p roduc t , 
S = p u r i t y of sugar p roduced , 
M = p u r i t y of final molasses, 
x = r ecovery of pol per cent pol in p r i m a r y p roduc t , 
Hence arises the common impression that the Winter-Carp formula is a 
special case of the S. J.M. formula. Originally intended to express the recovery 
of raw sugar, the Winter-Carp formula is now used, like the S.J.M., to express 
the recovery of pol from the quantity of pol present in the original material. 
Example— 
Given 130 tons of massecuite of Brix 95 and pol 66.5—hence 70 per cent 
purity, calculate the quantity of sugar recoverable. 
S.J.M. Formula—Assuming 100 purity for sugar, and molasses 
purity of 35— 
It is found that by substituting S = 100 and M = 28.57 in the S.J.M. 
formula, the Winter-Carp formula may be derived thus— 
158 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
The Winter-Carp formula was originally derived from the assumption 
that for every 100 parts of impurity in juice 40 parts of sucrose would be 
rendered unrecoverable. (Compare this with the c.c.s. formula.) 
To derive the Winter-Carp formula consider a juice of purity J containing 
100 parts of sucrose. Then 
Molasses in Stock—The estimation of molasses in stock follows simply 
from the calculation of recoverable pol, for— 
Tons pol in molasses = tons pol in stock — tons recoverable pol. 
The figure for pol in molasses thus derived may be used directly in the 
calculation of the pol balance. If it be desired to express the quantity as 
molasses, then 
Taking Stock—All pans, tanks, and other holding vessels should be 
calibrated so that the volume of the product in stock may be determined 
readily. Stocktaking is then usually carried out by recording the volume and 
temperature of each product, analysing a sample for Brix and pol, and 
entering the results into a table of the following form:— 
Stock Sheet 
Material 
A Massecuite 
AB Massecuite 
B Massecuite 
C Massecuite 
A Molasses 
AB Molasses 
B Molasses 
Syrup 
Juice 
Magma 
Temp. 
°C 
1 
Gal-
lons 
2 
Brix 
3 
*Brix 
at 
T°C 
4 
** Fac-
tor 
5 
P o l 
6 
Totals 
Purity 
7 
Weight 
in 
Tons 
8 
Tons 
Brix 
9 
Tons 
Pol 
10 
* Brix corrected for temperature from tables supplied. 
** From tables. 
Column 1 shows the actual temperature of the material when the volume 
(column 2) is measured. Columns 3, 6, and 7 are obtained from the analytical 
data. The values for column 4 must be corrected to the value corresponding 
to the actual temperature of the material when sampled. The factors of column 
5 are obtained from Table XX. The weight in tons (column 8) is obtained by 
multiplying column 2 by column 5 and dividing by 100, while columns 9 and 
10 are calculated by multiplying column 8 by columns 3 and 6 respectively. 
Totals are obtained for columns 9 and 10, and their ratio multiplied by 100 
shows the average purity of the materials in stock. Then from this value and 
the total tons of pol, the recoverable sugar may be calculated by applying 
the Recovery Formula. The volume of molasses expected may also be 
estimated, as outlined above. 
The method of measuring stock outlined above is not applicable to final 
molasses, which, after brief storage, is usually found to be highly aerated. 
The quantity of molasses in storage should be determined using a weight 
measuring device such as the pneumercator. This device has been available 
for a number of years and is well described in the paper by W. R. Dunford, 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 159 
160 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
Proceed ings Q.S.S.C.T. 1967. If such a device is n o t used , g r e a t ca re m u s t be 
t a k e n w h e n s amp l ing final molasses , in o rde r to ensu re t h a t a r e a s o n a b l y 
a c c u r a t e e s t i m a t e o f t h e a c t u a l a v e r a g e B r i x m a y b e o b t a i n e d . F o r adv ice i n 
m e a s u r i n g s tocks u n d e r t he se cond i t ions t h e r e a d e r i s referred t o t h e p a p e r b y 
N. S m i t h , P roceed ings Q.S.S.C.T. 1941. 
In recen t yea r s , w i t h t h e a d v e n t o f b u l k suga r hand l ing , one fu r t he r 
s tock q u a n t i t y h a s t o b e ca lcu la ted , t h a t o f t h e suga r he ld i n t h e b u l k b i n a t 
t h e e n d of a per iod. To o b t a i n an a c c u r a t e e s t i m a t e of th i s s tock , a b e l t 
weigher on t h e be l t feeding i n t o t h e suga r b in , o r a b in we igh ing device , s u c h 
as t h e load cell a r r a n g e m e n t ins ta l l ed a t one Q u e e n s l a n d mil l , s hou l d be 
employed , a n d these a re t o b e r e c o m m e n d e d . 
F o r week ly mill con t ro l pu rposes cons ide ra t ion h a s t o b e g iven t o t h e 
degree of a c c u r a c y r equ i r ed when e s t i m a t i n g s tock . F o r a week ly figure t h e 
a m o u n t o f t i m e a n d effort s p e n t i n s t o c k t a k i n g m a y n o t be c o m m e n s u r a t e 
w i t h t h e increased a c c u r a c y ob t a ined , b e a r i n g i n m i n d t h e fact t h a t a n y 
e r rors in s tock on ly affect t h e figure f rom week to week. F o r t h i s r ea son 
difficult a n d t i m e c o n s u m i n g s t o c k t a k i n g p rocedures , wh ich on ly resu l t in a 
v e r y smal l increase i n accu racy , a re n o t u s u a l l y emp loyed . I n m a n y mil ls , 
whe re t h e r e a r e no large v a r i a t i o n s in t h e p u r i t y o f m a t e r i a l s in process , 
ana lyses a re n o t ca r r i ed o u t on all i t e m s of s tock , t h e week ly ave rage ana lys i s 
for t h e m a t e r i a l conce rned i s t a k e n as t h e ana lys i s of t h e m a t e r i a l in s t ock 
a t t h e e n d o f t h e week. W h e n a d o p t i n g such p rac t i ces , however , careful 
cons idera t ion m u s t b e g iven t o t h e e r rors i n t r o d u c e d t o ensu re t h a t t h e overa l l 
e r ror in s tock does no t r e a c h a level w h e r e i t m a t e r i a l l y affects t h e week ly 
r ecove ry figure. 
M a s s e c u i t e C o m p o s i t i o n — I n order t o d e t e r m i n e t h e r e l a t ive q u a n -
t i t i es of s y r u p a n d molasses r e q u i r e d to p r o d u c e a m a s s e c u i t e of a defini te 
p u r i t y , t h e following fo rmula gives a close a p p r o x i m a t i o n . I t i s b a s e d on t h e 
a s s u m p t i o n t h a t t h e Br ix va lues o f b o t h s y r u p a n d molasses a re equa l , an 
a p p r o x i m a t i o n which i s u sua l ly exper ienced in p rac t i ce , p a r t i c u l a r l y w h e n 
t h e q u a n t i t i e s a re m e a s u r e d in t e r m s of t h e v o l u m e s of massecu i t e boi led on 
t h e respec t ive ma te r i a l s . 
L e t — p = p u r i t y of molasses , 
P = p u r i t y of s y r u p , 
M = p u r i t y of massecu i t e , 
x = p e r c e n t a g e of s t r ike de r ived f rom molasses , 
y = 100 — x = p e r c e n t a g e of s t r i ke d e r i v e d from s y r u p . 
A s s u m i n g un i fo rm B r i x — 
call this A. 
call t h i s B. 
These fo rmulae can be app l i ed to a n y m i x t u r e of m a t e r i a l s o f different 
pur i t i e s , a n d t h e ca lcu la t ion i s often c o n v e n i e n t l y ca r r i ed out b y u s i n g t h e 
" c r o s s " m e t h o d a s fo l lows:— 
Recovery and boiling house recovery may be expressed in terms of 
E.S.G. instead of pol by multiplying each by the E.S.G. factor of the s u g a r -
Recovery E.S.G. = pol recovery x E.S.G. factor 
In recent years the importance placed on E.S.G. figures has declined, 
and these figures are now seldom seen in literature. 
Crystal Content of Massecuite—The crystal content of a massecuite 
may be calculated from the analyses of the massecuite and the mother liquor 
of the massecuite. For the purposes of deriving formulae for crystal content 
it may be assumed that "crystal" has a dry substance content or a sucrose 
content or a true purity of 100 per cent. Thus three formulae may be derived, 
based on true analyses. Add to this the three formulae which may be drawn 
up on the basis of the apparent analyses, Brix, pol, and apparent purity, 
and it is found that six formulae are available for the calculation of crystal 
content. 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 161 
When it is desired to know the actual quantities of molasses and syrup 
necessary to give the strike, the following procedure should be followed:— 
Let— B — Brix of massecuite, 
b = Brix of syrup and molasses, 
X = quantity of molasses used per 100 massecuite, 
Y = quantity of syrup used per 100 massecuite. 
Expected Purity of Molasses—A formula derived statistically by the 
staff of the Sugar Research Institute is designed to give a target purity which 
is the lowest purity of molasses which could normally be expected to be 
attained from the material being processed. The expected true purity is 
calculated from the reducing sugar to ash ratio of the molasses in the following 
manner:— 
Expected purity = 40.67 — 17.80 log X 
where X = Reducing sugar/ash ratio 
Equivalent Standard Granulated (E.S.G.)—Not all the pol in raw 
sugar is recoverable, some being destined to pass out of the refinery in 
molasses. E.S.G. is intended to represent that portion of the pol in a raw 
sugar which is recoverable as pure sucrose. In the calculation of E.S.G. use 
is made of the Winter-Carp formula to derive the E.S.G. factor. 
100 parts total solids in massecuite. This is a useful figure, particularly as it 
may be calculated using only purity figures, which are the most commonly 
available for pan products. The crystal contents set out in Table XVIII are 
calculated by this formula. 
With six formulae available to calculate crystal content, the question 
arises as to the order of merit of the formulae in practice. Sucrose and true 
purity figures provide the best bases of calculation; pol and apparent purity 
figures yield results sufficiently accurate for routine work; dry substance gives 
reasonably satisfactory results; Brix gives unreliable results and should not 
be used to calculate crystal contents. If the method of separation of the mother 
liquor from the massecuite involves any significant degree of concentration or 
dilution, crystal content calculations must be based on purity. 
Rapid Method for Determining Weighted Average from Previous 
Average and Value for New Period—In preparing the weekly report, the 
chemist is required to give "To Date" values for each item, which involves 
considerable time and labour by the usual arithmetical method. The following 
is a simple, short method, and should be of interest to those chemists who are 
not acquainted with the procedure:— 
The previous "To Date" total (cane, molasses, or sugar) is divided by 
the new total, thus providing a factor. The value for each item in the new 
period is then subtracted from the previous average, and the difference is 
The formulae involving dry substance, Brix and pol are derived similarly 
and are analogous in form. 
If purity be adopted as a basis of calculation, the derivation is slightly 
different. It is convenient to regard crystal content as the recoverable sucrose, 
of 100 purity, per cent massecuite. The S. J.M. formula may be used to derive 
the recoverable sucrose per 100 sucrose in massecuite and this may be 
converted simply to the basis of per 100 parts of massecuite. 
Let the purities of massecuite and molasses be Pmass and Pmol respec-
tively, the dry substance per cent massecuite D.S.mass and the sucrose per 
cent massecuite Smass.Then 
Note that the form of the first term is analogous to that of the previous 
formulae, but the dry substance per cent massecuite is also involved in the 
complete expression. 
162 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
Suppose that the massecuite and mother liquor be analysed for sucrose 
contents. Then the crystal content may be derived as follows:— 
Suppose 100 parts of massecuite, of sucrose content S mass per cent, 
contain C per cent of crystal. Let the sucrose content of the mother 
liquid be S mol. Then, from a sucrose balance 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 163 
multiplied by the factor. The value so obtained is added to the new value 
to give the new average. If the value for any item, is greater in the new period 
than in the previous average, the difference will be negative, and the amount 
is actually subtracted. This is demonstrated by the following example:— 
Previous "To Date" values 
New Period 
To Date 
Tons Cane 
172,108 
18,307 
190,415 
Cane 
Fibre 
% 
13.42 
14.08 
13.48 
Pol 
% 
16.81 
15.75 
16.71 
Fibre Calculation— Pol Calculation— 
13.42 — 14.08 = -0.66 16.81—15.75 = 1.06 
—0.66 x 0.9039 = -0.60 1.06 x 0.9039 = 0.96 
14.08 + (-0.60) = 13.48 15.75 + 0.96 = 16.71 
Obviously the method cannot be applied to calculated values such as 
dilution, crushing rate, percentage lost time, etc.; these must be determined 
by employing the usual formulae. 
Performance Criteria 
Milling-—Numerous formulae have been devised to measure milling 
efficiency, but only two have been adopted in Queensland—Reduced Extrac-
tion and Lost Undiluted Juice per cent Fibre. 
Reduced Extraction—In the extraction formula it may be seen that, for 
constant values of pol in cane and pol and fibre in bagasse, the higher the 
fibre in cane, the lower the extraction. Accepting this as true in practice, the 
Reduced Extraction formula sets out to eliminate the effect of variations due 
to fibre per cent cane by "reducing" this figure to a standard 12.5 per cent. 
The formula was derived by Deerr, who argued along the following lines:— 
If e is the actual extraction, and / the fibre per cent cane, then v the 
absolute juice per cent fibre in bagasse is given by the expression 
criticism for it implies that the pol of the absolute juice is uniform, throughout 
the cross section of the cane stalk. This is far from correct though a parallel 
assumption in regard to Brix is much more reasonable. 
The main weakness of the formula is the implicit assumption that the 
higher the fibre content of the cane, the lower the extraction. If the higher 
fibred canes display improved response to milling and maceration the relation-
ship may actually be reversed. The reduced extraction formula would then 
become even worse than pol extraction as a measure of milling efficiency. 
Lost Undiluted Juice in Bagasse per cent Fibre—Since from the technical 
or operating point of view the work of a milling plant consists of the separa-
tion of juice from fibre, and since loss of juice in bagasse is caused only by 
fibre, the logical method of evaluating the technical efficiency of the milling 
station is by expressing the loss in bagasse in terms of undiluted juice per cent 
fibre. Obviously the comparison of results on a basis of pol extraction with 
differing fibre and pol contents of cane can be quite misleading if used as a 
criterion of efficiency of milling work. 
The lost undiluted juice per cent fibre is calculated by expressing the 
Brix in bagasse in terms of an equivalent amount of undiluted cane juice 
(the Brix of which is taken as equal to that of first expressed juice), as 
follows:— 
Lost undiluted juice per cent fibre = 
164 CALCULATIONS INVOLVED IN CHEMICAL CONTROL 
or, using the same nomenclature as for calculating extraction, and Bf for 
Brix of first expressed juice— 
It will be noted that the quantities involved in this expression are all 
determined directly and involve neither the assumptions of the c.c.s. formula 
nor the use of the figure for fibre in cane. 
Like reduced extraction, lost undiluted juice per cent fibre compensates 
for the quantity of fibre handled but can take no account of its quality. This 
formula is based on sounder principles than the reduced extraction formula, 
but suffers from the disadvantage of providing a value of zero for the limit 
of perfection and an upper limit approaching 1000. On this scale relative 
merits are not easily appreciated. 
In the absence of any complete criterion of the milling quality of cane, 
milling efficiency figures must continue to give only moderate satisfaction. 
Boiling House Efficiency—The influence of the purity of the raw 
material on recovery is so pronounced that recovery figures serve as a poor 
guide to efficiency. In Boiling House Efficiency the actual boiling house 
recovery is expressed as a percentage of the recovery indicated by the 
Winter-Carp recovery formula. Strictly the Winter-Carp recovery should be 
based on the purity of mixed juice, but as this is not generally available, the 
purity of first expressed juice is taken instead. 
I r r e spec t ive of i t s m e r i t s as a cr i ter ion of fac tory per formance , t h e 
coefficient of w o r k is t h e m o s t i m p o r t a n t figure in mil l con t ro l in Queens land 
since i t re la tes t h e sugar m a d e to t h e cane c rushed in t e r m s of t h e bas is on 
which these commodi t i e s are b o u g h t a n d sold. H e n c e t h e figure h a s h igh 
significance financially. As a m e a s u r e of fac tory pe r fo rmance t h e coefficient 
of w o r k embodies t h e deficiencies of t h e c.c.s. a n d n e t t i t r e formulae a n d 
m u s t b e accep ted w i t h cau t ion . 
As s t a t e d earlier, t h e c.c.s. fo rmula pos tu l a t e s a s t a n d a r d loss of sucrose 
in process . W o r k i n g to th i s s t a n d a r d , a mill t r e a t i n g 100 tons of c.c.s. wou ld 
recover 100 t o n s of p u r e sugar (100 n . t . ) , which would be equ iva len t to nea r ly 
106.4 t o n s of 94 n . t . sugar . T h e coefficient of work would be nea r ly 106.4. 
Th i s is somet imes r ega rded as t h e u p p e r l imit of t h e coefficient of work . T h e 
ideas t h a t (1) t h e u p p e r l imit of coefficient of work is 100, a n d (2) t h e u p p e r 
l imit i s a b o u t 106.4 a re b o t h er roneous . T h e u p p e r l imit i s va r iab le , b u t 
r ep resen t s a pe r fo rmance in which all t h e sucrose in t h e cane is recovered as 
p u r e sugar . A coefficient of w o r k of 106.4 a p p r o x i m a t e l y is t h e minimum va lue 
a t wh ich t h i s condi t ion could exis t . Th is m i n i m u m va lue would be o b t a i n e d 
f rom cane w i t h a m a x i m u m c.c.s. for i t s pol con ten t , i.e. con ta in ing no im-
pur i t i e s in t h e ju ice . I f all t h e sucrose in t h e cane could be recovered f rom 
cane con ta in ing impur i t i e s in i t s juice, a coefficient of work h igher t h a n 106.4 
wou ld be ob t a ined , e.g. consider cane of t h e following analysis . 
pol per cen t cane = 16.0 
Br ix per cent cane = 18.0 
c.c.s. = 15.0 
Po l recovered as p u r e suga r f rom 100 t o n s cane = 16.0 t ons 
16.0 t o n s a t 100 n . t . = 17.02 t o n s a t 94 n . t . 
T o n s of c.c.s. f rom 100 t o n s cane = 15.0 
CALCULATIONS INVOLVED IN CHEMICAL CONTROL 165 
T h e weakness of t h e boi l ing house efficiency formula is t h a t i t a ccep t s 
all t h e po l in t h e sugar as recoverab le pol . To c o m p e n s a t e for th i s t h e E .S .G. 
R e c o v e r y m a y be t a k e n , t h e figure der ived be ing Boil ing H o u s e Efficiency 
E.S .G. , o r Boil ing H o u s e Pe r fo rmance . A n o t h e r weaknes s i s t h a t t h e bas ic 
r ecovery d e p e n d s on ly u p o n t h e p u r i t y o f t h e or iginal ju ice , t h e r e b y t a k i n g 
a c c o u n t o f t h e q u a n t i t y , b u t n o t t h e n a t u r e o f t h e impur i t i e s . 
Va r ious a t t e m p t s h a v e been m a d e to e l imina te t h e effects of p u r i t y of 
or iginal m a t e r i a l on recovery , by " r e d u c i n g " t h e p u r i t y o f t h e m i x e d j u i ce 
to a s t a n d a r d of 85 pe r cen t . Hence such t e r m s as R e d u c e d Boil ing H o u s e 
R e c o v e r y a n d R e d u c e d Overa l l Recove ry h a v e been der ived. T h e r e i s d is-
a g r e e m e n t over t h e reason ing invo lved in reduc ing t h e recoveries to a s t a n d a r d 
ba sed on ju ice of 85 per cen t p u r i t y , and , as t h e r educed recover ies a re n o t 
used in Queens land , t h e formulae h a v e been o m i t t e d f rom th i s Manua l . 
Because of t h e n u m e r o u s deficiencies in t h e Boiling House Efficiency 
formula i t i s n o t n o r m a l l y considered to be of g rea t i m p o r t a n c e . 
Coef f ic ient o f W o r k — A s s t a t e d in t h e Definit ions, 
To carry out an efficiency test it would be necessary to measure the 
quantities of steam produced and fuel used during the time of the test and 
to determine the heat required per lb of steam and the calorific value of the 
fuel used. Suggestions covering these items will now be given. 
Steam Produced 
For the measurement of steam output, a positive type meter on the 
feedwater is recommended, together with a recording thermometer. Where 
any blowing down is done during the period concerned, the weight of water 
blown down must be estimated and deducted from the total weight of feed 
water. This is readily done by noting the depth of water removed from the 
boiler drum each time by blowing down, and calculating its volume and 
weight from the dimensions of the drum. With most mills the normal amount 
of blowing down during a weekly working period will probably be negligible 
(well below 1 per cent of total steam) and the blow-down need be estimated 
only in abnormal circumstances. Steam output may also be measured by 
flow meters; this, however, necessitates careful correction of the flow meter 
records for variations in steam pressure and temperature, as well as frequent 
checking of the meter. In this case no correction foi blowing down is required; 
on the other hand, steam blown off through the safety valves will, if of suffi-
cient amount, cause an error in the figures for steam output. 
Heat Required per lb of Steam 
The pressure and (when superheated) temperature of the steam should 
be registered and also the temperature of the feed water. Average values for 
the period of test are then calculated. 
For superheated steam the heat required per lb = H —(t — 32),* 
where H is the total heat of superheated steam in Btu per lb at the average 
temperature and pressure obtaining during the test period and t is the 
average feedwater temperature in °F. 
•Steam tables using the British system of units are based on a datum of 32 °F. 
CHAPTER XII 
THE BOILER STATION 
Introduction 
The large quantity of steam required by the factory for power and 
heating purposes is supplied by a boiler station where the chemical energy 
stored in the fuel is released by combustion in the furnaces and as much 
as possible transferred, in the form of heat, to the boilers proper. The steam 
generated by the boilers provides a very flexible medium for applying heat 
wherever it may be wanted and, when generated at a suitable working 
pressure, it may first be used in prime movers to supply all the mechanical 
and electrical power needed by the various factory processes. 
Boiler Efficiency 
It should be the aim in every factory to operate the boiler station at 
an efficiency which enables all steam requirements to be met by burning 
only the bagasse fuel which is available from the milling process. 
Boiler efficiencv for any period of time may be stated as: 
Fuel Used 
The most accurate way of determining the amount of fuel used is by 
direct weighing. Hand weighing by feeding the bagasse into a large box 
mounted on platform scales and then hand feeding the furnaces would be 
quite feasible for an efficiency test of a few hours' duration on a single boiler, 
but would be almost impossible for a test on the whole station. A continuous 
weigher would be ideal for such an overall test and when these weighers are 
installed for the purpose of chemical control the testing of boiler station 
efficiency will be very much simplified. In the meantime it is necessary to 
determine the weight of bagasse from the weight of cane crushed, and the 
percentages of fibre in the cane and the bagasse during the period, thus— 
, weight of cane x fibre per cent cane Weight of bagasse = —~ -^-^ fibre per cent bagasse 
Should the above method be used for determining the weight of fuel, 
allowance must be made for any bagasse removed from the boiler station 
for other purposes, also for any bagasse which might be saved during the 
period of the test. It is suggested that such quantities may be determined 
with sufficient accuracy by volume measurement allowing 10 lb/ft3 for piled 
bagasse. 
Allowance has also to be made for any extraneous fuel used during a 
test. However, as the furnaces are designed essentially for bagasse burning 
it would be more satisfactory to conduct any tests at a time when the mill 
had settled down to a steady crushing rate. There would then be little likeli-
hood of the boiler's requiring extraneous fuel. 
Calorific Value of the Fuel 
When a fuel is burned, heat is generated, and the quantity of heat 
liberated per unit weight of fuel is known as the calorific value and expressed 
in Btu per pound. Most fuels contain hydrogen which, when it burns, yields 
water in vapour form; furthermore, any water originally present in the fuel 
is also converted to vapour. This water vapour contains latent heat, re-
presenting a portion of the heat liberated by the combustion. If the water 
vapour be condensed the latent heat becomes available for inclusion in the 
total quantity of heat released. The calorific value determined under these 
conditions is known as the Gross Calorific Value, represented by the symbol 
Bh. The heat released per pound of fuel, not including any latent heat in the 
products of combustion, is known as the Net Calorific Value, designated Bi. 
It is customary to base all boiler calculations on gross calorific value, 
but comparisons between fuels, as between, say, bagasse and coal, or between 
bagasses of different moisture contents, are more reliably drawn on the basis 
of net calorific value. In practical boilers only the heat corresponding to the 
168 T H E BOILER STATION 
net calorific value is available for absorption, but, as stated above, boiler 
efficiencies and allied figures are related to gross calorific values. 
Bagasse.—Formulae giving the calorific value of bagasse have been 
worked out from determinations on Queensland bagasse and are as follows: 
Gross cal. value (Bh) = 8345 — 22 • 1 pol — 83-45 water 
Net „ „ {Bi) = 7783 — 22-1 pol — 88-27 water 
In these formulae pol and water represent the percentage of pol and 
moisture obtained from the analyses of final bagasse leaving the milling 
plant. Strictly speaking, a correction should be made for a reduction in 
moisture by evaporation between the mills and the boiler station. While such 
a collection may readily be established and applied, it is suggested that for 
routine calculations the figures for the bagasse leaving the final mill may be 
employed. This would under-estimate somewhat the calorific value (Bh) of 
the bagasse and so over-estimate the boiler efficiency and, in effect, credit 
the boiler house with any drying of bagasse between the final mill and the 
boilei furnaces. In any case the discrepancy in Bh would be fairly uniform 
and of no consequence for comparative purposes. 
Values of Bh for normal ranges of pol and moisture are given in Table 
XXXV. 
Wood.—The calorific value of wood depends mainly on its condition, i.e , 
how much moisture it contains. If no other information is available a B ^  
value of 6000 may be taken for air-dried wood containing 20 to 40 per cent 
moisture. The corresponding B\ is about 5300. 
Furnace Oil and Diesel Fuel.—The average gross calorific values of these 
fuels can be taken as 18,800 and 19,200 respectively. 
Molasses.—The calorific value of molasses depends on its moisture 
content and ash. The average values oi Bh and B\ for normal molasses can be 
taken as 5380 and 4600 respectively. 
Coal and Tar.—Coal and tar are about the only remaining substances 
which are likely to be used as supplementary fuels in the sugar industry. The 
gross calorific values can be taken as 11,000 and 16,500 respectively. 
Equivalent Bagasse.—Equivalent bagasse is assumed to be bagasse 
having a net calorific value of 3300 Btu per pound, calculated from bagasse 
of 50 per cent moisture and three per cent pol. This value is accepted as the 
standard for bagasse and all extraneous fuels. Therefore to calculate tons 
equivalent bagasse, the weight of bagasse produced is multiplied by the net 
calorific value (Table XXXV(b)) divided by 3,300. 
The extraneous fuels are calculated to equivalent bagasse, from the 
following formulae:— 
Tons equivalent bagasse = tons wood X 1.6 
= tons molasses x 1.4 
= tons coal X 3.5 
= tons oil X 5.5 
Measuring Boiler Efficiency Indirectly 
A certain proportion of the theoretical heat available from the bagasse 
fed into a boiler furnace is used to generate steam while the remainder is 
absorbed by various losses. It is possible to calculate the major losses fairly 
accurately while a reasonable estimate of the minor losses may be made from 
results obtained in previous tests on boilers of similar type. As the losses are 
THE BOILER STATION 169 
expressed as a pe r cen t age of t h e Bh va lue of t h e bagasse , t h e efficiency =. 
100 — losses. T h e m e t h o d gives a r ea sonab ly a c c u r a t e w a y of m e a s u r i n g 
boi ler efficiency w i t h o u t t h e l a b o u r o f weighing a n d h a n d feeding bagasse a n d 
w i t h o u t t h e difficulty of m e a s u r i n g t h e s t e a m p roduced . Moreover , for a n y 
p a r t i c u l a r boiler , t h e losses wh ich a re e s t i m a t e d can, u n d e r n o r m a l w o r k i n g 
condi t ions , be e x p e c t e d to r e m a i n c o n s t a n t while t h e losses which are calcu-
l a t e d inc lude those wh ich are u n d e r t h e ope ra to r ' s control . T h e m e t h o d t h e r e -
fore gives a t r u e gu ide as to h o w efficiently a boiler is be ing worked . 
T h e va r ious losses a re discussed below a n d formulae given for t hose 
which can be ca lcu la ted . 
C o n d e n s a t i o n L o s s 
T h e t e r m condensa t ion loss i s appl ied to t h e h e a t lost in t h e flue gas 
d u e to w a t e r v a p o u r . P a r t o f th i s v a p o u r comes from t h e or iginal bagas se 
a n d p a r t i s formed in t h e combus t i on process . 
100 (562 + 4 . 8 2 w ) 
Condensa t ion loss = = pe r cent Bh-
Bh 
w h e r e w = p e r cen t m o i s t u r e in bagasse . 
S e n s i b l e H e a t L o s s 
T h e f lue gas leaves t h e boiler a t a t e m p e r a t u r e above t h a t of t h e a t m o -
sphere , a n d t h u s p a r t of t h e h e a t of combus t ion leaves t h e boiler as sensible 
h e a t in t h e f lue gas . 
Table of values for lOOOK for use in formula for sensible heat loss. 
Per cent COa in 
flue gas, mt 
5 
6 
7 
8 
9 
10 
10.5 
11 
11.5 
12 
12.5 
13 
13.5 
14 
14.5 
15 
15.5 
16 
16.5 
17 
40 4 0 
78.9 
67.3 
58.9 
52.6 
47.6 
43.8 
42.1 
40.6 
39.2 
37.9 
36.7 
35.6 
34.7 
33.7 
32.9 
32.1 
31.3 
30.6 
29.9 
29.3 
4 2 
79.3 
67.7 
59.3 
52.9 
48.0 
44.1 
42.4 
40.9 
39.6 
38.2 
37.1 
36.0 
35.0 
34.1 
33.2 
32.4 
31.6 
31.0 
30.2 
29.6 
Per cent moisture in bagasse, w 
44 
79.6 
68.1 
59.7 
53.4 
48.5 
44.5 
42.8 
41.3 
39.9 
38.6 
37.4 
36.4 
35.4 
34.4 
33.6 
32.7 
32.0 
31.3 
30.6 
30.0 
46 
80.0 
68.4 
60.0 
53.7 
48.8 
44.9 
43.2 
41.7 
40.4 
39.1 
37.9 
36.9 
35.9 
34.9 
34.1 
33.2 
32.5 
31.7 
31.1 
30.5 
4 8 
80.5 
68.8 
60.4 
54.1 
49.2 
45.3 
43.6 
42.1 
40.7 
39.4 
38.3 
37.2 
36.2 
35.2 
34.4 
33.6 
32.9 
32.1 
31.4 
30.8 
50 
81.0 
69.4 
60.9 
54.6 
49.6 
45.8 
44.1 
42.6 
41.2 
39.9 
38.7 
37.6 
36.7 
35.7 
34.9 
34.1 
33.3 
32.6 
31.9 
31.3 
52 
81.5 
69.9 
61.4 
55.1 
50.1 
46.3 
44.6 
43.1 
41.7 
40.4 
39.2 
38.2 
37.2 
36.2 
35.4 
34.5 
33.8 
33.1 
32.4 
31.7 
54 
82.1 
70.5 
61.9 
55.7 
50.7 
46.8 
45.1 
43.6 
42.2 
41.0 
39.7 
38.7 
37.7 
36.7 
35.9 
35.1 
34.3 
33.6 
33.0 
32.3 
5 6 
82.7 
71.0 
62.5 
56.2 
51.3 
47.4 
45.7 
44.2 
42.8 
41.5 
40.3 
39.3 
38.3 
37.3 
36.5 
35.6 
34.9 
34.2 
33.5 
32.9 
Sensible h e a t loss = K (tF—tA) pe r cen t Bh-
where K is a c o n s t a n t depend ing on t h e C O a c o n t e n t of t h e f lue gas 
a n d t h e w a t e r con t en t of t h e bagasse (values for 1000K a re 
g iven in t h e a c c o m p a n y i n g Tab le ) . 
tp = flue ga s temperature °F. 
tA = a ir temperature °F . 
170 THE BOILER STATION 
Unburnt Gas Loss 
In the combustion of hydrocarbon fuels gaseous intermediate products 
are formed. The existence of such products in the flue gas represents a loss 
of heat. The most common instance is of carbon burning to CO instead of C02-
The unburnt gas loss may be determined from the following formula:— 
m2 = average reading of per cent unburnt gas registered by 
a Mono or similar type of recorder. 
The CO
 2 and per cent unburnt may best be determined from a flue gas 
analyser of the Mono type. The Mono is a recording instrument and very 
convenient to use as the difference between the readings of alternate strokes 
of the pen gives a measure of the unburnt gas. It is reasonable to assume that 
this unburnt gas is made up of CO and H2, in which case the actual quantity 
of unburnt would be two-thirds of the percentage shown by the difference 
between alternate strokes. 
Miscellaneous Losses 
These are made up of radiation loss, sensible heat loss in the ash, unburnt 
material in the ash and unburnt material in the fly ash. It is almost impossible 
to measure these losses, but in a series of tests cairied out by the Bureau on 
five water tube boilers they were found to have an average value of 8 • 3 per 
cent Bh at an average rate of evaporation of 4 -9 lb per ft2 of heating surface 
per hour. 
Two of the miscellaneous losses relate to ash. Rough calculations show 
that the sensible heat lost when hot ashes drop through the grate and are 
raked out of the ashpit would be of the order of 0 • 1 per cent Bh- Observations 
show that the amount of unburnt in the ash would also be very small when 
stated as a percentage of heat available in bagasse. It is therefore suggested 
that these two ash losses be neglected and the miscellaneous losses regarded 
as being made up of fly ash and radiation losses. 
Experiments carried out in 1950 indicate that fly ash loss is proportional 
to boiler rating and that a reasonable figure to adopt for a water tube boiler 
would be 2 per cent at a rating of 4 • 9 lb per ft2 of heating surface per hour. 
If the actual steam consumption of the factory is not known the following 
estimates of steam (from and at 212 °F)* per ton of cane could be used to 
arrive at the boiler rating:— 
Using quadruple evaporation without bleeding 61 per cent steam on cane 
Using quadruple with bleeding 58 
Using quintuple without bleeding 57 ,, ,, 
Using quintuple with bleeding 55 
It is generally accepted that radiation loss, expressed as per cent Bh, 
does not increase with rating, but, if anything, tends to decrease. Reasonable 
results should be obtained, however, if this loss be taken at 8-3—2 = 6 - 3 
per cent Bh for all ratings. 
Large boilers with water wall furnaces would tend to have a still smaller 
radiation loss and in such boilers it is probable that the miscellaneous losses 
would not exceed 6 per cent Bh-
•Steam raised from water at 212 °F without any change in temperature. The heat 
required for this conversion is 970.6 Btu/lb. 
THE BOILER STATION 171 
Flue Gas 
Flue Gas Composition 
For any particular flue gas temperature, boiler efficiency will improve 
as the amount of excess air going into the furnace is reduced—provided 
always that the air is supplied in such a way that there is little if any unburnt 
in the flue gas. The adjacent Table shows the relationship between the C02 
reading, which is really a measure of excess air, and the sensible heat loss. 
The last column also shows the importance of complete combustion, e.g.., the 
reduction in heat loss brought about by improving the C0 2 from 11 to 14 
per cent would be completely nullified if the combustion efficiency deteriorated 
sufficiently to yield an unburnt gas reading of one per cent on a Mono or 
similar recorder. 
Table showing sensible heat and unburnt gas losses. 
(Based on a flue gas temperature of 500 °F and a bagasse 
moisture of 50 per cent.) 
co2 
20.3 
17 
16 
15 
14 
13 
12 
11 
10 
Excess air 
per cent 
0 
19 
27 
35 
4 4 
56 
68 
84 
102 
Sensible heat 
loss in flue gas 
per cent Bh 
13.0 
13.5 
14.1 
14.8 
15.6 
16.5 
17.6 
19.6 
Loss caused by 
1 per cent unburnt 
in flue gas per cent Bh 
_ 
2 . 5 
2 . 6 
2 . 8 
3 . 0 
3 . 2 
3 . 5 
3 . 8 
4 . 2 
Flue Gas Temperature 
The higher the flue gas temperature the greater will be the sensible heat 
loss. The temperature must go up as the boiler rating is increased and the 
operator has no control over the efficiency in this regard. He can, however, 
obtain maximum efficiency at any given rating by making sure that the 
heating surfaces, on both water and gas sides, are kept as clean as possible. 
The sensible heat loss when the bagasse contains 50 per cent moisture 
and the flue gas 12-5 per cent C0 2 varies with temperature as follows:— 
Flue gas temperature °F 300 400 500 600 70C 
Sensible heat loss per cent Bh 8-5 12-4 16-2 20-2 24•( 
Operation at moderate rating would give a temperature of between 
500 and 600 °F. By fitting an economiser or air heater this could be brought 
down to 350 °F, which shows that such a unit can be worth up to about 
8 per cent in efficiency. 
Volume of Flue Gas 
To specify the capacity of an induced draught fan or fans for a boilei 
station it is necessary to determine the volume of flue gas which will t* 
172 THE BOILER STATION 
produced per minute when the factory is working at maximum crushing rate 
and all the bagasse is being burnt in the furnaces. The weight of flue gas 
which will be produced by each pound of this bagasse may be found from the 
following formula:— 
where w = per cent moisture in bagasse 
m\ == P e r cent CO2 in flue gas. 
Over the range of C0 2 and moisture values likely to be met, the specific 
volume of the flue gas may be taken as 25 • 1 ft3/lb at 500 °F. For any other 
Effect of Density on Fan Performance 
It is necessary to remember that most manufacturers state fan per-
formance in terms of "standard air" which has a density of 0-075 lb/ft3 
The volume delivered by a fan at a certain speed is independent of 
density but the pressure (or draught) will be proportional to the density. 
Therefore if a pressure of 3 in is required when handling flue gas at 500 °F 
(specific volume 25-1 ft3/lb = 0 - 0 4 lb/ft3 density) a fan giving a pressure 
The volume of air per minute may then be determined. 
However, if the fan is to be used with an air heater, the capacity must 
be increased to allow for a certain amount of recirculation as the only sure 
It is suggested that the fan capacity be determined for a C0 2 figure of 
12 1/2 per cent and increased by 10 per cent to allow for depreciation in service. 
The flue gas temperature could be taken as 600 °F. At full capacity the fan 
should be capable of giving a draught of 2 in water at the back of all boilers. 
The draught at the fan inlet should, for a simple installation and reasonably 
well designed flues, not have to exceed 2 1/2 in. If an economiser or fly ash 
eliminator be fitted extra draught must be provided to compensate for the 
resistance of these units. 
Horsepower Required for a Fan 
The following formula gives the horsepower required for a fan:— 
Forced Draught Fans 
To determine the capacity of a forced draught fan the maximum rate 
of burning of bagasse in the furnace must first be estimated and air required 
found from the following formula:— 
THE BOILER STATION 173 
way to avoid corrosion in a tube or plate type air heater is to arrange foi 
the in-going air to be at a temperature at least equal to the dewpoint temper-
ature of the flue gas. This dewpoint temperature depends on the moisture 
content of bagasse and per cent CO2 in the flue gas. At 50 per cent moisture 
and 12.5 per cent C0 2 it would be 148 °F and sufficient hot air must be added 
to the in-going atmospheric air to give a mixture of this temperature. Taking 
an atmospheric temperature of 70 °F and a hot air temperature of 370 °F 
the recirculation needed would be 
The combustion air required under the assumed conditions of moisture 
and C0 2 would be 4.65 lb per lb of bagasse = 7 1 - 5 ft3 at 148 °F. Therefore 
the volume of air to be handled by the fan would be 71.5 x 1.35 = 96.5 ft3 
per lb of bagasse burnt. This figure is suggested as being suitable for average 
Queensland conditions. 
Bagasse Moisture 
Bagasse moisture has a very big influence on the steaming capacity of 
the boilers and if steam troubles are being experienced an effort should be 
made to arrange mill settings so that the moisture in final bagasse does not 
exceed 50 per cent. Apart from making the bagasse easier to burn, reducing 
the moisture content is equivalent to increasing the fuel supply. For moistures 
in the neighbourhood of 50 per cent, one per cent reduction is equivalent to 
obtaining one per cent more fuel from the same quantity and quality of cane. 
The Treatment of Water for Boilers* 
The supply of unsuitable water to steam generating plants is not only 
uneconomical, but may be dangerous if adequate steps are not taken to 
minimize the cumulatively deleterious results. The desirable feed to all boilers 
is a suitably conditioned water, free from all unwanted salts and gases, and 
the maximum possible amount of such suitable water as is available must be 
fed to boiler plant. Where raw make-up or other unsuitable water must be 
fed to boilers there is, however, no excuse for allowing the impurities in this 
water to remain in the boiler in a harmful form. 
The problems of boiler water treatment have become magnified in recent 
years with the advent of large, modern, bent-tube, water-walled, high 
capacity boilers into the industry. Such boilers are particularly prone to 
damage from overloading and inadequate water conditioning, and it is false 
economy to run the risk of ruining or damaging an investment worth some 
half a million dollars for the sake of a small outlay on boiler feed water 
treatment. 
There are a number of British Standards available dealing with the 
subject of water treatment and it is strongly recommended that the following 
standards be purchased. 
B.S. 2486 "Treatment of Water for Land Boilers" 
B.S.1427 "Routine Control Methods of Testing Water Used in 
Industry" 
B.S. 1328 "Methods of Sampling Water Used in Industry" 
*The recommendations made under this section are approved by the Chief Inspector 
of Machinery. 
174 T H E BOILER STATION 
There are also a number of reputable commercial firms with long experi-
ence in this field, and, providing their recommendations are within the limits 
prescribed by British Standards, the advice of such firms can be profitably-
followed. The indiscriminate addition of boiler water additives whose com-
position is not specified by the manufacturer, should, however, be avoided. 
The objects of boiler water treatment are threefold, namely:— 
1. The prevention of scale on heating surfaces 
2. The prevention of corrosion and caustic embrittlement 
3. The production of clean steam free from entrained water or solids 
and these three criteria will now be discussed separately. 
The Prevention of Scale on Heating Surfaces 
The avoidance of scale on heating surfaces is most important, for, as well 
as reducing the efficiency of heat transfer to a boiler, heavy scale will cause 
overheating of the tube metal which, if sufficiently severe, can cause tube 
failure. 
Scale can be described as a hard adherent deposit on heating surfaces 
and is caused by the presence of three main chemical substances in the water; 
salts of calcium, magnesium, and silica. 
It is therefore important to provide a boiler feed water containing as few 
of these impurities as possible but, if the impurities must unavoidably be 
introduced, as they are in small quantities even in very efficient steam plants, 
they must be removed from the water before feeding it to the boiler, or 
additives must be introduced to the water so that scale will not form. 
The ideal answer to the problem is not to introduce water containing these 
compounds to the boiler. This is done, as far as possible, by returning con-
densed steam to the boiler as feed water wherever this can be obtained in an 
uncontaminated form. This practice reduces the usage of raw water, i.e. 
untreated water from outside the steam-condensate cycle, as far as possible. 
The use of clean condensate is the greatest single factor in the avoidance of 
boiler feed treatment problems. Where raw water make-up containing scale 
forming constituents must be added the scale-forming constituents of this 
water can be dealt with in three ways either singly or in combination, by 
distillation {i.e. evaporation), external water treatment (softening or ion 
exchange), or by internal water treatment. 
The use of distillation processes or external water treatment systems is, 
however, not economical under sugar industry conditions, and boiler water 
conditioning is carried out by what is known as internal treatment. 
Internal treatment entails the chemical treatment of the boiler water 
in such a manner that the scale forming substances are not deposited on the 
heating surface as scale, but precipitated as a mobile sludge which flows to 
the lowest point in the boiler and is removed in the blowdown. This is 
usually achieved by adding phosphate to the boiler water and by maintain-
ing an excess of alkalinity, by the addition of caustic soda. Under the 
alkaline conditions prevailing, the phosphate precipitates any calcium present 
as calcium phosphate sludge. The caustic alkalinity precipitates magnesium 
salts as magnesium hydroxide, also a mobile sludge. Any silica present will 
normally be absorbed on the magnesium hydroxide precipitate and removed, 
or may co-precipitate with magnesium as magnesium silicate. Thus all harm-
ful concentrations of scale forming compounds can be removed from the boiler 
THE BOILER STATION 175 
in the blowdown, providing the correct concentrations of phosphate and 
alkalinity are maintained at all times. 
The consumption of phosphate and alkali obviously depends on the 
quantity of scale forming compounds fed to the boiler, so that the cost of the 
treatment depends entirely on this factor. It is therefore of great importance 
that the maximum possible amount of good condensate be returned to the 
boiler and the minimum of poor quality water added. Thus make-up should 
be kept to a minimum and, where alternative sources of make-up water are 
available, the best source should be used. 
There is also a secondary reason for the avoidance of feed contamination 
by scale forming materials. The scale forming materials add solids to the 
boiler water and the chemicals added to control the scaling add further solids. 
This necessitates increased blowdown to maintain a safe solids level in the 
boiler water, as will be discussed in a subsequent section, and this results in 
some of the treatment chemicals being lost in blowdown. This causes an 
increased chemical demand to maintain the correct chemical concentrations, 
and this adds further solids to the water and so on. The net result is that the 
system can reach a stage where it chases its own tail, so to speak, and 
chemical costs are high due to wastage of chemicals in blowdown. Therefore 
the maximum usage of good condensate for boiler feed is of the utmost 
importance. 
The Prevention of Corrosion and Caustic Embrittlement 
Corrosion—Corrosion in a boiler is produced by two main causes, acidity 
and oxygen. 
Acidic conditions are corrosive to iron and steel, so that the material of a 
boiler will be eaten away if acid conditions are allowed to prevail for any 
length of time. The control of this problem is a relatively simple one. The 
boiler water must be kept alkaline at all times. This is in conformity with the 
internal method for the prevention of scale, as discussed in the previous 
section, and the provision of the correct alkalinity serves a dual purpose. 
The presence of dissolved oxygen in a boiler can cause very severe 
corrosion. Corrosion from this source, and sometimes from acids as well, 
normally occurs in the form of pits in the boiler shell or as wasting away at 
the tube ends. The fact that the corrosion is concentrated in small areas and 
not evenly distributed over the whole surface means that the effects are more 
severe. In extreme cases of pitting, the boiler drum finally becomes holed by 
pits which extend right through the metal. The theory of corrosion caused by 
the presence of oxygen is rather complex, but the process is actually a form 
of galvanic action. Due to stresses in a boiler shell, and to lack of complete 
uniformity of metal composition, under operating conditions certain areas of 
a boiler become anodes while others become cathodes. A current will pass 
between the anodic and the cathodic areas and this will cause the removal of 
metal from the anodic areas. The metal removed forms an hydroxide, under 
the alkaline conditions in the boiler, but in order to proceed, the galvanic 
action requires oxygen. If oxygen is present the action can continue indefinite-
ly and the anodic areas can be continually denuded of metal. The anodic 
areas, once established, remain localized, and severe corrosion occurs at these 
localized points, giving the typical pitting of oxygen corrosion. 
The answer to this problem is obviously to ensure that the boiler water 
contains no dissolved oxygen. The oxygen enters the boiler in the feed water 
and so conditions in the feed should be maintained so that a minimum amount 
of dissolved oxygen is present. The solubility of oxygen in water depends 
176 T H E BOILER STATION 
upon temperature and pressure. The solubility decreases with temperature, 
at a given pressure, so that it is obviously advantageous to maintain the boiler 
feed water at as high a temperature as possible. It is also essential to provide 
venting to the atmosphere in the feed system, so that any oxygen or other 
gases released from condensate, or raw water make-up, can be expelled. 
The vent should release a certain amount of vapour, in order that no atmo-
spheric oxygen can enter the system. Condensate collection vessels and feed 
tanks should be covered, except for the venting, and pump glands maintained 
in good order for the same reason. Thus once again the need for a maximum of 
steam condensate return is paramount, and for the purposes of oxygen content 
the condensate should be as hot as possible. In any steam plant some make-up 
must be used to replace unavoidable losses and the make-up should also be 
as hot as possible in order to have the minimum oxygen content. 
In large boiler plants feed de-aerators are used to remove oxygen before 
feed entry into the boiler. These units consist essentially of a combination 
heater and flash tank in which the boiler feed is heated and flashed, to allow 
dissolved oxygen to be released and removed. The residual oxygen left in the 
feed after the de-aerator is treated inside the boiler. 
For sugar mill installations de-aerators are usually uneconomical, as 
the oxygen present in the feed water can be removed chemically inside the 
boiler. This is normally achieved by the use of hydrazine or sodium sulphite. 
Hydrazine, a compound of nitrogen and hydrogen, N2H4 , is used in 
high pressure installations where dissolved solids are a problem, because both 
products of the reaction are inert, one being water and the other nitrogen. 
The latter goes out in the steam and is vented through the non-condensible 
gas vents. The commonly used substance for internal oxygen removal is 
sodium sulphite. This chemical absorbs oxygen to form sodium sulphate. 
The sodium sulphate formed is not scale forming and is beneficial from 
the point of view of embrittlement control, as will be seen later. This chemical, 
if added in the correct manner and in such quantities as to keep a reserve of 
sulphite in the boiler at all times, can completely remove all significant oxygen 
corrosion and, coupled with alkalinity control, should result in the complete 
avoidance of boiler corrosion. Once again, as with scale-forming materials, 
the feeding of oxygen or acids to the boiler should be avoided, as these cause 
increased dosage of chemicals, with consequent higher solids, greater blow-
down and the resultant chemical wastage. 
Caustic Embrittlement—There has been a certain amount of argument as 
to the existence and severity of cracking caused by a caustic environment, 
but it is now generally agreed that caustic embrittlement can only occur 
under the following conditions:— 
(a) The water in the boiler must contain free hydroxide alkalinity. 
(b) The caustic soda must become concentrated to an extent which is 
usually only possible in a joint or seam where evaporative leakage 
can take place. 
(c) The tensional stress in the steel must be high at the point where the 
concentration of caustic soda is occurring. 
There are several ways of ensuring that this cracking does not occur. 
If the phosphate level is high enough in a boiler, all the free hydroxide will be 
reacted with to form the harmless compound tri-sodium phosphate. This 
needs a very fine degree of chemical control, and while most of the alkalinity 
in a boiler will, under correct conditions, be in the form of tri-sodium phos-
phate, inhibitors are usually added to ensure that embrittlement cannot 
THE BOILER STATION 177 
occur . T h r e e c o m m o n inh ib i to r s a re used , s o d i u m su lpha t e , s o d i u m n i t r a t e , 
a n d q u e b r a c h o t a n n i n s . P r o v i d i n g these a re used cor rec t ly t h e inc idence o f 
caus t i c e m b r i t t l e m e n t , which i s r a r e in a n y case, c a n be d i scounted . 
T h e P r o d u c t i o n o f G l e a n S t e a m F r e e f r o m E n t r a i n e d W a t e r o r S o l i d s 
T h e p r e v e n t i o n of p r iming , or ca r ryover , in boilers d e p e n d s u p o n t h r e e 
m a i n f a c t o r s : — 
(a) T h e dissolved solids concen t r a t i on in t h e wa te r . 
(b) T h e presence of foam p roduc ing solids. 
(c) T h e degree a n d sever i ty of load f luctuat ions. 
A boi ler w a t e r con ta in ing a high solids c o n t e n t is m o r e p rone to foam 
t h a n one w i t h a low solids wa te r , a n d to th i s end , t h e solids c o n t e n t of a boi ler 
w a t e r m u s t be k e p t u n d e r cont ro l . Th is i s ach ieved by m e a n s o f b lowdown. 
All feed w a t e r will c o n t a i n some dissolved solids, a n d obvious ly , i f s t e a m free 
from e n t r a i n e d solids i s be ing p roduced , t h e solids will c o n c e n t r a t e in t h e 
boiler wa te r . To c o u n t e r a c t th is , some of t h e boiler w a t e r is b lowndown o u t of 
t h e boiler, a n d r ep laced by low solids feed. T h e a m o u n t of b lowdown neces-
s a r y will t h u s obvious ly d e p e n d u p o n t h e solids c o n t e n t of t he feed w a t e r a n d 
t h e accep t ab l e solids level in t h e boiler. B lowdown should be k e p t to a 
m i n i m u m , as s t ressed before, to avo id chemical losses, a n d therefore t h e solids 
c o n t e n t of t h e feed w a t e r should be k e p t to a m i n i m u m . Y e t a n o t h e r reason 
for t h e use of u n c o n t a m i n a t e d condensa te for feed. 
T h e a l lowable solids level in a boi ler will v a r y w i t h t h e t y p e of boi ler in 
use a n d t h e cond i t ions u n d e r which i t opera tes . T h e newer w a t e r wall boilers 
of h igh h e a t load ing will n o t t o l e ra t e t h e solids level accep tab le in t h e older 
t y p e s o f boiler a n d m u s t be w a t c h e d m o r e carefully, pa r t i cu la r ly u n d e r con-
d i t ions of f luctuat ing load. F l u c t u a t i n g load causes va r i a t ions in h e a t t ransfer 
across t h e boiler hea t ing surface a n d va r i a t i ons in pressure in t h e boiler d r u m . 
A s u d d e n increase in load causes d r u m pressure to d r o p which resu l t s in a 
r a p i d rise in w a t e r level, which , i f severe, can cause considerable p r iming . 
T h e m a i n foam p roduc ing condi t ions a re excessive a lka l in i ty a n d t h e 
presence of oil. Excess ive a lka l in i ty can be avo ided by chemica l con t ro l a n d 
t h e inc idence of oil shou ld be k e p t to a m i n i m u m by e l imina t ing oil c o n t a m i n -
a t i o n of t h e s t e a m as far as possible. Some of t h e oil u n a v o i d a b l y fed to a 
boi ler will be ca r r i ed d o w n wi th t h e a lka l i -phospha te p rec ip i t a t e , b u t oil 
c o n t a m i n a t i o n shou ld be min imized as i t h a s a n o t h e r serious effect. Oil 
globules can a t t a c h themse lves to t h e h e a t i n g surfaces of t h e boiler. I f t h i s 
occurs , t h e h e a t t ransfer res i s tance a t th i s po in t increases m a r k e d l y a n d t h e 
t u b e m a y o v e r h e a t a n d fail. Somet imes an t i - foam chemicals , usua l ly complex 
p o l y a m i d e s o r po lyoxides , a re i n t r o d u c e d i n t o t h e boi ler t o r educe t h e d a n g e r 
of foaming . 
B l o w d o w n f rom a boi ler also serves to r e m o v e t h e alkal i p h o s p h a t e 
p rec ip i t a t e , so t h a t b lowdown p o i n t s a re p laced a t t h e lowest levels i n t h e 
boiler . These p o i n t s a re opened a t in te rva l s , t h e f requency a n d i n t e rva l o f 
open ing d e p e n d i n g u p o n t h e a m o u n t o f b lowdown requ i red . In some of t h e 
m o d e r n boi lers a c o n t i n u o u s b l o w d o w n i s ins ta l led as well, u sua l ly in t h e t o p 
d r u m , to effect c o n t i n u o u s r e m o v a l of some of t h e h igh solids wa te r . 
S a m p l i n g , M e t h o d s o f A n a l y s i s a n d C h e m i c a l D o s a g e 
B . S . 1328 " M e t h o d s o f Sampl ing W a t e r used in I n d u s t r y " covers t h e 
sub jec t of s a m p l i n g fully a n d i t will suffice to s a y t h a t t h e w a t e r in each boi ler 
m u s t be s a m p l e d s e p a r a t e l y a n d t h e sample cooled before collecting. Coil t y p e 
coolers a r e usua l ly used for t h i s pu rpose . T h e s ample i s genera l ly t a k e n from 
THE BOILER STATION 
the boiler shell or from the water gauge. The sampling container should be a 
closed vessel, for accuracy of sulphite results, and it is axiomatic that the 
water from the sampling point should be allowed to run for a sufficient time 
before the sampling commences, to ensure that a representative sample is 
obtained. 
For good control it is recommended that the samples should be analysed, 
at least once a day, for: — 
Alkalinity, 
Phosphate, 
Sulphite, 
Hardness, 
Total Dissolved Solids 
Determination of pH at more frequent intervals can indicate whether any 
abnormal incidence of contamination has occurred. 
If sulphate is used for caustic embrittlement control, the sulphate to 
caustic ratio should be determined periodically. 
The methods of carrying out these analyses and the levels recommended 
in the boiler may vary slightly between treatment systems, but can be 
generally stated as follows:— 
Alkalinity—This is best determined by titration, as this is a more accu-
rate and sensitive method than pH measurement, although pH is useful for 
quick checks on boiler conditions. There are several methods of carrying out 
alkalinity titrations and the limits of alkalinity set out in the treatment being 
used should be adhered to. A minimum alkalinity is required for acidity 
control and for the correct operation of the alkali-phosphate treatment. This 
usually coincides with an alkalinity, to phenolphthalein, of approximately 
150 p.p.m. expressed as CaC03. A maximum alkalinity is obviously set to 
avoid foaming, and this is normally at about 800 p.p.m. of total alkalinity. 
These figures coincide with a pH range of approximately 10.5 to 11.5. 
Phosphate—Once again set limits vary a little but a figure of 50 to 60 
p.p.m. expressed as P 0 4 is normal. Excess phosphate is not harmful except 
in that it adds solids to the water. 
Sodium sulphite—The limits necessary for this compound to act effect-
ively depend upon the reaction time available and whether or not a catalysing 
agent is used. Sodium sulphite takes a definite time to absorb oxygen depend-
ing on the temperature and, if possible, the reaction should have time to 
proceed before the feed enters the boiler. The sulphite is thus best added well 
back in the feed system, but should be added after the system is vented. 
Adding sulphite before venting results in wastage of chemicals, because the 
sulphite will absorb oxygen which would have been removed in any case by 
venting. The rate of reaction can be speeded up by two methods, an increase 
of sulphite concentration and the presence of a catalyst (usually a cobalt salt) 
with the sulphite. The first method has the only objection that the solids 
content of the boiler is increased and more sulphite is lost in blowdown, 
while the catalyst has the drawback that the sulphite must sometimes be 
added and given time to react before the caustic is added, as high alkalinity 
may precipitate certain types of catalyst. With the first method a sulphite 
reserve of 100 to 200 p.p.m. as Na2S03 , is usually kept in the boiler, 
while with the second method a minimum reserve of some 40 p.p.m. is kept. 
The analysis for sulphite is a titration method which is a little more complex 
than an alkalinity determination, and is based on an iodimetric titration using 
starch as an indicator. 
THE BOILER STATION 179 
Hardness—If t h e a lka l in i ty level a n d p h o s p h a t e level a re correct , boi ler 
w a t e r h a r d n e s s will always be zero. A soap m e t h o d is sufficiently a ccu ra t e for 
t h i s d e t e r m i n a t i o n , a n d i t i s m e r e l y used as a double check for p h o s p h a t e 
a n d a lka l in i ty . 
Total Dissolved Solids—This is m o s t conven ien t ly d e t e r m i n e d as a r o u t i n e 
m a t t e r by us ing a special t y p e of h y d r o m e t e r . Th is m e t h o d should be checked 
per iodica l ly by a l a b o r a t o r y m e t h o d involv ing t h e e v a p o r a t i o n of a s a m p l e 
of w a t e r a n d weighing t h e res idue . T h e l imi ts for t o t a l dissolved solids v a r y , 
as s t a t e d before, d e p e n d i n g on t h e t y p e of boiler , t y p e of wa te r , s t ead iness 
of t h e load a n d use of an t i foam. T h e m a n u f a c t u r e r ' s r e c o m m e n d a t i o n s shou ld 
be a d h e r e d to in t h i s case. An t i foams , w h e n used, a re no rma l ly a d d e d in a 
fixed r a t i o to feed w a t e r f low. 
Caustic Embrittlement Control—Where t a n n i n s are used these a re nor -
m a l l y a d d e d wi th , a n d in a fixed p ropor t ion to p h o s p h a t e . N i t r a t e , w h e n 
used, is a d d e d so t h a t t h e r a t i o of n i t r a t e to a lka l in i ty is a ce r ta in m i n i m u m 
figure. T h e s a m e is t r u e of s u l p h a t e . T h e r a t i o of sod ium s u l p h a t e to caus t ic 
soda shou ld be a m i n i m u m of 2 .5 . A n y s u l p h a t e requi red , add i t iona l to t h a t 
p r o d u c e d by t h e ox ida t ion of su lphi te , i s a d d e d as s o d i u m s u l p h a t e . T h e s e 
n i t r a t e a n d s u l p h a t e t e s t s need n o r m a l l y on ly b e d o n e occasional ly a n d 
a r e often ca r r i ed ou t , as a service, by t h e chemica l t r e a t m e n t suppl ier . 
T h e ana lyses r equ i r ed for these d e t e r m i n a t i o n s a re r a t h e r complex in n a t u r e . 
De ta i l s of s imple m e t h o d s of ana lys is for a lka l in i ty , p h o s p h a t e , su lph i t e , 
ha rdnes s , t o t a l dissolved solids, a n d su lpha t e will be found in t h e r e l e v a n t 
c h a p t e r of th i s m a n u a l a n d fur ther in format ion can be found in B .S . 1427 
a n d B .S . 2690. O t h e r su i t ab le l a b o r a t o r y m e t h o d s m a y b e used a t t h e discre-
t ion of t h e ope ra to r . 
Methods of Chemical Dosage—Chemicals can be a d d e d to a boiler con-
t i nuous ly o r in s lug doses . In o rder to m a i n t a i n chemical concen t r a t ion a t an 
even level, c o n t i n u o u s dosing i s used wherever possible. T h u s caus t ic soda , 
s o d i u m su lph i t e a n d an t i foam (where used) a re no rma l ly dosed con t inuous ly . 
I f t h e s o d i u m su lph i t e i s n o t used w i t h acce lera tor all t h r e e chemica l s 
can be m i x e d t o g e t h e r a n d a d d e d con t inuous ly after t h e feed ven t . I f 
acce le ra to r i s used , t h e su lph i t e shou ld be added , by a s epa ra t e dos ing p u m p , 
as ea r ly in t h e s y s t e m as possible, a n d t h e caus t ic a d d e d j u s t before t h e feed 
en t e r s t h e boiler . T h e q u a n t i t i e s a d d e d are ca lcu la ted from t h e analyses of ,the 
w a t e r a n d ba sed on e s t i m a t e d d e m a n d . Sufficient chemicals for t h e n e x t 24 
h o u r s a re u s u a l l y m i x e d in a p r e d e t e r m i n e d q u a n t i t y of wa te r , a n d t h e dosing 
p u m p se t t o de l iver t h i s v o l u m e i n t h e 2 4 h o u r per iod. 
U n f o r t u n a t e l y , p h o s p h a t e c a n n o t be a d d e d con t inuous ly t o t h e feed 
lines, a s u n d e r these c i r cums tances , ca lc ium p h o s p h a t e can be p rec ip i t a t ed 
in t h e feed l ines t h u s g r a d u a l l y b locking t h e m . A h igh pressure s lug dos ing 
p u m p , w i t h individual connections to each boiler, i s no rma l ly u sed to a d d 
p h o s p h a t e accord ing to each boi ler ' s d e m a n d . Th is p u m p i s also conven ien t ly 
u sed to a d d caus t i c o r su lph i t e t o ind iv idua l boilers t o m a i n t a i n ba l anced 
c o n c e n t r a t i o n s b e t w e e n boilers, i f t h e y v a r y d u e to v a r y i n g load or feed 
cond i t ions . S lug dosage once in 24 h o u r s is n o r m a l l y sufficient, b u t i f t h i s is 
n o t so, a pH a n d t o t a l dissolved solids check can be t a k e n once a shift , to 
dec ide w h e t h e r a n y t h i n g a b n o r m a l h a s occurred , a n d fur ther ac t ion t a k e n 
if r equ i red . 
P r o b l e m s o f B o i l e r F e e d T r e a t m e n t P e c u l i a r t o t h e S u g a r I n d u s t r y 
T h e r e a r e ce r t a in p r o b l e m s of boiler feed t r e a t m e n t wh ich a re pecul iar 
t o t h e s u g a r i n d u s t r y . As well a s h a v i n g t o c o n t e n d w i t h t h e usua l con t a -
180 THE BOILER STATION 
minants, such as scale-forming compounds and oxygen, contamination of 
condensates by the material being processed may be caused by leaking heater 
tubes, and other faults. This results in sugar entering the feed water and, 
unfortunately, from the point of view of boiler feed treatment, this is most 
undesirable. Sugar and reducing sugars, under the influence of heat, break 
down in solution to form a series of acidic compounds known collectively as 
saccharic (or sugar) acids. It has been stressed, in the section under corrosion, 
that acid conditions are most corrosive to steel. Sugar contamination to any 
extent can result in very acid conditions in the boiler, and this will cause 
serious corrosion. To counteract the acidity from sugar contamination 
more caustic soda must be added to the boiler, resulting in increased, and 
sometimes dangerously high, solids levels in the boiler. This can cause carry-
over of water and solids. Cases of serious turbine trouble, due to carbon and 
other products building up on the turbine blades, are not unknown. The 
elimination of sugar contamination is therefore most important. To this end 
checks for sugar must be made regularly on the feed water and, if sugar in 
any significant concentration is found, the source must be located by further 
testing. The most serious contamination can be obtained from a split juice 
heater tube, as the juice in the heater is under pressure, and this can lead to 
gross contamination of condensates. Leaking effet and pan tubes can, of 
course, cause serious trouble, but this normally only occurs when the effets 
or pan concerned are shut down. 
Condensate checking can be carried out by various chemical means, 
from the simple, roughly quantitative alpha-naphthol test, to the more 
precise and complex methods. Obviously an instrument to monitor condensate 
contamination continuously, is the ideal answer. Various instruments using 
chemical methods have been developed for this purpose but, as yet, they are 
slow in reaction and rather tedious to maintain. Sugar contamination in a 
raw sugar factory is always in the form of impure solutions which carry other 
materials besides sugar. Many of these impurities are electrolytes, that is, 
they are ionized in solution, and are conductors of electric current. Thus the 
conductivity of a condensate can be a guide to its sugar content. At present 
sizeable contamination can be detected in this way, and the method can be 
used in conjunction with a multipoint conductivity recorder, which can 
monitor every source of boiler feed in rapid succession, and operate automatic 
valves to divert any contaminated condensate away from boiler feed. 
It can therefore be seen that for a sugar mill, the boiler feed should 
consist mainly of hot, un-contaminated exhaust steam condensate. Some 
make-up is always required and the make-up water should ideally be hot, 
to avoid dissolved oxygen, and as free from contamination as possible, to 
avoid scaling problems. The best source of make-up is usually the condensate 
from the steam space of the second effet vessel. This water is hotter and 
usually less contaminated with entrained juice than is water from vessels 
further down the set. At times, cold, raw water must be used as make-up. 
If possible, this should be heated and vented before pumping to the feed 
tank, so that the entry of dissolved oxygen is reduced to a minimum. The use 
of raw water can also be minimized by the provision of a reasonable amount 
of feed storage, as this can tide the boilers over short mill stops. A storage 
capacity approaching an hour's feed supply is desirable, if possible, and raw 
water should only be added once this storage is exhausted. 
If boiler water conditions are maintained correctly, at all times, the 
incidence of corrosion should be negligible, and the cleaning of boiler tubes 
completely avoided. 
CHAPTER XIII 
FIRST AID 
Shock 
Shock occurs with all injuries to a greater or lesser extent and may be 
serious enough to cause death. The symptoms are paleness, moist skin and 
trembling, and an expression of extreme anxiety. Keep the patient warm 
and cover with blankets or coats. The patient should lie flat, preferably with 
a pillow or two under the lower limbs. Lowering the head is usually un-
comfortable and not always essential. Do not move unnecessarily. Do not give 
fluids of any kind by mouth. Remove from danger, check haemorrhage, make 
comfortable. Await ambulance. 
Electric Shock 
Quickly switch off the current or cautiously remove contact from the 
patient with an insulator, e.g., a dry stick or dry towel. Start artificial 
respiration and external cardiac massage immediately (see later). Keep the 
patient warm with blankets and jars of hot water. Do not regard early rigidity 
as a sign for ceasing artificial respiration. It should be maintained for at least 
four hours. 
Heat Exhaustion 
After it is certain that the patient has collapsed due to heat exhaustion, 
plenty of cold water in which a salt tablet has been dissolved may be given, 
provided the patient is not nauseous or vomiting. Removal to hospital is 
imperative. 
Fainting 
The patient should lie flat as indicated under "Shock". Loosen the 
clothing round the patient's neck and see that he gets plenty of fresh air. 
Sprinkle face and chest with cold water. Give stimulants when the patient 
can swallow. 
Burns 
Dry Heat and Scalds—In the treatment of burns the main object is to 
exclude the air as quickly as possible from the injured part. For minor burns 
wash with plenty of soap and water. For such burns on the face and hands 
apply dressings with gauze or lint impregnated with sterile vaseline. On other 
parts of the body burns should be covered with tannic acid jelly. No dressing 
should be applied and cloths must not be replaced until the coagulum is dry. 
For serious burns apply sterile vaseline on gauze and remove to hospital. 
Acid—Wash immediately and thoroughly with cold water and then with 
dilute sodium bicarbonate solution. Apply picrate or boric ointment or 
acriflavine solution. 
Alkali—Wash immediately with large quantities of water then with a 
five per cent solution of acetic acid. Dress with picrate or boric ointment or 
sterile vaseline. 
Prepared in collaboration with the Division of Industrial Medicine, Department of 
Health. 
182 FIRST AID 
Burns in the Eyes—Flush immediately with large quantities of water. 
Irrigation of the eye should be continued for at least ten minutes, and often 
for longer periods after alkali splashes. Cover eye, refer to hospital for further 
treatment. 
Wounds 
Even severe bleeding may be stopped by the application of a very firm 
pressure bandage over the wound. A tourniquet should only be applied if 
it is obvious that the wound is unmanageable. If the wound is on the arm, 
leg, hand or foot and the blood is scarlet, apply the tourniquet four inches 
below the armpit or four inches below the groin. If the blood is dark and 
purplish apply the tourniquet below the wound. A piece of rubber tubing or 
a necktie will make a good tourniquet. NOTE—Under no conditions should 
the tourniquet be held tight for longer than 15 minutes at a time. Loosen it 
and allow blood to flow for a few seconds, then retighten it. Loosen but do 
not remove the tourniquet as soon as the blood clots. 
If the bleeding is copious and the wound is in a position where a tourni-
quet cannot be applied, place a pad of sterile gauze, soaked with acriflavine 
in the wound and apply a bandage. 
For slight cuts, clean the wound with acriflavine solution (1 in 1000) 
and apply a dressing of this material. 
General: All cases must be removed to hospital as soon as possible after 
first aid treatment is carried out. 
Poisoning 
Strong Acids—Mouth and lips may be stained. Do not induce vomiting. 
Give magnesium oxide, milk of magnesia or lime water immediately. Repeat 
at short intervals and wash out the mouth with one of the above materials. 
Do not give carbonates but milk or white of egg should be given. Combat 
collapse by placing patient in reclining position, and applying blankets, hot 
water bottles, etc. 
Alkalies—Mouth and lips may be stained. Do not induce vomiting, but 
give a five per cent solution of acetic acid, or vinegar until the alkali appears 
to be neutralised. Give white of egg or milk and combat collapse. 
Note—Cream or any vegetable oil may be given in each case. 
Carbolic Acid—Give milk or vegetable oil, induce vomiting, repeat oil, 
remove to hospital. 
Cyanide—Speed is essential. 
A doctor should be telephoned immediately and advised that intra-
venous antidotes and the necessary syringes are held by the laboratory 
concerned if such is the case. Unless cyanide accidents are more than a remote 
possibility, it should not be necessary to hold ampoules of the antidotes, but 
the capsules described hereunder are essential. 
If cyanide has been swallowed or if the patient has been poisoned in a 
contaminated atmosphere, observe the following procedure:— 
(1) Remove patient immediately to uncontaminated atmosphere. 
(2) Break capsule of amyl nitrite under the patient's nose every five (5) 
minutes. 
(3) Inject ten ml of sodium nitrite three per cent intravenously, followed 
immediately by 50 ml of sodium thiosulphate 25 per cent. 
FIRST AID 183 
(4) Artificial respiration must be maintained continuously if patient is 
not breathing. 
Phosphorus—Induce vomiting, give four oz of mineral oil, followed by 
saline purge, e.g. Epsom salts. Note—To induce vomiting, give fairly large 
amount of milk, water, coca-cola etc. and push finger far down back of tongue. 
Gases and Fumes 
Corrosive Gases—Carry the patient into fresh air and apply artificial 
respiration if necessary. Combat collapse. Give oxygen if available. 
Carbon Monoxide, Hydrogen Sulphide and Nitrous Fumes—Remove the 
patient to fresh air. Apply artificial respiration and give oxygen. Combat 
collapse. 
Artificial Respiration 
Artificial respiration may be applied in any circumstances where the 
patient has ceased to breathe, e.g., drowning, electrocution, cyanide poison-
ing, gassing or other causes. 
Mouth-to-mouth resuscitation is the most effective method and may be 
applied as follows:— 
Place patient on his back and rapidly clear obstructions in the mouth. 
Stretch the neck by tilting the head back as far as possible. 
Hold the head back at all times. 
Pinch nostrils closed with thumb and fore-finger of one hand and keep 
the jaw open and the chin up with the other hand. 
Take a deep breath, open your mouth wide, and seal your lips around 
the patient's mouth. 
Blow air into the patient and watch to see that his chest rises. 
If this does not happen, tilt the head further and lift the chin up again. 
If the chest rises, remove your mouth and the patient's chest will collapse. 
Continue inflation in this way at least ten to 12 times a minute. 
External Cardiac Massage 
If the patient is unconscious, not breathing and apparently pulseless, 
immediately initiate both mouth-to-mouth resuscitation as above, and car-
diac (heart) massage. Place patient face up. Get someone else to proceed with 
mouth-to-mouth resuscitation. Kneel beside patient. Apply palm of one hand 
over the bottom of the chest plate (breast bone). Bring palm of the other hand 
on top of the first. Now bring your weight rhythmically down at about a rate 
of 50 to 60 times a minute. Continue for 20 minutes. 
Foreign Body in the Eye 
If possible remove with corner of a clean handkerchief, but use great 
care; if not, wash out with boracic lotion. Apply a pad and bandage firmly 
to prevent movement of the eyelid. If the surface of the eyeball is injured 
use only irrigation and send for a doctor. 
Alternate treatment—Apply eyedrops of albucid soluble ten per cent in 
water (sodium sulphacetamide) by pulling forward lower lid and using a small 
rubber sponge. Remove foreign body with the sponge if possible. If this fails 
apply a pad and bandage as before and send for expert treatment. If the 
surface of the eyeball is injured apply the albucid drops, the pad and bandage, 
and send for a doctor. 
REFERENCE TABLES 
Table No. TITLE Page 
I Temperature Corrections to Readings of Brix Hydrometers (Cali-
brated at 20 °C.) 186 
II Schmitz's Table for Sucrose (Pol) in Juice for Use in the Dry Lead 
Method with Undiluted Solutions. Normal Weight of 26.000 g. 188 
I I I Pol Bagasse from Polariscope Reading (400 mm Tube) and Moisture 
Content. (Ratio of water to bagasse =10:1). (Clarified with dry lead). 193 
IV Milligrammes of Reducing Sugars Required to Reduce 10 ml Feh-
ling's Solution (Lane and Eynon Method). 195 
V Milligrammes of Reducing Sugars Required to Reduce 10 m 
Fehling's Solution (Lane and Eynon Method) at Low Sucrose 
Concentrations. To be Used with the Chemical Method of Sucrose 
Analysis. 196 
VI Specific Rotation of Sugars. 197 
VII Refractive Indices of Sugar Solutions at 20 °C in Air at 20 °C, 
760 mm Pressure and 50 per cent Relative Humidity. 198 
VIII International Table of Temperature Corrections for the Abbe Re-
fractometer Calibrated at 20 °C. 199 
IX Clerget Divisors. 200 
X Subtractive Temperature Corrections for Clerget Divisors. 200 
XI Dilution Indicator of Raw Sugar. 201 
X I I Solubility of Sucrose in Water in g Sucrose (S) per 100 g Water 
According to Charles, Amer. Chem. Soc, 1958 Abst. of Papers 
p. 100. Reported in Honig "Principles of Sugar Technology", 2, 228. 201 
XI I I Solubility of Sucrose in Water in g Sucrose (S) per 100 g Solution 202 
(Charles). 
XIV Densities of Solutions of Cane Sugar at 20 °C in g/ml. (This table 
is the basis for standardizing hydrometers indicating per cent of 
sugar at 20 °C). 203 
XV Brix, Apparent Density, Apparent Specific Gravity, and Grammes 
of Sucrose per 100 ml of Sugar Solutions. (NBS—C440, 1942, p. 632). 206 
XVI Weight per Unit Volume of Sugar Solutions at 20 °C. 216 
XVII Degree of Supersaturation—All Values Being Prefixed by 1. 217 
XVIII Crystal Content of Massecuites. 218 
XIX (a) Stock Recovery. 219 
X I X (b) Stock Recovery. 220 
X I X (c) Stock Recovery. 221 
XX Factors to be Used in Calculating Weight per Gallon of Molasses. 222 
X X I Weights as Decimals of Ton. 222 
X X I I Density (g/ml) of Water at Temperatures from 0 to 102 °C. Ac-
cording to M. Thiesen, Wiss. Abh. der Physikalisch-Technischen 
Reichsanstalt, 4, No. 1; 1904. 223 
X X I I I Corrections for Temperature (in g) to Be Added to Weight of Water 
Contained to Obtain Volume (in ml) of Vessel at 20 °C. Nominal 
Capacity 1,000 ml. (For vessels made of soda glass). 224 
REFERENCE TABLES 
Table No. 
XXIV 
XXV 
XXVI 
XXVII 
XXVIII 
X X I X 
X X X 
X X X I 
X X X I I 
X X X I I I 
XXXIV 
XXXV 
XXXVI 
XXXVII 
XXXVII I 
Corrections for Atmospheric Pressure (in g) to Be Added to or Sub-
tracted from the Weight of Water Contained to Obtain Volume 
(in ml) of Vessel at Standard Temperature and Pressure. 225 
Requirements for Apparatus for Use in the Analysis of Cane for 
Payment Purposes. 226 
Properties of Saturated Steam. 229 
Temperature Conversion Table. 231 
Equivalents 
Volume and Capacity Equivalents. 
Mass Equivalents. 
Density Equivalents. 
Linear Measure Equivalents. 
Surface and Area Equivalents. 
Pressure Equivalents. 
Heat, Energy and Work Equivalents. 
Heat Flow Equivalents. 232 
Mensuration of Surfaces and Solids. 234 
Circles: Diameters, Areas, Circumferences. 235 
Capacities of Vertical Cylindrical Tanks (UK gal). 235 
Capacities of Rectangular Tanks (UK gal) for Each Foot of Depth. 236 
Capacity of Horizontal Cylindrical Tanks at Varying Levels. 237 
i = depth of liquid, 
d = diameter of vessel. 
Amount of CaO in Milk of Lime of Various Densities at 15 °C. 237 
Fuel Value of Bagasse. 238 
Boiling Point Elevation of Sugar Solutions and Cane Juices (°F) at 
760 mm Pressure. 239 
Table for Rapid Filterability Test. 240 
International Atomic Weights, 1966 (Published by the C.R.C. 
Handbook of Chemistry and Physics). 242 
' 
0 
5 
0 
1 
12 
13 
14 
15 
16 
17 
18 
19 
50 
21 
22 
23 
24 
25 
26 
27 
28 
29 
JO 
M 
12 
J3 
\4 
\5 
0 
0.30 
0.36 
0.32 
0.31 
0.29 
0.26 
0.24 
0.20 
0.17 
0.13 
0.09 
0.05 
0.04 
0.10 
0.16 
0.21 
0.27 
0.33 
0.40 
0.46 
0.54 
0.61 
0.69 
0.76 
0.84 
0.91 
0.99 
5 
0.49 
0.47 
0.38 
0.35 
0.32 
0.29 
0.26 
0.22 
0.18 
0.14 
0.10 
0.05 
0.05 
0.10 
0.16 
0.22 
0.28 
0.34 
0.41 
0.47 
0.55 
0.62 
0.70 
0.78 
0.85 
0.93 
1.01 
10 
0.65 
0.56 
0.43 
0.40 
0.36 
0.32 
0.29 
0.24 
0.20 
0.15 
0.10 
0.05 
0.06 
0.11 
0.17 
0.23 
0.30 
0.36 
0.42 
0.49 
0.56 
0.63 
0.71 
0.79 
0.87 
0.95 
1.02 
15 20 
0.77 0.89 
0.65 0.73 
0.48 0.52 
0.44 0.48 
0.40 0.43 
0.35 0.38 
0.31 0.34 
0.26 0.28 
0.22 0.23 
0.16 0.18 
0.11 0.12 
0.06 0.06 
0.06 0.06 
0.12 0.12 
0.17 0.19 
0.24 0.26 
0.31 0.32 
0.37 0.40 
0.44 0.46 
0.51 0.54 
0.59 0.61 
0.66 0.68 
0.74 0.76 
0.82 0.85 
0.90 0.93 
0.98 1.02 
1.06 1.10 
25 
0.99 
0.80 
0.57 
0.51 
0.46 
0.41 
0.36 
0.30 
0.25 
0.19 
0.13 
0.06 
0.07 
0.13 
0.20 
0.27 
0.34 
0.40 
0.48 
0.56 
0.63 
0.70 
0.79 
0.87 
0.96 
1.04 
1.13 
30 35 40 45 
Subtract from observed per 
1.08 
0.86 
0.60 
0.55 
0.50 
0.44 
0.38 
0.32 
0.26 
0.20 
0.13 
0.07 
1.16 
0.91 
0.64 
0.58 
0.52 
0.46 
0.40 
0.33 
0.27 
0.20 
0.14 
0.07 
1.24 
0.97 
0.67 
0.60 
0.54 
0.48 
0.41 
0.34 
0.28 
0.21 
0.14 
0.07 
Add to observed 
0.07 
0.14 
0.21 
0.28 
0.35 
0.42 
0.50 
0.58 
0.66 
0.73 
0.82 
0.90 
0.99 
1.07 
1.16 
0.07 
0.14 
0.21 
0.29 
0.36 
0.44 
0.52 
0.60 
0.68 
0.76 
0.84 
0.93 
1.01 
1.10 
1.18 
0.07 
0.14 
0.22 
0.30 
0.38 
0.46 
0.54 
0.61 
0.70 
0.78 
0.86 
0.95 
1.03 
1.12 
1.20 
1.31 
1.01 
0.70 
0.63 
0.56 
0.49 
0.42 
0.36 
0.28 
0.21 
0.14 
0.07 
50 
cent. 
1.37 
1.05 
0.72 
0.65 
0.58 
0.51 
0.44 
0.36 
0.29 
0.22 
0.15 
0.08 
per cent. 
0.08 
0.15 
0.23 
0.31 
0.38 
0.47 
0.54 
0.62 
0.70 
0.78 
0.87 
0.95 
1.04 
1.12 
1.21 
0.08 
0.16 
0.24 
0.32 
0.39 
0.47 
0.55 
0.63 
0.71 
0.79 
0.88 
0.96 
1.05 
1.13 
1.22 
55 
1.41 
1.08 
0.74 
0.66 
0.59 
0.52 
0.45 
0.37 
0.30 
0.23 
0.15 
0.08 
0.08 
0.16 
0.24 
0.32 
0.39 
0.48 
0.56 
0.64 
0.72 
0.80 
0.88 
0.97 
1.05 
1.14 
1.22 
60 
1.44 
1.10 
0.75 
0.68 
0.60 
0.53 
0.46 
0.38 
0.31 
0.23 
0.15 
0.08 
0.08 
0.16 
0.24 
0.32 
0.40 
0.48 
0.56 
0.64 
0.72 
0.80 
0.89 
0.97 
1.06 
1.14 
1.23 
65 
1.47 
1.12 
0.76 
0.69 
0.61 
0.54 
0.46 
0.38 
0.31 
0.24 
0.16 
0.08 
0.08 
0.16 
0.24 
0.32 
0.40 
0.48 
0.56 
0.64 
0.72 
0.80 
0.89 
0.97 
1.06 
1.14 
1.23 
70 
1.49 
1.14 
0.77 
0.70 
0.62 
0.55 
0.47 
0.39 
0.32 
0.24 
0.16 
0.08 
0.09 
0.16 
0.24 
0.32 
0.39 
0.48 
0.56 
0.64 
0.72 
0.81 
0.89 
0.97 
1.06 
1.14 
1.22 
75 
1.50 
1.16 
0.78 
0.71 
0.63 
0.56 
0.47 
0.39 
0.32 
0.25 
0.16 
0.09 
0.09 
0.17 
0.25 
0.33 
0.39 
0.49 
0.57 
0.65 
0.73 
0.81 
0.89 
0.97 
1.06 
1.14 
1.22 
80 
1.50 
1.17 
0.79 
0.72 
0.64 
0.56 
0.48 
0.40 
0.33 
0.25 
0.16 
0.09 
0.09 
0.17 
0.25 
0.33 
0.39 
0.49 
0.57 
0.65 
0.73 
0.81 
0.89 
0.97 
1.06 
1.14 
1.22 
85 
1.51 
1.18 
0.80 
0.73 
0.64 
0.57 
0.48 
0.40 
0.33 
0.25 
0.17 
0.09 
0.09 
0.17 
0.25 
0.33 
0.38 
0.48 
0.56 
0.64 
0.72 
0.81 
0.89 
0.97 
1.06 
1.14 
1.22 
90 
1.51 
1.19 
0.81 
0.74 
0.65 
0.57 
0.48 
0.41 
0.34 
0.26 
0.17 
0.09 
0.09 
0.17 
0.25 
0.33 
0.38 
0.48 
0.56 
0.64 
0.72 
0.81 
0.89 
0.97 
1.05 
1.13 
1.21 
Table I—Temperature Corrections to Readings of Brix Hydrometers (Calibrated at 20 °C) £ 
Temperature °C Observed per cent of sugar 
Table I—continued. 
Tmperature 
°C 
p 
0 
1.07 
1.15 
1.24 
1.33 
1.42 
1.51 
1.61 
1.71 
1.81 
1.91 
2.01 
2.12 
2.23 
2.35 
2.46 
2.58 
2.70 
2.81 
2.93 
3.05 
3.18 
3.31 
3.43 
3.56 
3v69 
5 
1.09 
1.17 
1.26 
1.35 
1.45 
1.54 
1.64 
1.74 
1.84 
1.94 
2.05 
2.16 
2.26 
2.37 
2.48 
2.60 
2.72 
2.83 
2.95 
3.07 
3.20 
3.33 
! 3.46 
! 3.59 
3.72 
10 
1.12 
1.21 
1.29 
1.38 
1.47 
1.56 
1.66 
1.76 
1.86 
1.96 
2.07 
2.18 
2.28 
2.39 
2.50 
2.62 
2.74 
2.85 
2.97 
3.09 
3.22 
3.35 
3.47 
3.60 
3.73 
15 
1.15 
1.24 
1.33 
1.42 
1.51 
1.60 
1.70 
1.80 
1.90 
2.00 
2.11 
2.21 
2.32 
2.42 
2.53 
2.64 
2.76 
2.87 
2.99 
3.12 
3.23 
3.35 
3.48 
3.60 
3.73 
20 
1.19 
1.28 
1.36 
1.45 
1.54 
1.63 
1.73 
1.83 
1.93 
2.03 
2.14 
2.24 
2.35 
2.45 
2.56 
2.67 
2.78 
2.90 
3.01 
3.12 
3.24 
3.36 
3.48 
3.60 
3.72 
25 
1.22 
1.31 
1.39 
1.48 
1.57 
1.67 
1.76 
1.86 
1.95 
2.05 
2.15 
2.26 
2.36 
2.47 
2.57 
2.68 
2.79 
2.90 
3.01 
3.12 
3.24 
3.35 
3.47 
3.58 
3.70 
Observed 
30 35 
per cent of sugar 
40 
Add to observed 
1.25 
1.34 
1.42 
1.51 
1.62 
1.69 
1.79 
1.88 
1.98 
2.07 
2.17 
2.27 
2.38 
2.48 
2.58 
2.69 
2.80 
2.90 
3.01 
3.12 
3.23 
3.34 
3.45 
3.56 
3.67 
1.27 
1.36 
1.44 
1.53 
1.62 
1.71 
1.81 
1.90 
2.00 
2.09 
2.19 
2.29 
2.39 
2.49 
2.59 
2.69 
2.80 
2.90 
3.01 
3.11 
3.22 
3.33 
3.43 
3.54 
3.65 
1.29 
1.38 
1.46 
1.55 
1.64 
1.73 
1.82 
1.92 
2.01 
2.10 
2.20 
2.30 
2.39 
2.49 
2.59 
2.69 
2.79 
2.90 
3.00 
3.10 
3.20 
3.31 
3.41 
3.52 
3.62 
45 50 
per cent. 
1.30 
1.39 
1.47 
1.56 
1.65 
1.74 
1.83 
1.92 
2.01 
2.10 
2.20 
2.29 
2.39 
2.48 
2.58 
2.68 
2.78 
2.88 
2.98 
3.08 
3.18 
3.29 
3.39 
3.50 
3.60 
1.31 
1.39 
1.48 
1.56 
1.65 
1.74 
1.83 
1.92 
2.01 
2.10 
2.20 
2.29 
2.39 
2.48 
2.58 
2.68 
2.78 
2.87 
2.97 
3.07 
3.17 
3.27 
3.37 
3.47 
3.57 
55 
1.31 
1.39 
1.48 
1.56 
1.65 
1.74 
1.83 
1.92 
2.01 
2.10 
2.19 
2.29 
2.39 
2.48 
2.57 
2.67 
2.76 
2.86 
2.95 
3.05 
3.15 
3.25 
3.34 
3.44 
3.54 
60 
1.32 
1.40 
1.49 
1.57 
1.66 
1.75 
1.84 
1.92 
2.01 
2.10 
2.19 
2.28 
2.38 
2.47 
2.56 
2.65 
2.75 
2.84 
2.94 
3.03 
3.12 
3.22 
3.31 
3.41 
3.50 
65 
1.32 
1.40 
1.49 
1.57 
1.66 
1.75 
1.83 
1.92 
2.00 
2.09 
2.18 
2.27 
2.36 
2.45 
2.54 
2.63 
2.72 
2.82 
2.91 
3.00 
3.09 
3.19 
3.28 
3.38 
3.47 
70 
1.31 
1.39 
1.48 
1.56 
1.65 
1.74 
1.82 
1.91 
1.99 
2.08 
2.17 
2.26 
2.34 
2.43 
2.52 
2.61 
2.70 
2.79 
2.88 
2.97 
3.06 
3.15 
3.25 
3.34 
3.43 
75 
1.31 
1.39 
1.48 
1.56 
1.65 
1.73 
1.82 
1.90 
1.99 
2.07 
2.16 
2.24 
2.33 
2.41 
2.50 
2.59 
2.68 
2.76 
2.85 
2.94 
3.03 
3.12 
3.21 
3.30 
3.39 
80 
1.30 
1.39 
1.47 
1.56 
1.64 
1.72 
1.81 
1.89 
1.98 
2.06 
2.14 
2.23 
2.31 
2.40 
2.48 
2.57 
2.65 
2.74 
2.82 
2.91 
3.00 
3.09 
3.17 
3.26 
3.35 
85 
1.30 
1.39 
1.47 
1.56 
1.64 
1.72 
1.80 
1.89 
1.97 
2.05 
2.13 
2.21 
2.30 
2.38 
2.46 
2.54 
2.63 
2.71 
2.80 
2.88 
2.97 
3.05 
3.14 
3.22 
3.31 
90 
1.29 
1.38 
1.46 
1.55 
1.63 
1.71 
1.79 
1.88 
1.96 
2.04 
2.12 
2.20 
2.28 
2.36 
2.44 
2.52 
2.60 
2.69 
2.77 
2.85 
2.93 
3.02 
3.10 
3.19 
3.27 
This table is calculated using the data on thermal expansion of sugar solutions by Plato assuming the instrument to be of Jena 16111 glass. 
The table should be used with caution and only for approximate results when the temperature differs much from the standard temperature or 
from the temperature of the surrounding air. 
Table H—Schmitz's Table for Sucrose (Pol) in Juice for Use in the Dry Lead Method with Undiluted Solutions. 
Normal Weight of 26.000 g. 
Polariscope 
reading 
-2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
26 
29 
30 
31 
32 33 
34 
35 
36 
37 
38 
39 
40 
1 0 
0-26 
0-52 
0-78 
104 
1-30 
1 5 
0-26 
0-52 
0-78 
1-04 
130 
1-56 
1-82 
Tenths of the 
polariscope 
reading 
0-1 
0-2 
0-3 
0-4 
0-5 
2 0 
026 
0-52 
0-78 
1-04 
1-29 
1-55 
1-81 
2-07 
2 5 
026 
0-52 
0-78 
1 0 3 
129 
1-55 
1-81 
207 
2-33 
3 0 
0-26 
0-62 
0-77 
103 
1-29 
1-55 
1-81 
2-06 
2-32 
258 
2-84 
3 5 
0-26 
0-51 
0-77 
1-03 
1-29 
1-54 
1-80 
2-06 
232 
2-57 
2-83 
3-09 
3-35 
BRixl-OtolOO 
Per cent 
sucrose 
0-02 
0-05 
0-07 
0-10 
0-13 1 
Tenths of the 
polariscope 
reading 
0-6 
0-7 
0-8 
0-9 
4 0 
0-26 
0-51 
0-77 
103 
1-28 
1-54 
1-80 
2-06 
2-31 
2-57 
2-83 
3 0 8 
3-34 
3-60 
3-85 
4 5 
0-26 
0-51 
0-77 
1 0 3 
1-28 
1-54 
1-80 
2-05 
2-31 
2-56 
2-82 
308 
3-33 
3-59 
3-85 
4-10 
4-36 
Per cent 
sucrose 
0-15 
0-18 
0-20 
0-23 
Degrees Brix 
5 0 
026 
051 
0-77 
102 
1-28 
1-54 
1-70 
205 
2-30 
2-56 
2-82 
3>07 
333 
3-58 
3-84 
410 
4-35 
4-61 
4-86 
5 5 
0'26 
0-51 
0-77 
102 
1-28 
1-53 
1-79 
2-04 
2-30 
2-55 
2-81 
3-07 
3-32 
3-58 
3-83 
4-09 
4-34 
460 
4-85 
511 
5-36 
6 0 
0-25 
0-51 
0-76 
102 
1-27 
1-53 
1-78 
204 
2-29 
2-55 
2-80 
306 
3-31 
3-57 
3-82 
4-08 
4-33 
4-59 
4-84 
5-10 
5-35 
5-61 
5-86 
6 5 
0-25 
0-51 
0-76 
102 
1-27 
1-53 
1-78 
2 04 
2-29 
2-54 
2-80 
305 
331 
3-56 
3-82 
4-07 
433 
4-58 
4'83 
5-09 
534 
5-60 
5-85 
611 
6-36 
7 0 
0-25 
0-51 
0-76 
1-02 
1-27 
1-52 
1-78 
2 0 3 
2-29 
2-54 
2-80 
3 05 
3-30 
3'56 
3-81 
406 
4-32 
4-57 
4-82 
508 
5-33 
5-59 
5-84 
6 09 
6-35 
6-60 
6-86 
7-5 
0-25 
0-51 
076 
1-01 
1-27 
1-52 
1-77 
203 
2-28 
253 
2-79 
3-04 
3-29 
3-55 
3-80 
4-06 
4-31 
4-56 
4-82 
5-07 
5-32 
5-58 
5-83 
6-08 
634 
6-59 
6-84 
7-10 
7-35 
8 0 
025 
0-51 
0-76 
1-01 
1-26 
1-52 
1-77 
202 
2-28 
2-53 
2-78 
304 
329 
3-54 
3-79 
4-05 
4-30 
4-55 
4-81 
5-06 
5-31 
5-56 
5-82 
6-07 
6-32 
6-58 
6-83 
7-08 
7-34 
7-59 
7-84 
8-5 
0-25 
0-50 
0-76 
1-01 
1-26 
1-51 
1-77 
2 02 
2-27 
2-52 
2-78 
303 
3-28 
3-53 
3-79 
4'04 
4-29 
4-54 
4-80 
5-05 
5-30 
5-55 
5-81 
6 06 
6-31 
656 
6-82 
707 
7-32 
7-57 
7-83 
8-08 8-33 
9 0 
0-25 
0-60 
0-76 
1-01 
1-26 
1-51 
1-76 
2-02 
2-27 
2-52 
2-77 
302 
3-28 
353 
3-78 
403 
4-28 
4-54 
4-79 
5-04 
5-29 
554 
5-79 
605 
6-30 
6-55 
6-80 
7-05 
7-31 
7-56 
7-81 
8-06 8-31 
8-57 
8-82 
9 5 
0 2 5 
0-50 
0-75 
101 
1-26 
151 
1-76 
2-01 
226 
2-51 
2-77 
3 02 
3-27 
3-52 
3-77 
4-02 
4-27 
4-53 
4-78 
5-03 
5-28 
5-53 
5-78 
6 03 
6-29 
6-54 
6-79 
7-04 
7-29 
7-54 
7-79 
8 05 8-30 
8-55 
8-80 
9-05 
9-30 
10 0 
0-25 
0-50 
0-75 
1-00 
1-25 
1-51 
1-76 
201 
2-26 
2-51 
2-76 
3-01 
3-26 
3-51 
3-76 
4-02 
4-27 
4-52 
4-77 
5-02 
527 
5-52 
5-77 
6-02 
627 
6-52 
6-78 
7-03 
7-28 
7-53 
7-78 
8 0 3 8-28 
8-63 
8-78 
9 03 
9-29 
9-54 
9-79 
10 5 
0-25 
0-50 
0-75 
1-00 
1-25 
1-50 
1-75 
2 00 
2-25 
2-50 
275 
301 
3-26 
351 
3-76 
401 
4-26 
4-51 
4-76 
5-01 
5-26 
5-51 
5-76 
601 
6-26 
6-51 
6-76 
7-01 
7-26 
7-51 
7-76 
801 8-26 
8-52 
8-77 
902 
9-27 
9-52 
9-77 
10-02 
11 0 
0-25 
0-50 
0-75 
100 
1-25 
150 
1-75 
2-00 
2-25 
2-50 
2-75 
300 
3-25 
3-50 
3-75 
400 
4-25 
4-50 
4-75 
500 
5-25 
5-50 
5-75 
6-00 
6-25 
6-50 
6-76 
700 
7-25 
7-50 
7-75 
8-00 8-25 
8-50 
8-75 
9 0 0 
9-25 
950 
9-75 
10-00 
Polariscope 
reading 
_ 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
Polariscope 1 
readmg 
1 
2 
3 4 
5 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
11-5 1 
0-25 
0-50 
0-75 
1-00 
1-25 
1-50 
1-75 
2-00 
2-24 
2-49 
2-74 
2-99 
3-24 
3-49 
3-74 
3-99 
4-24 
4-49 
474 
499 
5-24 
5-49 
5-74 
6-99 
6-24 
6-49 
6-74 
6-98 
7-23 
7-48 
7-73 
7-98 
8-23 
8-48 
8-73 
8-98 
9-23 
9-48 
9-78 
1 9-98 
12-0 1 
0-25 
0-50 
0-75 
1-00 
1-24 
1-49 
1-74 
1-99 1 
2-24 
2-49 
2-74 
2-99 
3-24 
3-49 
3-73 
3-98 
4-23 
4-48 
4-73 
1 4-98 
5-23 
5-48 
5-73 
5-97 
6-22 
6-47 
6-72 
6-97 
7-22 
7-47 
7-72 
7-97 
8-22 
8-46 
8-71 
8-96 
9-21 
9-46 
9-71 
1 9-96 
12-5 1 
0-25 
0-50 
0-74 
0-99 
1-24 
1-49 
1-74 
1-99 
2-24 
2-48 
2-73 
2-98 
3-23 
3-48 
3-73 
398 
4-22 
4-47 
4-72 
4-97 
5-22 
5-47 
5-71 
5-96 
6-21 
646 
6-71 
6-96 
7-21 
7-45 
7-70 
7-95 
8-20 
8-45 
8-70 
8-94 
919 
9-44 
9-69 
1 9-94 
13-0 
0-25 
0-50 
0-74 
0-99 
1-24 
1-49 
1-74 
1-98 
2-23 
2-48 
2-73 
2-98 
3-22 
3-47 
3-72 
3-97 
4-22 
4-46 
4-71 
4-96 
5-21 
5-45 
5-70 
5-95 
6-20 
6-45 
669 
6-94 
7-19 
7-44 
7-69 
7-93 
8-18 
8-43 
8-93 
9-17 
9-42 
9-67 
0-92 
13-5 
0-25 
0-49 
0-74 
0-99 
1-24 
1-48 
1-73 
1-98 
2-23 
2-47 
2-72 
2-97 
3-22 
3-46 
3-71 
3-96 
4-21 
4-45 
4-70 
4-95 
5-20 
5-44 
5-69 
5-94 
6-19 
6-43 
6-68 
6-93 
7-18 
7-42 
7-67 
7-92 
8-17 
8-41 
8-66 
8-91 
9-16 
9-40 
9-65 
9-90 
14-0 
0-25 
0-49 
0-74 
0-99 
1-23 
1-48 
1-73 
1-98 
2-22 
2-47 
2-72 
2-96 
3-21 
3-46 
3-70 
3-95 
420 
4-45 
4-69 
4-94 
5-19 
6-43 
5-93 
6-17 
6-42 
6-67 
6-91 
7-16 
7-41 
7-66 
7-90 
8-15 
8-40 
6-64 
8-89 
9-14 
9-38 
9-63 
9-88 
145 
0-25 
049 
0-74 
0-99 
1-23 
1-48 
1-73 
1-97 
2-22 
2-46 
2-71 
2-96 
3-20 
3-45 
3-70 
3-94 
4-19 
4-44 
4-68 
4-93 
5-18 
5-42 
5-67 
5-92 
6-16 
6-41 
6-65 
6-90 
7-15 
7-39 
7-64 
7-89 
8-13 
8-38 
8-63 
8-87 
912 
9-37 
9-61 
9-86 
Degr 
15 0 
0:74 
0-98 
1-23 
1-48 
1-72 
1-97 
2-21 
2-46 
2-71 
2-95 
3-20 
3-44 
3-69 
3-94 
4-18 
4-43 
4-67 
4-92 
5-17 
5-41 
5-66 
5-90 
6-15 
6-39 
6-64 
6-89 
7-13 
7-38 
7-62 
7-87 
8-12 
8-36 
8-61 
8-85 
9-10 
9-35 
959 
I 9-84 
ees Brix 
15-5 
0:98 
1-23 
1-47 
1-72 
1-96 
2-20 
2-45 
2-70 
2-95 
319 
3-44 
3-68 
3-93 
417 
4-42 
4-66 
4-91 
5-15 
5-40 
565 
5-89 
614 
6-63 
6-87 
7-12 
7-36 
7-61 
7-85 
8-10 
8-35 
8-59 
8-84 
908 
9-33 
9-57 
I 9-82 
16 0 
1-47 
1-71 
1-96 
2-20 
2-45 
2-69 
2-94 
3-18 
3-43 
3-67 
3-92 
416 
4-41 
4-65 
4-90 
5-14 
5-39 
5-63 
5-88 
612 
6-37 
6-61 
6-86 
7-10 
7-35 
7-59 
7-84 
8-08 
8-33 
8-57 
8-82 
906 
9-31 
9-55 
9-80 
16 5 
1-96 
2-20 
2-44 
2-69 
2-93 
318 
3-42 
3-67 
3-91 
4-16 
4-40 
4-64 
4-89 
5 1 3 
5-38 
5-62 
5-87 
6 1 1 
6-36 
6-60 
6-85 
7-09 
7-33 
7-58 
7-82 
8-07 
8-31 
8-56 
8-80 
9 05 
9-29 
9-53 
9-78 
17 0 
2-44 
2-93 
317 
3-42 
3-66 
3-90 
415 
4-39 
4-64 
4-88 
512 
5-37 
5-61 
5-86 
610 
6-34 
6-59 
6-83 
7-08 
7-32 
7-56 
7-81 
8-05 
8-30 
8-54 
8-78 
903 
9-27 
9-51 
9-76 
17-5 
2:92 
317 
3-41 
3-65 
3-90 
414 
4-38 
4-63 
4-87 
511 
5-36 
5-60 
5-84 
6-09 
6-33 
6-57 
6-82 
706 
7-30 
7-55 
7-79 
8-03 
8-28 
8-52 
8-77 
901 
9-25 
9-50 
9-74 
18 0 
3-40 
3-64 
3-89 
413 
4-37 
4-62 
4-86 
510 
5-35 
5-59 
5-83 
6-07 
6-32 
6-56 
6-80 
7 05 
7-29 
7-53 
7-78 
8-02 
8-26 
8-50 
8-75 
8-99 
9-23 
9-48 
9-72 
18 5 
3-88 
412 
4-36 
4-61 
4-85 
5 09 
5-33 
5-58 
5-82 
606 
6-30 
6-55 
6-79 
7-03 
7-27 
7-52 
7-76 
8-00 
8-24 
8-49 
8-73 
8-97 
9-21 
9-46 
9-70 
190 
4-'36 
4-60 
4-84 
508 
5-32 
5-57 
5-81 
605 
6-29 
6-53 
6-78 
7-02 
7-26 
7-50 
7-74 
7-99 
8-23 
8-47 
8-71 
8-95 
9-20 
9-44 
9-68 
19 5 
4-83 
507 
5-31 
5-55 
5-80 
604 
6-28 
6-52 
6-76 
7-00 
7-24 
7-49 
7-73 
7-97 
8-21 
8-45 
8-69 
8-94 
918 
9-42 
9-66 
20 0 
5-30 
6-54 
5-78 
6-02 
6-27 
6-51 
6-75 
6-99 
7-23 
7-47 
7-71 
7-95 
819 
8-43 
8-68 
8-92 
916 
9-40 
9-64 
Polariscope 
reading 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
Table II—continued. 
Table II—continued. 
REFERENCE TABLES 191 
Table II—continued. 
REFERENCE TABLES 
Table IIA—Table of Factors for the Calculation of Pol Per Cent Juice from Pol 
Reading for Use in the Dry Lead Method with Undiluted Solutions 
Pol per cent juice = Pol Reading Pol Factor 
Degrees 
Brix 
0.5 
1.0 
1.5 
2.0 
2.5 
3.0 
3.5 
4.0 
4.5 
5.0 
5.5 
6.0 
6.5 
7.0 
7.5 
8.0 
8.5 
9.0 
9.5 
10.0 
10.5 
11.0 
11.5 
12.0 
12.5 
13.0 
13.5 
14.0 
14.5 
15.0 
15.5 
16.0 
Factor 
3.84273 
3.85023 
3.85769 
3.86519 
3.87273 
3.88027 
3.88785 
3.89546 
3.90308 
3.91077 
3.91842 
3.92615 
3.93388 
3.94165 
3.94942 
3.95723 
3.96512 
3.97296 
3.98088 
3.98881 
3.99677 
4.00473 
4.01277 
4.02081 
4.02885 
4.03696 
4.04508 
4.05327 
4.06146 
4.06965 
4.07792 
4.08619 
Degrees 
Brix 
16.5 
17.0 
17.5 
18.0 
18.5 
19.0 
19.5 
20.0 
20.5 
21.0 
21.5 
22.0 
22.5 
23.0 
23.5 
24.0 
24.5 
25.0 
25.5 
26.0 
26.5 
27.0 
27.5 
28.0 
28.5 
29.0 
29.5 
30.0 
30.5 
31.0 
31.5 
32.0 
Factor 
4.09450 
4.10285 
4.11119 
4.11962 
4.12804 
4.13650 
4.14496 
4.15350 
4.16204 
4.17062 
4.17923 
4.18788 
4.19658 
4.20527 
4.21400 
4.22277 
4.23158 
4.24042 
4.24931 
4.25819 
4.26712 
4.27608 
4.28508 
4.29412 
4.30315 
4.31227 
4.32138 
4.33054 
4.33973 
4 34896 
4.35823 
4.36750 
The values have been calculated to sixteen significant figures and rounded to six significant figures 
using the rounding rule in British Standards 1957 
NOTE 2.— Due to rounding errors and differences in original data there may be discrepancies in the 
second decimal place of pol between values calculated using these factors and those obtained from Table 
II. Providing sufficient significant figures are used in the calculation the values obtained using the pol 
factors of this table are to be considered the correct results. 

Table III'—Pol Bagasse from Polariscope Reading (400 mm Tube) and Moisture Content. 
(Ratio of water to bagasse = 10:1). (clarified with dry lead). 
Table III—continued. 
REFERENCE TABLES 195 
Table IV—Milligrammes of Reducing Sugars Required to Reduce 10 ml 
Fehling's Solution (Lane and Eynon Method). 
•Calculated by extrapolation. 
196 R E F E R E N C E TABLES 
Table V — M i l l i g r a m m e s o f Reducing S u g a r s Required to Reduce 10 ml 
F e h l i n g ' s So lu t ion (Lane a n d E y n o n M e t h o d ) a t L ow S u c r o s e 
C o n c e n t r a t i o n s . 
REFERENCE TABLES 197 
T a b l e VI—Specific Rota t ion of S u g a r s . 
198 R E F E R E N C E TABLES 
Table VII—Refractive Indices of S u g a r So lut ions at 20 °G in Air at 
20 °G, 760 mm P r e s s u r e and 50 per cent Relat ive Humidi ty . 
The following values are according to the smoothed measured values of the Physi-
kalisch-Technische Bundesanstal t in West Germany, and have been computed from the 
polynomial adopted by the ICUMSA 1966. 
P = sugar concentration as percentage by weight in air at 20 °C 760 mm pressure 
and 50 per cent relative humidity. 

200 R E F E R E N C E TABLES 
Laboratory Manua l for Queens land S u g a r Mi l l s 
Table IX—Glerget Div i sors . 
When analyses are conducted according to Jackson Gillis Method IV, the presently 
accepted formula for conversion of polariscope (saccharimeter) readings to sucrose con-
centration is: 
where S = sucrose per cent in sample. 
P = direct reading calculated to basis of normal solution. 
P1 = invert reading calculated to basis of normal solution. 
m = concentration of dissolved solids in g per 100 ml of solution as read 
in polariscope. 
t = temperature in °C. 
The basic value 132.63 applies to the Walker method of inversion (heat to 65 °C , 
add acid, allow to cool). For inversion by the U.S. Customs method (add acid, immerse 
in 60 °C bath, stir for 3 min, hold for 7 more min, cool quickly) the basic value is 132.56, 
whilst for inversion at room temperature (24 h) the value is 132.66. 
For invertase inversion the Clerget divisor is given by the formula— 
132.1 + 0.0833 (m — 13) — 0.53 (/ — 20). 
Using the Walker method of inversion some useful Clerget divisors, at 20 °C, are : 
J u i c e s — T h e divisor is related to the Brix as follows: 
Table IX (a) 
S u g a r s — F o r all sugars the value 132. 63 at 20 °C may be adopted. 
Molasses—For normal samples of molasses the value 131.88 at 20 °C may be 
adopted. 
For other materials or other methods of inversion the divisor must be calculated 
from the specific data . All Clerget divisors must be corrected for temperature according 
to the table. 
Table X—Subtract ive T e m p e r a t u r e Correct ions for Clerget Div i sors . 
REFERENCE TABLES 201 
Table XI—Dilution Indicator of R a w Sugar . 
Table XII—Solubil i ty of Sucrose in Water in g Sucrose (S) per 100 g 
Water According to Charles, Amer . Chem. S o c , 1958 Abst. of Papers p. 
10D. Reported in Honig "Principles of Sugar Technology", 2, 228. 
202 REFERENCE TABLES 
Table XIII—Solubility of Sucrose in Water in g Sucrose (S) per 100 g 
Solution.* (Charles.) 
°c 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
S 
64.41 
64.48 
64.56 
64.64 
64.73 
64.82 
64.92 
65.02 
65.11 
65.22 
65.33 
65.44 
65.56 
65.68 
65.80 
65.93 
66.06 
66.19 
66.33 
°C 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
S 
66.47 
66.61 
66.75 
66.90 
67.05 
67.21 
67.36 
67.52 
67.69 
67.85 
68.02 
68.19 
68.36 
68.54 
68.72 
68.89 
69.08 
69.26 
°C 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 
50 
51 
52 
53 
54 
S 
69.45 
69.64 
69.83 
70.02 
70.22 
70.41 
70.61 
70.81 
71.01 
71.21 
71.42 
71.63 
71.84 
72.05 
72.26 
72.47 
72.68 
72.90 
°C 
55 
56 
57 
58 
59 
60 
61 
62 
63 
64 
65 
66 
67 
68 
69 
70 
71 
72 
S 
73.11 
73.33 
73.55 
73.77 
73.99 
74.21 
74.43 
74.66 
74.88 
75.10 
75.33 
75.56 
75.78 
76.01 
76.24 
76.46 
76.69 
76.92 
°C 
73 
74 
75 
76 
77 
78 
79 
80 
81 
82 
83 
84 
85 
86 
87 
88 
89 
90 
S 
77.15 
77.38 
77.60 
77.83 
78.06 
78.29 
78.52 
78.75 
78.97 
79.20 
79.43 
79.66 
79.88 
80.11 
80.33 
80.56 
80.78 
81.01 
*Beware of confusion between this Table and Table XII. 
Table XIV—Densities of Solutions of Cane Sugar at 20 °C in g/ml.*. 
(This table is the basis for standardizing hydrometers indicating per cent of sugar at 20 °C). 
Per 
sugar 
0 
1 
2 
3 ' 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
.0 
0.998234 
1.002120 
1.006015 
1.009934 
1.013881 
1.017854 
1.021855 
1.025885 
1.029942 
1.034029 
1.038143 
1.042288 
1.046462 
1.050665 
1.054900 
1.059165 
1.063460 
1.067789 
1.072147 
1.076537 
1.080959 
1.085414 
1.089900 
1.094420 
1.098971 
1.103557 
1.108175 
1.112828 
1.117512 
1 1.122231 
.1 
0.998622 
1.002509 
1.006405 
1.010327 
1.014277 
1.018253 
1.022257 
1.026289 
1.030349 
1.034439 
1.038556 
1.042704 
1.046881 
1.051087 
1.055325 
1.059593 
1.063892 
1.068223 
1.072585 
1.076978 
1.081403 
1.085861 
1.090351 
1.094874 
1.099428 
1.104017 
1.108639 
1.113295 
1.117982 
1 1.122705 
.2 
0.999010 
1.002897 
1.006796 
1.010721 
1.014673 
1.018652 
1.022659 
1.026694 
1.030757 
1.034850 
1.038970 
1.043121 
1.047300 
1.051510 
1.055751 
1.060022 
1.064324 
1.068658 
1.073023 
1.077419 
1.081848 
1.086309 
1.090802 
1.095328 
1.099886 
1.104478 
1.109103 
1.113763 
1.118453 
1.123179 
.3 
0.999398 
1.003286 
1.007188 
1.011115 
1.015070 
1.019052 
1.023061 
1.027099 
1.031165 
1.035260 
1.039383 
1.043537 
1.047720 
1.051933 
1.056176 
1.060451 
1.064756 
1.069093 
1.073461 
1.077860 
1.082292 
1.086757 
1.091253 
1.095782 
1.100344 
1.104938 
1.109568 
1.114229 
1.118923 
1 1.123653 
Tenths of 
.4 
0.999786 
1.003675 
1.007580 
1.011510 
1.015467 
1.019451 
1.023463 
1.027504 
1.031573 
1.035671 
1.039797 
1.043954 
1.048140 
1.052356 
1.056602 
1.060880 
1.065188 
1.069529 
1.073900 
1.078302 
1.082737 
1.087205 
1.091704 
1.096236 
1.100802 
1.105400 
1.110033 
1.114697 
1.119395 
1.124128 
per cent 
.5 
1.000174 
1.004064 
1.007972 
1.011904 
1.015864 
1.019851 
1.023867 
1.027910 
1.031982 
1.036082 
1.040212 
1.044370 
1.048559 
1.052778 
1.057029 
1.061308 
1.065621 
1.069964 
1.074338 
1.078744 
1.083182 
1.087652 
1.092155 
1.096691 
1.101259 
1.105862 
1.110497 
1.115166 
1.119867 
1.124603 
.6 
1.000563 
1.004453 
1.008363 
1.012298 
1.016261 
1.020251 
1.024270 
1.028316 
1.032391 
1.036494 
1.040626 
1.044788 
1.048980 
1.053202 
1.057455 
1.061738 
1.066054 
1.070400 
1.074777 
1.079187 
1.083628 
1.088101 
1.092607 
1.097147 
1.101718 
1.106324 
1.110963 
1.115635 
1.120339 
1.125079 
.7 
1.000952 
1.004844 
1.008755 
1.012694 
1.016659 
1.020651 
1.024673 
1.028722 
1.032800 
1.036906 
1.041041 
1.045206 
1.049401 
1.053626 
1.057882 
1.062168 
1.066487 
1.070836 
1.075217 
1.079629 
1.084074 
1.088550 
1.093060 
1.097603 
1.102177 
1.106786 
1.111429 
1.116104 
1.120812 
1.125555 
.8 
1.001342 
1.005234 
1.009148 
1.013089 
1.017058 
1.021053 
1.025077 
1.029128 
1.033209 
1.037318 
1.041456 
1.045625 
1.049822 
1.054050 
1.058310 
1.062598 
1.066921 
1.071273 
1.075657 
1.080072 
1.084520 
1.089000 
1.093513 
1.098058 
1.102637 
1.107248 
1.111895 
1.116572 
1.121284 
1.126030 
.9 
1.001731 
1.005624 
1.009541 
1.013485 
1.017456 
1.021454 
1.025481 
1.029535 
1.033619 
1.037730 
1.041872 
1.046043 
1.050243 
1.054475 
1.058737 
1.063029 
1.067355 
1.071710 
1.076097 
1.080515 
1.084967 
1.089450 
1.093966 
1.098514 
1.103097 
1.107711 
1.112361 
1.117042 
1.121757 
1.126507 
Per 
cent 
sugar 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
*All weights in vacuo—International Critical Tables 2, 343. © 
REFERENCE TABLES 
R E F E R E N C E TABLES 
which may be utilized for converting apparent density into true density, and vice 
versa, by considering tha t M, the weight in vacuo, and W, the apparent weight, refer 
to 1 ml, since t rue density is defined as the weight in vacuo of 1 ml, and the apparent 
density as the weight of 1 ml of substance in air with brass weights, p is the density of 
air, which has been taken as 0.0012046; d1 the density of the solution, d2 the density 
of the weights, which has been taken as 8.4 g/ml. 
Column 3 gives the apparent specific gravity at 20CC. The values in this column were 
obtained by dividing the apparent density in column 2 by the apparent density of 
water at 20°C, which was taken as 0.997174. 
Column 4 gives the grammes sucrose (weighed in vacuo) per 100 ml of solution. 
The values in the table were calculated in three sections by different individuals; 
thus from 40 to 60 Brix by Peters and Phelps (BS Tech. Paper T338, 1927); 60 to 
83.9 Brix by Brewster and Phelps (NBS Research Paper RP536, 1933); and the re-
maining values, 0 to 40 and 84 to 93 Brix by Snyder, Saunders, and Golden of the 
National Bureau of Standards. After the computations were completed, the tabulations 
were made by rounding off the values to the last figure given. The values are considered 
exact to ± 1 in the fifth decimal. 
Percentage 
of sucrose 
by weight (Brix) 
1 
0 . 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
1 . 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
Apparent 
density at 
20 °C 
2 
0.99717 
.99756 
.99795 
.99834 
.99872 
.99911 
.99950 
.99989 
1.00028 
.00067 
1.00106 
.00145 
.00184 
.00223 
.00261 
.00300 
.00339 
.00378 
.00417 
.00456 
Apparent 
specific 
gravity at 
20 °C/20 °C 
3 
1.00000 
.00039 
.00078 
.00117 
.00156 
.00194 
.00233 
.00272 
.00312 
.00351 
1.00390 
.00429 
.00468 
.00507 
.00546 
.00585 
.00624 
.00663 
.00702 
.00741 
Grammes of | 
per 100 ml 
weight 1 
4 
0.000 
.100 
.200 
.300 
.400 
.500 
.600 
.701 
.801 
.902 
1.002 
.103 
.203 
.304 
.405 
.506 
.607 
.708 
.809 
.911 
Percentage 
of sucrose 
by weight (Brix) 
1 
2 . 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
• 7 
. 8 
. 9 
3 . 0 
• 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
Apparent 
density at 
20 °C 
2 
1.00495 
.00534 
.00574 
.00613 
.00652 
.00691 
.00730 
.00769 
.00809 
.00848 
1.00887 
.00927 
.00966 
.01006 
.01045 
.01084 
.01124 
.01163 
.01203 
.01243 
Apparent 
gravity at 
20 °C/20 °C 
3 
1.00780 
.00819 
.00859 
.00898 
.00937 
.00977 
.01016 
.01055 
.01094 
.01134 
1.01173 
.01213 
.01252 
.01292 
.01331 
.01371 
.01410 
.01450 
.01490 
.01529 
Grammes of 
sucrose 
per 100 ml 
weight 
4 
2.012 
.113 
.215 
.317 
.418 
.520 
.622 
.724 
.826 
.928 
3.030 
.132 
.234 
.337 
.439 
.542 
.644 
.747 
.850 
.953 
206 R E F E R E N C E TABLES 
T A B L E XV 
Brix , Apparent Density, Apparent Specific Gravity, and G r a m m e s 
of Sucrose per 100 ml of Sugar Solut ions 
(NBS—C440, 1942, p. 632) 
Column 1 gives Brix»or percentage of sucrose in the solution. 
Column 2 gives apparent density, tha t is, the weight in air with brass weights of 1 ml 
of solution at 20 °C. The values in this column correspond to the values of t rue density 
(table XIV), having been obtained by means of the formula 
R E F E R E N C E TABLES 207 
T a b l e XV—continued 
208 R E F E R E N C E TABLES 
T a b l e XV—continued 
REFERENCE TABLES 209 
T a b l e XV—continued 
210 R E F E R E N C E TABLES 
T a b l e XV—continued 
REFERENCE TABLES 211 
T a b l e XV—continued 
212 R E F E R E N C E TABLES 
T a b l e XV—continued 
Percentage 
of sucrose 
by weight (Brix) 
1 
54.0 
54.1 
54.2 
54.3 
54.4 
54.5 
54.6 
54.7 
54.8 
54.9 
55.0 
55.1 
55.2 
55.3 
55.4 
55.5 
55.6 
55.7 
55.8 
55.9 
56.0 
56.1 
56.2 
56.3 
56.4 
56.5 
56.6 
56.7 
56.8 
56.9 
57.0 
57.1 
57.2 
57.3 
57.4 
57 .5 
57.6 
57.7 
57.8 
57.9 
58 .0 
58.1 
58.2 
58.3 
58.4 
58.5 
58.6 
58.7 
58.8 
58.9 
Apparent 
density at 
20 °C 
2 
1.25084 
141 
197 
2 5 4 
311 
1.25367 
4 2 4 
481 
5 3 8 
594 
1.25651 
7 0 8 
7 6 5 
8 2 2 
8 7 9 
1.25936 
1.25993 
1.26050 
108 
165 
1.26222 
2 7 9 
337 
3 9 4 
4 5 2 
1.26509 
5 6 6 
6 2 4 
682 
739 
1.26797 
8 5 4 
9 1 2 
9 7 0 
1.27028 
1.27086 
143 
2 0 1 
2 5 9 
317 
1.27375 
4 3 3 
4 9 2 
5 5 0 
6 0 8 
1.27664 
7 2 4 
7 8 2 
841 
899 
Apparent 
specific 
gravity at 
20 °C/20 °C 
3 
1.25439 
4 9 5 
552 
6 0 9 
6 6 6 
1.25723 
7 8 0 
8 3 6 
8 9 3 
9 5 0 
1.26007 
0 6 4 
122 
179 
2 3 6 
1.26293 
3 5 0 
4 0 8 
4 6 5 
5 2 2 
1.26580 
637 
6 9 5 
752 
8 1 0 
1.26868 
9 2 5 
1.26983 
1.27041 
0 9 8 
1.27156 
2 1 4 
2 7 2 
3 3 0 
3 8 8 
1.27446 
5 0 4 
5 6 2 
6 2 0 
6 7 8 
1.27736 
7 9 4 
8 5 3 
9 1 1 
1.27969 
1.28028 
0 8 6 
1 4 5 
2 0 3 
2 6 2 
Grammes of 
sucrose 
per 100 ml 
weight 
4 
67.601 
.757 
.912 
68.069 
.225 
.381 
.537 
.694 
.851 
69.008 
69.164 
.322 
.479 
.636 
.794 
69.951 
70.109 
.267 
.425 
.583 
70.742 
70.900 
71.059 
.217 
.376 
.535 
.694 
71.854 
72.013 
.173 
72.332 
.492 
.652 
.812 
72.973 
73.133 
.293 
.454 
.615 
.776 
73.937 
74.098 
.260 
.421 
.583 
.744 
74.906 
75.068 
.230 
.393 
Percentage 
by weight (Brix) 
1 
59 .0 
59.1 
59.2 
59.3 
59.4 
59.5 
59.6 
59.7 
59.8 
59.9 
60.0 
60.1 
60.2 
60.3 
60.4 
60.5 
60.6 
60.7 
60.8 
60.9 
61.0 
61.1 
61.2 
61.3 
61.4 
61.5 
61.6 
61.7 
61.8 
61.9 
62.0 
62.1 
62.2 
62.3 
62.4 
62.5 
62.6 
62.7 
62.8 
62.9 
63 .0 
63.1 
63.2 
63.3 
63.4 
63.5 
63.6 
63.7 
63.8 
63.9 
Apparent 
density at 
20 °C 
2 
1.27958 
1.28017 
0 7 5 
134 
1 9 3 
251 
309 
367 
4 2 6 
4 8 5 
1.28544 
6 0 2 
661 
7 2 0 
7 7 9 
8 3 8 
897 
9 5 6 
1.29015 
0 7 4 
1.29133 
193 
2 5 2 
3 1 1 
3 7 0 
4 3 0 
4 8 9 
5 4 8 
6 0 8 
667 
1.29726 
7 8 6 
8 4 5 
9 0 5 
9 6 6 
1.30025 
0 8 5 
145 
2 0 5 
2 6 5 
1.30325 
3 8 5 
4 4 6 
5 0 6 
5 6 6 
6 2 6 
6 8 6 
747 
8 0 7 
867 
Apparent 
gravity at 
20 °C/20 °C 
3 
1.28320 
3 7 9 
437 
497 
5 5 6 
6 1 4 
672 
731 
7 8 9 
849 
1.28908 
9 6 6 
1.29025 
0 8 4 
143 
2 0 3 
2 6 2 
321 
3 8 0 
4 3 9 
1.29498 
559 
6 1 8 
677 
7 3 6 
796 
8 5 5 
9 1 5 
9 7 5 
1.30034 
1.30093 
153 
2 1 2 
2 7 3 
3 3 4 
3 9 3 
4 5 3 
5 1 3 
5 7 3 
6 3 3 
1.30694 
7 5 4 
8 1 5 
8 7 5 
9 3 6 
9 9 4 
1.31055 
117 
177 
237 
Grammes of 
sucrose 
per 100 ml 
weight 
in vacuo 
4 
75.555 
.718 
.880 
76.043 
.207 
.369 
.533 
.696 
.860 
77.024 
77.188 
.351 
.515 
.680 
.844 
78.009 
.173 
.338 
.503 
.668 
78.833 
.999 
79.165 
.330 
.496 
.662 
.828 
.995 
80.161 
.328 
80.494 
.661 
.828 
.995 
81.162 
.329 
.497 
.665 
.833 
82.001 
82.169 
.337 
.506 
.674 
.843 
83.012 
.180 
.360 
.519 
.688 
REFERENCE TABLES 213 
T a b l e XV—continued 
Percentage 
of sucrose 
by weight (Brix) 
1 
64.0 
64.1 
64.2 
64.3 
64.4 
64.5 
64.6 
64.7 
64.8 
64.9 
65.0 
65.1 
65.2 
65.3 
65.4 
65.5 
65.6 
65.7 
65.8 
65.9 
66.0 
66.1 
66.2 
66.3 
66.4 
66.5 
66.6 
66.7 
66.8 
66.9 
67.0 
67.1 
67.2 
67.3 
67.4 
67.5 
67.6 
67.7 
67.8 
67.9 
68.0 
68.1 
68.2 
68.3 
68.4 
68.5 
68.6 
68.7 
68.8 
68.9 
Apparent 
density at 
20 °C 
2 
1.30927 
988 
1.31048 
108 
169 
2 2 9 
2 9 0 
3 5 0 
4 1 2 
4 7 3 
1.31533 
5 9 4 
655 
716 
777 
837 
8 9 8 
959 
1.32019 
081 
1.32142 
2 0 3 
2 6 4 
3 2 5 
3 8 5 
4 4 6 
5 0 9 
5 7 0 
632 
6 9 3 
1.32754 
8 1 6 
8 7 8 
939 
1.33001 
062 
124 
186 
2 4 8 
3 0 9 
1.33371 
4 3 3 
4 9 5 
557 
619 
681 
7 4 3 
8 0 5 
867 
9 3 0 
Apparent 
specific 
gravity at 
20 °C/20 °C 
3 
1.31297 
359 
4 1 8 
4 7 9 
5 4 0 
6 0 0 
661 
7 2 3 
784 
8 4 5 
1.31905 
9 6 6 
1.32028 
0 8 9 
150 
2 1 0 
2 7 1 
332 
3 9 3 
4 5 5 
1.32516 
577 
6 3 8 
699 
759 
8 2 0 
884 
9 4 5 
1.33007 
0 6 8 
1.33129 
192 
2 5 4 
3 1 5 
377 
4 3 8 
5 0 0 
562 
6 2 5 
6 8 6 
1.33748 
8 1 0 
8 7 2 
9 3 5 
997 
1.34059 
121 
183 
2 4 5 
3 0 9 
Grammes of 
per 100 ml 
weight 
in vacuo 
4 
83.858 
84.028 
.198 
.367 
.538 
.708 
.879 
85.049 
.220 
.391 
85.561 
.733 
.904 
86.076 
.248 
.419 
.591 
.763 
.935 
87.107 
87.280 
.453 
.626 
.798 
.971 
88.142 
.318 
.492 
.666 
.839 
89.012 
.187 
.361 
.536 
.711 
.885 
90.060 
.235 
.411 
.585 
90.761 
.937 
91.112 
.288 
.464 
.641 
.817 
. 993 
92.169 
.347 
Percentage j 
of sucrose j 
by weight (Brix) 
1 
69.0 
69.1 
69.2 
69.3 
69.4 
69.5 
69.6 
69.7 
69.8 
69.9 
70.0 
70.1 
70.2 
70.3 
70.4 
70.5 
70.6 
70.7 
70.8 
70.9 
71.0 
71.1 
71.2 
71.3 
71.4 
71.5 
71.6 
71.7 
71.8 
71.9 
72.0 
72.1 
72.2 
72.3 
72.4 
72.5 
72.6 
72.7 
72.8 
72.9 
73.0 
73.1 
73.2 
73.3 
73.4 
73.5 
73.6 
73.7 
73.8 
73.9 
Apparent 
density at 
20 °C 
2 
1.33992 j 
1.34054 
116 
179 
241 
3 0 4 
3 6 6 
4 2 9 
491 
5 5 4 
1.34616 
6 7 9 
742 
8 0 5 
867 
9 3 0 
9 9 3 
1.35056 
119 
182 
1.35245 
3 0 8 
371 
4 3 4 
4 9 8 
561 
6 2 5 
6 8 8 
751 
8 1 4 
1.35877 
9 4 0 
1.36004 
067 
131 
194 
2 5 8 
3 2 2 
3 8 5 
4 5 0 
1.36514 
5 7 8 
6 4 2 
7 0 5 
769 
8 3 3 
8 9 6 
9 6 0 
1.37024 
0 8 8 
Apparent 
specific 
gravity at 
20°C/20°C 
3 
1.34371 
4 3 3 
4 9 5 
558 
621 
684 
746 
809 
871 1 
9 3 4 
1.34997 
1.35060 
123 
186 
2 4 8 
311 
3 7 5 
4 3 8 
501 
564 
1.35627 
691 
7 5 4 
817 
881 
9 4 4 
1.36008 
0 7 2 
135 
198 
1.36261 
3 2 4 
3 8 9 
4 5 2 
5 1 6 
5 7 9 
6 4 3 
707 
771 
836 
1.36900 
9 6 4 
1.37028 
0 9 2 
156 
2 2 0 
2 8 3 
347 
4 1 1 
4 7 6 
Grammes of 
per 100 ml 
weight 
4 
92.524 
.701 
.878 
93.056 
.233 
.411 
.589 
.767 
.945 
94.123 
94.302 
.481 
.660 
.839 
95.017 
.197 
.376 
.556 
.736 
.916 
96.096 
.276 
.456 
.636 
.817 
.998 
97.179 
.360 
.541 
.722 
97.904 
98.085 
.268 
.449 
.632 
.814 
.997 
99.179 
.362 
.545 
99.728 
.912 
100.095 
.278 
.462 
.646 
.827 
101.014 
.198 
.383 
214 R E F E R E N C E TABLES 
T a b l e XV—-continued 
Percentage 
of sucrose 
by weight (Brix) 
1 
7 4 . 0 
7 4 . 1 
7 4 . 2 
7 4 . 3 
7 4 . 4 
7 4 . 5 
7 4 . 6 
7 4 . 7 
7 4 . 8 
7 4 . 9 
7 5 . 0 
7 5 . 1 
7 5 . 2 
7 5 . 3 
7 5 . 4 
7 5 . 5 
7 5 . 6 
7 5 . 7 
7 5 . 8 
7 5 . 9 
7 6 . 0 
7 6 . 1 
7 6 . 2 
7 6 . 3 
7 6 . 4 
7 6 . 5 
7 6 . 6 
7 6 . 7 
7 6 . 8 
7 6 . 9 
7 7 . 0 
7 7 . 1 
7 7 . 2 
7 7 . 3 
7 7 . 4 
7 7 . 5 
7 7 . 6 
7 7 . 7 
7 7 . 8 
7 7 . 9 
7 8 . 0 
7 8 . 1 
7 8 . 2 
7 8 . 3 
7 8 . 4 
7 8 . 5 
7 8 . 6 
7 8 . 7 
7 8 . 8 
7 8 . 9 
Apparent 
density at 
20 °C 
2 
1 . 3 7 1 5 3 
217 
281 
3 4 5 
4 1 0 
4 7 5 
5 3 9 
6 0 4 
668 
733 
1 . 3 7 7 9 7 
862 
9 2 6 
991 
1 . 3 8 0 5 5 
119 
184 
2 4 9 
3 1 4 
3 7 9 
1 . 3 8 4 4 4 
5 1 0 
5 7 5 
6 4 0 
7 0 5 
7 7 0 
8 3 5 
9 0 0 
9 6 5 
1 . 3 9 0 3 0 
1 . 3 9 0 9 6 
161 
2 2 5 
291 
3 5 6 
4 2 2 
4 8 8 
5 5 4 
6 1 9 
6 8 5 
1 . 3 9 7 5 1 
8 1 6 
882 
9 4 8 
1 . 4 0 0 1 3 
0 7 9 
145 
211 
277 
3 4 3 
Apparent 
gravity at 
20 °C/20 °C 
3 
1 . 3 7 5 4 1 
6 0 5 
669 
733 
798 
8 6 4 
9 2 8 
9 9 3 
1 . 3 8 0 5 7 
122 
1 . 3 8 1 8 7 
2 5 2 
3 1 6 
381 
4 4 5 
1 . 3 8 5 1 0 
575 
6 4 0 
7 0 5 
7 7 0 
1 . 3 8 8 3 5 
9 0 2 
967 
1 . 3 9 0 3 2 
097 
162 
2 2 8 
2 9 3 
358 
4 2 3 
1 . 3 9 4 8 9 
5 5 4 
6 1 9 
685 
7 5 0 
8 1 6 
8 8 2 
9 4 9 
1 . 4 0 0 1 4 
0 8 0 
1 . 4 0 1 4 6 
211 
277 
3 4 4 
4 0 9 
4 7 5 
541 
607 
6 7 4 
7 4 0 
Grammes of 
per 100 ml 
weight 
4 
1 0 1 . 5 6 8 
. 7 5 3 
. 9 3 7 
1 0 2 . 1 2 2 
. 3 0 8 
. 4 9 3 
. 6 7 9 
. 8 6 5 
1 0 3 . 0 5 0 
. 2 3 7 
1 0 3 . 4 2 3 
. 6 0 9 
. 7 9 6 
. 9 8 3 
1 0 4 . 1 7 0 
1 0 4 . 3 5 6 
. 5 4 3 
. 7 3 1 
. 9 1 9 
1 0 5 . 1 0 6 
1 0 5 . 2 9 4 
. 4 8 2 
. 6 7 0 
. 8 5 9 
1 0 6 . 0 4 7 
. 2 3 6 
. 4 2 4 
. 6 1 3 
, 8 0 2 
. 9 9 1 
1 0 7 . 1 8 1 
. 3 7 0 
. 5 6 0 
. 7 5 0 
. 9 4 0 
1 0 8 . 1 3 0 
. 3 2 0 
. 5 1 1 
. 7 0 1 
. 8 9 2 
1 0 9 . 0 8 4 
. 2 7 4 
. 4 6 6 
. 6 5 7 
. 8 4 8 
1 1 0 . 0 4 1 
. 2 3 2 
. 4 2 5 
. 6 1 7 
. 8 0 9 
Percentage 
of sucrose 
by weight (Brix) 
1 
7 9 . 0 
7 9 . 1 
7 9 . 2 
7 9 . 3 
7 9 . 4 
7 9 . 5 
7 9 . 6 
7 9 . 7 
7 9 . 8 
7 9 . 9 
8 0 . 0 
8 0 . 1 
8 0 . 2 
8 0 . 3 
8 0 . 4 
8 0 . 5 
8 0 . 6 
8 0 . 7 
8 0 . 8 
8 0 . 9 
8 1 . 0 
8 1 . 1 
8 1 . 2 
8 1 . 3 
8 1 . 4 
8 1 . 5 
8 1 . 6 
8 1 . 7 
8 1 . 8 
8 1 . 9 
8 2 . 0 
8 2 . 1 
8 2 . 2 
8 2 . 3 
8 2 . 4 
8 2 . 5 
8 2 . 6 
8 2 . 7 
8 2 . 8 
8 2 . 9 
8 3 . 0 
8 3 . 1 
8 3 . 2 
8 3 . 3 
8 3 . 4 
8 3 . 5 
8 3 . 6 
8 3 . 7 
8 3 . 8 
8 3 . 9 
Apparent 
density at 
20 °C 
2 
1 . 4 0 4 0 9 
4 7 5 
541 
607 
6 7 4 
7 4 0 
8 0 6 
872 
9 3 9 
1 . 4 1 0 0 5 
1 . 4 1 0 7 2 
138 
2 0 4 
2 7 1 
3 3 7 
4 0 4 
4 7 2 
537 
6 0 4 
671 
1 . 4 1 7 3 7 
8 0 4 
8 7 1 
938 
1 . 4 2 0 0 5 
0 7 2 
139 
2 0 6 
2 7 3 
3 4 0 
1 . 4 2 4 0 7 
4 7 5 
5 4 3 
6 1 0 
677 
7 4 4 
811 
8 7 8 
9 4 6 
1 . 4 3 0 1 3 
1 . 4 3 0 8 1 
148 
2 1 6 
2 8 3 
351 
4 1 9 
4 8 8 
5 5 5 
6 2 3 
6 9 1 
Apparent 
specific -
gravity at 
20 °C/20 °C 
3 
1 . 4 0 8 0 6 
8 7 2 
9 3 8 
1 . 4 1 0 0 5 
0 7 2 
138 
2 0 4 
2 7 0 
337 
4 0 4 
1 . 4 1 4 7 1 
537 
6 0 3 
6 7 0 
737 
8 0 4 
8 7 2 
9 3 7 
1 . 4 2 0 0 4 
0 7 2 
1 . 4 2 1 3 8 
2 0 5 
2 7 2 
3 3 9 
4 0 6 
4 7 4 
541 
608 
6 7 5 
742 
1 . 4 2 8 1 0 
8 7 8 
9 4 6 
1 . 4 3 0 1 3 
0 8 0 
148 
2 1 4 
2 8 2 
3 5 0 
417 
1 . 4 3 4 8 6 
5 5 3 
621 
6 8 8 
7 5 6 
8 2 4 
8 9 4 
961 
1 . 4 4 0 2 9 
097 
Grammes of 
per 100 ml 
weight 
4 
1 1 1 . 0 0 2 
. 1 9 5 
. 3 8 8 
. 5 8 1 
. 7 7 5 
. 9 6 8 
1 1 2 . 1 6 1 
. 3 5 4 
. 5 4 9 
. 7 4 3 
1 1 2 . 9 3 8 
1 1 3 . 1 3 1 
. 3 2 6 
. 5 2 1 
. 7 1 5 
. 9 1 1 
1 1 4 . 1 0 6 
. 3 0 1 
. 4 9 7 
. 6 9 2 
1 1 4 . 8 8 8 
1 1 5 . 0 8 4 
. 2 8 0 
. 4 7 7 
. 6 7 3 
. 8 7 0 
1 1 6 . 0 6 7 
. 2 6 4 
. 4 6 1 
. 6 5 8 
1 1 6 . 8 5 6 
1 1 7 . 0 5 3 
. 2 5 2 
. 4 4 9 
. 6 4 7 
. 8 4 5 
1 1 8 . 0 4 4 
. 2 4 3 
. 4 4 2 
. 6 4 1 
1 1 8 . 8 4 0 
1 1 9 . 0 3 9 
. 2 3 9 
. 4 3 8 
. 6 3 8 
. 8 3 8 
1 2 0 . 0 3 9 
. 2 3 8 
. 4 3 9 
. 6 4 0 
REFERENCE TABLES 215 
T a b l e XV—continued 
Percentage 
of sucrose 
by weight (Brix) 
84 
85 
86 
87 
8 8 
l 
. 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
. 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
. 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
. 0 
. 1 
. 2 
. 3 
. 4 
.5 
. 6 
. 7 
. 8 
. 9 
0 
1 
2 
3 
. 4 
. 5 
6 
7 
8 
9 
Apparent 
density at 
20 °C 
2 
1.43758 
.43826 
.43894 
.43962 
1.44030 
.44098 
.44166 
.44234 
.44303 
.44371 
1.44439 
.44507 
.44576 
.44644 
.44712 
.44781 
.44849 
.44918 
.44986 
1.45055 
1.45124 
.45192 
.45261 
.45330 
.45398 
.45467 
.45536 
.45605 
.45674 
.45743 
1.45812 
.45881 
.45950 
1.46019 
.46088 
.46157 
.46227 
.46296 
.46365 
.46434 
1.46504 
.46573 
.46643 
.46712 
.46782 
.46851 
.46921 
.46990 
1.47060 
.47130 
Apparent 
Specific 
gravity at 
20 °C/20 °C 
3 
1.44165 
.44234 
.44302 
.44370 
.44438 
.44507 
.44575 
.44643 
.44712 
.44780 
1.44848 
.44917 
.44985 
1.45054 
.45123 
.45191 
.45260 
.45329 
.45397 
.45466 
1.45535 
.45604 
.45673 
.45741 
.45810 
.45879 
.45949 
1.46018 
.46087 
.46156 
1.46225 
.46294 
.46364 
.46433 
.46502 
.46572 
.46641 
.46710 
.46780 
.46849 
1.46919 
.46989 
1.47058 
.47128 
.47198 
.47267 
.47337 
.47407 
.47477 
.47547 
Grammes of 
sucrose 
per 100 ml 
weight 
in vacuo 
4 
120.841 
121.042 
.243 
.444 
.646 
.847 
122.049 
.251 
.453 
.655 
122.858 
123.061 
.263 
.466 
.670 
.873 
124.076 
.280 
.484 
.688 
124.892 
125.096 
.301 
.505 
.710 
.915 
126.121 
.326 
.531 
.737 
126.943 
127.149 
.355 
.562 
.768 
.975 
128.182 
.389 
.596 
.803 
129.011 
.219 
.426 
.635 
.843 
130.051 
.260 
.468 
.677 
.886 
Percentage 
of sucrose 
by weight (Brix) 
1 
8 9 . 0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
90.0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
91.0 
• 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
92.0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
93.0 
. 1 
. 2 
. 3 
. 4 
. 5 
. 6 
. 7 
. 8 
. 9 
Apparent 
density at 
20 °C 
2 
1.47199 
.47269 
.47339 
.47409 
.47479 
.47548 
.47618 
.47688 
.47758 
.47828 
1.47898 
.47968 
1.48039 
.48109 
.48179 
.48249 
.48320 
.48390 
.48460 
.48531 
1.48601 
.48672 
.48742 
.48813 
.48883 
.48954 
1.49024 
.49095 
.49166 
.49236 
1.49307 
.49378 
.49449 
.49520 
.49591 
.49662 
.49733 
.49804 
.49875 
.49946 
1.50017 
.50088 
.50159 
.50230 
.50302 
.50373 
.50444 
.50516 
.50587 
.50659 
Apparent 
gravity at 
20 °C/20 °C 
3 
1.47616 
.47686 
.47756 
.47826 
.47897 
.47967 
1.48037 
.48107 
.48177 
.48247 
1.48317 
.48388 
.48458 
.48529 
.48599 
.48669 
.48740 
.48810 
.48881 
.48951 
1.49022 
.49093 
.49164 
.49234 
.49305 
.49376 
.49447 
.49518 
.49588 
.49659 
1.49730 
.49801 
.49872 
.49944 
1.50015 
.50086 
.50157 
.50228 
.50299 
.50371 
1.50442 
.50513 
.50585 
.50656 
.50728 
.50799 
.50871 
.50942 
1.51014 
.51086 
Grammes of 
sucrose 
per 100 ml 
weight in 
vacuo 
4 
131.096 
.305 
.515 
.725 
.935 
132.145 
.355 
.565 
.776 
.987 
133.198 
.409 
.620 
.832 
134.043 
.255 
.467 
.680 
.892 
135.104 
135.317 
.530 
.743 
.956 
136.170 
.383 
.597 
.811 
137.025 
.239 
137.454 
.668 
.883 
138.098 
.313 
.529 
.744 
.960 
139.176 
.392 
139.608 
.824 
140.041 
.257 
.474 
.691 
.908 
141.126 
.343 
.561 
216 R E F E R E N C E TABLES 
Table XVI—Weight per Unit Volume of S u g a r Solut ions at 20°C 
Brix 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 
50 
Weight in air 
lb/ft3 
62.253 
62.492 
62.739 
62.978 
63.225 
63.472 
63.727 
63.973 
64.228 
64.482 
64.744 
65.006 
65.260 
65.522 
65.791 
66.053 
66.322 
66.592 
66.868 
67.138 
67.414 
67.691 
67.975 
68.260 
68.544 
68.828 
69.113 
69.404 
69.696 
69.995 
70.287 
70.586 
70.893 
71.192 
71.499 
71.806 
72.112 
72.426 
72.741 
73.055 
73.376 
73.698 
74.020 
74.349 
74.678 
75.007 
75.336 
75.673 
76.017 
76.354 
76.690 
lb/gal 
10.00 
10.038 
10.078 
10.112 
10.156 
10.196 
10.237 
10.276 
10.317 
10.358 
10.400 
10.442 
10.483 
10.525 
10.568 
10.610 
10.653 
10.697 
10.741 
10.785 
10.829 
10.874 
10.919 
10.965 
11.011 
11.056 
11.102 
11.149 
11.196 
11.244 
11.291 
11.339 
11.388 
11.436 
11.485 
11.535 
11.584 
11.634 
11.685 
11.735 
11.787 
11.839 
11.890 
11.943 
11.996 
12.049 
12.102 
12.155 
12.211 
12.265 
12.319 
ton/100 gal 
.4456 
.4474 
.4491 
.4509 
.4526 
.4544 
.4562 
.4580 
.4598 
.4616 
.4635 
.4653 
.4672 
.4691 
.4709 
.4728 
.4748 
.4767 
.4786 
.4806 
.4826 
.4846 
.4866 
.4886 
.4906 
.4927 
.4947 
.4968 
.4989 
.5010 
.5031 
.5053 
.5074 
.5096 
.5118 
.5140 
.5162 
.5184 
.5207 
.5229 
.5252 
.5275 
.5298 
.5321 
.5345 
.5369 
.5392 
.5416 
.5440 
.5465 
.5489 
Brix 
51 
52 
53 
54 
55 
56 
57 
58 
59 
60 
61 
62 
63 
64 
65 
66 
67 
68 
69 
70 
71 
72 
73 
74 
75 
76 
77 
78 
79 
80 
81 
82 
83 
84 
85 
86 
87 
88 
89 
90 
91 
92 
93 
94 
95 
96 
97 
98 
99 
100 
Weight in air 
lb/ft3 
77.042 
77.386 
77.738 
78.089 
78.441 
78.800 
79.151 
79.518 
79.877 
80.244 
80.618 
80.984 
81.358 
81.732 
82.114 
82.488 
82.877 
83.258 
83.647 
84.036 
84.425 
84.822 
85.218 
85.622 
86.018 
86.430 
86.834 
87.238 
87.647 
88.068 
88.480 
88.898 
89.317 
89.744 
90.170 
90.597 
91.023 
91.457 
91.891 
92.325 
92.766 
93.207 
93.649 
94.097 
94.546 
lb/gal 
12.376 
12.431 
12.487 
12.543 
12.600 
12.658 
12.714 
12.773 
12.831 
12.890 
12.950 
13.009 
13.069 
13.129 
13.190 
13.250 
13.312 
13.374 
13.437 
13.499 
13.562 
13.625 
13.689 
13.754 
13.817 
13.884 
13.949 
14.013 
14.095 
14.147 
14.213 
14.280 
14.347 
14.414 
14.484 
14.553 
14.621 
14.691 
14.760 
14.831 
14.901 
14.972 
15.043 
15.115 
15.187 
ton/100 gal 
.5514 
.5539 
.5564 
.5589 
.5614 
.5640 
.5665 
.5691 
.5717 
.5743 
.5769 
.5796 
.5823 
.5850 
.5877 
.5904 
.5931 
.5959 
.5986 
.6014 
.6042 
.6070 
.6099 
.6127 
.6156 
.6185 
.6214 
.6243 
.6273 
.6302 
.6332 
.6362 
.6392 
.6422 
.6453 
.6483 
.6514 
.6545 
.6576 
.6607 
.6638 
.6670 
.6702 
.6733 
.6765 
.6798 
.6830 
.6862 
.6895 
.6928 
Table XVII—Degree of Supersaturation—All Values Being Prefixed by 1. 
218 R E F E R E N C E TABLES 
Table XVIII—Crystal Content of Massecuites* 
Purity drop 
Mass. 
puritj 
90 
89 
88 
87 
86 
85 
84 
83 
82 
81 
80 
79 
78 
77 
76 
75 
74 
73 
72 
71 
70 
69 
68 
67 
66 
65 
64 
93 
62 
61 
50 
59 
68 
57 
56 
55 
T 1 5 
60.0 
57.7 
55.6 
53.6 
51.7 
50.0 
48.4 
46.9 
45.5 
44.1 
42.9 
41.7 
40.5 
39.5 
38.5 
37.5 
36.6 
35.7 
34.9 
34.1 
33.3 
15 
!
 32.6 
31.9 
31.2 
30.6 
30.0 
29.4 
28.8 
28.3 
27.8 
27.3 
26.8 
26.3 
25.9 
25.4 
25.0 
16 
61.5 
59.3 
57.1 
55.2 
53.3 
51.6 
50.0 
48.5 
47.1 
45.8 
44.4 
43.2 
42.1 
41.0 
40.0 
39.0 
38.1 
37.2 
36.4 
35.6 
34.8 
16 
34.0 
33.3 
32.7 
32.0 
31.4 
30.8 
30.2 
29.6 
29.1 
28.6 
28.1 
27.6 
27.1 
26.7 
26.2 
17 
63.0 
60.7 
58.6 
56.7 
54.8 
53.1 
51.5 
50.0 
48.6 
47.2 
45.9 
44.7 
43.6 
42.5 
41.5 
40.5 
39.5 
3S.6 
37.8 
37.0 
36.2 
17 
35.4 
34.7 
34.0 
33.3 
32.7 
32.1 
31.5 
30.9 
30.4 
29.8 
29.3 
28.8 
28.3 
27.9 
27.4 
18 
64.3 
62.1 
60.0 
58.1 
56.3 
54.5 
52.9 
51.4 
50.0 
48.6 
47.4 
46.2 
45.0 
43.9 
42.9 
41.9 
40.9 
40.0 
39.1 
38.3 
37.5 
18 
36.7 
36.0 
35.3 
34.6 
34.0 
33.3 
32.7 
32.1 
31.6 
31.0 
30.5 
30.0 
29.5 
29.0 
28.6 
19 
65.5 
63.3 
61.3 
59.4 
57.6 
55.9 
54.3 
52.8 
51.4 
50.0 
48.7 
47.5 
46.3 
45.2 
44.2 
43.2 
42.2 
41.3 
40.4 
39.6 
38.8 
19 
38.0 
37.3 
36.5 
35.8 
35.2 
34.5 
33.9 
33.3 
32.8 
32.2 
31.7 
31.1 
30.6 
30.2 
29.7 
20 
66.7 
64.5 
62.5 
60.6 
58.8 
57.1 
55.6 
54.1 
52.6 
51.3 
50.0 
48.8 
47.6 
46.5 
45.5 
44.4 
43.5 
42.6 
41.7 
40.8 
40.0 
20 
39.2 
38.5 
37.7 
37.0 
36.4 
35.7 
35.1 
34.5 
33.9 
33.3 
32.8 
32.3 
31.7 
31.3 
30.8 
P 
21 
65.6 
63.6 
61.8 
60.0 
58.3 
56.8 
55.3 
53.8 
52.5 
51.2 
50.0 
48.8 
47.7 
46.7 
45.7 
44.7 
43.7 
42.9 
42.0 
41.2 
22 
41.5 
40.7 
40.0 
39.3 
38.6 
37.9 
37.3 
36.7 
36.1 
35.5 
34.9 
34.4 
33.8 
33.3 
32.8 
22 
64.7 
62.9 
61.1 
59.4 
57.9 
56.4 
55.0 
53.7 
52.4 
51.2 
50.0 
48.9 
47.8 
46.8 
45.8 
44.9 
44.0 
43.1 
42.3 
24 
43.6 
42.9 
42.1 
41.4 
40.7 
40.0 
39.3 
38.7 
38.1 
37.5 
36.9 
36.4 
35.8 
35.3 
34.8 
23 
63.9 
62.1 
60.5 
59.0 
57.5 
56.1 
54.8 
53.5 
52.3 
51.1 
50.0 
48.9 
47.9 
46.9 
46.0 
45.1 
44.2 
43.4 
26 
45.6 
44.8 
44.1 
43.3 
42.6 
41.9 
41.3 
40.6 
40.0 
39.4 
38.8 
38.2 
37.7 
37.1 
36.6 
24 
63.2 
61.5 
60.0 
58.5 
57.1 
55.8 
54.5 
53.3 
52.2 
51.1 
50.0 
49.0 
48.0 
47.1 
46.2 
45.3 
44.4 
28 
47.5 
46.7 
45.9 
45.2 
44.4 
43.8 
43.1 
42.4 
41.8 
41.2 
40.6 
40.0 
39.4 
38.9 
38.3 
25 
62.5 
61.0 
59.5 
58.1 
56.8 
55.6 
54.3 
53.2 
52.1 
51.0 
50.0 
49.0 
48.1 
47.2 
46.3 
45.5 
30 
49.2 
48.4 
47.6 
46.9 
46.2 
45.5 
44.8 
44.1 
43.5 
42.9 
42.3 
41.7 
41.1 
40.5 
40.0 
*With apparent purities the crystal content per cent Brix is derived. The use of 
true purities gives crystal per cent dry substance. To obtain crystal per cent massecuite 
multiply by Brix or dry substance per unit of massecuite. 
REFERENCE TABLES 219 
Table XIX (a)—Stock Recovery. 
Total pol and recoverable pol in tons per 100 gallons of stock, when the apparent 
purity of final molasses is 30. 
64 1 
66 
68 
70 
72 
74 
76 
78 
80 
82 
84 
86 
88 
90 
92 
94 
96 
98 
100 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
.169 
.080 
.175 
.084 
.182 
.087 
.190 
.090 
.197 
.094 
.204 
.097 
.212 
.101 
.219 
.104 
.227 
.108 
.235 
.112 
.243 
.116 
.251 
.120 
.259 
.123 
.268 
.127 
.276 
.132 
.285 
.136 
.294 
.140 
.303 
.144 
.312 
.149 
.187 
.107 
.195 
.111 
.203 
.116 
.211 
.120 
.219 
.124 
.227 
.130 
.235 
.134 
.244 
.139 
.252 
.144 
.261 
.149 
.270 
.154 
.279 
.159 
.288 
.165 
.297 
.170 
.307 
.175 
.317 
.181 
.326 
.186 
.336 
.192 
.346 
.198 
.206 .225 .243 
.134 .160 .187 
1 .214 
.139 
.223 
.145 
.232 
.150 
.240 
.156 
.249 
.162 
.259 
.168 
.268 
.174 
.277 
.180 
.287 
.186 
.297 
.193 
.307 
.199 
.317 
.206 
.327 
.212 
.338 
.219 
.348 
.226 
.359 
.233 
.370 
.240 
.381 
.247 
.234 
.167 
.243 
.174 
.253 
.180 
.262 
.187 
.272 
.194 
.282 
.202 
.292 
.209 
.303 
.216 
.313 
.224 
.323 
.231 
.335 
.239 
.346 
.247 
.357 
.255 
.368 
.263 
.380 
.271 
.392 
.280 
.404 
.288 
.416 
.297 
.253 
.195 
.263 
.203 
.274 
.211 
.284 
.219 
.295 
.227 
.306 
.235 
.317 
.244 
.328 
.252 
.339 
.261 
.351 
.270 
.362 
.279 
.374 
.288 
.387 
.297 
.399 
.307 
.411 
.316 
.424 
.326 
.437 
.336 
.450 
.346 
.262 .281 
.214 .241 
.273 
.223 
.284 
.232 
.295 
.241 
.306 
.250 
.317 
.259 
.329 
.269 
.341 
.278 
.353 
.288 
.365 
.298 
.378 
.308 
.390 
.319 
.403 
.329 
.416 
.340 
.430 
.351 
.443 
.362 
.457 
.373 
.471 
.384 
.485 
.396 
.292 
.251 
.304 
.261 
.316 
.271 
.328 
.281 
.340 
.292 
.353 
.302 
.365 
.313 
.378 
.324 
.391 
.335 
.405 
.347 
.418 
.358 
.432 
.370 
.446 
.382 
.460 
.394 
.475 
.407 
.490 
.420 
.504 
.432 
.520 
.445 
.300 
.267 
.312 
.278 
.324 
.290 
.337 
.301 
.350 
.312 
.363 
.324 
.376 
.336 
.390 
.348 
.403 
.360 
.417 
.373 
.432 
.385 
.446 
.398 
.461 
.411 
.476 
.425 
.491 
.438 
.506 
.452 
.522 
.466 
.538 
.480 
.554 
.495 
.318 
.294 
.331 
.306 
.345 
.319 
.358 
.331 
.372 
.343 
.385 
.356 
.400 
.369 
.414 
.383 
.429 
.396 
.443 
.410 
.459 
.424 
.474 
.438 
.490 
.453 
.505 
.467 
.522 
.482 
.538 
.497 
.555 
.513 
.572 
.528 
.589 
.544 
.337 
.321 
.351 
.334 
.365 
.347 
.379 
.360 
.393 
.375 
.408 
.389 
.423 
.403 
.438 
.417 
.454 
.432 
.470 
.447 
.486 
.462 
.502 
.478 
.518 
.494 
.535 
.509 
.552 
.526 
.570 
.543 
.587 
.559 
.605 
.577 
.624 
.594 
The tons pol in residual molasses may be obtained by subtracting tons recoverable 
pol from tons pol in stock. 
Total 
Brix pol(T) Apparent purity of product 
of 
pro— Recov. 
duct pol(R) 45 50 55 60 65 70 75 80 85 90 
220 R E F E R E N C E TABLES 
Table XIX (b)—Stock Recovery. 
Total pol and recoverable pol in tons per 100 gallons of stock, when the apparent 
purity of final molasses is 35. 
Brix 
of 
duct 
6 4 
6 6 
6 8 
7 0 
7 2 
7 4 
7 6 
7 8 
8 0 
8 2 
8 4 
8 6 
8 8 
9 0 
9 2 
9 4 
9 6 
9 8 
1 0 0 
Total 
pol(T) 
Recov. 
pol(R) 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
4 5 
.169 
.058 
.175 
.060 
.182 
.062 
.190 
.065 
.197 
.067 
.204 
.070 
.212 
.072 
.219 
.075 
.227 
.077 
.235 
.080 
.243 
.083 
.251 
.086 
.259 
.089 
.268 
.091 
.276 
.093 
.285 
.098 
.294 
.100 
.303 
.103 
.312 
.107 
5 0 
.187 
.086 
.195 
.090 
.203 
.094 
.211 
.097 
.219 
.101 
.227 
.105 
.235 
.108 
.244 
.112 
.252 
.116 
.261 
.120 
.270 
.124 
.279 
.129 
.288 
.133 
.297 
.137 
.307 
.142 
.317 
.146 
.326 
.151 
.336 
.155 
.346 
.160 
5 5 
.206 
.115 
.214 
.120 
.223 
.125 
.232 
.130 
.240 
.135 
.249 
.140 
.259 
.145 
.268 
.150 
.277 
.155 
.287 
.160 
.297 
.166 
.307 
.173 
.317 
.177 
.327 
.183 
.338 
.189 
.348 
.195 
.359 
.201 
.370 
.207 
.381 
.213 
Apparent purity of product 
6 0 
.225 
.144 
.234 
.150 
.243 
.156 
.253 
.162 
.262 
.168 
.272 
.174 
.282 
.181 
.292 
.187 
.303 
.194 
.313 
.201 
.323 
.207 
.335 
.214 
.346 
.222 
.357 
.229 
.368 
.236 
.380 
.243 
.392 
.251 
.404 
.259 
.416 
.266 
6 5 
.243 
.173 
.253 
.180 
.263 
.187 
.274 
.194 
.284 
.202 
.295 
.209 
.306 
.217 
.317 
.225 
.328 
.233 
.339 
.241 
.351 
.249 
.362 
.257 
.374 
.266 
.387 
.274 
.399 
.283 
.411 
.292 
.424 
.301 
.437 
.310 
.450 
.320 
7 0 
.262 
.202 
.273 
.210 
.284 
.218 
.295 
.227 
.306 
.235 
.317 
.244 
.329 
.253 
.341 
.262 
.353 
.271 
.365 
.281 
.378 
.290 
.390 
.300 
.403 
.310 
.416 
.320 
.430 
.330 
.443 
.340 
.457 
.351 
.471 
.362 
.485 
.373 
7 5 
.281 
.230 
.292 
.240 
.304 
.249 
.316 
.259 
.328 
.269 
.340 
.279 
.353 
.289 
.365 
.300 
.378 
.310 
.391 
.321 
.405 
.332 
.418 
.343 
.432 
.354 
.446 
.366 
.460 
.378 
.475 
.389 
.490 
.402 
.604 
.414 
.520 
.426 
8 0 
.300 
.259 
.312 
.270 
.324 
.281 
.337 
.291 
.350 
.303 
.363 
.314 
.376 
.325 
.390 
.337 
.403 
.349 
.417 
.361 
.432 
.373 
.446 
.386 
.461 
.399 
.476 
.412 
.491 
.425 
.506 
.438 
.522 
.452 
.538 
.466 
.554 
.480 
8 5 
.318 
.288 
.331 
.300 
.345 
.312 
.358 
.324 
.372 
.336 
.385 
.349 
.400 
.362 
.414 
.375 
.429 
.388 
.443 
.401 
.459 
.415 
.474 
.429 
.490 
.443 
.505 
.457 
.522 
.472 
.538 
.487 
.555 
.501 
.572 
.517 
.589 
.533 
9 0 
.337 
.317 
.351 
.330 
.365 
.343 
.379 
.356 
.393 
.370 
.408 
.384 
.423 
.398 
.438 
.412 
.454 
.427 
.470 
.441 
.486 
.456 
.502 
.472 
.518 
.487 
.535 
.503 
.552 
.519 
.570 
.536 
.587 
.552 
.605 
.569 
.624 
.586 
The tons pol in residual molasses may be obtained by subtracting tons recoverable 
pol from tons pol in stock. 
REFERENCE TABLES 
Table XIX (c)—Stock Recovery. 
Total pol and recoverable pol in tons per 100 gallons of stock, when the apparent 
purity of final molasses is 40. 
Brix 
of 
duct 
6 4 
6 6 
68 
7 0 
7 2 
7 4 
7 6 
7 8 
8 0 
8 2 
8 4 
8 6 
8 8 
9 0 
9 2 
9 4 
9 6 
9 8 
1 0 0 
Total 
pol(T) 
Recov. 
1 pol(R) 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
T 
R 
4 5 
.169 
.031 
.175 
.032 
.182 
.034 
.190 
.035 
.197 
.036 
.204 
.038 
.212 
.039 
.219 
.041 
.227 
.042 
.235 
.043 
.243 
.045 
.251 
.046 
.259 
.048 
.268 
.050 
.276 
.051 
.285 
.053 
.294 
.054 
.303 
.056 
.312 
.058 
5 0 
.187 
.062 
.195 
.065 
.203 
.068 
I . 2 1 1 
.070 
.219 
.073 
.227 
.076 
.235 
.078 
.244 
.081 
.252 
.084 
.261 
.087 
.270 
.090 
.279 
.093 
.288 
.096 
.297 
.099 
.307 
.102 
.317 
.105 
.326 
.109 
.336 
.112 
.346 
.115 
5 5 
.206 
.094 
.214 
.097 
.223 
.101 
.232 
.105 
.240 
.109 
.249 
.113 
.259 
.118 
.268 
.122 
.277 
.126 
.287 
.130 
.296 
.135 
.307 
.139 
.317 
.144 
.327 
.149 
.338 
.153 
.348 
.158 
.359 
.163 
.370 
.168 
.381 
.173 
Apparent purity of product 
60 
.225 
.125 
.234 
.129 
.243 
.135 
.253 
.140 
.262 
.145 
.272 
.151 
.282 
.157 
.292 
.163 
.303 
.168 
.313 
.173 
.324 
.180 
.335 
.186 
.346 
.192 
.357 
.199 
.368 
.205 
.380 
.211 
.392 
.217 
.404 
.224 
.416 
.231 
65 
.243 
.156 
.253 
.162 
.263 
.169 
.274 
.175 
.284 
.182 
.295 
.189 
.306 
.196 
.317 
.203 
.328 
.210 
.339 
.217 
.351 
.225 
.362 
.232 
.374 
.240 
.387 
.248 
.399 
.255 
.411 
.263 
.424 
.272 
.437 
.280 
.450 
.288 
7 0 
.262 
.167 
.273 
.194 
.284 
.202 
.295 
.210 
.306 
.218 
.317 
.227 
.329 
.235 
.341 
.244 
.353 
.252 
.365 
.260 
.378 
.269 
.390 
.279 
.403 
.288 
.416 
.298 
.430 
.307 
.443 
.316 
.457 
.326 
.471 
.336 
.485 
.346 
7 5 
.281 
.218 
.292 
.227 
.304 
.236 
.316 
.246 
.328 
.255 
.340 
.265 
.353 
.274 
.365 
.284 
.378 
.294 
.391 
.304 
.405 
.315 
.418 
.325 
.432 
.336 
.446 
.347 
.460 
.358 
.475 
.369 
.490 
.381 
.504 
.392 
.520 
.404 
8 0 
.300 
.250 
.312 
.259 
.324 
.270 
.337 
.280 
.350 
.291 
.363 
.302 
.376 
.314 
.390 
.325 
.403 
.336 
.417 
.347 
.432 
.359 
.446 
.371 
.461 
.384 
.476 
.397 
.491 
.408 
.506 
.421 
.522 
.435 
.538 
.448 
.554 
.462 
8 5 
.318 
.281 
.331 
.292 
.345 
.303 
.358 
.315 
.372 
.327 
.385 
.340 
.400 
.353 
.414 
.366 
.429 
.379 
.443 
.392 
.459 
.405 
.474 
.418 
.490 
.432 
.505 
.447 
.522 
.460 
.538 
.474 
.555 
.489 
.572 
.504 
.589 
.519 
9 0 
.337 
.312 
.351 
.235 
.365 
.338 
.379 
.351 
.393 
.364 
.408 
.378 
.423 
.393 
.438 
.406 
.454 
.420 
.470 
.435 
.486 
.450 
.502 
.465 
.518 
.480 
.535 
.495 
.552 
.511 
.570 
.527 
.587 
.544 
.605 
.560 
.624 
.577 
The tons pol in residual molasses may be obtained by subtracting tons recoverable 
pol from tons pol in stock. 
221 
Table XX—Factors to be U s e d in Calculating Weight per Gallon of Molasses . 
Temp. °C 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
Factor A 
0.99975 
0.99978 
0.99980 
0.99983 
0.99985 
0.99988 
0.99990 
0.99993 
0.99995 
0.99998 
1.00000 
1.00003 
1.00005 
1.00008 
1.00010 
Factor B 
1.0013 
1.0014 
1.0015 
1.0016 
1.0017 
1.0019 
1.0021 
1.0023 
1.0025 
1.0027 
1.0028 
1.0030 
1.0033 
1.0035 
1.0038 
Temp. °C 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
Factor A 
1.00013 
1.00015 
1.00018 
1.00020 
1.00023 
1.00025 
1.00028 
1.00030 
1.00033 
1.00035 
1.00038 
1.00040 
1.00043 
1.00045 
1.00048 
1.00050 
Factor B 
1.0040 
1.0043 
1.0046 
1.0048 
1.0051 
1.0054 
1.0057 
1.0060 
1.0064 
1.0067 
1.0070 
1.0074 
1.0077 
1.0081 
1.0085 
1.0089 
Table XXI—Weights as Dec imal s of Ton. 
lb 
1 
2 
3 
4 
5 
6 
7 
ton 
.00045 
.00089 
.00134 
.00178 
.00223 
.00268 
.00312 
lb 
8 
9 
10 
11 
12 
13 
14 
ton 
.00357 
.00401 
.0045 
.0049 
.0054 
.0058 
.0062 
lb 
15 
16 
17 
18 
19 
20 
21 
ton 
.0067 
.0071 
.0076 
.0080 
.0085 
.0089 
.0094 
lb 
22 
23 
24 
25 
26 
27 
28 
ton 
.0098 
.0103 
.0107 
.0111 
.0116 
.0120 
.0125 
2 qr = . 025 ton, 3 qr = . 0375 ton and 4 qr = 1 cwt = . 05 ton. 
222 R E F E R E N C E TABLES 
R E F E R E N C E TABLES 223 
Table XXII—Density* (g/ml) of Water at Temperatures from 0 to 102 °C. 
According to M. Thiesen, Wiss. Abh. der Physikalisch-Technischen Reichsanstalt, 4, 
No. 1; 1904. 
Temp. °C 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
2 0 
2 1 
2 2 
2 3 
2 4 
2 5 
2 6 
2 7 
2 8 
2 9 
3 0 
3 1 
3 2 
3 3 
3 4 
Density 
0.99987 
0.99993 
0.99997 
0.99999 
1.00000 
0.99999 
0.99997 
0.99993 
0.99988 
0.99981 
0.99973 
0.99963 
0.99952 
0.99940 
0.99927 
0.99913 
0.99897 
0.99880 
0.99862 
0.99843 
0.99823 
0.99802 
0.99780 
0.99756 
0.99732 
0.99707 
0.99681 
0.99654 
0.99626 
0.99597 
0.99567 
0.99537 
0.99505 
0.99473 
0.99440 
Temp. °C 
3 5 
3 6 
3 7 
3 8 
3 9 
4 0 
4 1 
4 2 
4 3 
4 4 
4 5 
4 6 
4 7 
4 8 
4 9 
5 0 
5 1 
52 
5 3 
5 4 
5 5 
5 6 
5 7 
5 8 
5 9 
6 0 
6 1 
6 2 
6 3 
6 4 
6 5 
6 6 
6 7 
6 8 
6 9 
Density 
0.99406 
0.99371 
0.99336 
0.99299 
0.99262 
0.99225 
0.99186 
0.99147 
0.99107 
0.99066 
0.99024 
0.98982 
0.98940 
0.98896 
0.98852 
0.98807 
0.98762 
0.98715 
0.98669 
0.98621 
0.98573 
0.98524 
0.98478 
0.98425 
0.98375 
0.98324 
0.98272 
0.98220 
0.98167 
0.98113 
0.98059 
0.98005 
0.97950 
0.97894 
0.97838 
Temp. °C 
7 0 
7 1 
7 2 
7 3 
7 4 
7 5 
7 6 
7 7 
7 8 
7 9 
8 0 
8 1 
8 2 
8 3 
8 4 
8 5 
8 6 
8 7 
8 8 
8 9 
9 0 
9 1 
9 2 
9 3 
9 4 
9 5 
9 6 
9 7 
9 8 
9 9 
1 0 0 
1 0 1 
1 0 2 
Density 
0.97781 
0.97723 
0.97666 
0.97607 
0.97548 
0.97489 
0.97428 
0.97368 
0.97307 
0.97245 
0.97183 
0.97120 
0.97057 
0.96994 
0.96930 
0.96865 
0.96800 
0.96734 
0.96668 
0.96601 
0.96534 
0.96467 
0.96399 
0.96330 
0.96261 
0.96192 
0.96122 
0.96051 
0.95981 
0.95909 
0.95838 
0.95765 
0.95693 
1 imperial gallon of water at 62° F (16.7°C) weighs 10.0 lb. 
1 cubic foot of water at 62° F (16.7° C) weighs 62.288 lb. 
*The values in the above table, when divided by 0.099892, give the weight in pounds of 1 gallon of water 
at the corresponding temperatures. 

R E F E R E N C E TABLES 225 
226 R E F E R E N C E TABLES 
Table XXV 
Requirements for Apparatus for U s e in the Analys i s of Cane for 
Payment Purposes 
When apparatus is used for the analysis of cane for payment purposes it must 
conform either to a specification from a recognised Standards authority or to the follow-
ing requirements. 
Brix Hydrometers 
The hydrometer must be of an approved shape, size and construction. The scale 
shall correspond to one of the following ranges: 0 to 10, 10 to 20, 15 to 25, 20 to 30. It 
shall be calibrated to read degrees Brix at 20 °C and the range shall be divided in inter-
vals of one tenth of one degree with full numbering at each unit graduation mark. The 
graduation lines shall be fine, of uniform thickness and at right angles to the axis of 
the hydrometer. The scale shall be firmly secured inside the stem and without twist. 
The readings must conform to a tolerance of ± 0.1° Brix at any point of the scale. 
The following inscriptions shall be clearly marked on the scale within the stem and 
shall not encroach on the scale or numbering. 
(a) The makers name 
(b) Serial number 
(c) Brix or per cent of sugar by weight 
(d) Temp. 20 °C 
Polarimeter or Saccharimeter tubes 
The tube must be straight. The length of the tube at 20 °C shall be within ± 0.03 
per cent of the nominal lengths of 100 and 200 mm. The ends of the tube must be 
parallel and ground flat in a plane at right angles to the axis of the tube and no detect-
able change in reading should be observed on rotating the tube. 
Each end must project beyond the ferrule or threaded collar to a distance not 
exceeding 1 mm, such tha t a cover glass placed over the end of the tube does not touch 
any other par t of the tube. 
Cover g lasses 
Cover glasses for polarimeter or saccharimeter tubes must be made of clear optical 
glass and free from strain. They must have plane parallel surfaces free from scratches. 
The edges should be slightly bevelled to prevent chipping. A thickness of 1. 5 to 2 mm 
is desirable for tubes of 200 mm length. 
Polar imeters and Saccharimeters 
These must be in a satisfactory condition mechanically and optically. The error at 
any point of the scale must not exceed ± 0 . 1 scale degrees. It is recommended tha t 
they should be calibrated in terms of the International Sugar Scale corresponding to a 
normal weight of 26. 000 grammes. 
T h e r m o m e t e r s 
Thermometers are to be of mercury in glass, solid stem, or of an approved enclosed 
scale type. All ranges up to a maximum of 110 °C to include zero. The maximum error 
allowed is 1.0 °C. Total immersion thermometers are preferred. Inscriptions should 
include the maker or vendors name or mark and the immersion for which the ther-
mometer is calibrated. 
Refractometers 
These must be in satisfactory condition mechanically and optically. The maximum 
error at any point of the scale should be the equivalent of 0. 2 degrees Brix. 
Balances 
These should be within accepted tolerances for sensitivity and reproducibility 
corresponding to the maximum capacity of the balance. Efficient damping is required 
for rapid weighing. 
Weights 
Weights to lOOg should conform to Class B tolerances as specified by the National 
Standards Laboratory Australia. 
Weights of nominal values from lOOg to 1kg should conform to tolerances of 15 
parts in 100,000. 
REFERENCE TABLES 227 
Table XXV—continued 
T o l e r a n c e s (B Class) for Apparatus for General Use 
in Sugar Factory Laboratories 
The tolerances shown in this Table have been compiled from specifications issued 
by the British Standards Institution. They are recommended as being suitable for 
apparatus for general use. 
Flasks—One mark volumetric 
Nominal capcity ml 
Tolerance ± ml 
5 
0.04 
10 
0.04 
2 5 
0.06 
5 0 
0.10 
100 
0.15 
2 0 0 
0.30 
2 5 0 
0.30 
5 0 0 
0.50 
1000 
0.80 
2000 
1.20 
(British Standard 1792:1960 endorsed as Australian Standard R.20-1961) 
S u g a r F l a s k s 
Type 1—two graduation marks. 
Type 2—single graduation mark for polarization of sugars. 
Nominal capacity ml 
Tolerance ± ml 
(British Standard 675:1953) 
Nominal 
capacity ml 
1 
2 
5 
5 
10 
10 
2 5 
2 5 
5 0 
100 
Subdivision 
m l 
0.01 
0.02 
0.02 
0.05 
0.02 
0 . 1 
0.05 
0 . 1 
0 . 1 
0 . 2 
Tolerance on 
capacity ± ml 
0.01 
0.02 
0.02 
0.04 
0.02 
0.05 
0.05 
0 . 1 
0 . 1 
0 . 2 
Delivery times 
m i n . 
2 0 
2 0 
50 
2 0 
100 
15 
8 5 
35 
7 5 
6 5 
max. 
5 0 
5 0 
120 
5 0 
2 0 0 
4 0 
170 
70 
150 
1 3 0 
(British Standard 846:1962 endorsed as Australian Standard R. 10-1964) 
Pipettes—One mark bulb 
Nominal capacity ml 
Tolerance ± ml 
Delivery times (seconds) 
minimum 
maximum 
1 
.015 
5 
15 
2 
. 0 2 
5 
15 
5 
. 0 3 
10 
2 5 
10 
. 0 4 
10 
2 5 
15 
. 0 5 
15 
3 0 
2 0 
. 0 6 
2 0 
4 0 
2 5 
. 0 6 
2 0 
4 0 
5 0 
. 0 8 
2 0 
5 0 
1 0 0 
. 1 2 
3 0 
6 0 
(British Standard 1583:1961 endorsed as Australian Standard R. 16-1962) 
228 R E F E R E N C E TABLES 
T a b l e XXV—continued 
Graduated Pipettes 
Type 1—for delivery from zero mark to graduation marks. 
Type 2—for delivery down to jet. 
Nominal capacity ml 
Subdivisions ml 
Tolerance ± ml 
1 
.01 
.01 
2 
.02 
.02 
5 
.05 
.05 
10 
.10 
.10 
25 
.10 
.20 
Delivery times, all sizes 
Type 1 Minimum 15 s Maximum 30 s 
Type 2 Minimum 10 s Maximum 25 s 
(British Standard 700:1962, amendment No. 1 published 7/5/1963) 
Measuring Cylinders,—unstoppered 
Nominal capacity ml 
Tolerance ± ml 
(British Standard 604:1952 endorsed as Australian Standard R.6-1953) 
Thermometers—Mercury in glass type 
Range °C 
— 5 to +100 
— 20 to + 6 0 
50 to 110 
99 to 160 
150 to 210 
— 5 to + 1 0 5 
— 5 to +105 
— 5 to +105 
— 5 to +250 
— 5 to +360 
95 to 205 
British 
Standard 
593 
593 
593 
593 
593 
1704 
593 
1704 
1704 
1704 
593 
Graduation 
interval deg C 
0.1 
0.2 
0.2 
0.2 
0 .2 
0 .5 
1.0 
1.0 
1.0 
1.0 
1.0 
Tolerance ± °C 
Total 
immersion 
0.2 
0 .3 
0 .3 
0.4 
0.6 
0 .5 
0 .3 
1.0 
1.0 
2 .0 
0 .5 
Partial 
immersion 
0 .4 
0.4 
0 .6 
0.8 
1.2 
0.6 
0.6 
1.0 
1.0 
3.0 
1.0 
Metric Weights 
Nominal 
value kg 
Tolerance ± rag 
5 
2 5 0 
3 
150 
2 
100 
1 
5 0 
Nominal value g 
Tolerance ± mg 
5 0 0 
2 5 
3 0 0 
15 
2 0 0 
10 
100 
5 
5 0 
2 . 5 
3 0 
1 . 5 
2 0 
1 . 0 
10 
to 
0 .1 
0 . 5 
0.05 
to 
0.001 
0 . 2 
For values not tabulated the tolerances are the same as those given for the next 
larger tabulated value. The tolerances for burettes, graduated pipettes, graduated 
cylinders, and thermometers apply to the whole of the graduated portion or to any 
fraction of it. 


R E F E R E N C E TABLES 231 
Table XXVII—Temperature Conversion Table. 
(Albert Sauveur.) 
c 
— 17.8 
-17.2 
— 16.7 
-16.1 
— 15.6 
— 15.0 
-14.4 
-13.9 
— 13.3 
-12.8 
-12.2 
— 11.7 
-11.1 
-10.6 
-10.0 
- 9.44 
— 8.89 
- 8.33 
- 7.78 
- 7.22 
- 6.67 
- 6.11 
- 5.56 
— 5.00 
— 4.44 
- 3.89 
— 3.33 
- 2.78 
- 2.22 
— 1.67 
- 1.11 
— 0.56 
0.00 
0.56 
1.11 
1.67 
2.22 
2.78 
3.33 
3.89 
4.44 
5.00 
5.56 
6.11 
6.67 
7.22 
7.78 
8.33 
8.89 
9.44 
10.0 
10.6 
11.1 
11.7 
12.2 
12.8 
13.3 
13.9 
14.4 
15.0 
15.6 
16.1 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 
50 
51 
52 
53 
54 
55 
56 
57 
58 
59 
60 
61 
F 
32.0 
33.8 
35.6 
37.4 
39.2 
41.0 
42.8 
44.6 
46.4 
48.2 
50.0 
51.8 
53.6 
55.4 
57.2 
59.0 
60.8 
62.6 
64.4 
66.2 
68.0 
69.8 
71.6 
73.4 
75.2 
77.0 
78.8 
80.6 
82.4 
84.2 
86.0 
87.8 
89.6 
91.4 
93.2 
95.0 
96.8 
98.6 
100.4 
102.2 
104.0 
105.8 
107.6 
109.4 
111.2 
113.0 
114.8 
116.6 
118.4 
120.2 
122.0 
123.8 
125.6 
127.4 
129.2 
131.0 
132.8 
134.6 
136.4 
138.2 
140.0 
141.8 
C 
16.7 
17.2 
17.8 
18.3 
18.9 
19.4 
20.0 
20.6 
21.1 
21.7 
22.2 
22.8 
23.3 
23.9 
24.4 
25.0 
25.6 
26.1 
26.7 
27.2 
27.8 
28.3 
28.9 
29.4 
30.0 
30.6 
31.1 
31.7 
32.2 
32.8 
33.3 
33.9 
34.4 
35.0 
35.6 
36.1 
36.7 
37.2 
37.8 
38.3 
38.9 
39.4 
40.0 
40.6 
41.1 
41.7 
42.2 
42.8 
43.3 
43.9 
44.4 
45.0 
45.6 
46.1 
46.7 
47.2 
47.8 
48.3 
48.9 
49.4 
50.0 
60.6 
62 
63 
64 
65 
66 
67 
68 
69 
70 
71 
72 
73 
74 
75 
76 
77 
78 
79 
80 
81 
82 
83 
84 
85 
86 
87 
88 
89 
90 
91 
92 
93 
94 
95 
96 
97 
98 
99 
100 
101 
102 
103 
104 
105 
106 
107 
108 
109 
110 
111 
112 
113 
114 
115 
116 
117 
118 
119 
120 
121 
122 
123 
F 
143.6 
145.4 
147.2 
149.0 
150.8 
152.6 
154.4 
156.2 
158.0 
159.8 
161.6 
163.4 
165.2 
167.0 
168.8 
170.6 
172.4 
174.2 
176.0 
177.8 
179.6 
181.4 
183.2 
185.0 
186.8 
188.6 
190.4 
192.2 
194.0 
195.8 
197.6 
199.4 
201.2 
203.0 
204.8 
206.6 
208.4 
210.2 
212.0 
214 
216 
217 
219 
221 
223 
225 
226 
228 
230 
232 
234 
235 
237 
239 
241 
243 
244 
246 
248 
250 
252 
253 
C 
51.1 
51.7 
52.2 
52.8 
53.3 
53.9 
54.4 
55.0 
55.6 
56.1 
56.7 
57.2 
57.8 
58.3 
58.9 
59.4 
60.0 
60.6 
61.1 
61.7 
62.2 
62.8 
63.3 
63.9 
64.4 
65.0 
65.6 
66.1 
66.7 
67.2 
67.8 
68.3 
68.9 
69.4 
70.0 
70.6 
71.1 
76.7 
82.2 
87.8 
93.3 
98.9 
100 
104 
110 
116 
121 
127 
132 
138 
143 
149 
154 
160 
166 
171 
177 
182 
188 
193 
199 
204 
124 
125 
126 
127 
128 
129 
130 
131 
132 
133 
134 
135 
136 
137 
138 
139 
140 
141 
142 
143 
144 
145 
146 
147 
148 
149 
150 
151 
152 
153 
154 
155 
156 
157 
158 
159 
160 
170 
180 
190 
200 
210 
212 
220 
230 
240 
250 
260 
270 
280 
290 
300 
310 
320 
330 
340 
350 
360 
370 
380 
390 
400 
F 
255 
257 
259 
261 
262 
264 
266 
268 
270 
271 
273 
275 
277 
279 
280 
282 
284 
286 
288 
289 
291 
293 
295 
297 
298 
300 
302 
304 
306 
307 
309 
311 
313 
315 
316 
318 
320 
338 
356 
374 
392 
410 
413 
428 
446 
464 
482 
500 
518 
536 
554 
572 
590 
608 
626 
644 
662 
680 
698 
716 
734 
752 
232 R E F E R E N C E TABLES 
Table XXVII—continued. 
c 
210 
216 
221 
227 
232 
238 
243 
249 
254 
260 
266 
271 
277 
410 
420 
430 
440 
450 
460 
470 
480 
490 
500 
510 
520 
530 
F 
770 
788 
806 
824 
842 
860 
878 
896 
914 
932 
950 
968 
986 
C 
282 
288 
293 
299 
304 
310 
316 
321 
327 
332 
338 
343 
349 
540 
550 
560 
570 
580 
590 
600 
610 
620 
630 
640 
650 
660 
F 
1004 
1022 
1040 
1058 
1076 
1094 
1112 
1130 
1148 
1166 
1184 
1202 
1220 
C 
354 
360 
366 
371 
377 
382 
388 
393 
399 
404 
410 
416 
421 
670 
680 
690 
700 
710 
720 
730 
740 
750 
760 
770 
780 
790 
F 
1238 
1256 
1274 
1292 
1310 
1328 
1346 
1364 
1382 
1400 
1418 
1436 
1454 
NOTE.—The numbers in bold face type refer to the temperature either in degrees Centigrade or 
Fahrenheit which it is desired to convert into the other scale. If converting from degrees Fahrenheit 
to degrees Centigrade the equivalent temperature will be found in the left column, while if converting 
from degrees Centigrade to degrees Fahrenheit, the answer will be found in the column on the right. 
Table XXVIII—Equivalents. 
Volume and Capacity Equivalents. 
in» 
1 
1,728 
277.42 
231 
61.03 
ft3 
0.0005787 
1 
0.1605 
0.1337 
0.03531 
U K gal 
0.00360 
6.225 
1 
0.833 
0.22 
US gal 
0.00433 
7.481 
1.2 
1 
0.2642 
litres 
0.01639 
28.32 
4.546 
3.785 
1 
m« 
1.639 x I0-« 
0.02832 
4.546 x 10~3 
3.785 x 10~s 
1 x 10-» 
M a s s Equivalents. 
kg 
1 
0.02835 
0.4536 
1,016 
907.2 
1,000 
oz 
35.27 
1 
16 
35,840 
32,000 
35,274 
lb 
2.205 
0.0625 
1 
2,240 
2,000 
2,205 
Long ton 
0.0009842 
0.0000279 
0.0004464 
1 
0.8929 
0.9842 
Short ton 
0.001102 
0.00003125 
0.0005 
1.12 
1 
1.102 
Metric (tonne) 
0.001 
0.00002835 
0.0004536 
1.016 
0.9072 
1 
REFERENCE TABLES 233 
Table XXVIII—continued. 
Density Equivalents. 
g/ml 
1 
0.01602 
lb/ft3 
62.43 
lb/UK gal 
10 
.1604 
Linear Measure Equivalents. 
k m 
10-6 
2.54 x 10-5 
3.048 x 10-* 
9.144 x 10-* 
c m 
105 
1 
2.54 
30.48 
914.4 
in 
39,370 
0.3937 
12 
36 
f t 
3,280.83 
0.032808 
0.0833 
1 
3 
y d 
1,093.61 
0.010936 
0.02778 
0.3333 
1 
mile 
micro-
metre 0.62137 
0.62 x 10~4 
0.158 x 10-4 
0.1894 x 10-3 
0.5682 x 10~3 
10» 
10* 
25,400 
304,801 
914,402 
Surface and Area Equivalents. 
Pressure Equivalents. 
R E F E R E N C E TABLES 
Table XXVIII—continued. 
Heat, Energy and Work Equivalents. 
Heat F low Equivalents. 
cal/sec cm2 
1 
.0002778 
.0000754 
cal/h cm2 
3,600 
1 
0.2714 
Btu/h ft2 
13,263 
3.684 
1 
REFERENCE TABLES 
Table XXX—Circles: Diameters, Areas, Circumferences. 
235 
Table XXXII—Capacities of Rectangular Tanks (UK gal) for Each Foot of Depth. 
Tank width 
(ft in) 
0—6 . 
1—0 . 
1-6 . 
2—0 . 
2 - 6 . 
3—0 . 
3—6 . 
4—0 . 
4—6 . 
5—0 . 
5—6 . 
6 - 0 . 
6—6 . 
7—0 . 
7—6 . 
8 - 0 . 
Tank length (ft in) 
0-6 
1.56 
3.12 
4.68 
6.24 
7.80 
9.36 
10.92 
12.48 
14.04 
15.60 
17.16 
18.72 
20.28 
21.84 
23.40 
24.96 
1—0 
3.12 
6.24 
9.36 
12.48 
15.60 
18.72 
21.84 
24.96 
28.08 
31.20 
34.32 
37.44 
40.56 
43.68 
46.80 
49.92 
1-6 
4.68 
9.36 
14.04 
18.72 
23.40 
28.08 
32.76 
37.44 
42.12 
46.80 
51.48 
56.16 
60.84 
65.52 
70.20 
74.88 
2—0 
6.24 
12.48 
18.72 
24.96 
31.20 
37.44 
43.68 
49.92 
56.16 
62.40 
68.64 
74.88 
81.12 
87.36 
93.60 
99.84 
2—6 
7.80 
15.60 
23.40 
31.20 
39.00 
46.80 
54.60 
62.40 
70.20 
78.00 
85.80 
93.60 
101.40 
109.20 
117.00 
124.80 
3—0 
9.36 
18.72 
28.08 
37.44 
46.80 
56.16 
65.52 
74.88 
84.24 
93.60 
102.96 
112.32 
121.68 
131.04 
140.40 
149.76 
3 - 6 
10.92 
21.84 
32.76 
43.68 
54.60 
65.52 
76.44 
87.36 
98.28 
109.20 
120.12 
131.04 
141.96 
152.88 
163.80 
174.72 
4—0 
12.48 
24.96 
37.44 
49.92 
62.40 
74.88 
87.36 
99.84 
112.32 
124.80 
137.28 
149.76 
162.24 
174.72 
187.20 
199.68 
4—6 
14.04 
28.08 
42.12 
56.16 
70.20 
84.24 
98.28 
112.32 
126.36 
140.40 
154.44 
168.48 
182.52 
196.56 
210.60 
224.64 
5 - 0 
15.60 
31.20 
46.80 
62.40 
78.00 
93.60 
109.20 
124.80 
140.40 
156.00 
171.60 
187.20 
202.80 
218.40 
234.00 
249.60 
5—6 
17.16 
34.32 
51.48 
68.64 
85.80 
102.96 
120.12 
137.28 
154.44 
171.60 
188.76 
205.92 
223.08 
240.24 
257.40 
274.56 
6 - 0 
18.72 
37.44 
56.16 
74.88 
93.60 
112.32 
131.04 
149.76 
168.48 
187.20 
205.92 
224.64 
243.36 
262.08 
280.80 
299.52 
6—6 
20.28 
40.56 
60.84 
81.12 
101.40 
121.68 
141.96 
162.24 
182.52 
202.80 
223.08 
243.36 
263.64 
283.92 
304.20 
324.48 
7—0 
21.84 
43.68 
65.52 
87.36 
109.20 
131.04 
152.88 
174.72 
196.56 
218.40 
240.24 
262.08 
283.92 
305.76 
327.60 
349.44 
REFERENCE TABLES 237 
Table XXXIII—Capacity of Horizontal Cylindrical Tanks at Varying Levels. 
i = depth of liquid 
d = diameter of vessel. 
i /d 
. 0 1 
. 0 2 
. 0 3 
. 0 4 
. 0 5 
. 0 6 
. 0 7 
. 0 8 
. 0 9 
. 1 0 
. 1 1 
. 1 2 
. 1 3 
. 1 4 
. 1 5 
. 1 6 
. 1 7 
. 1 8 
. 1 9 
. 2 0 
. 2 1 
. 2 2 
. 2 3 
. 2 4 
. 2 5 
fraction of 
total 
.0017 
.0048 
.0087 
.0134 
.0187 
.0245 
.0308 
.0375 
.0446 
.0520 
.0598 
.0680 
.0764 
.0851 
.0941 
.1033 
.1127 
.1224 
.1323 
.1424 
.1527 
.1631 
.1737 
.1845 
.1955 
i /d 
. 2 6 
. 2 7 
. 2 8 
. 2 9 
. 3 0 
. 3 1 
. 3 2 
. 3 3 
. 3 4 
. 3 5 
. 3 6 
. 3 7 
. 3 8 
. 3 9 
. 4 0 
. 4 1 
. 4 2 
. 4 3 
. 4 4 
. 4 5 
. 4 6 
. 4 7 
. 4 8 
. 4 9 
. 5 0 
fraction of 
total 
.2066 
.2178 
.2292 
.2407 
.2523 
.2640 
.2759 
.2878 
.2998 
.3119 
.3241 
.3364 
.3487 
.3611 
.3735 
.3860 
.3986 
.4112 
.4238 
.4364 
.4491 
.4618 
.4745 
.4873 
.5000 
i /d 
. 5 1 
. 5 2 
. 5 3 
. 5 4 
. 5 5 
. 5 6 
. 5 7 
. 5 8 
. 5 9 
. 6 0 
. 6 1 
. 6 2 
. 6 3 
. 6 4 
. 6 5 
. 6 6 
. 6 7 
. 6 8 
. 6 9 
. 7 0 
. 7 1 
. 7 2 
. 7 3 
. 7 4 
. 7 5 
fraction of 
total 
.5127 
.5255 
.5382 
.5509 
.5636 
.5762 
.5888 
.6014 
.6140 
.6265 
.6389 
.6513 
.6636 
.6759 
.6881 
.7002 
.7122 
.7241 
.7360 
.7477 
.7593 
.7708 
.7822 
.7934 
.8045 
i /d 
. 7 6 
. 7 7 
. 7 8 
. 7 9 
. 8 0 
. 8 1 
. 8 2 
. 8 3 
. 8 4 
. 8 5 
. 8 6 
. 8 7 
. 8 8 
. 8 9 
. 9 0 
. 9 1 
. 9 2 
. 9 3 
. 9 4 
. 9 5 
. 9 6 
. 9 7 
. 9 8 
. 9 9 
1.00 
fraction of 
total 
.8155 
.8263 
.8369 
.8473 
.8576 
.8677 
.8776 
.8873 
.8967 
.9059 
.9149 
.9236 
.9320 
.9402 
.9480 
.9554 
.9625 
.9692 
.9755 
.9813 
.9866 
.9913 
.9952 
.9983 
1.0000 
Table XXXIV—Amount of CaO in Milk of Lime of Various Densit ies at 15 °C. 
238 R E F E R E N C E TABLES 
Table XXXV—Fuel Value of Bagasse . 
(a) G r o s s Calorific Value (Bh). 
Formula Bh = 8345 — 22.1 pol — 83.45 water Btu/lb. 
Moisture 
per cent bagasse 
38 
3 9 
4 0 
41 
4 2 
4 3 
4 4 
4 5 
4 6 
47 
4 8 
4 9 
5 0 
51 
52 
5 3 
5 4 
5 5 
Pol per 
1 . 0 
5,152 
5,068 
4,985 
4,901 
4,818 
4,735 
4,651 
4,568 
4,484 
4,401 
4,317 
4,234 
4,150 
4,067 
3,984 
3,900 
3,817 
3,733 
Interpolations: 
per cent moisture. 
subtract 
. 1 
8 
1 . 5 
5,141 
5,057 
4,974 
4,890 
4,807 
4,723 
4,640 
4,557 
4,473 
4,390 
4,306 
4,223 
4,139 
4,056 
3,972 
3,889 
3,806 
3,722 
. 2 
17 
2 . 0 
5,130 
5,046 
4,963 
4,879 
4,796 
4,712 
4,629 
4,546 
4,462 
4,379 
4,295 
4,212 
4,128 
4,045 
3,961 
3,878 
3,795 
3,711 
. 3 
2 5 
cent bagasse 
2 . 5 
5,119 
5,035 
4,952 
4,868 
4,785 
4,701 
4,618 
4,535 
4,451 
4,367 
4,284 
4,201 
4,117 
4,034 
3,950 
3,867 
3,783 
3,700 
3 . 0 
5,108 
5,024 
4,941 
4,857 
4,774 
4,690 
4,607 
4,523 
4,440 
4,357 
4,273 
4,190 
4,106 
4,023 
3,939 
3,856 
3,772 
3,689 
4 .5 
33 42 
. 6 
5 0 
3 . 5 
5,097 
5,013 
4,930 
4,846 
4,763 
4,679 
4,596 
4,512 
4,429 
4,346 
4,262 
4,179 
4,095 
4,012 
3,928 
3,845 
3,761 
3,678 
. 7 
5 8 
4 . 0 
5,085 
5,002 
4,919 
4,835 
4,752 
4,668 
4,585 
4,501 
4,418 
4,334 
4,251 
4,168 
4,084 
4,001 
3,917 
3,834 
3,750 
3,667 
.8 | .9 
67 75 
Approximate formula Bh = Dry Substance x 82 Btu/lb. 
(b) Net Calorific Value (B1). 
Formula B1 = 7783 — 22.1 pol — 88.27 water Btu/lb. 
Moisture 
per cent 
bagasse 
38 
3 9 
4 0 
41 
4 2 
4 3 
4 4 
4 5 
4 6 
47 
4 8 
4 9 
5 0 
5 1 
5 2 
5 3 
5 4 
5 5 
Interpolat 
per cent 
subtract 
1 . 0 
4,407 
4,318 
4,230 
4,142 
4,054 
3,965 
3,877 
3,789 
3,701 
3,612 
3,524 
3,436 
3,347 
3,259 
3,171 
3,083 
2,994 
2,906 
1 . 5 
4,396 
4,307 
4,219 
4,131 
4,043 
3,954 
3,866 
3,778 
3,690 
3,601 
3,513 
3,425 
3,336 
3,248 
3,160 
3,072 
2,983 
2,895 
ions: 
moisture . 1 
9 
Pol per cent bagasse 
2 . 0 
4,385 
4,296 
4,208 
4,120 
4,031 
3,943 
3,855 
3,767 
3,679 
3,590 
3,502 
3,414 
3,325 
3,237 
3,149 
3,061 
2,972 
2,884 
. 2 
18 
2 . 5 
4,373 
4,285 
4,197 
4,109 
4,020 
3,932 
3,844 
3,756 
3,668 
3,579 
3,491 
3,403 
3,314 
3,226 
3,138 
3,050 
2,961 
2,873 
. 3 
2 6 3 
3 . 0 
4,362 
4,274 
4,186 
4,098 
4,009 
3,921 
3,833 
3,745 
3,657 
3,568 
3,480 
3,392 
3,303 
3,215 
3,127 
3,039 
2,950 
2,862 
4 
5 
3 . 5 
4,351 
4,263 
4,175 
4,087 
3,998 
3,910 
3,822 
3,734 
3,646 
3,557 
3,469 
3,381 
3,292 
3,204 
3,116 
3,028 
2,939 
2,851 
. 5 
4 4 
. 6 
5 3 
4 . 0 
4,340 
4,252 
4,164 
4,076 
3,987 
3,899 
3,811 
3,723 
3,635 
3,646 
3,458 
3,370 
3,281 
3,193 
3,105 
3,017 
2,928 
2,840 
. 7 
6 2 
4 . 5 
4,329 
4,241 
4,153 
4,064 
3,976 
3,888 
3,800 
3,712 
3,624 
3,535 
3,448 
3,358 
3,270 
3.182 
3,094 
3,006 
2,917 
2,829 
. 8 
70 
. 9 
79 
REFERENCE TABLES 239 
Table XXXVI—Boiling Point Elevation of Sugar Solutions and Cane Juices (°F) at 760 mm Pressure. 
Brix 
10 
15 
20 
25 
30 
35 
40 
45 
50 
55 
60 
65 
70 
75 
80 
85 
90 
94 
100 
0.2 
0.4 
0.5 
0.7 
1.1 
1.4 
1.8 
2.5 
3.2 
4.1 
5.4 
6.8 
9.2 
12.6 
16.9 
23.4 
35.3 
54.9 
90 
0.2 
0.4 
0.5 
0.9 
1.3 
1.6 
2.0 
2.7 
3.4 
4.5 
5.8 
7.4 
9.9 
13.5 
18.0 
24.7 
36.9 
80 
0.2 
0.4 
0.5 
0.9 
1.3 
1.8 
2.3 
3.2 
4.0 
5.0 
6.5 
8.1 
10.8 
14.4 
18.9 
25.9 
38.2 
Purity 
70 
0.2 
0.4 
0.7 
1.1 
1.4 
2.0 
2.7 
3.6 
4.5 
5.6 
7.2 
8.8 
11.7 
15.5 
20.3 
27.5 
40.3 
60 
0.4 
0.5 
0.7 
1.3 
1.8 
2.3 
3.1 
4.0 
5.0 
6.3 
7.9 
9.6 
12.8 
16.9 
22.1 
29.5 
42.7 
50 
0.4 
0.5 
0.9 
1.4 
2.0 
2.5 
3.4 
4.3 
5.6 
7.0 
8.8 
10.8 
13.9 
18.2 
23.6 
31.3 
45.5 
40 
0.4 
0.7 
1.1 
1.6 
2.2 
2.9 
3.8 
4.9 
6.1 
7.7 
9.7 
11.7 
14.9 
19.4 
25.4 
34.4 
240 R E F E R E N C E TABLES 
Table XXXVII 
Showing weights of pure sugar syrup filtered (between 2 and 7 minutes after appli-
cation of pressure) at various temperatures, under the standard conditions of the Rapid 
Filterability Test, viz. 
0.48 per cent filter aid on solids 
9 .0 pH obtained by buffer 
(This table applies only to Celite 505 standardized in October 1966. When this batch is 
exhausted, any further supply of filter aid will be accompanied by a table appropriate 
to the new batch.) 
R E F E R E N C E TABLES 241 
T a b l e XXXVII—Continued 
Temp. °C 
22.0 
. 1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
23.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
24.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
25.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
26.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
Wt. of nitrate 
(grammes) 
177 
178 
179 
179 
180 
180 
181 
182 
182 
183 
183 
184 
185 
185 
186 
186 
187 
188 
188 
189 
189 
190 
191 
191 
192 
192 
193 
194 
194 
195 
196 
196 
197 
197 
198 
199 
199 
200 
200 
201 
202 
202 
203 
204 
204 
205 
205 
206 
207 
207 
Temp. °C 
27.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
28.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
29.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
30.0 
.1 
.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
31.0 
.1 
. 2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 
Wt. of nitrate 
(grammes) 
208 
208 
209 
210 
210 
211 
212 
212 
213 
213 
214 
215 
215 
216 
217 
217 
218 
218 
219 
220 
220 
221 
222 
222 
223 
224 
224 
225 
225 
226 
227 
227 
228 
229 
229 
230 
231 
231 
232 
233 
233 
234 
234 
235 
236 
236 
237 
238 
238 
239 
242 R E F E R E N C E TABLES 
Table XXXVIII—International A t o m i c Weights , 1966 
(Published by the C.R.C. Handbook of Chemistry and Physics.) 
N O T E : The above atomic weights are based on the isotope CI2, whereas previous 
tables were based on 0 = 16.000. 
INDEX 
First Aid, 181 
A 
Absolute juice, 1 
Absorptiometer, 41 
Acid, definition of, 145 
dissociation of, 144 
normal solutions, 91 
Air in juice, 96 
Alkali, definition, 145 
Alkalinity, 139, 178 
Alkalis, normal solutions, 91 
Amici prisms, 15 
Analyser prism, 22 
Analysis of— 
bagasse, 102 
boiler water, 138, 177 
cane, 104 
effluents, 130 
filter cake, (see mud) 
gums, 126 
lime, 132 
mud, 124 
sugar, 116 
water, 143 
Analytical methods— 
contents for, 94 
for specific analyses, refer to the individual 
analysis involved, 
Angular rotation, 23 
Apparent (analyses), 1 
Ash, 1 
determination, 114 
B 
Back roller juice, 1 
Bagacillo, 1 
pol added to filter cake by, 155 
Bagasse—• 
analysis, 102 
Brix, 153 
moisture, 102 
pol, 103 
calorific value, 168 
definition, 1 
equivalent, 168 
per cent cane, 154 
preparation of sample, 81, 102 
samples, preservation, 81 
sampling, 81 
wet disintegrator, 103 
Balance— 
analytical, 51 
constant load, 52 
for coarse weighing, 51, 57 
requirement for cane payment (table XXV) 
sensitivity, 52 
setting up the, 53 
testing, 55, 77 
weighing, 54 
weights, 53 
Basic lead acetate— 
analysis, 88 
dry, 88 
safety precautions, 88 
solution, 88 
specification, 88 
Bichromate filter, 27 
Birefringence, effect of, 21, 34 
Boiler efficiency, 166 
condensation loss, 169 
measurement, 168 
miscellaneous losses, 170 
sensible heat loss, 169 
unburnt gas loss, 170 
Boiler water— 
alkalinity, 84, 139, 178 
analysis, 138, 178 
reagents for, 84 
chemical dosage, 179 
hardness, 141, 179 
phosphates, 140, 178 
removal of oxygen, 176 
sampling, 177 
sugar in, 180 
sulphates in, 142, 179 
sulphites in, 141, 178 
total dissolved solids, 142, 177, 179 
treatment, 139, 173 
prevention of scale, 174 
problems in sugar industry, 179 
Boiler station, the, 166 
Boiling house efficiency, 164 
E.S.G., 165 
recovery, 153, 165 
reduced, 165 
Brix— 
definition, 1 
determination— 
by hydrometer, 95 
by pycnometer, 62 
by refractometer, 18, 95, 105 
for cane payment, 96 
indirect cane analysis, 105 
of mill products, 95 
of sugar solution, 67 
significance of, 97 
temperature corrections in, 97 
refractometer, 1 
Brix hydrometer— 
calibration, 75 
dimensions, 67 
for cane payment, 96 
ranges, 67 
requirement for cane payment (table XXV) 
scale, 66, 67 
temperature of calibration, 67 
temperature corrections, 67, table 1 
tolerance, (table XXV) 
Buffer solutions— 
reagents for, 85 
Bulk density, prepared cane, 1 
Burettes— 
calibration, 71 
specification, (table XXV) 
tolerance, 71 
Calcite, 21, 22 
Calculations in chemical control, 151 
boiling house efficiency, 164 
boiling house recovery, 153, 165 
c.c.s. formula, 2, 106 
clarified juice per cent cane, 156 
coefficient of work, 165 
concentration and evaporation, 156 
crystal content, 161 
dilution, 155 
equivalent standard granulated, 161 
evaporation coefficient, 156 
expected puri ty of molasses, 161 
extraction, 153 
reduced extraction, 163 
maceration per cent fibre, 155 
materials balances, 151 
overall recovery, 153 
pol balance, 152 
empirical system, 152 
direct analysis, 153 
recovery formulae, 157 
S.J.M., 157 
Winter-Carp., 157 
retention (rotary fiters), 156 
taking stock, 159 
weekly report, 160 
to date averages, 162 
Calibration of— 
Brix hydrometers, 75 
pol tubes, 75, 77 
thermometers, 75 
volumetric glassware, 69, 77 
burettes, 71 
flasks, 70 
measuring cylinders, 73 
pipettes, 72 
Calomel electrode, 147 
Calorific values of fuels, 167 
Canada balsam, 21 
Cane— 
analysis, 104 
direct, 104 
whole stalk, 107 
Brix by disintergrator method, 105 
C.C.S., 1, 106 
definition, 1 
fibre, 107 
maturity, 19, 78 
moisture, 105 
pol in cane, 152 
pol by disintergrator method, 105 
pol in open cells, 106 
sample preparation, 105 
sampling, 78 
Cane maturity, 78 
by refractometer, 19 
Caustic cleaning solution— 
determination of concentration, 133 
Caustic embrittlement, 175, 179 
C C S — 
definition, 1 
formula, 2 
C e l l -
Faraday, 30, 33 
saturation, 137 
Chemical control, calculations, 151 
Chemical dosage of boilers, 179 
Clarifiability test, 133 
reagents, 85 
Clarified juice— 
definition, 2 
per cent cane, 156 
pH measurement, 149 
phosphates, 129 
turbidity measurement, 42 
Cleansing solution, glassware, 69, 86 
Clerget— 
divisors, 111 
method for sucrose, 108 
Coal, calorific value, 168 
Coefficient of supersaturation, 136 
Coefficient of work, 165 
definition, 2 
upper limit, 165 
Colorimetry, 42 
Colorimetric determination— 
pH, 145 
phosphates, 128 
starch, 123 
Colour, in raw sugar, 124 
Commercial cane sugar— 
definition, 1 
formula, 2 
Co mparator— 
colour, 140 
measurement of pol tubes, 77 
measurement of pH, 146 
Compression ratio (milling), 2 
Concentration, definition, 136 
Concentration and evaporation formulae, 156 
Condensate, 2 
sugar in, 180 
Condensation loss, 169 
Continuous sampler, 79 
Corrosion, in boilers, 139, 175 
Cover glasses, 77 
requirement for cane payment (table XXV) 
strain, 37, 77 
Crystal content, 2, 161 
Crystallizer drop, 2 
Cutter-grinder, 105 
Cyclone purity of molasses, 2, 136 
Cylinders, measuring, 73 
Definitions, 1 
Densimetric methods of analysis, 58 
hydrometer, 65 
pycnometer, 60 
Density of a substance, 58 
relative, 58 
Dextran, 3 
Dextrorotation, 23 
Dichroic film, 20 
Diffraction grating, 41 
Dilution indicator, 3 
Dilution, per cent clarified juice, 155 
per cent fibre, 155 
per cent mixed juice, 155 
per cent undiluted juice, 3, 155 
Dilution water, 3, 155 
Disintegrator, wet, 103, 104 
Dispersion— 
prism, 10 
rotatory, 24, 26 
Dissociation constant of water, 144 
244 
c 
D 
INDEX 2 4 5 
Dosage of chemicals to boilers, 179 
Double refraction, 21 
Dry substance— 
definition, 3 
determination, 100 
Josse method, 101 
sand method, 100 
Drying oven, Spencer type, 102 
E 
E.D.T.A., 85 
Effets, overall evaporation coefficient of, 156 
Effluents, sugar detection in, 130 
Electrode— 
calomel, 147 
glass, 148 
hydrogen, 146 
Electrolytes, 144 
Electrolytic dissociation theory, 144 
Equivalent bagasse, 168 
Equivalent Standard Granulated (E.S.G.), 
161 
Escribed volume, 3 
Evaporation coefficient of effets, overall, 156 
Evaporation formula, 156 
Expected purity of molasses, 161 
Extraction— 
calculation, 153 
definition, 3 
pol, 3, 153 
reduced, 6, 163 
Extraneous matter, 3 
F 
Fans— 
boiler, 171 
forced draught, 172 
horse power required, 172 
induced draught, 171 
performance, 172 
Faraday effect, 23 
Faraday cell, 30, 33 
Fehling's solutions— 
reagents, 90 
standardization, 90 
Fibre— 
definition, 3 
determination— 
prepared cane method, 107 
whole stalk method, 107 
in bagasse, 153 
in cane, 78, 107 
in mud, 126 
Filling ratio, 3 
Filter— 
retention, 156 
washing water, 155 
Filterability— 
definition, 3 
reagents for, 85 
test, 119 
Filter cake (see Mud), 3, 125 
sampling, 82 
Filtrate, 3 
Final molasses (see molasses) 
First aid, 181 
First expressed juice, 3 
Flasks, 69, 70 
specification, (table XXV) 
standardization, 70 
sugar polarization, 117 
tolerance, 71 
Flue gas— 
composition, 171 
heat losses in, 171 
temperature, 171 
volume, 171 
Formula— 
c.c.s., 2 
crystal content, 161 
expected purity of molasses, 161 
gross calorific value of bagasse, 168 
lost undiluted juice per cent fibre, 164 
net calorific value of bagasse, 168 
recovery, 157 
S.J.M., 157 
Winter-carp, 158 
reduced extraction, 163 
Fuel—• 
bagasse moisture influence, 173 
calorific value, 167 
equivalent bagasse, 168 
used, 167 
weight of fuel, 167 
G 
Glass electrode, 148 
Glassware—-
calibration, 69, 77 
cleansing solution, 69, 86 
volumetric, 69 
specifications, 69 
tolerances, (table XXV) 
Grain size, raw sugar, 121 
Gravity solids, 4 
purity, 4 
Grist, raw sugar, 121 
Gums, 4 
analysis, 126 
reagents for, 93 
H 
Half shadow angle, 25 
Hand refractometer, 18 
Hardness analysis, boiler water, 141, 179 
H e a t -
in steam, 166 
losses, 168 
condensation, 169 
in flue gas, 171 
sensible heat, 169, 171 
unburnt gas, 170 
required, by factory, 170 
Herles' reagent, 87 
Hydrochloric acid— 
for sucrose inversion, 92 
normal solution, 91 
Hydrogen electrode, 146 
Hydrogen ion concentration (see pH), 144 
Hydrometer, 65 
Brix, 66, 67 
requirement for cane payment (table XXV) 
for total dissolved solids in boiler water, 
142, 179 
scale, 65 
testing of, 75 
Hygroscopic water, 4, 104, 105 
246 
I 
Imbibition, 4 
Impurities, 4 
Indicators, 86, 145 
pH range, 86 
preparation, 86 
Insoluble solids— 
in clarifier feed, 124 
in mud, 124 
International sugar scale, 24, 35 
ICUMSA definition, 35 
Interference filter, 32, 33 
Inversion of sucrose— 
by hydrochloric acid, 108, 110 
by invertase, 108 
Walker method, 110 
U.S. Customs method, 111 
Invertase, 108, 110, 112 
Invert sugar, 4 
standard solution, 90 
Ions, 144 
J 
Jackson-Gillis modification IV, 110 
divisors, 111 
method, 110 
reagents, 92 
Java ratio, 4 
Juice— 
absolute, 1 
air bubbles in, 96 
back roller, 1 
Brix, 1, 95 
clarified, 2 
per cent cane, 156 
pH, 149 
extraction, 3 
first expressed, 3 
gums in, 127 
last expressed, 4 
lost undiluted, per cent fibre, 164 
mixed, 4 
pH, 149 
phosphate, 129 
pol, 97 
preservation, 89 
primary, 5 
residual, 6, 104 
sampling, 79 
suspended matter in, 96 
temperature, 96 
undiluted, 6 
lost in bagasse, 164 
L 
Laboratory reagents, 83 
Laevorotation, 23 
Last expressed juice, 4 
Lead acetate— 
basic, 88 
neutral, 89 
powder, 88 
solution, 88 
specifications, 88 
Lead compounds, 88 
safety precautions, 88 
Lenses, 45 
I N D E X 
I L i g h t -
amplitude of wave, 8 
dispersion, 10, 15, 18, 24, 27 
double refraction, 21, 34 
filter, 27, 29, 31, 32 
frequency, 9 
linearly polarised, 9, 20 
monochromatic, 17, 24, 26, 41 
nature of, 8 
plane polarized, 9, 22 
refraction, 9 
source, 10, 26 
spectrum, 8, 10 
wavelengths, 8 
Lime— 
addition, 149 
automatic to juice, 149 
analysis— 
available CaO, 132 
neutralizing value, 132 
pH control, 149 
quality, 132 
Lime sucrose reagent, 85 
Lippich polarizer, 25 
Litre, 68 
Losses— 
heat, 169 
miscellaneous, 170 
pol, 152 
undetermined, 152 
Lost undiluted juice per cent fibre, 164 
M 
Maceration—-
definition, 4 
per cent fibre, 155 
Magma, 4 
Magnification, 45 
Massecuite— 
composition formula, 160 
crystal content, 161 
definition, 4 
purity, 4 
sampling, 80 
Materials balances— 
pol balance, 152 
quanti tat ive data, 151 
stock, 152, 159 
Maturity testing, 19, 78 
Meniscus— 
correction, 96 
setting of, 69, 70, 71 
Metrology laboratory, 75 
N.A.T.A. registration, 75 
Microscope, 8, 42 
construction, 43 
micrometer eyepiece, 47 
micrometer stage, 47 
projection type, 48 
table of magnifications, 45 
Millilitre, 68 
Milling— 
efficiency, 163 
extraction, 3, 153 
loss, 4 
lost undiluted juice in bagasse, 164 
performance criteria, 163 
reduced extraction, 6, 163 
Mixed juice, 4 
Moisture— 
bagasse, 102 
cane, 105 
filter cake, (see mud) 
mud, 126 
raw sugar, 119 
Spencer-type oven for, 102 
Molasses— 
analysis— 
Brix, 95 
pol, 100 
reducing sugars, 112 
sucrose, 112 
total sugars, 112 
calorific value, 168 
cyclone purity, 2, 136 
definition, 4 
expected purity ,161 
in stock, 158 
measuring device, 159 
sampling, 80 
supersaturation coefficient, 136 
Monochromatic light, 17, 24, 26, 41 
M u d -
analysis, 124 
fibre, 126 
insoluble solids, 124 
moisture, 126 
pol, 126 
soluble solids, 125 
solids, 4 
N 
N.A.T.A. registrations, 75 
Net titre, 5 
Nicol prism, 21 
Non sucrose, 5 
Non sugars, 5 
Normal quartz plate, 35 
Normal solutions, 91 
Normal sugar solution, 35 
definition, 36 
formula for calculation of wavelengths, 37 
rotation of, 35 
Normal weight, 5, 36 
No-void volume, 5 
O i l -
calorific value, 168 
Optical activity, 9, 23 
quartz, 23 
sugar solutions, 23 
Optical instruments, 8 
care of, 49 
microscope, 42 
projection type, 48 
polarimeter, 24 
refractometer, 11 
saccharimeter, 24, 26 
spectrophotometer, 40 
Optic axis, 21, 23 
Other organic matter, 5 
Oven— 
Spencer type, 102 
Overall evaporation coefficient of effets, 156 
Overall recovery, 153 
Oxygen, in boiler water, 175 
P 
Pellet's continuous tube, 37 
p H — 
brom. thymol blue disc, 146 
buffer solutions, 85, 149 
clarified juice, 149 
colour comparator, 146 
control, 149 
definition, 144 
determination, 144, 149 
indicators, 86, 145 
measurement, 145 
colorimetric method, 145 
electrometric method, 146 
meters, 149 
recorder, 149 
sugar mill products, 149 
temperature compensation, 149 
test papers, 145 
value of boiler water, 178 
Phosphates— 
analysis, 87, 94, 128 
reagents for, 87 
colour comparator, 140 
determination in— 
boiler water, 140, 178 juice, 129 
raw sugar, 128 
syrup, 129 
soluble and insoluble, 129 
Photomicrography, 49 
Photomultiplier, 31, 34 
Pipettes— 
calibration, 72 
delivery time, 72 
graduated, 73 
specification, (table XXV) 
tolerance, 73 
Pneumercator, 159 
Poisons, 83 
P o l -
added to filter cake by bagacillo, 155 
balance— 
empirical system, 152 
direct analysis, 153 
definition, 5 
determination— 
bagasse, 103 
cane, 105 
juice, 97 
molasses, 100 
mud, 126 
pan products, 100 
sugar, 116 
temperature corrections, 38, 99, 118 
extraction, 3, 153 
indirect cane analysis, 105 
in open cells, 106 
losses, 152 
methods of analysis— 
dry lead, 97 
Herles', 99 
normal weight, 98 
reagents for, 87 
Polarimeter— 
automatic, 8, 24, 29 
construction of, 24, 30 
photo electric, 30 
requirement for cane payment (table XXV) 
I N D E X 247 
o 
248 I N D E X 
standardization, 35 
sugar, 26 
Polarimeter tubes, 37, 75 
calibration, 75, 77 
requirement for cane payment (table XXV) 
Polarimetry, 23 
Polariscope (see Polarimeter and sacchari-
meter) 
Polarized light, 20 
by dichroic film, 20 
extraordinary ray, 21 
linearly, 20, 23 
ordinary ray, 21 
Polarizer prism, 21 
Prepared cane analysis, 104 
Preservation of samples— 
for analysis, 81, 89 
for storage conditions, 89 
Preservatives, 89 
reagents for, 89 
Pressure filter, 120 
purity of molasses, 136 
Primary juice 5 
Primary mud, 5 
Prisms— 
amici, 15 
analyser, 22 
calcite, 21 
dispersion, 10, 15 
Nicol 21 
polarizer, 21, 25 
refractometer, 14, 17 
Purity— 
apparent, 1, 5 
gravity, 5 
true, 5 
Pycnometer, 60 
constant, 63 
temperature effects, 63 
determination— 
Brix 62 
specific gravity, 62 
volume, 60 
Q 
Quartz plates, 35 
compensator, 27 
for Bendix polanmeter, 35 
normal, 35 
specification (table XXV) 
standardization of polarimeters by, 35 
strain, 77 
testing, 35, 77 
Quartz wedge compensation, 26 
R 
Raw sugar— 
analysis, 116 
ash, 115 
colour, 124 
moisture, 119 
phosphates, 128 
polarization, 116 
reducing sugars, 113 
starch, 123 
dilution indicator, 3 
filterability test, 119 
gram characteristics, 121 
net titre, 5 
other organic matter , 5 
sampling, 80 
temperature corrections for pol, 39, 118 
tons E S G , 161 
Reabsorption factor, 6 
Reagents for— 
boiler water analysis, 84 
buffer solutions, 85 
clarifiability test, 85 
filterabihty, 85 
glass cleaning solution, 86 
indicators, 86 
phosphate analysis, 87 
pol determination, 87 
preservatives, 89 
reducing sugar analysis, 90 
standard acids and alkalis, 91 
starch analysis, 92 
sucrose analysis, 92 
sugar detection, 92 
water analysis, 93 
Recovery— 
boiling house, 153 
E S G , 161 
formula, 157 
overall, 153 
pol in stock, 159 
reduced overall, 165 
Reduced extraction, 6, 163 
Reducing sugars— 
definition, 6 
determination, 113 
molasses, 112 
reagents for, 90 
total, 112 
Reducing sugar ash ratio, 6, 114 
Refractive index, 9 
angle of incidence, 9, 11 
angle of refraction, 9 
impure sugar solutions, 18 
measurement, 11, 19 
temperature effect, 10, 18 
Refractometer, 8, 11 
Abbe, 14 
adjustment, 16 
automatic, 8, 19 
critical angle, 11, 19 
dipping or immersion, 17 
dry substance determination by, 18 
hand, 18 
high accuracy, 17 
requirement for cane payment (table XX1 
scale, 18 
testing of, 77 
Refractometer Brix, 1, 6, 18 
Relative density, 58 
Remelt, 6 
Residual juice, 6 
Retention, rotary filter, 156 
Rotatory dispersion, 24, 26 
S 
Saccharimeter, 8, 24, 26 
automatic, 30 
calibration of scale, 28, 77 
construction, 27 
definition, 26 
effect of illumination, 29 
I N D E X 2 4 9 
examination, 77 
influence of temperature, 39 
International sugar scale, 24, 35 
light filter, 27, 29, 31, 32 
quartz wedge compensation, 27 
requirement for cane payment (table XXV) 
scale, zero adjustment, 29 
standardization, 35 
tolerance, 77 
Sample— 
container, 79, 82 
identification, 79 
preservation, 82, 89 
Sampler— 
automatic, 79 
care of, 82 
continuous, 79 
pitot tube type, 80 
Sampling— 
bagasse, 81 
boiler water, 177 
cane, 78, 107 
prepared, 78 
filter cake, 82 juice, 79 
massecuite, 80 
molasses, 80 
raw sugar, 80 
syrup, 80 
Saturation-definition, 136 
Saturation cell, 137 
Scale on boiler heating surfaces, 174 
Schmitz's table for pol, formula, 99 
Seed, 6 
Sensible heat loss, 169 
Set opening, 6 
Settling test, C.S.R. laboratory, 133 
Sieves— 
British standard, 122 
Tyler, 122 
S.J.M. formula, 157 
Sodium D line, 10 
S o l i d s -
dissolved, in boiling water, 142, 179 
in mud, 124 
insoluble, 124 
soluble, 125 
soluble, 1 
s u s p e n d e d -
definition, 6 
in juices, 96 
total dissolved—boiler water, 142 
Solubility coefficient, 136 
Specific gravity— 
bottle, 60 
definition, 58 
determination, 59 
by hydrometer, 65 
by pycnometer, 60, 62 
sugar solutions, 59 
Specific rotation, 23 
Spectrophotometer, 8, 40 
optical system, 41 
use of— 
colour, total, 124 
gums, 126 
phosphate determination, 128, 140 
starch determination, 123 
trace sugars, 130 
turbidity measurement, 42 
Spencer-type drying oven, 102 
Standard invert sugar solution, 90 
Standardization— 
acids and alkalis, 91 
Fehling's solution, 90 
normal solutions, 91 
polarimeters, 35 
quartz plates, 77 
refractometers, 18 
soap solution, 141 
weights, 56, 77 
S t a r c h -
indicator solution, 84 
in raw sugar, 123 
reagents for analysis, 92, 123 
standard solution, 92, 123 
Steam— 
dry saturated, 167 
heat required, 166 
produced, 166 
superheated, 166 
Stock— 
bulk sugar in, 160 
materials balance, 152 
molasses in, 158 
taking, 159 
Strain, in glass, 23, 34 
Sucrose— 
analysis, 92, 108, 112 
reagents, 92 
definition, 6 
in high purity material, 108 
in low purity material, 112 
methods— 
chemical, 112 
Clerget, 108, 110 
invertase, 108 
Jackson and Gillis modification IV, 110 
normal weight, 5, 36 
recoverable, 157 
solubility, definition, 136 
Sugar analysis— 
ash, 115 
filterability, 119 
grain size, 121 
moisture, 119 
phosphate, 128 
polarization, 116 
reducing sugars, 113 
starch, 123 
total colour attenuation, 124 
Sugar, definition, 6 
Sugars— 
by refractometer, 18 
detection of, in effluents, 130 
in boiler water, 180 
influence of temperature on rotation, 38 
99, 118 
optical rotation of, 23 
reducing, 6, 113 
specific gravities of, 59 
total, 112 
Sugar detection— 
methods, 130 
reagents, 92 
Supercel, 87 
250 
Supersaturation— 
coefficient, 136 
determination, 136 
Suspended solids, 6 
in juice, 96 
Syrup— 
definition, 6 
phosphate determination in, 129 
sampling, 80 
Tar, calorific value, 168 
Temperature e f f e c t s -
boiler feed water analysis, 142, 177 
pH determination, 145 
pol reading, 38, 99, 118 
refractive index, 10 
sugar solutions, 38, 99, 118 
Thermometer, 73 
calibration, 75 
emergent column error, 74 
requirement for cane payment (table XXV) 
To date, averages, 162 
Tolerances for laboratory apparatus (see 
table XXV) 
Total dissolved solids—boiler water, 142, 179 
Total sugars— 
by refractometer, 18 
definition, 6 
estimation of, 112 
Toxic materials, 83 
True purity, 5 
Turbidimeter, 8 
Turbidity, 6 
Turbidity measurement, clarified juice, 42 
Unburnt gas loss, 
Undetermined loss, 
U 
170 
152 
Undiluted juice, 6 
dilution per cent, 155 
lost in bagasse per cent fibre, 164 
Verdet constant, 23 
Volumetric coefficient, 6 
Volumetric equipment, 68 
units of volume, 68 
Volumetric glassware, 69 
calibration, 77 
meniscus setting, 69, 70, 71 
specifications, 69 
standard temperature, 69, 70 
W 
Water— 
analysis— 
chlorides, 143 
reagents, 93 
dilution, 3 
dissociation constant, 144 
hygroscopic, 4 
Weighing— 
by substitution, 52 
coarse, 57 
general precautions in, 54 
method of, 54 
Weighted average for " to da te" figures, 162 
Weights— 
requirement for cane payment (table XXV) 
standardization, 77 
tolerances (table XXV) 
Winter-Carp formula, 158 
Wood, calorific value, 168 
Work opening, 7 
Work ratio, 7 
I N D E X 
V 
T