which is the most practical for general work.* The analy-
sis by pipette is distinctly American, as is also the gravi-
meter method, while the volumetric method is used in
Europe. For solutions having a small percentage of sugar,
such as pulp and waste waters, there can be no doubt but
that the volumetric method is the best, as a large amount
of the solution is necessary in order to secure accurate
results. Natural water is used in sugar analysis, but it
should be tested to see that it has no optical activity.
The beginner is advised to read Chapter I. carefully lo
learn the manipulation of all the apparatus used in analysis
before studying this chapter.
1 1. The Preparation of the Sample for analysis varies
with the different substances, and is given for each one
under its proper paragraph.
12. Clarification. After the solution to be tested is
measured, or is weighed out into the flask, the impurities
must be precipitated to render it clear and colorless enough
for polarization. This is done by the use of a sub-acetate
* Nt)TE. Solutions having a brix of over 24 must be diluted, in order to make
an apparent purity test by the methods here outlined.
44 GENERAL METHODS OF ANALYSIS.
of lead solution. The amount of the lead to use varies
with the color and impurity of the solution to be tested
but no more than is necessary should be used. In low-
grade syrups 5 to 7 CC is often necessary, while a granulated
sugar solution can be polarized without clarification. Add
a few drops of the lead solution, and rotate the flask
gently to mix the contents. Then let a drop flow down
the neck and side of the flask ; if this drop is lost upon en-
tering the solution, it indicates that the precipitation is not
complete and that more lead solution must be added, but if
it can be traced after entering the solution by its clear
track down the side of the flask, it shows that the clarifi-
cation is complete.
The U. S. Department of Internal Revenue, in its regu-
lations* relative to the bounty on domestic sugar, gives the
following : " The use of sub-acetate of lead should, in all
cases, be followed by the addition of * alumina cream '
(aluminic hydrate suspended in water), (t)in about double
the volume of the sub-acetate solution used, for the purpose
of completing the clarification, precipitating excess of lead,
and facilitating filtration. In many cases of high grade
sugars, especially beet sugars, the use of alumina alone
may be sufficient for clarification without the previous
addition of sub-acetate of lead."
In ordinary work it is not generally considered neces-
sary to use any other clarifying agent than lead acetate.
The precipitate given by the lead solutions causes a very
* U. S. Internal Revenue, Series 7 to 17, Revised.
t See paragraph 128 for preparation of "Alumina Cream/
GENERAL METHODS OF ANALYSIS. 45
slight error in polarization, on account of its volume. In
the presence of this precipitate the fluid tested is not
actually diluted up to 100 CC , but to 100 CC , minus the volume
of the precipitate. In beets this error is about .17 per
cent., and in diffusion juice, .27 per cent., while in green
syrup it is estimated to be as high as .63 per cent.J This
refers to tests made by the volumetric method.
When invert sugar is present a serious error very often
result by the formation of laevulosate of lead, which is a
salt of low specific rotary power, and sometimes the left-
hand rotation is almost, if not entirely, destroyed. (G L,.
SPENCER.) The addition of enough acetic acid to give the
solution an acid reaction will prevent this error.
13. Filling the Flask. After the addition of sufficient
lead solution, the flask is filled to the proper mark and is
well shaken, the thumb being placed over the top of the
flask In nearly all cases the solution should stand for
from 5 to 10 minutes before being filtered. When it is
known that there is only a small amount of sugar con-
tained this is unnecessary, and in beet, cossette, and diffu-
sion juice tests it allowed to stand the solution soon be-
comes too dark to polarize.
14. The Volumetric Method of analysis is used in
Europe for determining all " apparent purities," but in the
United States it is generally used only for solutions con-
taining a very small amount of sugar such as pulp and waste
waters. A flask graduated to 100 and 110 CC or to 50 and
J See Tucker's Manual of Sugar Analysis, third edition, page 166.
46 GENERAL METHODS OF ANALYSIS.
55 CC is rinsed with the solution to be tested, and is then
filled with it to the lower mark (50 or 100). Add
sufficient lead acetate to precipitate the impurities
and fill to the higher mark (55 or 110) with water.
Filter and polarize a part of the filtrate in a 200 mm
tube. The reading multiplied by *.286 was formerly taken
to show the percentage of sugar in the solution, but this
multiplication is now divided by the specific gravity as the
increase in density lowers the specific rotatory power of the
Table V. may be used for determining the per cent,
sugar from the polariscope reading. For example, the
brix of a solution is 16.5 and the temperature correction
.3, making the corrected brix 16.8, and the polariscope
reading is 33.6. By referring to the table we first find at
the top of the page, the degree brix 17.0 as it is nearest to
16.8. In the column under 17 we find the line of polar-
iscope degree 33, as it is the whole degree of the polari-
scope reading obtained, and the percentage of sugar given
is 8.82. The tenths obtained is 6, and at the side of the
table under "degree brix from 12.5 to 20.0," we find .6=
.16. Adding .16 to 8.82 gives 8.98, the percentage of
sugar in the solution tested. The per cent, sugar is divided
by the brix and multiplied by 100 to give the apparent
purity, 8.98 16 8 x 100 53 45, apparent purity.
* A polariscope is made for 26.048 gr. of a solution made up to lOOcc to show
the percentage of sugar it contains, and if a solution containing 26.048 percent,
of sugar is read directly in the polariscope, the instrument will show 100 per
cent. Hence each reading of 1 shows .26048 per cent, of sugar. When a solution
is diluted 10 per cent, to allow for lead acetate (as above,) each reading of 1 will
show 10 per cent, more than .26048 or .286 iti round numbers.
GENERAL METHODS OF ANALYSIS. 47
15. The Pipette Test is made as follows: Carefully
take the brix and also the temperature of the solution to
be tested. Fill the pipette to the graduation corresponding
to the reading of the brix. (3.)t Diop the solution into
a 100 CC flask and wash the pipette, as described in 3. Add
enough lead acetate to the flask to precipitate all impurities
and leave a clear fluid above. Then fill to the mark with
water. After filtering, fill a 200 mm tube with a portion of
the filtrate, and polarize. Divide the reading by two, as
the pipette contained double normal weight. The per cent,
of sugar thus obtained, divided by the brix, with the tem-
perature correction and multiplied by 100, will give the
16. The Gravimeter, invented by W. K. Gird, is a
mechanical device by which the solution is measured off
and placed in the flask by the operation of taking the dens-
ity. It is based on the principle that a substance im-
mersed in a fluid displaces its own weight of the fluid.
The following explanation of the apparatus was prepared
for " Beet Sugar Analysis " by the inventor.
"In the illustration (Fig. 23) A represents the main
tube, to hold the solution under treatment ; B, overflow
pipe ; C, air vent, to prevent siphonage, constructed in
funnel form, to facilitate cleaning; D, an index finger point-
ing to the saccharometer, constructed so as to swing cut
of the way when necessary, and to stand, for convenience
of reading, say five graduations above the surface of the
fluid ; E, saccharometer, weighing exactly .26048 gr . and F,
point of discharge into the flask ; G, drip funnel; and H is
cock for letting out the fluid from A.
t Finding the per cent, sugar is done by weight, hence it is not influenced
by temperature, and the uncorrected reading of the brix is drawn into the
48 GBNKRAL METHODS OF ANALYSIS.
GENERAL METHODS OF ANALYSIS. 49
The operator closes the aperature F with his finger
and fills the main tube with the solution until it shows full
at C. Skimming off the foam from the top of the main
tube, he removes his finger and permits the excess to escape
to the last drop, which must be removed. This will leave
the tube B moistened with the fluid under analysis so that
the condition will be left precisely the same as it will be
after the delivery of the discharge hereafter explained.
There can be no loss or no gain, either in quantity or
quality. Next, place a 100 CC flask under the overflow F
and insert the saccharometer in the usual manner, Jetting
it go down slowly until it floats free. The fluid will come
out at E ; bring up the mouth of the flask so as to catch
the last drop. The fluid in the flask will now weigh
exactly e. g. 26.048 gr , being the quantity displaced by the
saccharometer having that weight. Now, bring the point
D to the index on the saccharometer and note the reading,
to which add (10), representing the height of the finger
above the surface."
The solution in the flask is cleared with lead acetate,
filtered and the filtrate polarized in a 200 mra tube, the read-
ing giving the direct per cent, sugar. In taking the brix,
note the temperature on the thermometer I, and divide the
per cent, sugar by the corrected brix and multiply by 100
to find the apparent purity.
The principal source of error in using the gravimeter is
in having saccharometers incorrect in weight. Either
normal or double normal weight instruments may be used,
but it is difficult to make them exact. Another error to
guard against is allowing the saccharometer to sink down
too far. This is simply a matter of care, and can be easily
GENERAL METHODS OF ANALYSIS.
avoided. The gravimeter may be used for solutions having
a medium and low brix, but is hardly adapted for thick
juices and syrups.
1 7. Analysis by Weight is usually made where great
accuracy is required, and sometimes it is necessary when
only a sm all
amount is obtain-
able of the sub-
stance to be ana-
lyzed. For thin
solutions and beets
take double normal
weight, but for
thick solutions and
are not so easily
dissolved, use nor-
mal weight. Half
normal weight is Fi - 24 -
used when only a small sample is to be had. The substance
to be tested is carefully weighed in a tared scoop and then
washed from the scoop into a 100 CC flask, or with beets,
into the special beet flask. The scoops best suited for this
method of analysis are of German silver, with long lips.
(See F. 18.) After the substance is all in the flask, clear
with lead acetate, fill to the mark, filter and read. In solu-
tions where the purity by weight is to be determined, the
specific gravity is found (2a) and the per cent, sugar is
divided by the degree brix which equals the specific grav-
ity obtained. This is multiplied by 100. In the analysis
of massecuites, and sometimes of solutions, the dry sub-
stance is found (2c), the division of the per cent, sugar by
GENERAL METHODS OF ANALYSIS. 51
the dry substance, and multiplying by 100, giving the real
purity. Fig. 24 will show the kind and quality of balance
suited for weighings in sugar analysis.
Per cent. Sugar found by weight, 75.1.
Per cent. Dry Substance, 85.3.
75.1 -f- 85.3 x 100=88.0+, the real purity.
Per cent. Sugar found by weight 50.0.
Specific gravity, 1.4375 or 83.2 Brix.
50 o -: 83.2 x 100 = 60.09 or 60.1, purity by weight.
18. NonWNormal Analysis. It rarely, yet sometimes
happens that some other weight than normal or half-normal
weight must be taken for polarization. In this case the
substance is carefully weighed out, dissolved and made up
to 100 CC , with the addition of lead acetate, and polarized in
a 200 mm tube, the per cent, of sugar being calculated
according to the formula
P x 26.048.
In which P represents the polarization and W the weight
A sample of 11 gr. of a massecuite is weighed out and polarized,
the polarization being 36.8. According to the formula
36.8 x 26.048 = 958.57 = 87.14, per cent, sugar in sample.
19. Quotient of Purity is the percentage of sugar con-
tained in the total solids. It is always spoken of simply as
"purity." The only exact method for determining the
quotient of purity is described in 17, and is called the
" real purity." The "purity by weight" described in the
same paragraph is considered in some factories to be suffi-
ciently exact for syrup analysis. The " apparent purity"
(14, 15 and 16,) is used for nearly all analyses in the
52 GENERAL METHODS OF ANALYSIS.
chemical control of the daily run of factories. It is not
exact, as the Brix saccharometer is used for determining
the total solids, and this instrument is based on a scale
which assumes all the solids to be pure sugar. The
presence of other solids in an impure solution makes the
brix reading too high and the purity consequently too
low. It is not affected alike b}^ all impurities*, hence its
inaccuracy varies, but the purity found is usually fioin 2 to
4 lower than the real purity. After obtaining the per
cent, sugar and the degree Brix, the apparent purity can be
determined by the use of Table VI.
20. The Value Coefficient is used by some European
factories in the purchase ot beets, the price paid being ac-
cording to the coefficient. It is also used to some extent in
determining the value of juices in factory work. The
Sucrose x purity
ITJTT = value coefficient.
21. The Saline Quotient is considered by French
chemists to show how near a substance is exhausted of
crystallizable sugar. The supeiintendents of French fac-
tories pay more attention to it than to purity ; in fact, they
practically neglect figuring on purity bases (E. E. BRYS-
SELBOUT). Some chemists consider it of especial value to
new factories in the study of beets and j uices. The formula is :
Per cent Sucrose -j per cent. Ash = Saline Quotient.
For the analysis of ash see 34b. Determine the
sugar by weight.
22. The Rendement is a formula tor determining the
amount of refined sugar that can be made from a substance
or solution. It is :
Per cent. Sucrose (per cent ash x 5) = per cent, refined sugar.
* See Tucker's Manual of Su^ ar Analysis, 3rd edition, page 112.
Apparatus in M.
1. Apparatus for testing CO 2 in gas.
2. Kiehle machine for beets and cossettes.
3. Meat chopper for cossettes.
4. Power grinder for beets.
5. Hand grinder for beets.
6. Beet block and knife.
7. Beet box for beet samples.
8. Press for obtaining juice from'beets or|cossettes.
9. Press for pulp.
10. Hand grinder for pulp.
11. The same in parts.
INDIVIDUAL SUGAR ANALYSES.
23. (a) Beets. A bushel basket full of beets is
taken as a sample from each wagon, or samples from two or
three wagon loads (from the same
farmer) may be tared and analyzed as
one sample. The sample is dumped on
-S the floor in one pile and mixed. From
this pile the " tarer " takes a sample
weighing 50 pounds, using a shovel to
take the beets from the floor. The beets
are cleaned thoroughly in a washing
machine and are then tared by cutting
off the tops squarely at the point where
the first leaves have grown (see Fig. 25.)
All hairs are scraped off, and all roots
that are ^ of an inch, or les^, in diameter, are removed.
The sample is then reweighed
and the difference between its
weight and 50 pounds, multi-
plied by 2, gives the per cent,
of tare. Twenty average beets
are then taken from the sample
to test in the laboratory. They
are weighed (preferably with
metric weights) and the average weight is recorded. The
common platform scales with scoop are used in weighing.
Each beet is then cut perpendicularly as equally as possi-
ble, into four parts, and one of the quarter sections of each
beet is taken to make up the sample for analyzing. The
56 INDIVIDUAL SUGAR ANALYSES.
beet block and knife used for this purpose are shown in m6.
There are a number of machines constructed for cutting
out certain parts of the beets which are considered to give
the best average sample, but the above method is very
practical, being both rapid and accurate.
(b) The sample is grated up similarly to horse radish and
the juice from the pulp thus obtained is squeezed through a
cloth by pressure. The grater and press generally used are
shown in m4 and m8. The cylinder of the grater should
make about 500 revolutions a minute. After being grated
up the sample is in a box (m4) and is dumped upon a
clean, dry cloth. The edges of the cloth are then folded
together, placed in the press and pressure applied. The
juice flowing out should be received in a bucket which is
clean and dry inside. All the juice possible should be
squeezed out. From the bucket a portion of the juice is
poured into a cylinder very carefully, so as to make as little
foam as possible, and is allowed to stand as long as may be
necessary (from 10 to 20 minutes), to let all the bubbles of
air come to the top. Skim off the foam with a spoon and
analyze by either the volumetric method or pipette test.
The use of too little or too much lead will give a dark solu-
tion after filtering. The continuous polarization tube
described in 7d is of especial value in beet work when a
large number of samples are to be tested, and is as accurate
as the ordinary tube when used properly. The per cent,
sugar is figured into apparent purity. On account of the
fibre in the beet the per cent, of sugar is less than is found
by analysis to be in the juice. The sugar in beets is usually
considered to be 95 per cent, of the sugar in juice, but in
dry years it is often taken as 94 per cent. For determining
the amount of fibre in beets see (f) of this paragraph. The
analysis of the beet may be recorded in this way :
INDIVIDUAL SUGAR ANALYSES. 57
Average weight 348 gr.
Per cent. Sugar in juice 15.4.
Per cent. Sugar in beet (95 percent) 14.6.
(c) Water Digest. A flask is especially made for this
test, being graduated to 201. 4 CC and 221. 4 CC . It is the same
as a 200 CC plus 20 per cent, flask with 1.4 CC allowed for the
fibre in the beet. Grind the beets to be tested as fine as
possible. Weigh out double normal weight and wash into
flask using an amount of water which will bring the con-
tents of the flask up to a volume of about 180 CC . Add 5 CC
of lead acetate and heat in a water bath at 75C. A stick
about eight inches long and slightly thicker than a lead
pencil may be placed in the flask to use in pushing down
any foam that may rise. The length of time required for
heating varies according to the way the beets are ground.
MR. E. TURCK and the author in a series of experiments
found that the beets ground with a horse radish grater had
to be heated for 45 minutes to give accurate results, while
beets crushed to an exceedingly fine pulp in a specially
made machine (the Kiehle) could be thoroughly diffused
in 15 minutes. After heating sufficiently, cool to 17>^ C
and make up to the 201.4 CC mark. Very often in this test
it will be found necessary to fill to Hie upper mark, in
which case deduct 10 per cent, of the reading. When the
lower mark is used, the reading in a 200 mm tube shows
the per cent, of sugar in the beet.
This test may be made as above in a 100 CC flask, but the
foam which usually forms make the operation more diffi-
cult than with the larger flask. It is also slightly less
accurate as no provision is made for the^fifetfei^the beet.
58 INDIVIDUAL SUGAR ANALYSES.
(d) The Alcohol Extraction is considered by many chem-
ists to be the only exact method for determining the per-
centage of sugar in beets. The apparatus for this analysis
is shown in Fig. 27. A wide-mouthed 200 CC flask contain-
ing 150 CC of ^-per cent, alcohol is placed in a water bath,
which is well covered. The top of the flask is connected
by a rubber stopper with an extraction apparatus, prefer-
ably the Sickel-Soxhlet which is shown in the illustration.
Into the cylinder A of the apparatus is placed 52.096 gr of
the sample which is prepared in the same way as the sam-
ple for the water digestion. The cylinder should be of
such size and so made that the substance to be tested does
not come higher than the upper turn of the siphon D-
The sample may be washed into the cylinder with alcohol,
and more alcohol added until the fluid comes up in D to the
upper turn. A L,iebig condensor is now attached to the
upper part of the extraction apparatus by a rubber stopper
and some suitable arrangement made to keep a flow of cold
water through the condensor. This can be done by siphon-
age, as shown in the illustration. Heat is now applied and
the alcohol distilled. The gas passes up through the tube
C to the condensor, where it is condensed, and falls into the
tube A, going back to the flask through the siphon D.
This distillation and redistillation is kept up until the fluid
coming back through the siphon is colorless. The length
of the operation varies, but is usually about two hours, and
the fluid in the apparatus goes back about four times.
When finished, the flask is separated from the apparatus
and cooled. About 4 CC of lead acetate are then added and
the contents made up to the mark with alcohol. Shake well,
filter with precautions against evaporation, and polarize,
the reading being the per cent, sugar in beet.
INDIVIDUAL SUGAR ANALYSES.
(e) Alcohol Digest. This is made the same as the
water 'digestion, alcohol being used instead of water. Care
must be taken to
ration of the al-
cohol. It may
be avoided by
ftask in the
water bath and
the top of the
flask by a rub-
ber stopper, a
tube l cm in di-
about 65 cm long,
the tube acting
as a condenser
(/) The Fi-
bre in Beet is
by a compari-
son of the tests
of sugar in
beet b y the
tion, and of sugar in juice by the volumetric or pip-
ette method. A large sample is ground up and well
mixed and is then divided, a smaller portion being used
INDIVIDUAL, SUGAR ANALYSES. 6 1
for the alcohol digest and the larger portion for the juice
test, the juice being pressed out and tested as in B, dividing
the per cent, sugar found to be in the beet by the per cent,
sugar in the juice, the ratio of the sugar in beet to sugar in
juice is found. This percentage subtracted from 100 will
give the percentage of fibre.
Per cent, sugar by alcohol digest = 15.2.
Per cent, sugar found in juice = 16.1.
15.2 '- 16.1 = 94.4 per cent.
100 94.4 = 5.6, the per cent, of fibre.
A direct determination of the fibre may be made by
taking the residue remaining in the cylinder A (Fig. 20,)
after the alcohol extraction*, and drying first at 90C and
finally at 100C to constant weight. The weight of the
residue divided by 52.096 and multiplied by 100 will give
the per cent, of fiber. This is Scheibler's method.
Or) Beets in the Field. When a beet is young the
weight of the leaves is proportionately much greater than
that of the root, but as the plant grows the difference be-
comes gradually less until at maturity the condition is re-
versed and the root weighs much more than the leaves.
The knowledge of the relation between the roots and the
leaves is of value to the agriculturist in many ways, one in-
dication being that an increase in the proportion of roots
is an increase in the contents of sugar. Hence, in testing
beets before maturity, a record should always be made of
the weight of the roots and of the tops, the relation of the
roots to the total weight being calculated by dividing the
* To be sure that all soluble matter is extracted, the residue should be washed
62 INDIVIDUAL SUGAR ANALYSES.
former by the latter. The leaves are cut off squarely at the
point where the first leaves have grown, as shown in Fig
Four beets are tested, the leaves of which weigh 2324s r and the
roots 18288 r .
2324gr 4 = 581gr, average weight of leaves.
1828g f -, 4 = 457gr, average weight of roots.
= .44 or 44 per cent., proportion of roots to
(581 + 457) 1038
total weight. In recording the analysis, the average weight of the