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JC-NRLF

AND ITS PRODUCTS

AND WOLL,

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

i ;

DR. S. M. BABCOCK
Inventor of the Babcock Milk Test

TESTING MILK

ITS PRODUCTS

A MANUAL FOR DAIRY STUDENTS, CREAMERY- AND CHEESE

FACTORY OPERATORS, FOOD CHEMISTS, AND

DAIRY FARMERS

E. H. FARRINGTON and F. W. WOLL

Professor in Charge of Dairy School Professor of Agr'l Chemistry

Of the University of Wisconsin

lUitb ailuBtratfons

EIGHTEENTH REVISED AND ENLARGED EDITION

MADISON, WIS.
MENDOTA BOOK COMPANY

1908
ALL, RIGHTS RESERVED

CANTWELL PRINTING COMPANY
MADISON, WIS.

Preface to First EcTition.

The present volume is intended for the use of dairy students,
factory operators, dairymen, food chemists, and others interested
in the testing or analysis of milk and its products. The subject
has been largely treated in a popular manner; accuracy and
clearness of statement, and systematic arrangement of the sub-
ject matter have, however, been constantly kept in mind. The
aim has been to make the presentation intelligible to students,
with no further training than a common-school education, but
their work will naturally be greatly lightened by the aid of an
able teacher.

Complete directions for making tests of milk and other dairy
products are given; difficulties which the beginner may meet
with are considered in detail, and suggestions offered for avoid-
ing them. It is expected that a factory operator or practical
dairyman, by exercising common sense and ordinary care, can
obtain sufficient knowledge of the subject through a study of
the various chapters of this book to make tests of milk, cream,
etc., even if hei has had no previous experience in this line.

For the benefit of advanced dairy students who are somewhat
familiar with chemistry and chemical operations, Chapter XIV
has been added giving detailed instructions for the complete
chemical analysis of milk and other dairy products. The detec-
tion of preservatives and of artificial butter or filled cheese has
also been treated in this connection.

As the subject of milk testing is intimately connected with
the payment for the milk delivered at butter- and cheese fac-
tories, and with factory dividends, a chapter has been devoted
to a discussion of the various systems of factory book-keeping,
and tables greatly facilitating the work of the factory secretary
or bookkeeper have beein prepared and are included in the
Appendix.

Madison, Wis., October 1, 1897.

31082

Preface to Eighteenth Edition.

Each year that passes brings some valuable contributions to
our knowledge of the subjects treated in this book and a fre-
quent revision of it is therefore desirable. The present edition
contains descriptions of methods and apparatus that have stood
the test of actual use during the past few years; the new infor-
mation published since the; last revision of the book, has been
carefully sifted, and what was deemed of sufficient importance
has been incorporated in such detail as the scope of the book
permitted; many changes and additions suggested by the expe-
rience of the authors have also been introduced.

The book has, in brief, been subjected to a renewed critical
examination and careful revision. Among thei new subjects dis-
cussed in this edition may be mentioned: Analysis of ice cream;
estimation of water in butter by thei Gray, Patrick, Irish, Dean,
and Wisconsin oven methods; the Marschall acid test; the McKay
and Michels' sampling tubes; milk and cream overrun; the Gott-
lieb method -of determining fat in milk; the Hart casein test;
standards for Babcock glassware, etc. The general adoption of
the book as a text or reference book in American dairy schools,
as well as the favorable reception which it has been accorded by
the dairy public in general, will, it is hoped, be further justified
by the present revision.

Acknowledgment is due to the following parties for loan
of electrotypes, viz.: Creamery Pkg. Mfg. Co., Chicago, 111.;
Vermont Farm Machine Co., Bellows Falls, Vt. ; Dairy Specialty
Co., West Chester, Pa.; D. H. Burrell & Co., Little Falls, N. Y.;
De Laval Separator Co., New York City; Henry Tromner, Phila-
delphia, Pa.; Torsion Balance Co., New York City; Bausch &
Lomb Opt. Co., Eochester, N. Y.; J. G. Cherry, Cedar Eapids,
la.; Marschall Dairy Laboratory, Madison, Wis., and Interna-
tional Instrument Co., Cambridge, Mass.

Madison, Wis., Jan. 4, 1908.

Table of Contents.

PAGE

Introduction 1

Chap. I. COMPOSITION OF MILK AND ITS PRODUCTS ... 10

Composition of milk: Water. Fat. Casein and albu-
men. Milk sugar (lactose). Ash. Other components.
Colostrum milk. Composition of milk products.

Chap. II. SAMPLING MILK 23

Sweet milk. Partially churned milk. Sour milk. Frozen
milk.
Chap. III. THE BABCOCK TEST — MILK 28

A. Directions for making the test:

Sampling. Adding acid. Mixing milk and acid. T^hirl-
ing bottles. Adding water. Measuring the fat.

B. Discussion of the details of the test:

1. Glassware. Test bottles. Marking test bottles. Ap-
paratus for cleaning test bottles. Pipettes. "Fool pi-
pettes. " Acid measures. The Swedish acid-bottle. Cali-
bration of glassware: With water; with mercury. The
Trowbridge method of calibration. Calibration of skim-milk
and cream test bottles, of pipettes and acid cylinders.

2. Centrifugal machines. Speed required for the com-
plete separation of the fat. Ascertaining the necessary
speed of testers. Hand testers. Power turbine and elec-
trical testers.

3. Sulfuric acid. Testing the strength of acid. The
Swedish acid tester. Thei color of the fat column an index
to the strength of the acid used. Influence of temperature
on the separation of fat.

4. Water to be used in the Babcock test. Reservoir for
water. .

5. Modifications of the Babcock test. The Russian milk
test. Bartlett's modification. Siegf eld's modification.
Bausch and Lomb centrifuge.

Chap. IV. THE BABCOCK TEST — CREAM 75

Errors of measuring cream. Weighing cream for test-
ing. Cream-test bottles. The Winton cream bottle, 'ixie
bulb-necked cream bottle. Cream-weighing scales. Measur-
ing cream for testing. Use of milk test bottle. Use of
5 cc. pipette. Proper readings of cream tests.
Chap. V. THE BABCOCK TEST — OTHER MILK PRODUCTS . 88

Skim milk, butter milk and whey. The double-necked
test bottle. The Wagner test bottle. The double-sized
skim milk bottle. Butter. Cheese. Condensed milk. Ice
cream.

vi Testing Milk and Its Products.

Chap. VI. THE LACTOMETER AND ITS APPLICATION . . . 100

The Quevenne lactometer. Influence of temperature.
N. Y. Board of Health lactometer. Reading the lactome-
ter. Time of taking lactometer readings. Influence of solid
preservatives on lactometer readings. Cleaning lactometers.
Testing the accuracy of lactometers. Calculation of milk
solids. Adulteration of milk. Legal standards. The spe-
cific gravity of milk solids. Calculation of extent of adul-
teration: Skimming. Watering. Watering and skimming.

Chap. VII. TESTING THE ACIDITY OF MILK AND CREAM . 117

Cause of acidity in milk. Methods of testing acidity.
Manns7 test. Devarda's acidimeter. The alkaline-tablet
test. Determination of acidity in sour cream. Spillman's
cylinder. The Marschall acid-test. Rapid estimation of the
acidity of apparently sweet milk and cream. Detection of
boracic-acid preservatives in milk. "Alkaline Tabs. "

Chap. VIII. TESTING THE PURITY OF MILK 135

The Wisconsin curd test. The fermentation test. The
Monrad rennet test. The Marschall rennet test.

Chap. IX. TESTING MILK ON THE FARM 140

Variations in milk of single cows. Number of tests re-
quired during a period of lactation in testing cows. When
to test a cow. Sampling milk of single cows. Composite
samples. Variations in herd milk. Influence of heavy grain
feeding and of pasture on the quality of milk. Method of
improving the quality of milk.

Chap. X. COMPOSITE SAMPLES OF MILK 158

Methods of taking composite samples. Use of tin dip-
per. Drip sample. The Scovell, McKay, and Michels' sam-
pling tubes. One-third sample pipette. Preservatives for
composite samples. Care of composite samples. Fallacy
of averaging percentages. A patron 's dilemma.

Chap. XI. CREAM TESTING AT CREAMERIES 175

The space system. The oil-test churn. The Babcock test
for cream. Gathering and sampling hand-separator cream.
Chap. XII. CALCULATION OF BUTTER- AND CHEESE YIELD . 186

A. Calculation of yield of butter: Butter-fat test and
yield of butter. Variations in composition of butter. Over-
run of churn over test. Factors influencing the overrun for
milk and for cream. Calculation of milk and cream over-
run. Conversion factor for butter fat. Butter yield from
milk of different richness. Use of butter chart. Use of
overrun table.

B. Calculation of yield of cheese: From fat. From sol-
ids not fat and fat. From casein and fat.

Table of Contents. vii

Chap. XIII. CALCULATING DIVIDENDS 202

A. Calculating dividends at creameries: Proprietary
creiameries. Co-operative creameries. Illustrations of cal-
culations of dividends. Paying for butter delivered. Bela-
tive-value tables. Milk- and cream dividends.

B. Calculating dividends at &iees& factories: Proprie-
tary factories. Co-operative factories.

Chap. XIV. CHEMICAL ANALY^S OP MILK AND ITS PROD-
UCTS . . ^ 215

Milk. The Gottlieb method; Hart's casein test. Cream,
skim milk, butter milk, whey, condensed milk.

Butter. Complete analysis in the same sample. Eapid
estimation of water in butter: Gray's, Patrick's, Irish's,
Dean's, and Wisconsin high-pressure oven methods. A prac-
tical method of estimating salt in butter. Detection of arti-
ficial butter. Eeichert-Wollny method (Volatile acids).
Tests for the detection of oleomargarine and renovated but-
ter: The boiling test. The Waterhouse test.

Cheese. Detection of oleomargarine cheese (" Filled"
cheese).

Tests for adulteration of milk and cream. Detection o£-
coloring matter, and of pasteurized milk or cream. Boiled
milk. Gelatine and starch in cream. Macroscopic impuri-
ties. Detection of preservatives in dairy products: Boracic
acid. Bi-carbonate of soda. Fluorids. Salicylic acid.
Formaldehyde.

Government standards of purity for milk and its prod-
ucts. Standards for Babcock glassware.

Appendix 254

Table I. Composition of milk and its products.
Table II. State and city standards for dairy products.
Table III. Quevenne lactometer degrees corresponding
to the scale of the N. Y. Board of Health lactometers.

Table IV. Value of 100S~100 for specific gravities from

1.019 to 1.0369.

Table V. Correction table for specific gravity of milk.

Table VI. Per cent, of solids not fat, corresponding to
0 to 6 per cent, of fat and lactometer readings of 26 to 36.

Directions for the use of Tables VII, VIII, IX and XI.

Table VII. Pounds of fat in 1 to 10,000 pounds of milk
testing 3 to 5.35 per cent.

Table VIII. Pounds of fat in 1 to 1,000 Ibs. of cream
testing 12.0 to 50.0 per cent. fat.

Table IX. Amount due for butter fat, in dollars and
cents, at 12 to 25 cents per pound.

Table X. Eelative-value tables.

viii Testing Milk and Its Products.

PAGE

Table XI. Butter chart, showing calculated yield of
butter, in pounds, from 1 to 10,000 pounds of milk testing
3.0 to 5.3 per cent, of fat.

Table XII. Overrun table, showing pounds of butter
from 100 pounds of milk.

Table XIII. Yield of cheese, corresponding to 2.5 to 6
per cent, of fat, with lactometer readings of 26 to 36.

Table XIV. Comparisons of Fahrenheit and Centigrade
(Celcius) thermometer scales.

Table XV. Comparison of metric and customary weights
and measures.

Suggestions regarding the organization of co-operative
creameries and cheese factories.

Constitution and by-laws for co-operative factory asso-
ciations.

Index 286

Testing Milk and its Products

INTRODUCTION.

The need of a rapid, accurate and inexpensive method
of determining the amount of butter fat in milk and
other dairy products became more and more apparent,
in this country and abroad, with the progress of the
dairy industry, and especially with the growth of the
factory system of butter and cheese making during the
last few decades. So long as each farmer made his own
butter and sold it to private customers or at the village
grocery, it was not a matter of much importance to
others whether the milk produced by his cows was rich
or poor. But as creameries and cheese factories mul-
tiplied, and farmers in the dairy sections of our coun-
try became to a large extent patrons of one or the other
of these, a system of equitable payment for the milk
or cream delivered became a vital question.

i. Nearly all the creameries in existence in this coun-
try up to about 1890 were conducted on the cream-
gathering plan: the different patrons creamed their
milk by the gravity process, and the cream was hauled
to the creamery, usually twice or three times a week,
where it was then ripened and churned. The patrons
were paid per inch of cream furnished. This quantity

was supposed to make a pound of butter, but cream
i

2 Testing Milk and Its Products.

from different sources, or even from the same sources
at different times, varies greatly in butter-producing
capacity, as will be shown under the subject of cream
testing (2031). The system of paying for the number
of creamery inches delivered could not therefore long
give satisfaction.

The proposition to take out a small portion, a pint or
half a pint, of the cream furnished by each patron, and
determine the amount of butter which these samples
would make on being churned in so-called test churns,
found but a very limited acceptance, on account 'of the
labor involved and the difficulty of producing a first-class
article from all the small batches of butter thus ob-
tained.

2. The introduction of the so-called oil test churn in
creameries, which followed the creamery-inch system,
marked a decided step in advance, and it soon came
into general use in gathered-cream factories (202). In
this test, glass tubes of about % inch internal diameter
and nine inches long, are filled with cream to a depth
of five inches, and the cream is churned ; the tubes are
then placed in hot water, and the column of melted
butter formed at the top is read off by means of a scale
showing the number of pounds of butter per creamery
inch corresponding to different depths of melted but-
ter. While the oil test is capable of showing the differ-
ence between good and poor cream, it is not sufficiently
accurate to make satisfactory distinctions between dif-
ferent grades of good and poor cream.2 As a result,

1 Refers to paragraph numbers.

9 Wlscon-in experiment station, bulletin 12. (Soonlso umlor203.)

Introduction. 3

perfect justice cannot be done to different patrons of
creameries where payments for cream delivered are
made on the basis of this test.

3. In cheese factories, and since the introduction of
the centrifugal cream separator, in separator creamer-
ies, the problem of just payment for the milk furnished
by different patrons was no less perplexing than in the
case of gathered-cream factories. By the pooling sys-
tem generally adopted, each patron received payment
in proportion to the number of pounds of milk deliv-
ered, irrespective of its quality. Patrons delivering rich
milk naturally will not be satisfied with this system
when they find that their milk is richer than that of
their neighbors. The temptation to fraudulently in-
crease the amount of milk delivered by watering, or to
lower its quality by skimming, will furthermore prove
too strong for some patrons ; the fact that it was diffi-
cult to prove any fraud committed, from lack of a re-
liable and practical method of milk analysis, rendered
this pooling system still more objectionable.

4. As another instance in which the need of a simple
test for determining the fat content of different kinds
of milk was strongly felt, may be mentioned the case of
private dairymen and breeders of dairy cattle who de-
sired to ascertain the butter-producing capacities of the
individual cows in their herds. The only manner in
which this could be done, was by the cumbersome
method of trial churnings : by saving the milk of the
cow to be tested, for a day or a week, and churning
separately the cream obtained. This requires a large
amount of work when a number of cows are to be

4 Testing Milk and Its Products.

tested, and can not therefore be done except in com-
paratively few cases, with cows of great excellence or
by farmers having abundant hired help.

5. Introduction of milk tests. The first method
which fulfilled all reasonable demands of a practical
and reliable milk and cream test was the Babcock test,
invented by Dr. S. M. Babcock, of the Wisconsin agri-
cultural experiment station. A description of the test
was first published in July, 1890, as bulletin No. 24 of
that Station, entitled: A new method for the estimation
of fat in milkf especially adapted to creameries and
cheese factories. This test, which is now known and
adopted in all parts of the world where dairying is an
important industry, was not, however, the first method
proposed for this purpose which could be successfully
operated outside of chemical laboratories. It was pre-
ceded by a number of different methods, the first one
published in this country being Short's method, in-
vented by Mr. F. G.' Short and described in bulletin
No. 16 of Wisconsin experiment station (July 1888).

6. Short's test. In this ingenious method, a certain quan-
tity of milk (20 cc.1) was boiled with an alkali solution and
afterwards with a mixture of sulfuric and acetic acids; a layer
of insoluble fatty acids separated on top of the liquid and was
brought into the graduated neck of the test bottles by. addition
of hot water; the reading gave the per cent, of fat in the sam-
ple of milk tested.

Short's method did not find very wide application, both be-
cause it was rather lengthy and its manipulations somewhat dif-
ficult for non-chemists, and because several other methods were
published shortly after it had been given to the public.

7. Other milk tests. Of these may be mentioned, besides
the Babcock test already spoken of, the Failyer and Willard

i See 48, footnote.

Introduction. 5

method,1 Parsons' method,2 Cochran's test,3 tne Patrick or Iowa
station test,4 and the Beimling (Leffmann and Beam) test.8 Of
foreign methods published at about the same time, or previously,
the Lactocrite,6 Liebermann's method,7 the Schmid,8 Thorner,*
Nahm,10 Bose-Gottlieb,11 sin-acid method,12 and the Gerber sal-
method13 may be noted.

8. All these tests were similar in principle, the solids
not fat of the milk being in all cases dissolved by the
action of one or more chemicals, and the fat either
measured as such in a narrow graduated tube, or
brought into solution with ether, gasoline, etc., and a
portion thereof weighed on evaporation of the solvent.
While this principle is an old one, having been em-
ployed in chemical laboratories for generations, its
adaptation to practical conditions, and the details as
to apparatus and chemicals used were, of course, new
and different in each case. The American tests given
were adopted to a limited extent within the states in
which they originated and even outside of them, as in
the case of the Short, Patrick and Beimling methods.
The Babcock test, however, soon replaced the different
methods mentioned, and during the past fifteen years

1 Kansas experiment station report, 1888, p. 149.

2 N. H. experiment station report, 1888, p. 69.

3 Journal of Anal. Ohem., Ill (1889), p. 381.

* la. exp. sta., bull. No. 8, Feb, 1890; Iowa Homestead, June 14, 1889.

5 Vermont exp. sta., bull. No. 21, September, 1890. For description
of these and other volumetric methods of milk analysis, see Wiley, Agri-
cultural Analysis, Vol. Ill, p. 490 et seq ; Wing, Milk and its Products, p.
33 et seq, and Snyder, Chemistry of Dairying, pp. 112-113.

6 Analyst, 1887, p. 6.

7 Fresenius1 Zeitschr., 22, 383.

8 Ibid., 27, 464.

9 Ohem. Oentralbl., 1892, 429.

10 Milch-Zeitung, 1894, No. 35; 1897, No. 50.

11 Landw. Vers. Stat., 40, 1.

12 Milch-Zeitung, 1904, No. 27.

13 Milch-Zeitung, 1906, No. 8.

6 Testing Milk and Its Products.

or more it has been in almost exclusive use in creamer-
ies and cheese factories in this country, where payments
are made on the basis cf the quality of the milk deliv-
ered, as well as in the routine work in experiment sta-
tion laboratories, and among milk inspectors and pri-
vate dairymen.

9. The Babcock test. The main cause why the
Babcock test has replaced all competitors is doubtless
to be sought in its simplicity and its cheapness. It has
but few manipulations, is easily learned, and is cheap,
both in first cost and as regards running expenses.

The test is furthermore speedy, accurate,1 and easily
applied under practical conditions, and may therefore
safely be considered the -best milk test available at the
present time.

The method is applicable not only to whole milk, but
to cream, skim milk, butter milk, whey, condensed milk,
and (if a. small scale for weighing out the sample is
available, to cheese and butter.2

With all its advantages, the Babcock milk test is not
in every respect an ideal test. The handling of the
very corrosive sulfuric acid requires constant care and
attention; the speed of the tester, the strength of the
acid, the temperature of the milk to be tested, and other
points, require constant watching, lest the results ob-
tained be too low or otherwise unsatisfactory. In the
hands of careful operators the test can, however, al-
ways be relied upon to give most satisfactory results.

1 For u summary of com pa rat i\ «• :ni;i ]>><•> m:i<l«- l>v tin- HaU-cu-k test
and uravinn-t He analysis up to 1892, see Hoard's Dairyman, Oct. 7, 1892,
p. -j.-rtW); also Schrott-Fiechtl, Milrh/eltung, 1896, p. 183 et seq.

2 Tin- P.abcock test, like the ethrr-rxt rartion method gives,
somewhat too low results in the case of skim milk (l>7.)

Introduction.

10. Foreign methods. In European countries four
practical milk and cream tests, besides the Babcock test,
are in use at the present time, viz.: Gerber 's acid-
butyrometer, the lactocrite,De Laval's butyrometer, and
Fjord's centrifugal cream
test.1

Of these the last test
given has never, to our
knowledge, been intro-
duced into this country,
and the first three only
on a small scale.

11. The Gerber method2

(fig. 1) is essentially the old
Beimling method (7), worked
out independently by the
Swiss chemist, Dr. N. Gerber.
In this test sulfuric acid of
the same strength as in the
Babcock test is used, and a
small quantity of amyl alco-
hol is added. The amyl alcohol facilitates the separation of the
fat, but may introduce a source of error on account of impuri-
ties contained therein, when the results obtained with a new lot of
alcohol can not be checked against gravimetric analysis or against
tests made with amyl alcohol known to give correct results. This
method is, however, extensively used in European countries, hav-
ing there practically replaced the Babcock test or been adopted
in preference to it.

12. The Lactocrite was one of the earliest practical milk
tests introduced. It was invented by De Laval in 1886. The
acids used in this test are lactic acid (originally, acetic acid)

1 The Lister- Babcock milk test advertised in English papers and
known as such in England, is the regular Babcock test, to which the
English manufacturers have prefixed their name; the same applies to
the Ahlborn- Babcock method and the Krugmann- Babcock method.

2 Gerber, Die praktische Milchpriifung, 7th edition, 1900.

Fig. 1. The Gerber acid-
butyrometer.

Testing Milk and Its Products.

with a mixture of hydrochloric and sulfuric acids. This test is
now but rarely met with.

13. In the De Laval butyrometer (fig. 2) the same acid is
used as in the Babcock test, but the tubes employed and the
manipulations of the method differ materially from this test; a
smaller sample of milk is taken (only 2 cc.) and a correspond-

FIG. 2. De Laval's butyrometer.

ingly small quantity of acid used. Where a large number of
milk samples are tested every day, as is the case, for instance,
in European milk control stations, the butyrometer may be
preferable to the Babcock test; but it requires more skill of the
operator and does not work satisfactorily in case of sour, lop-
pered, or partially churned milk.

14. Fjord's centrifugal cream tester1 (fig. 3) is exten-
sively used in Denmark and is mentioned in this connection as it
furnishes, as a rule, a reliable method for comparing the qual-
ity of different lots of milk. The method was published in 1878,
by the late N. J. Fjord, director of the state experiment station
in Copenhagen, through whose exertions and on whose authority
it was introduced into Danish creameries in the middle of the

1 State Danish experiment station, Copenhagen, sixth and ninth
reports, 1885-7.

Introduction.

eighties. No chemicals are added in this test, the milk being
simply placed in glass tubes, seven inches long and about two-
thirds of an inch in diameter, and whirled for twenty minutes
at a rate of 2000 revolutions per minute at 55°G (131°F.).
The reading of the cream layer thus obtained gives the per cent,
of cream, and not of butter
fat, in the sample tested. One
hundred and ninety-two sam-
ples of milk can be tested
simultaneously. Within the
limits of normal Danish herd
milk, the results obtained cor-
respond to the per cents of fat
present in the samples, one per
cent, of cream being equal to
about 0.7 per cent, of fat;
outside of these limits the test
is, however, unreliable, especially in case of very rich milk and
strippers7 milk. Only sweet milk can be tested by this method.
Milk tests proper, like the Gerber, Babcock and De Laval tests,
have during recent years been introduced into Denmark, and
these will in all probability in time force the Fjord cream test
out of Danish creameries, for similar reasons that relegated to
obscurity the gravity cream tests.1

1 Among foreign milk te-ts in use abroad should also be mentioned
the Lindstrom butyrometer and the Wollny refractometer, both of which,
in the hands of trained chemist*, may prove better adapted for use
where a very large number of samples are to be tested at a time, than
any other milk test available.

FIG. 8. Fjord's centrifugal cream
tester.

CHAPTER I.
COMPOSITION OF MILK AND ITS PRODUCTS.

Before taking up the discussion of the Babccck milk
test, a brief description of the chemistry of milk and its
products is given, so that the student may understand
what are the components of dairy products, and the re-
lation of these to each other. Only such points as have
a direct bearing upon the subject of milk testing and
the use of milk tests in butter and cheese factories or
private dairies will be treated in this chapter, and the
reader is referred to standard works on dairying for
more detailed information in regard to the composition
of dairy products.

15. Composition of milk. Milk is composed of the
following substances: water, fat, casein, albumen, milk
sugar, and ash. A few other substances are present in
small quantities, but they are hardly of any practical
importance and will not be considered here. The com-
ponents of the milk less the water are known collect-
ively as milk solids or total solids, and the total solids
less the fat, i. e., casein, albumen, milk sugar, and ash,
are often spoken of as solids not fat or the non-fatty
milk solids. The milk serum includes all components
of the milk less the fat ; the serum solids are therefore
another name for the solids not fat; when given, they
are, however, generally calculated to per cent, of milk
serum, not of milk. If, e. g., a sample of milk contains

Composition of Milk and Its Products. 11

nine per cent, of solids not fat, and three per cent, of
fat, the milk serum will make up 97 per cent, of the
milk, and the serum solids, 9 x 10° = 9.28 per cent.

97
of the milk serum.

16. Water. The amount of water contained in cow's
milk ranges from 82 to 90 per cent. Normal cow's milk
will not, as a rule, contain more than 88 per cent, of
water, nor less than 84 per cent. In states where there
are laws regulating the sale of milk, as is the case in
eighteen states of the Union (see Appendix, Table II),
the maximum limit for water in milk in all instances
but one (South Carolina) is 88 per cent. ; the state men-
tioned allows 88.5 per cent, of water in milk offered
for sale within her borders. The effect of fraudulently
increasing the water content of milk by watering is con-
sidered under Adulteration of Milk (121).

17. Fat. The fat in milk is net in solution, but sus-
pended as very minute globules, which form an emul-
sion with the milk serum; the globules are present in
immense numbers, viz., on the average about one hun-
dred millions in a single drop of milk ; a quart of milk
will contain about two thousand billions of fat globules,
a number written with thirteen figures. The sizes of
the globules in the milk from the same cows vary ac-
cording to the stage of the period of lactation, the glob-
ules being largest at the beginning cf the lactation
period, and gradually decreasing in size with its prog-
ress. Different breeds of cows have fat globules of
different average sizes ; the Channel Island cows are
thus noted for the relatively large fat globules of their

12 Testing Milk and Its Products.

milk, while the lowland breeds, the Ayrshire, and other
breeds have uniformly smaller globules. The diameter
of average sized fat globules in fresh milkers is about
0.004 millimeter, or one six-thousandth of an inch ; that
is, it takes about six thousand such globules placed side
by side to cover one inch in length. The globules of
any I sample of milk vary greatly in size; the largest
globules are recovered in the cream when the milk is
set/or run through a cream separator, and the smallest
ones remain in the skim milk; thoroughly skimmed sep-
arator skim milk contains only a small number of very
minute fat globules.

Milk fat is composed of so-called glycerides of the
fatty acids, i. e., compounds of the latter with glycerin ;
some of the fatty acids are insoluble in water, viz.,
palmitic, stearic, and oleic acids, while others are solu-
ble and volatile, the chief ones among the latter being
butyric, caprylic, and capronic acids. The glycerides
of the insoluble fatty acids make up about 92 per cent,
of the pure milk fat; about 8 per cent, of the glycer-
ides of volatile fatty acids are therefore found in nat-
ural milk- (and butter-) fat. The distinction between
natural and artificial butter lies mainly in this point,
since artificial butter (butterine, oleomargarine) as well
as other solid animal fats contain only a very small
quantity of volatile fatty acids. The glycerides of the
volatile fatty acids are unstable compounds, and are
easily decomposed through the action of bacteria or
light ; the volatile fatty acids thus set free, principally
butyric acid, are the cause of the unpleasant odor nret
with in rancid butter.

Composition of Milk and Its Products. 13

Cow's milk generally contains between three and six
per cent, of fat; in American milk we find, on the
average, toward four per cent, of fat. The milk from
single cows in perfect health will occasionally go below
or above the limits given, but mixed herd milk rarely
falls outside of these limits. The standard adopted by
the U. S. government for fat in milk is 3.25 per ct.
The legal standard for fat in milk in most states of the
Union is 3 per cent. ; Rhode Island allows milk contain-
ing 2.5 per cent, of fat to be sold as pure, while Georgia
and Minnesota require it to contain 3.5 per cent., and
Massachusetts 3.7 per cent, (in the months of May and
June; see Appendix, Table II).

18. Casein and albumen. These belong to the so-
called nitrogenous substances, distinguished from the
other components of the mifk by the fact that they con-
tain the element nitrogen. Another name is albumin-
oids or protein compounds. Casein is precipitated by
rennet in the presence of soluble calcium salts, and by
dilute acids and certain chemicals ; albumen is not acted
upon by these agents, but is coagulated by heat, a tem-
perature of 170° F. being sufficient to effect a perfect
coagulation. The casein, fat, and water, are the main
components of nearly all kinds of cheese. In the manu-
facture of cheddar and most other solid cheeses, the
casein is coagulated by rennet, and the curd thus
formed holds fat and whey mechanically, the latter
containing in solution small quantities of non-fatty
milk solids. The albumen goes into the whey and is
lost for cheese making; in some countries it is also made
into cheese by evaporating the whey under constant

14 Testing Milk and Its Products.

stirring ; whole milk of cows or goats is often added and
incorporated into such cheese (primosi, gjetost).

Casein is present in milk partly in solution, in the
same way as milk sugar, soluble ash-materials and albu-
men, and partly in suspension, in an extremely fine col-
loidal condition, mixed or combined with insoluble cal-
cium phosphates. The casein and calcium phosphates
in suspension in milk may be retained on a filter made
of porous clay (so-called Cliamberland filters).

About 80 per cent, of the nitrogenous compounds of
normal cow 's milk are made up of casein ; the rest is
largely albumen. If the amount of casein in milk be
determined by precipitation with rennet *or dilute acids,
and the albumen by boiling the filtrate frcm the casein
precipitate, it will be found that the sum of these two
compounds do not make up the total quantity of nitro-
genous constituents in the milk. The small remaining
portion (about five per cent, of the total nitrogenous
constituents) has been called by various authors, globu-
lin, albumose, hemi-albumose, nuclein, nucleon, proteose,
etc. The nitrogenous constituents of milk are very un-
stable compounds, and their study presents many and
great difficulties ; as a result we find that no two scien-
tists who have made a special study of these compounds
agree as to their properties, aside from those of casein
and albumen, or their relation to the nitrogenous sub-
stances found elsewhere in the animal body. For our
pose we may, however, consider the nitrogen com-
pounds of milk as made up of casein and albumen, and
the term casein and albumen, as used in this book, is
meant to include the total nitrogenous constituents of

Composition of Milk and Its Products. 15

milk, obtained by multiplying the total nitrogen con-
tent of the milk by 6.25.1

The quantity of casein in normal cow's milk will vary
from 2 to 4 per cent., and of albumen, from .5 to .8 per
cent. The total content of casein and albumen ranges
between 2.5 and 4.6 per cent, the average being about
3.2 per cent. Milk with a low fat content will contain
more casein and albumen than fat, while the reverse is
generally true in case of milk containing more than 3.5
per cent, of fat.

19. Milk sugar or lactose belongs to the group of
organic compounds known as carbohydrates. It is a
commercial product manufactured from whey and is
obtained in this process as pale white crystals, of less
sweet taste and less soluble in water than ordinary
sugar (cane sugar, sucrose). About 70 per cent, of the
solids in the whey, and 33 per cent, of the milk solids,
are composed of milk sugar.

When milk is left standing for some time, viz., from
one to several days, according to the temperature of the
surrounding medium it will, as a rule, turn sour and
soon become thick and loppered. This change in the
composition and appearance of the milk is brought
about through the action of acid-forming bacteria on
the milk sugar. These are present in ordinary milk in
immense numbers, and under favorable conditions of
temperature multiply rapidly, feeding on the milk sugar

1 The factor 6.25 is generally used for obtaining the casein and albu-
men from the total nitrogen in the milk, although 6.37 would be more
correct, since these substances, according to our best authorities, con-
tain on the average 15.7 per cent, of nitrogen ( y1-^ = 6.8?)

16 Testing Milk and Its Products.

as they grow, and decomposing it into lactic acid. When
this change alone occurs, there is not necessarily a loss
in the nutritive value of the milk, since milk sugar
breaks up directly into lactic acid, as shown by the fol-
lowing chemical formula:

C14H22011H20 (lactose) =4 C3H003 (lactic acid).1

Ordinarily the souring of milk is, however, more
complicated, and other organic bodies, like butyric acid,
alcohol, etc., and gases like carbonic acid are formed,
resulting in a less in the feeding value of the milk.
While sour milk may therefore contain a somewhat
smaller proportion of food elements than sweet milk,
it will generally produce better results when fed to
farm animals, especially pigs, than is obtained in feed-
ing similar milk in a sweet condition. The cause of this
may lie in the stimulating effect of the lactic acid of
sour milk on the appetites of the animals, or in its aid-
ing digestion by increasing the acidity of the stomach
juices.

That the souring of milk is due to the activities of
bacteria present therein is shown clearly by the fact
that sterile milk, i. e., milk in which all germ life has
been killed, will remain sweet for any length of time
when kept free from infection.

The amount of milk sugar found in normal cow's
milk varies from 3.5 to 6 per cent., the average content
being about 5 per cent. ; in sour milk this content is
decreased to toward 4 per cent.

1 One molecule of mtlk sugar is composed of 12 atoms of carbon (O)r
±> j i toms of hydrogen (H). 11 atoms ofoxyjrrn <O>, and one molecule of
water (H2O). In the s;iint' way, the lactic-acid molecule consists of 3
atom- of carbon, »} atoms of hydrogen, and 3 atoms of oxygen.

Composition of Milk and Its Products. 17

20. Ash. The ash or mineral substances of milk are
largely composed of chlorids and phosphates of sodium,
potassium, magnesium and calcium; iron oxid and sul-
furic and other acids are also present in small quanti-
ties among the normal mineral milk components. The
amounts of the different bases and acids found in milk
ash have been determined by a number of chemists ; the
average figures obtained are given in the following
table, calculated per 100 parts of milk (containing .75
per cent, of ash) and per 100 parts of milk ash.

Mineral Components of Milk.

In per cent, of Milk. In per cent, of Ash.

Potassium oxid (K2O) 19 per ct. 25.64 per ct.

Sodium oxid (Na2O) 09 12.45

Lime (CaO) 18 24.58

Magnesia (MgO) 02 3.09

Iron oxid (Fe2O3) 002 .34

Phosphoric anhydrid (P2O5)... .16 21.24

Chlorin (Cl) 12 16.34

.762 per ct. 103.68 per ct.

Less oxygen, corresponding to

chlorin . . .012 3.68

.75 100.00

The combinations in which the preceding bases and
acids are contained in the milk are not known with cer-
tainty. According to Soldner, 36 to 56 per cent, of the
phosphoric acid found in milk, and from 53 to 72 per
cent, of the lime, are present in suspension in the milk
as di- and tri-calcium phosphates, and may be filtered
out by means of Chamberland filters (18), or by long
continued centrifuging (Babcock1). The rest of the
ash constituents are dissolved in the milk serum.

1 Wis. experiment station, twelfth report, p. JKi.
2

18 Testing Milk and Its Products.

The ash content of normal cow's milk varies but lit-
tle, as a rule only between .6 and .9 per cent, with an
average of .7 per cent. Milk with a high fat content
generally contains about .8 per cent, of ash; strippers'
milk always has a high ash content, at times even ex-
ceeding one per cent. Ordinarily, the mineral constitu-
ents are least liable to variations of any of the com-
ponents of the milk.

21. Other components. Besides the milk constitu-
ents enumerated and described in the preceding pages,
normal milk contains a number of substances which are
present in but small quantities and have only scientific
interest, such as the milk gases (carbonic acid, oxygen,
nitrogen), citric acid, lecithin, cholesterin, urea, hypo-
xanthin, lactochrome, etc.

22. Average composition. The average percentage
composition of cow's milk will be seen from Table I in
the Appendix. The following statement shows the lim-
its within which the components of normal American
cow's milk are likely to come:

Minimum. Maximum. Average.

Water 82.0 per ct. 90.0 per ct. 87. 4 per ct.

Fat 2.3 7.8 3.7

Casein and albumen 2.5 4.6 3.2

Milk sugar 3.5 6.0 5.0

Ash 6 .9 .7

23. Colostrum milk. The liquid secreted directly
after parturition is known as colostrum milk or biest-
ings. It is a thick, yellowish, viscous liquid; its high
content of albumen and ash is characteristic, and also
its low content of milk sugar. Owing to the large quan-

Composition of Milk and Its Products. 19

tity of albumen which colostrum contains, it will coagu-
late on being heated toward the boiling point. In the
course of four or five days the secretion of the udder
gradually changes from colostrum to normal milk; the
milk is considered fit for direct consumption or for the
manufacture of cheese and butter, when it does not co-
agulate on boiling and is of normal appearance as re-
gards color, taste, and other properties. For composi-
tion of colostrum milk, see Appendix, Table I.

24. Composition of milk products. In addition to
its use for direct consumption, milk is the raw-material
from which cream, butter, cheese, and condensed milk
are obtained.

When milk is left standing for some time or subjected
to centrifugal force, it will separate into two distinct
parts, cream and skim milk. The proportion of each
part which is obtained, and their chemical composition,
will depend on the method by which the separation is
effected; in the so-called gravity process where the
cream is separated on standing— either in shallow pans
in the air, or in deep cans, submerged in cold water— a
less complete separation is reached, since the skim milk
obtained is richer in fat than when the separation takes
place through the action of centrifugal force.

The milk is now always in modern creameries skimmed
by means of cream separators. Separator cream will
contain from 15 to 50 per cent, of fat, according to the
adjustment of the separator and of the milk supply;
ordinarily it contains about 55 per cent, of fat. Cream
of average quality, in addition to the fat content given,
consists of about 66 per cent, of water, 3.8 per cent.

20 Testing Milk and Its Products.

casein and albumen, 4.3 per cent, milk sugar, and .5 per
cent. ash.

The skim milk is made up of the milk serum (15) and
a small amount of fat, viz., toward .4 per cent, when
obtained by the gravity process, and less than .2 per
cent, in the case of separator skim milk. Milk set in
shallow pans in the air, or in deep cans in water above
60° F., will give skim milk containing one-half to over
one per cent, of fat. Skim milk is used as a food for
young farm animals or as human food, and in this
country only in exceptional cases, for the manufacture
of cheese.

25. Cream is used for the manufacture of butter or
for direct consumption. In the former case a certain
amount of acidity is generally allowed to develop there-
in previous to the churning process. This secures a
more complete churning and produces peculiar flavors
in the butter, without which it would seem insipid to
the majority of people in this country. Nearly all
American butter is salted before being placed on the
market. Salt is a preservative and for a limited length
of time prevents butter from spoiling. Unsalted butter
made from sweet cream is a common food article in
Southern and Middle Europe, but only an insignificant
amount is manufactured and consumed in America;
salted butter made in Europe also contains considerably
less salt than American butter (see Appendix, Table I).
Butter contains all the fat of the cream except a small
portion which goes into the butter milk, and a small
unavci(l;il)l(k mechanical loss incident to the handling of
the products. Butter should contain at least 80 per

Composition of Milk and Its Products. 21

cent, of fat and ordinarily contains about 83 per cent. ;
besides this amount of fat, butter is generally composed
of water, about 13 per cent., curd and milk sugar 1 per
cent., and salt 3 per cent.

Butter milk has a composition similar to skim milk,
but varies much more than this product, according to
the acidity, temperature, and thickness of the cream,
and other churning factors. It contains about 9 per
cent, of solids, viz., milk sugar (and lactic acid) 4 per
cent., casein and albumen 4 per cent., fat .3 per cent.,
and ash .7 per cent.

26. The quantities of butter and by-products obtained
in the manufacture of butter are as follows : 1000 Ibs.
of milk of average quality will give about 850 Ibs. of
skim milk and 145 Ibs. of cream (separator slime and
mechanical loss, 5 Ibs.) ; this amount of cream will make
about 42 Ibs. of butter and 100 Ibs. of butter milk (me-
chanical loss, 3 Ibs.).

27. In the manufacture of American cheddar cheese,
whole milk is heated to about 86° F., and a small amount
of rennet extract is added, which coagulates the casein ;
the albumen of the milk is not precipitated by rennet
and remains in solution (18). " Green " cheese, as taken
from the press, is made up, roughly speaking, of 37 per
cent, of water, 34 per cent, of fat, 24 per cent, of albu-
minoids (nearly all casein), and about 5 per cent, of
milk sugar, lactic acid, and ash (largely salt). In the
curing of cheese there is some less by drying, but the
main changes occur in the breaking up of the firm curd
into soluble and digestible nitrogenous compounds, pep-
tones, amids, etc.

22 Testing Milk and Its Products.

Whey is the by-product obtained in the manufacture
of cheese. It consists of water and less than 7 per cent,
of solids; of the latter about 5 per cent, is milk sugar,
.8 per cent, albumen, .6 per cent, ash, and .3 per cent,
fat. Whey is generally used for feeding farm animals ;
it is the raw-material from which milk sugar and whey
cheese are made.

28. Condensed milk is manufactured from whole milk
or from partially skimmed milk. In many brands a
large quantity of sugar (25 per cent, or more) is added
to the condensed milk in the process of manufacture so
as to secure perfect keeping quality in the product.
Brands to which no sugar has been added are also on
the market, and in case of such brands the relation be-
tween the various solid constituents of the condensed
milk will be essentially the same as that between the
constituents of milk solids. Condensed milk should con-
tain at least 9% fat, and must be free from preserva-
tives and other foreign substances (except sugar).

Tables are given in the Appendix showing the aver-
age composition of the various milk products.

Questions.

1. What is the average composition of cow's milk; state briefly
the properties of the various constituents.

2. What is meant by total solids; solids not fat; milk serum;
serum solids?

3. What is colostrum milk? Give its average composition, and
in what particulars it mainly differs from normal milk.

4. Give the average composition of cream, skim milk, butter-
milk, whey, butter and cheddar cheese.

5. Explain the distribution of the components of milk in (a)
butter-making, (b) cheese-making.

CHAPTER II.
SAMPLING MILK.

29. The butter fat in milk is not in solution, like
sugar dissolved in water, but the minute fat globules or
drops, in which form it occurs, are held in suspension
in the milk serum (17). Being lighter than the serum,
the fat globules have a tendency to rise to the surface
of the milk. If, therefore, a sample of milk is left
standing for even a short time, the upper layer will
contain more fat than the lower portion. This fact
should always be borne in mind when milk is sampled.
The rapidity with which fat rises in milk can be easily
demonstrated by allowing a quantity of sweet milk to
stand in a cylinder or a milk can for a few minutes,
and testing separately the top, middle and bottom layer
of this milk.

The amount of mixing necessary to evenly distribute
the constituents of milk throughout its mass may be as-
certained by adding a few drops of cheese color to a
quart of milk. The yellow streaks through the milk
will be noticed until it has been poured several times
from one vessel to another, when the milk will have a
uniform pale yellow color. Stirring with a stick or a
dipper will not produce an even mixture so quickly or
so completely as pouring the milk a few times from o
vessel to another ; in sampling milk for testing it should
always be mixed by pouring, just before the milk is
measured into the bottle ; if several tests are made of a
sample, the milk should be poured before each sampling.

24 Testing Milk and Its Products.

•
30. Partially churned milk. A second difficulty

sometimes met with in sampling whole milk arises from
the fact that a part of the butter fat may be separated
in the form of small butter granules, by too zealous mix-
ing or by reckless shaking in preparing the sample for
testing. This will happen most readily in case of milk
from fresh cows or milk containing exceptionally large
fat globules. When some of the butter granules are
thus churned out, they quickly rise to the surface of
the milk after pouring and cannot again be incorporated
in the milk by simple mixing; it is, therefore impossi-
ble to obtain a fair sample of such milk for testing
without taking special precautions which will be ex-
plained in the following. The granules of butter may
be so small as to pass into the pipette with the milk and
the quantity measured thus contain a fair proportion
of them, but they will be found sticking to the inside
of the pipette when this is emptied, and thus fail to be
carried into the test bottle with the milk.

A similar partial churning of the milk will sometimes
take place in the transportation cans. "When such milk
is received at the factory, the butter granules are caught
by the strainer cloth through which the milk is poured,
and are thus lost both to the factory and to the farmer.
This separated fat cannot be added to the cream or to
the granular butter, without running the risk of mak-
ing mottled butter, and it will not enter into the sam-
ple of milk taken for testing purposes.

When milk samples are sent by mail or express in
small bottles, or carried to the place of testing, they
often arrive with lumps rf Imllor floating in the milk

Sampling Milk. 25

or sticking to the glass. This churning of the milk can
be easily prevented by completely filling the bottle or
the can. If there is no space left for the milk in which to
splash around, the fat will not be churned out in transit.

31. Approximately accurate results may generally be
obtained with a partially churned sample of milk, if a
teaspoonful of ether be added to it. After adding the
ether, cork the bottle and shake it until the lumps of
butter are dissolved. This ether solution of the butter
will mix with the milk and from the mixture a fairly
satisfactory sample may generally be taken. The dilu-
tion of milk by the ether introduces an error in the
testing, and only the smallest quantity of ether neces-
sary to dissolve the lumps of butter should be used. If
desired, a definite quantity of ether, say five per cent,
of the volume of the sample of milk to be tested, may
be added ; in such cases the result of the test must be
increased by the per cent, of ether added.

EXAMPLE. — To a 4-oz. sample (120 cc.) of partially churned
milk, 5 per cent, or 6 cc., of common ether are added; the mix-
ture gave an average test of 4 2 per cent. The test must be in-
creased by Yg0X4.2=.21, and the original milk therefore con-
tained 4.2+.21=4.41 per cent, of fat.

Milk containing ether must be mixed cautiously with
acid in making a test, so as to avoid loss of the contents
of the bottle by the sudden boiling of the ether due to
the heat evolved in mixing the milk and the acid.

Instead of adding ether to partially churned sam-
ples, the milk may be heated to about 110° F. for a
few minutes, so as to melt the butter granules; the
sample is now shaken vigorously until a uniform mix-
ture of milk and melted butter is obtained, and a pi-
petteful then quickly drawn from the sample.

26 Testing Milk and Its Products.

32. Sampling sour milk. When milk becomes sour,
the casein is coagulated and the mechanical condition of
the milk thereby changed so as to render difficult a cor-
rect sampling. The butter fat is not, however, changed
in the process of souring; this has been shown by one
of us, among others, in a series of tests which were
measured from one sample of sweet milk into six test
bottles. A test of the milk in one of these test bottles
was made every month for six months, and approxi-
mately the same amount of fat was obtained in the
tests throughout the series, as was found originally in
the milk when tested in a sweet condition.1 If the milk
is in condition to be sampled, its souring does not there-
fore interfere with its being tested by the Babcock test
or with the accuracy of the results obtained.

In order to facilitate the sampling of sour or lop-
/ pered milk, some chemical may be added which will re-
dissolve the coagulated casein and produce a uniform
mixture that can be readily measured with a pipette.
Any alkali (powdered potash or soda, or liquid ammo-
nia) will produce this effect. Only a very small quan-
tity of powdered alkali is necessary for this purpose.
The complete action of the alkali on sour milk requires
a little time, and the operator should not try to hasten
the solution by adding too much alkali. An excess of
alkali will often cause such a violent action of the sul-
furic acid on the milk to which the acid is added (on
account of the heat generated or the presence of car-
bonates in the alkali) that the mixture will be thrown

l See Hoard's Dairyman, April 8, 1892. The same holds true for
cream, as shown by Winton (U. S. Dept. Agr., Div. of Chemistry, bull.
48, p. 112).

Testing Milk and Its Products. 27

out of the neck of the test bottle when this is shaken in
mixing the milk and the acid (37). When powdered
alkali is added to the milk, it should be allowed to
stand for a while, with frequent shaking, until the curd
is all dissolved and an even translucent liquid is ob-
tained. Such milk may become dark-colored by the ac-
tion of the alkali, but this color does not interfere with
the accuracy of the test.

Instead of powdered soda or potash, these substances
dissolved in water (soda or potash lye), or strong am-
monia, may be used for the purpose of dissolving the
coagulated casein in sour milk. In this case, a definite
proportion of alkali solution must be taken, however, 5
per cent, of the volume of milk being usually sufficient,
and the results obtained are increased accordingly.

33. Sampling frozen milk. When milk freezes, it
separates into two distinct portions : Milk crystals,
largely made up of water, with a small admixture of fat
and other solids, and a liquid portion, containing nearly
all the solids of the milk. In sampling frozen milk it
is therefore essential that the liquid and the frozen part
be warmed and thoroughly mixed by pouring gently
back and forth from one vessel into another; the sam-
ple is then taken and the test proceeded with in the
ordinary manner (36).

Questions.

1. What precautions must be taken in sampling milk? Give
reasons.

2. How can a fair sample be taken of (a) partially churned
milk, (b) sour milk, (c) frozen milk?

3. If 15 cc. of ammonia are added to 500 cc. of sour milk,
and a test of 3.45 obtained, what is the correct test of the milk?

CHAPTER III.

THE BABCOCK TEST.

34. The Babcock test is based on the fact that strong
sulfuric acid will dissolve all non-fatty solid constitu-
ents of milk and
other dairy products,
and thus enable the
fat to separate on
standing. To effect a
speedy and complete
separation of the fat,
the bottles holding
the mixture of milk
and acid are placed
in a centrifugal ma-
chine, a so-called
tester, and whirled
for four minutes ; hot
water is then added
so as to bring the
liquid fat into the
graduated neck of
the test bottles, and
after a repeated
whirling, the length
of the column of fat is read off, showing the per cent,
of fat contained in the sample tested.

FIG. 4. The first Babcock tester made.

The Babcock Test. 29

Sulfuric acid is preferable to other mineral acids for
the purpose mentioned, on account of its affinity to
water ; when mixed with milk, the mixture heats greatly,
thus keeping the fat liquid without the application of
artificial heat and rendering possible a distinct reading
of the column of fat brought into the neck of the test
bottles.

So far as is known, any kind of milk can be tested
by the Babccck test. Breed, period of lactation, qual-
ity or age of the milk is of no importance in using this
method, so long as a fair sample of milk can be secured.
In cases of samples of milk or other dairy products
rich in solids it requires a little more effort to obtain a
thorough mixture with the acid than with dairy prod-
ucts low in solids, like skim milk or whey, which may
be readily mixed with the acid.

A.— DIRECTIONS FOR MAKING THE TEST.

35. The various steps in the manipulation of the
Babcock test are discussed in the following pages; at-
tention is drawn to the difficulties which the beginner
and others may encounter in the use of the test, and
the necessary precautions to be observed in order to
obtain accurate and satisfactory results are explained
in detail. The effort has been to treat the subject ex-
haustively and from a practical point of view, so that
persons as yet unfamiliar with the test may turn to
the pages of this book for help in any difficulties which
they may meet in their work in this line.

36. Sampling. The sample to be tested is first mixed
by pouring the milk from one vessel to another two or

Testing^. M'ilk and Its Products.

three times, so that every portion thereof will
contain a uniform amount of butter fat (29).
The measuring pipette (fig. 6), which has a
capacity of 17.6 cubic centimeters,1 is filled with
the milk immediately after the
mixing i§ completed, by suck-
ing the milk into it until this
rises a little above the mark
around the stem of the pipette;
the forefinger is then quickly
placed over the end of the pi-
pjette before the milk runs down
below the mark. By slightly
releasing the pressure of the
finger on the end of the pipette,
the milk is now allowed to run
down until it just reaches the
mark on the stem ; the quantity
of milk contained in the pi-
pette will then, if this is cor-
rectly made, be exactly 17.6 cc.
The finger should be dry in
measuring out the milk so that
the delivery of milk may be
readily checked by gentle pres-
sure on the upper end of the
It 1 ill pipette.

The point of the pipette is
now placed in the neck of a
test bottle (fig. 5),

FIG. 5. Bibcock milk,-. , ,

testbottio. n.'incock

pette.

1 See p. 45, foot note.

"^x

JV0

The ^a^coc^^L/BRA^

and the milk is allowed to flow slowly down the inside
of the neck. Care must be taken that none of the milk
measured out is lost in this transfer. The portion of
the milk remaining in the point of the pipette is blown
into the test bottle.
The best and saf-
est manner of hold-
ing the bottle and the
pipette in this trans-
fer is shown in fig.
7. Fig. 8 shows a
position which should
be avoided, since by
holding the bottle in

this way, there is P danger that some of the

milk may completely fill
the neck of the bottle,
and as a result, flow
over the top of the neck.
Pipettes, the lower
part of which slip read-
ily into the necks of the
test bottles, may be
emptied by lowering
the pipette into the
neck of the bottle till
it rests on its rim, when
the milk is allowed to

FIG. 7. The right way of emptying

pipette into test bottle. run into the test bottle. ,

37. Adding acid. The acid cylinder (fig. 9) hold-
ing 17.5 cc., is filled to the mark with sulfuric acid of

Testing Milk and Its Products.

a specific gravity of 1.82-1.83. This amount of acid is
carefully poured into the test bottle containing the milk.
In adding the acid, the test bottle is conveniently held
at an angle (see fig. 7), so that the acid will run down
the wall of the bottle and
not run in a small stream into
the center of the milk, the
bottle being slowly turned
around and the neck thus
cleared of adhering milk. By
pouring the acid into the
middle of the test bottle,
there is also a danger of com-
pletely filling this with acid,
in which case the plug of
acid formed will be pushed
over the edge of the neck by
the expansion of the air in
the bottle, and may be spilled
on the hands of the operator.
The milk and the acid in
the test bottle should be in
two distinct layers, without
much of a black
band of partially
mixed liquids be- :
tween them. Such

a dark layer is of- into trst hotti. .

ten followed by an indistinct separation of the fat in
the final reading. The cause of this may be that a par-
tial mixture of acid and milk before the acid is diluted

FIG. 8. The wrong way of emptying pipette

The Babcock Test. 33

with the water of the milk may bring about too strong
an action of the acid on this small portion of the milk,
and thus char the fat contained therein. The appear-
ance of black flocculent matter in or below the col-
umn of fat which generally results, in
either case renders a correct measurement'
difficult and at times even impossible; if
the black specks occur in the fat column
itself, the readings are apt to be too high;
if below it, the difficulty comes in decid-
ing where the column of fat begins.

38. Mixing milk and acid. After add-
ing the acid, this is carefully mixed with:
the milk by giving the test bottle a rotary
motion. In doing this, care should be
acid cyiinde?.' taken that the liquid is not shaken into
the neck of the test bottle. When once begun, the mix-
ing should be continued until completed ; a partial and
interrupted mixing of the liquids will often cause more
or less black material to separate with the fat when the
test is finished. Clots of curd which separate at first
by the action of the acid on the milk, must be entirely
dissolved by continued and careful shaking of the bot-
tle. Beginners sometimes fail to mix thoroughly the
milk and the acid in the test bottle. As the acid is
much heavier than the milk a thin layer of it is apt to
be left unnoticed at the bottom of the bottle, unless this
is vigorously shaken toward the end of the operation.

The mixture becomes hot by the action of the acid' on
the water in the milk and turns dark colored, owing 'to
the effect of the strong sulfuric acid on the nitrogenous
constituents and the sugar in the milk.

34 Testing Milk and Its Products.

Colostrum milk or milk from fresh cows will form a
violet colored mixture with the acid, due to the action
of the latter on the albumen present in such milk in
considerable quantities (23).

When milk samples are preserved by means of potas-
ium bichromate (190), and so much of this material has
been added that the milk has a dark yellow or reddish
color, the mixture of milk and acid will turn greenish
black, and a complete solution is rendered extremely
difficult on account of the toughening effect of the, bi-
chromate on the precipitated casein. The difficulty is
still more pronounced with milk preserved with for-
maldehyd.

39. Whirling bottles. After the milk and the acid
have been completely mixed, the test bottle is at once
placed in the centrifugal machine or tester and whirled
for four or five minutes at a speed of 600 to 1200 revo-
lutions per minute, according to the diameter of the
tester (66). It is not absolutely necessary to whirl the
test bottles in the centrifuge as soon as the milk and
the acid are mixed, although this method of procedure
is much to be preferred ; they may be left in this condi-
tion for any reasonable length of time (24 hours, if
necessary) without the test being spoiled. If left until
the mixture 'becomes cold, the bottles should, however,
be placed in warm water (of about 160° F.) for about
15 minutes before whirling.

Four minutes at full speed is sufficient for the first
whirling of the test bottles in the centrifuge; this will
brin£ all fat to the surface of the liquid in the bottle.

The Babcock Test.

— 7

4O. Adding water. Hot water is now added by means
of a pipette or some special device (10 in fig. 58), until
the bottles are filled to near the scale on the neck (80).
The bottles are whirled again at full speed for one min-
ute, and hot water added a second time, until the lower
part of the column of fat comes within the scale on the
neck of the test bottle, preferably to the 1 or 2 per
cent, mark, so as to allow for the sinking of the column
of fat, due to the gradual cooling of the contents of the
bottle. By dropping the water directly on the fat in
the second filling, the column of fat will be washed free
from light flocculent matter, which might otherwise be
entangled therein and render the
reading uncertain or too high. A
final whirling for one or two min-
utes completes the separation of
_j the fat.

41. Measuring the fat. The
amount of fat in the neck of the
bottle is measured by the scale or
graduations on the neck. Each
division of the scale represents
two-tenths of one per cent, of fat,
and the space filled by the fat
shows the per cent, of butter fat
contained in the sample tested.
FIG. 10. Measuring the The fat * measured from the
B0abcno?kt0efstf^ttre.a lower line of separation between
the fat and the water, to the top of the fat column, at
the point &, shown in the figure, the reading being thus
taken from a to h, and not to c or to d. Comparative

36 Testing milk and its Products.

gravimetric analyses have shown that the readings ob-
tained in this manner gi^ correct results. While the
lower line of the fat column is nearly straight, the upper
one is curved, and errors in the reading are therefore
easily made, unless the preceding rule is observed.

The fat obtained should form a clear yellowish liquid
distinctly separated from the acid solution beneath it.
There should be no black or white sediment in or below
the column of fat, and no bubbles or foam on its sur-
face. The bottles must be kept warm until the read-
ings are made, so that the column of fat will have a
sharply defined upper and lower meniscus. When the
testing is done in a cold room, it is a good plan to place
the bottles in a pail with water of 140° F. be-
fore readings are made. The readings should always
be made when the fat has a temperature of about 140°
F. ; too low results will be obtained if the fat is allowed
to cool below 120° F., and too high if readings are
taken above 150°. The fat separated in the Babcock
test solidifies at about 100° F. If the fat is partly sol-
idified, it is impossible to make an accurate reading.1

42. Readings of tests of milk made in steam turbine
testers with tightly closed covers which prevent the free
escape of exhaust steam (71) , will come .2 to .3 per cent.

x The effect of differences in the temperature of the fat on the read-
ings obtained will be seen from the following: If 110 and 150° F. be
taken as the extreme temperatures at which readings can be made,
this difference of 40° F. (22.8° O.) would HIM UP a difference in the volume
of the fat column obtained in case of 10 per cent, milk, of .00064 x 2 x 22.3
= .028544 cc., or .14 per cent., .00064 being the expansion coefficient of pure
butter fat per degree Centigrade between 50 and 100° O. fZune, Anal y si-
des Beurre*, I, 87), and 2, the volume of the fat in cc. contained In 17.6 cc.
of 10 per cent. milk. On 5 per cent milk this «-xtn»me difference would
therefore be about .07, or nearly one-tenth, of one per cent.

The Babcock Test. 37

too high if the temperature of the fat is allowed to rise
to that of the exhaust steam^during the process of whirl-
ing. In such cases the test bottles must be allowed to
cool to about 140°, by placing them in water of this
temperature for a few minutes, before readings are
taken.1

A pair of dividers will be found convenient for meas-
uring the fat, and the liability of error in reading is
decreased by their use. The points of the dividers are
placed at the upper and lower limits of the fat column
(from a to 6 in fig. 10). The dividers are now lowered,
one point being placed at the zero mark of the scale,
and the mark at which the other point touches the scale
will show the per cent, of fat in the sample tested..
The dividers must be tight in the joint to be of use for
this purpose.

B. — DISCUSSION OF THE DETAILS OF THE
BABCOCK TEST.

43. The main points to be observed as to apparatus
and testing materials in order to obtain correct and
satisfactory results by this test will now be considered,
and such suggestions and help offered as have been
found needful from past experience with a great variety
of samples of milk, apparatus, and accessories. *

1. — GLASSWARE.

44. Test bottles. The test bottles should have a ca-
pacity of about 50 cc., or less than two ounces; they
should be made of well-annealed glass that will stand

1 See Wis. experiment station rep. XVII, p. 76.

38 Testing Milk and Its Products.

sudden changes of temperature without breaking, and
should be sufficiently heavy to withstand the maximum
centrifugal force to which they are likely to be sub-
jected in making tests. This force may, on the average,
be not far from 30.65 Ibs. (see 66), which is the pres-
sure exerted in whirling the bottles filled with milk and
acid in a centrifugal machine of 18 inches diameter at
a speed of 800 revolutions per minute.

Special forms of test bottles used in testing cream
and skim milk are described under the heads of cream
and skim-milk testing (89, 90, 91, 99).

When 17.6 cc., or 18 grams of milk (48), are meas-
ured into the Babcock test bottle, the scale on the neck
of the bottles will show directly the per cent, of fat
found in the milk. The scale is graduated from 0 to
10 per cent. 10 per cent, of 18 grams is 1.8 grams. As
the specific gravity of pure butter fat (i. e., its weight
compared with that of an equal volume of pure water)
at the temperature at which the readings are made
(about 140° P.), is 0.9, then 1.8 grams of fat will oc-
cupy a volume of J^-=2 cubic centimeters. The space
between the 0 and 10 per cent, marks on the necks of
the test bottles must therefore hold exactly 2 cubic cen-
timeters. The scale is divided into 10 equal parts, each
part representing one per cent., and each of these is
again sub-divided into five equal parts. Each one of the
latter divisions therefore represents two-tenths of one per
cent, of fat when 17.6 cc. of milk is measured out. The
small divisions are sufficiently far apart in most Bab-
cock test bottles to make possible the estimation of one-
tenth, or even five-hundredths, of one per cent, of fat
in the samples tested.

The Babcock Test. 39

As the necks of Babcock test bottles vary in diame-
ter, each separate bottle must be calibrated by the manu-
facturers ; the length of the scale is not, for the reasons
given, apt to be the same in different bottles.1

If the figures and lines of the scale become indistinct
by use, the black color may be restored by rubbing a
soft pencil over the scale, or by the use of a piece of
burnt cork after the scale has been rubbed with a little
tallow. On wiping the neck with a cloth or a piece of
paper the black color will show in the etchings of the
glass, making these plainly visible.

45. Marking test bottles. Test bottles can now be
bought with a small band or portion of their neck or
body ground or "frosted," for numbering the bottles
with a lead pencil. Bottles without this ground label
can be roughened at any convenient spot by using a wet
fine file to roughen the smooth surface of the glass.
There is this objection to the latter method that unless
carefully done, it is apt to weaken the bottles so that
they will easily break, and to both methods, that the
lead pencil marks made on such ground labels may be
effaced during the test if the bottles are not carefully
handled. Small strips of tin or copper with a number
stamped thereon are sometimes attached to a collar
around the necks of the bottles. They are, however,
easily lest, especially when the top of the bottle is

1 A flat-bore test bottle and one with a brass collar and screw used
for opening and closing a small hole in the neck of the test bottle have
been placed on the market by an Eastern manufacturer. These have
been tried by us, and were not found to possess any particular advan-
tage over the round-neck bottles; in fact, are more subject to errors of
calibration.

40 Testing Milk and Its Products.

slightly broken, or at any rate, are soon corroded so
that the numbers can only be seen with difficulty.

The best and most permanent label for test bottles is
made by scratching a number with a marking diamond

on the glass di-
rectly above the
scale on the neck
of the bottles or
by grinding a
number on the
bottle itself. In
ordering an " out-
fit, or test bottles
alone, the oper-
— ator may specify

FIG. 12. Waste-acid jar. that the bottles

are to be marked 1 to 24, or as many as are bought,
and the dealer will then put the numbers on with a
marking diamond.

A careful record should be kept of the number of the
bottle into which each particular sample of milk is
measured. Mistakes are often made when the operator
trusts to his memory for locating the different bottles
tested at the same time.

46. Cleaning test bottles. The fat in the neck of
the test bottles must be liquid when these are cleaned.
In emptying the acid the bottle should be shaken in
order to remove the white residue of sulfate of limr,
etc., from the bottom; if the acid is allowed to drain
out of the bottle without shaking it, this residue will
be found to stick very tenaciously to the bottom of the
bottle in the subsequent cleaning with water.

The Babcock Test.

A convenient method of emptying test bottles is shown
in the illustration (fig. 12). After reading the fat col-
umn, the bottles are placed neck down, in the half-inch
holes of the board cover of a five-gallon stoneware jar.

FIG. 13. Apparatus for cleaning test bottles. A, apparatus in posi-
tion; the water flows from the reservoir through the iron pipe b into
the inverted test bottle d through the brass tube c, screwed into the
iron pipe. B shows construction of the rubber support on which the
test bottles rest;/, sink.

An occasional shaking while the liquid is running from
the bottles will rinse off the preciptate of sulfate of
lime. A thorough rinsing with boiling hot water is

Testing Milk and Its Products.

generally sufficient to remove all grease and dirt, as
well as acid solution from the inside of the bottles.
The apparatus shown in fig. 13 will be found convenient
for this purpose. After the bottles have been rinsed a
second time, they may be placed in an inverted posi-
tion to drain, on a galvanized iron rack, as shown in
fig. 14, where they are kept until needed. The outside

of the bottles should
occasionally be wiped
clean and dry.

47. The amount of
unseen fat that clings
to test bottles used

FIG. 14. Draining-rack for test bottles. for testing milk or

cream, is generally not sufficient to be noticed in test-
ing whole milk, but it plays an important part in test-
ing samples of separator skim milk. It may be readily
brought to light by making a blank test with clean
water in bottles used for testing ordinary milk, which
have been cleaned by simply draining the contents and
rinsing once or twice with hot water; at the conclusion
of the test the operator will generally find that a few
drops of fat will collect in the neck of the bottles, some-
times enough to condemn a separator.

Boiling hot water will generally clean the grease from
glassware for a time, but all test bottles should, in ad-
dition, be given an occasional bath in some weak alkali
or other grease-dissolving solution. Persons doing con-
siderable milk testing will find it of advantage to pro-
vide themselves with a small copper tank, fig. 15,
which can be filled with a weak alkali-solution. After

The Babcock Test.

having been rinsed with hot water, the test bottles are
placed in the hot solution in the tank, where they may
be left completely covered with the liquid. If the tank
is provided with a small faucet at the bottom, the liquid
can be drawn off when the test bottles are wanted. A
tablespoonful of
some cleaning pow-
der to about two
gallons of water
will make a very
satisfactory solu-
tion ; sal soda,
Gold Dust, Lewis9
lye or Babbitt's
potash are very
efficient for this
purpose. The
cleansing proper-
ties of solutions of
any of these sub-
stances are in-
creased by warm-
ing the liquid. The FIG'15' Tank for cleaning test bottles.

test bottles must be rinsed twice with hot water after
they are taken from this bath.

An excellent cleaning solution that can be used for
a long time, may be made of one-half pound bichromate
of potash to one gallon of sulfuric acid.1

An arrangement for cleaning a number of test bot-
tles at the same time is shown in fig. 16. 2 III shows the

1 Michels, Am. Cheesemaker, Jan. 1903.

2 Wisconsin experiment station, bull. 129.

Testing Milk and Its Products.

frame in which the "bottles are placed, one in each
socket; the metal plate E is put over the necks of the
bottles which pass through the holes in it up to the
shoulder of the bottles. The pins F, F, are then pushed
through holes in the rods D-D, and the plate and bot-
tles are thus firmly held in the crate. When secured in

FIG. 16. A convenient devise for cleaning test bottles.

this way, the frame full of bottles may be placed in a
pail or tank of hot water as in I. They will soon fill
with water and the time of filling the bottles one at a
time thus saved. When ready to empty the bottles, the
frame is reversed and placed in the position shown in II.
One or two rinsings in boiling hot water is usually
sufficient to effectually clean the bottles, but when they
have been allowed to get greasy they can be dipped into
a pail of hot dilute lye; this will saponify the grease
and after one or two rinsings in clean hot water the
bottles will be bright and clean.

The Babcock Test. 45

The black stains that sometimes stick to the inside of
test bottles after prolonged use, can be removed with a
little muriatic acid, or by means of a small stiff brush.
48. Pipette. The difference in the weights of various
samples of normal milk generally falls within compara-
tively narrow limits ; if a given volume of water weighs
one pound, the same volume of the usual grades of nor-
mal milk will weigh frcm 1.029 to 1.033 pounds, or on
the average, 1.03 Ibs. 18 grams of water measures 18
cc.1 ; 18 grams of milk will therefore take up a smaller
volume than 18 cc., viz., 18 divided by 1.03, which is
\vry nearly 17.5. This is the quantity of milk taken
in the Babcock test. A certain amount of
milk will adhere to the walls of the pi-
pette when it is emptied, and this thin film
has been found to weigh about one-tenth'
of a gram; consequently 17.6 cc. has been
adopted as the capacity of the pipette used
for delivering 18 grams of milk.

r\ LJ

For convenience in measuring the milk,

FIG. 17. Pipette

points— the shape of the pipette is of importance.

A, proper con-

, Pi The mark on the stem should be two inches

construction. Qr more from the upper end of the pip_

ette. The lower part should be small enough to fit
loosely into the neck of the test bottle, and not con-
tracted to a fine hole at the point ; the point should be

-1 Cubic centimeters (abbreviated: cc.) are the standard used for
measuring volume in the metric system, similar to the quart or pint
measure iii our ordinary system of measures. One quart is equal to a
little less than 1,000 cubic centimeters (1 liter). In the same way, grams
represent weight, like pounds and ounces. One cc. of water at ^Centi-
grade weighs 1 gram; 1,000 grams < = 1 kilogram) are equal to 2.2 Ibs."
Avoirdup. (See Appendix for Comparisons of metric and customary
weights and measures.)

46 Testing Milk and Its Products.

large enough to allow a quick emptying of the pipette
(fig. 17) and not so large that it is difficult to use it.
An opening of less than % in. diameter will be found
satisfactory.

49. Fool pipettes. Soon after the Babcock test began to be
generally used at creameries as a basis of payment for the milk,
a creamery supply house put on the market a 20 cc. milk-meas-
uring pipette, which was claimed to show the exact butter value
of milk, instead of its content of butter fat, as is the case in
using the ordinary 17.6 cc. pipette. A 20 cc. pipette will de-
liver 2.4 ct. more milk than a 17.6 cc. pipette, (or 13.6 per cent,
more), and the results obtained by using these pipettes will,
therefore, be about 13.6 per cent, too high. In considering the
subject of Overrun (214) it is noted that the excess of butter
yield over the amount of fat contained in a certain quantity of
milk will range from about 10 to 16 per cent., or on the average,
about 12 per cent. 20 cc. pipettes may, therefore, give approxi-
mately the yield of butter obtained from a quantity of milk,
but as will be seen, this yield is variable, according to the skill
of the butter maker and according to conditions beyond his con-
trol; it cannot therefore be used as a standard in the same man-
ner as the fat content of the milk. Similar 22 cc. pipettes were
also sent out. These pipettes created a great deal of confusion
during the short time they were on the market, and were popu-
larly termed "fool" pipettes. It is not known that such pi-
pettes have been sold of late years.

A recent Wisconsin law makes it a misdemeanor to use in
that state other than 17.6 cc. pipettes for measuring milk where
this is paid for by the Babcock test.1

50. Acid measures. A 17.5 cc. glass cylinder (fig. 9)
for measuring the acid is generally included in the out-
fit, when a Babcock tester is bought. This cylinder an-
swers every purpose if only occasional tests are made;
the acid is poured into the cylinder from the acid bottle
as needed, or a quantity of acid sufficient for the num-
ber of test bottles to be whirled at a time, is poured

l Laws of 1903, chapter 48.

The Babcock Test.

into a small glass beaker provided with a lip, or into a
small porcelain pitcher; these may be more easily
handled than the heavy acid bottle or jug, and the acid
measure is then filled from such a vessel.

Where a considerable number of tests are made regu-
larly, the acid can be measured into the test bottles
faster and with less danger of spilling, by using some
one of the many devices proposed for this purpose.
There is some objection to nearly all of these appliances,
automatic pipettes, burettes, etc., although they will
often give good satisfaction for a time while new. Sul-
furic acid is very corrosive,
and operators, as a rule, take
but poor care of such appara-
tus, so that it is a very diffi-
cult matter to design a form
which will remain in good
working order for any length
of time. Automatic pipettes
attached to acid bottles or res-
ervoirs, to prove satisfactory,
must be made entirely of glass,
and strong, of simple construc-
tion, tightly closed and quickly
operated.

51. The Swedish acid bot-
tle answers these requirements the side tube is made to hold
better than any other device 17'5cc'°f
known to the writers at the present time. Its use is
easily understood (see fig. 18) ; it gives good satisfac-
tion if the hole in the glass stop-cock through which the

FIG.

Swedish acid-bottle;

48 Testing Milk and Its Products.

acid passes has a diameter of at least one-eighth of an
inch, as is generally the case. We have used or in-
spected some half a dozen other devices, which have
been placed on the market by various dealers for de-
livering the acid, but cannot recommend them for use
in factories or outside of chemical laboratories.

52. Instead of measuring out the acid, Bartlett1 has suggested
adding 20 cc. directly to the milk in the test bottles, till the mix-
ture rises to a mark on the body of the bottle at the point
where this will hold 37.5 cc., i. e., the total volume of milk and
acid (83). This method of adding the acid is in the line of sim-
plicity, but has not become generally adopted. If the method is
used, the marks should be put on by the manufacturers, as the
operator in attempting to do so will be apt to weaken or break
the bottles.

CALIBRATION OF GLASSWARE.

53. Test bottles. The Babcock milk test bottles are
so constructed that the scale of graduation on the neck
measures a volume of 2 cubic centimeters, between the
zero and the 10 per cent, marks (44). The standards
adopted by Eastern experiment stations for test bottles
and other Babcock glassware are given at the close of
this book (306). It will be seen that the limit of error
for test bottles is one of the smallest graduations on the
scale, or .2 per cent. The correctness of the gradua-
tions may be easily ascertained by one of the following
methods :

54. (A.) Calibration with water. This may be done
by means of a delicate pipette or burette, or by weigh-
ing the water that the graduated portion of the neck
will hold.

1 Maine «'\p<>rim<'nt station, bull. 31.

The Babcock Test. 49

a, Measuring the water. Fill the test bottle with
water to the zero mark on the scale; remove any sur-
plus water and dry the inside of the neck with a piece
of filter paper or clean blotting paper; then measure
into the bottle 2 cc. of water from an accurate pipette
or burette, divided to -I of a cubic centimeter. If the
graduation is correct, 2 cc. will fill the neck exactly to
the 10 per cent, mark of the scale.

b, Weighing the water. Fill the bottle with water
to the zero mark of the scale and remove any surplus
water in the neck, as before. Weigh the bottle with the
water contained therein. Now fill the neck with water
to the 10 per cent, mark, and weigh again. The differ-
ence between these weights should be 2 grams.

In all cases where calibrations are to be made, the
test bottles, or other glassware to be calibrated, must be
thoroughly cleaned beforehand with strong sulfuric
acid or soda lye, and washed repeatedly with pure
water, and dried. Glassware is not clean unless water
will run freely over its surface, without leaving any
adhering drops.

55- (B). The Trowbridge method of calibration.1
An extremly simple and accurate method of calibrating
test bottles has been proposed by Mr. 0. A. Trowbridge
of Columbus, Wis. He conceived the idea of measur-
ing the capacity of the graduated portion of the neck
of a milk test bottle with a piece of metal which is care-
fully filed to such a size that it will displace exactly
two cubic centimeters of water. He used a thirty-penny
wire nail, cutting off the head of the nail and attaching

1 Hoard's Dairyman, Mar. 8, 1901, by DeWltt Goodrich.

50 Testing Milk and Its Products.

to it a short piece of fine wire. Manufacturers have
improved on this rather crude device and standard
measures for calibrating test bottles may
now be bought of any dairy supply house
(see fig. 19).

When a test bottle is to be calibrated
by this standard measure, it is filled with
water to the zero mark on the neck of the
bottle. The water adhering to the neck is
carefully removed with a strip of blotting
paper, and the measure is then lowered
into the test bottle, as shown in the illus-
tration. If the water rises from 0 to 10
on the neck when the upp r point of Ihe
measure is submerged in the water, the
scale is correct. If greater variations than
.2 per cent, occur, the bottle should be re-
jected.

The figure shows one of these calibrator
made in two sections, so that the accuracy
of the 5 per cent., as well as the 10 per-
cent, mark on the scale may he ascer-
tained.

56. The standard measure. In the place
of an iron nail, as originally proposed, a
FIG. 19. The piece of metal or glass rod may be adv«n-

Trowbridge

calibrator. tageously used as a standard measure. 1 he
standardization of this measure is most conveniently
done by weighing. Since the specific gravities of iron.
copper, brass, and glass are 7.2, 8.7, 8.5, and about 2.7,
respectively, pieces of these materials replacing 2 cc. of

The Babcock Test. 51

a liquid, will weigh 14;, 17.4, 17.0 and 5.4 grams, for
iron, copper, brass and glass in the order given.

A measure of the right weight may be suspended by
a very fine copper or platinum wire (melted into the
glass rod if this material be chosen), and is used di-
rectly for calibrating test bottles as described above.
Before a measure so made is used as a standard, its ac-
curacy should be determined by weighing the amount
of water of a temperature of 17.5° C, which it replaces.
The specific gravity of glass especially, varies somewhat
according to its composition, so that a standardization
of a measure by weight alone cannot be depended upon
to always give correct results.

In submerging the measure in the test bottle to be
calibrated, care must be taken that all air bubbles are
removed before the position of the meniscus1 of the
water is noted; if a metal standard measure is used, it
must be kept free from rust or tarnish.

57. (C.) Calibration with mercury. 27.10 grams of
metallic mercury are weighed into the perfectly clean and dry
test bottle. Since the specific gravity of mercury is 13.55,
double this quantity will occupy a volume of exactly 2 cubic
centimeters (48). The neck of the test bottle is then closed
with a small, smooth and soft cork, or a wad of absorbent cot-
ton, cut off square at one end, the stopper being pressed down
to the first line of the graduation. The bottle is now inverted
so that the mercury will run into its neck. If the total space
included between the 0 and 10 marks is just filled by the two
cubic centimeters of mercury, the graduation is correct. Bot-
tles, the whole length of the scale of which vary more than two-
tenths of one per cent., are inaccurate and should not be used.

The mercury may be conveniently transferred from one test
bottle to another, by means of a thin rubber tube which is
slipped over the end of the necks of both bottles, and one weigh-

52 Testing Milk and Its Products.

ing of mercury will thus suffice for a number of calibrations.
In transferring the mercury, care must be taken that none of it
is lost, and that small drops of mercury are not left sticking to
the walls of the bottle emptied. A sharp tap on the bottle
with a lead pencil will help to remove minute drops of mercury
from the inside. Unless the bottles to be calibrated are per-
fectly clean and dry, it is impossible to transfer all the mer-
cury from one bottle to another.

After several calibrations have been made, the mercury should
be weighed again in order to make certain that none has been
lost by the various manipulations. Scales similar to those shown
in figs. 34 and 35 (91) are sufficiently delicate for making these
weighings.

58. Test bottles may also be calibrated with mercury by weigh-
ing the bottles filled with mercury to the zero mark, and again
when filled to the 10 mark. This is the official method for test-
ing bottles adopted by Eastern states (see 306).

59. Cleaning mercury. Even with the best of care, mercury
used for calibration of glassware will gradually become dirty,
so that it will^not flow freely over a clean surface of glass. It
may be cleaned from mechanical impurities, dust, grease, water,
etc., by filtration through heavy filter paper. This is folded in
the usual way, placed in an ordinary glass funnel and its point
perforated with a couple of pin holes. The mercury will pass
through in fine streams, leaving the impurities on the filter
paper. Mercury may be freed from foreign metals, zinc, lead,
etc., sometimes noticed as a grayish, thin film on its surface,
by leaving it in contact with common nitric acid for a number
of hours; the mercury is best placed in a shallow porcelain or
graniteware dish and the nitric acid poured over it, the dish
being covered to keep out dust. The acid solution is then care-
fully poured off and the mercury washed with water; the latter
is in turn poured off, and the last traces of water absorbed by
means of clean, heavy filter paper.

The mercury to be used for calibration of glassware should
be kept in a strong bottle, closed by an ordinary stopper. In
handling mercury, care must be taken not to spill any portion
of it; finger-rings should be removed when calibrations with mor-
cury are to be made.

The Babcock Test. 53

Mercury forms the most satisfactory and accurate material
for calibration of test bottles, on account of its heavy weight
and the ease with which it may be manipulated. Equally correct
results may, however, with proper care be obtained by using
water for the calibration.

60. Intermediate divisions. The space between 0
and 10 on the scale of the Babcock test bottle is divided
into 50 divisions, each five of which, as previously
shown, represent 1 per cent. (44). Since these in-
termediate divisions are generally made with a dividing
machine, they are as a rule correct, but it may happen
that they have been inaccurately placed, although the
space between 0 and 10 is correct. The accuracy of the
intermediate divisions can be ascertained by sliding
along the scale a strip of paper upon which has been
marked the space occupied by one per cent, and com-
paring this space with those of each per cent, on the
scale.

61. Calibration of skim milk test bottles. The
value of each division on the common double-necked
skim milk bottles (99) is one-twentieth, or .05 of one
per cent. ; there are ten of these divisions in the whole
scale which, therefore, measures .5 per cent, of fat. It
requires very careful work to calibrate this scale and it
is best done by weighing the amount of mercury which
will just fill the space of 1 cc. between the first and the
last divisions (53) ; the correct weight of this mercury
is 1.359 grams.

62. Calibrating cream test bottles. The cream bot-
tles may be calibrated by any of the methods given for
milk bottles. The neck of a cream test bottle that meas-
ures thirty per cent, fat will hold 6 cc., and 6 grams of
water or 81.54 grams of mercury.

54 Testing Milk and Its Products.

The Trowbridge method of calibrating milk test bot-
tles may also be found convenient for cream bottles and
the same standard measure used, the part of the scale
from 0 to 10 being calibrated first, then that from 10 to
20, and from 20 to 30 per cent, in the same way.

63. Pipette and acid cylinder. The pipette and the
acid cylinder used in the Babcock test may be calibrated
by any of the methods already given. Sufficiently ac-
curate results are obtained by weighing the quantity of
water which each of these pieces of apparatus will hold,
viz., 17.6 grams and 17.5 grams, respectively. The
necessity of previous thorough cleaning of the glassware
is evident from what has been said in the preceding.
The pipette and the acid measure may be weighed
empty and then again when filled to the mark with
pure water, or the measureful of water may be emptied
into a small weighed vessel, and this weighed a second
time. In either case the weight of the water contained
in the pipette or acid measure is obtained by difference.1

Calibrations of the acid cylinder are generally not
called for, except as a laboratory exercise, since small
variations in the amount of acid measured do not affect
the accuracy of the test.

2.— CENTRIFUGAL MACHINES.

64. The capacity of the testing machine to be selected
should be governed by the number of tests which are
likely to be made "at one time. For factory purposes a

1 One cubic centimeter of distilled water weighs 1 grnm, when
weighed In a vacuum at the temperature of the maximum density of
water (4°O); for the purpose of calibration of glassware used in the
Babcock test, sufficiently accurate results are, however, obtained by
weighing the water in the air and at a low room temperature (60° F.)

The Babcock Test. 55

twenty-four or a thirty-two bottle tester is large enough,
and to be preferred to a larger tester, even if a large
number of samples are to be tested at a time. The
operator can use his time more economically in running
a machine of this size than one holding fifty or sixty
bottles; the work of filling or cleaning the bottles and
measuring the fat can be done while the tester is run-
ning if a double supply of bottles is at hand. Large
testers require more power than smaller ones, and when
sixty tests are made at a time, the fat column in many
bottles will get cold, before the operator has time to
read them, unless special precautions are taken for
keeping the bottles warm.

65. The tester should be securely fastened to a solid
foundation and set so that the revolving wheel is level.
The latter must be carefully balanced in order that the
tester may run smoothly at full speed when empty. A
machine that trembles when in motion is neither sat-
isfactory nor safe, and the results obtained are apt to
be too low. High-standing machines are more likely to
cause trouble in this respect than low machines, and
should therefore be subjected to a severe test before
they are accepted.

If all sockets are not filled with bottles when a test
is to be made, the bottles must be placed diametrically
opposite one another so that the machine will be bal-
anced when run. The bearings should be kept cleaned
and oiled with as much care as the bearings of a cream
separator.

The cover of the machine should always be kept
closed while the bottles are whirled, and should not be

56 Testing Milk and Its Products.

removed until the machine stops; it should be tight
fitting, since test bottles sometimes break while the ma-
chine is running at full speed, and every possible pre-
caution should be taken to protect the operator from
any danger from spilled acid or broken glass.

66. Speed required for the complete separation of
the fat. There is a definite relation between the diame-
ter of the Babcock testers and the speed required for a
perfect separation of the fat. In the preliminary work
with the Babcock test the inventor found that with the
machine used, the wheel of which had a diameter of
eighteen inches, it was necessary to turn the crank, so
as to give the test bottles seven or eight hundred revo-
lutions per minute, in order to obtain a maximum sepa-
ration of fat; later work has shown that this speed is
ample. Taking therefore this as a standard, the centri-
fugal force to which the contents of the test bottles are
subjected when supported on an eighteen-inch wheel
and turned 800 revolutions per minute, can be calcu-
lated as follows:

The centrifugal force, F, acting on the bottles is expressed by
the formula

in which w — the weight of the bottle with contents, in pounds;
v = the velocity, in feet per second, and r = the radius of the
wheel in feet.

When the wheel is turned 800 times a minute, a bottle sup-
ported on its rim will travel 2?rrX 8e°0°=2x3.1415XftX%0:r::62-83
feet per second. The weight of a bottle, with milk and acid, is
about 3 ounces, or fa of a pound. Substituting these values
for v and w, gives

The Babcock Test. 57

The bottles are, therefore, under the conditions given, sub-
jected to a pressure of about 30.65 pounds. In order to calcu-
late the speed required for obtaining this force in case of ma-
chines of other diameters, the value of v in formula (I) is
found from

32-2

Substituting the values for F and w, we have

/32.2X30.65r /— —
v=]/ — j — =i/o264r

In this equation the values r = 5, 6, 7, 8, 9, 10, 11, 12 inches
are substituted in each case (T5.,, ^ /f, . . . JJ feet), and the
velocity in feet per second then found at which the bottles are
whirled when placed in wheels of diameters 10 to 24 inches, and
subjected in each case to a centrifugal force of 30.65 Ibs. As

the number of revolutions per minute =7r- -, v being as before

2 Trr

the velocity in feet per second, and r the radius of the wheel,
the speed at which the wheel must be turned is found by sub-
stituting for v the values obtained in the preceding calculations
in case of wheels of different diameters. The results of these
calculations are given in the following table:

Diameter Velocity in feet Number of revolutions

of wheel, D. per second, v. of wheel per minute.

10 46.84 1074

12 51.31 980

14 55.43 909

16 59.26 848

18 62.84 800

20 66.24 759

22 69.47 724

24 72.56 693
These figures show that a tester, for instance, 24 inches in

diameter, requires less than 700 revolutions per minute for a

perfect separation of the fat in Babcock bottles, while a ten-
inch tester must have a speed of nearly 1100 revolutions, in
order to obtain the same result.

58 Testing Milk and Its Products.

The speed at which testers of different diameters should be
run to effect a complete separation has been calculated by Prof.
C. L. Beach in the following manner.1 The same standard as
before is taken, viz., 800 revolutions for an 18-inch tester (radius
9 inches) ; then if x designate the radius of the tester and y the
speed required, we have

The figures obtained by the use of this formula are similar
to those given in the preceding table.

67. To find the number of turns of the handle corre-
sponding to the number of revolutions made by the
wheel, the handle is given one full turn, and the number
of times which a certain point or part of the wheel re-
volves, is noted. If the wheel has a diameter of 20
inches, and revolves 12 times for one turn of the handle,
the latter should be turned M>==63 times a minute (see

table), or about once every second, in order to effect a
maximum separation of fat. By counting the number of
revolutions, watch in hand, and consulting the preceding
table, the operator will soon note the speed which must
be maintained in case of his particular machine. It is
vitally important that the required speed be always
kept up ; if through carelessness, worn-out or dry bear-
ings, low steam pressure, etc., the speed is slackened, the
results obtained will be too low ; it may be a few tenths,
or even more than one per cent. Care as to this point
is so much the more essential, as the results obtained
by too slow whirling may seem to be all right, a clear

1 Private communication.

The Babcock Test. 59

separation of fat being often obtained, even when the
fat is not completely separated.

68. Ascertaining the necessary speed of testers. In

buying a tester the operator should first of all satisfy
himself at what speed the machine must be run to give
correct results ; the preceding table will serve as a guide
on this point. He should measure out a dozen tests of
the same sample of milk, and whirl half the number at
the speed required for machines of the diameter of his
tester. Whirl the other half at a somewhat higher
speed. If the averages of the two sets of determinations
are the same, within the probable error of the test (say,
less than one-tenth of one per cent.), the first whirling
was sufficient, as it is believed will generally be the case.
If the second set of determinations come higher than the
first set, the first whirling was too slow, and a new series
of tests of the same sample of milk should be made to
ascertain that the speed in the second set of determina-
tions was sufficient.

This method will test not only the speed required
with the particular machine at hand, but will also serve
to indicate the correctness of the calibration of the bot-
tles. A large number of tests of the same sample of
milk made as directed (pouring the milk once or twice
previously to taking out a pipetteful for each test)
should not vary more than two-tenths of one per cent,
at the outside, and in the hands of a skilled operator
will generally come within one-tenth of one per cent.
If greater discrepancies occur, the test bottles giving
too high or too low results should be further examined,
and calibrated according to the directions already given
(53 et seq.).

Testing Milk and Its Products.

69. Hand testers. When only a few tests are made
at a time, and at irregular intervals, as in case of dairy-
men who test
single cows in
their herds, a
small hand test-
er answers every

may be had in
sizes from two
to twelve bot-
'tles. In select-
ing a particular
make of tester
the dairyman

FIG. 20. Type of Babcock hand testers. has the choice

of a large number of different machines. Most of the
first machines placed on the market for this purpose
were so cheaply and
poorly constructed as
to prove very unsat-
isfactory after hav-
ing been in use for a
time. The competi-
tion between manu-
facturers of dairy
supplies and the
clamor of dairymen

for Something cheap, FIG. 21. Type of Babcock hand tester-.

fully accounted for this condition of affairs. This ap-
plies especially to the early machines made with belts

The Babcock Test. ^ 61

or friction application of power. Hand testers made
with cog-geared wheels can be depended on to give the
necessary speed when run according to the manufactur-
ers' directions; the earlier machines of this kind were
very noisy, but at the present time the best machines
on the market are of this type. These are provided
with spiral cog-gearing and ball bearings, are strongly
made and will run smoothly and with little noise (figs.
20 and 21) ; in cog-geared machines the bottles are al-
ways whirled at the speed which the number of turns
made by the crank would indicate.

70. Power testers. For factory purposes, steam tur-
bine machines (figs. 22-25) are most satisfactory when
well made and well cared for. They should always be
provided with a speed indi-
cator and steam gauge, both
for the purpose of knowing
that sufficient speed is at-
tained, and to prevent what
may be serious accidents
from a general smash-up, if
the turbine "runs wild" by
turning on too much steam.
The revolving wheel of the

tester should be made of FlG>22< Ty pe of ^abcock steam
wrought or malleable iron, or lters-

of wire, so that it will not be broken by the centrifugal
force and cause accidents. The swinging pockets
.which hold the test bottles in some machines should
be so made that the bottles will not strike the
center of the revolving frame when in a horizontal posi-

Testing Milk and Its Products.

tion. Tests have often been lost by the end of the neck
catching at the center, the bottles thus failing to take
an upright position when the whirling stops.

71. The exhaust steam pipe of turbine testers should
not have too many turns in it or be much reduced in
size from that of the opening in the tester. A free es-
cape of the exhaust steam is necessary to prevent the
steam collecting in the test bottle chamber and over-
heating the test bottle when whirled (41).

The cover of the tester should have an opening pro-
vided with a sliding damper or some arrangement by
which it can be closed when desired. If whole milk or
cream is being tested, this hole should be open so that a
draft of air may enter the test bottle chamber during the

whirling, and force
the steam out of
the bottle cham-
ber into the ex-
h a u s t pipe. If
skim milk is being
tested, the open-
ing in the cover
should be closed.
This shuts off the
draft of air, and
the exhaust steam
heats the test bot-
tles during whirl-

FIG. 23. Type of Babcock electrical testers, ing to 200° F. in

some cases. This high temperature aids in separating
the fat in skim milk and gives fairly correct tests of

The Babcock Test.

FIG. 24. Type of Babcock turbine testers (for
testing cream in9-in. cream bottles).

samples contain-
ing less than one-
tenth per cent,
fat. Some of
the most recent
makes of turbine
testers are pro-
vided with holes
in the covers and
dampers. A ther-
mometer is also
placed in the
cover.
Babcock testers

run by electricity have lately been put
on the market by a couple of manu-
facturers (fig. 23). Where no steam,
but electrical current is available, these
machines may be in-
stalled to great advan-
tage, as they are con-
venient to use and may
be depend* d on to run
at the required speed.
Some provision for get-
ting hot water must be
at hand in using elec-
trical Babcock testers/

FIG. 25. Type of Babcock steam turbine
testers.

1 The method of installation of a 40-bottle electrical Babcock tester
is described in detail lit Kept. Dept. of Health, City of Chicago, 1906
p. 18.

64 Testing Milk and Its Products.

3.— SULFURIC ACID.

72. The sulfuric acid to be used in the Babcoek test
should have a specific gravity of 1.82-1.83.1 The com-
mercial sulfuric acid (sometimes called oil of vitriol)
is commonly used ; it can be bought for about 2 cents a
pound in carboy lots and 25 cents or less a quart at re-
tail. One quart of acid is sufficient for fifty tests. The
acid should be kept in stoppered glass bottles, prefer-
ably glass or rubber stoppered ones, since a cork stop-
per is soon dissolved by the acid and rendered useless.
If the bottle is left uncorked, the acid will absorb
moisture from the air and after a time will become too
weak for use in this test.

Lead is the only common metal which is not dissolved
by strong sulfuric acid ; where considerable milk testing
is done, it is therefore desirable to provide a table cov-
ered with sheet lead on which the acid may be handled.
The acid dissolves iron, tin, wood and cloth, and
burns the skin. If acid is accidently spilled, plenty of
water should be used at once to wash it off. Ashes,
potash, soda, and ammonia neutralize the action of the
acid, and a weak solution of any one of these alkalies
can be used after the acid has been washed off with
water. The red color caused by the action of the acid
en clothing can be removed by wetting the spot with
weak ammonia water; the ammonia must, however, bo
applied while the stain is fresh, and is in its turn
washed off with water.

1 A specific gravity of 1.82 means that a given volume of the arid
weighs 1.82 times as much as the same volume of water at the same
temporal un- (see also under Lactometer, 109).

The Babcock Test. §5

73. Testing the strength of acid. The strength of
the acid can be easily tested by the use of a balance like
that shown in fig. 34 (91). A dry test bottle is weighed,^
and then filled with acid exactly to the zero mark, or
to any ether particular line of the scale. It is then
again weighed accurately; the difference between these
two weights will give the weight of the acid in the bot-
tle. The bottle is then emptied and rinsed thoroughly
with water (until the water has no longer an acid
taste) ; it is then filled with water to the same line as
before and weighed; the difference between this weight
and that of the empty bottle gives the weight of the
same volume of water as that of the acid weighed. The
specific gravity of the acid is obtained by dividing the
weight of the acid by the weight of the water. If the
quotient comes between 1.82 and 1.83 the strength of
the acid is correct. The outside of the test bottle should
always be wiped dry before the liquids are weighed in
it. Unless great care is taken in measuring the acid
and the water, and in weighing both these and the
test bottle, the results obtained will not be trustworthy.

74. Acid that is a little too strong can be used by
taking less than the required amount for each test, e. g.,
about 15 cc. Operators are warned against reducing
the strength of the acid by adding water to it, as acci-
dents may easily occur when this is done. A too strong
acid can, if desired, be weakened by simply leaving the
bottle uncorked for a time, Or by pouring the acid into
a bottle containing a small quantity of water. In the
latter case the first portions of acid should be added
carefully, a little at a time, shaking the bottle after

66 Testing Milk and Its Products.

each addition, so as not to cause it to break on account
of the heat evolved in mixing the acid and the water.
Never dilute sulfuric acid by pouring water into it.

A helpful suggestion for using acid that is too strong
or would give a charred fat on account of high tem-
perature of acid or milk, or both, has been made by M.
L. Holm, Assistant Chemist Chicago Dept. of Health,
viz., to add 2 cc. of 80 per cent, glycerin (80 parts of
commercial glycerin and 20 parts of water, by volume)
to the milk sample, prior to adding the acid.1 The gly-
cerin protects the milk to some extent from the acid be-
fore the two are mixed, and a clear fat may thus often
be secured under otherwise unfavorable conditions. The
results appear not to be influenced by the addition of
the glycerin.

75. If the acid is a little too weak, correct results
may be obtained by using more than the specified quan-
tity, say 20 cc. If a good test is not obtained with this
quantity of acid, a new lot must be secured, as its spe-
cific gravity in such a case is below 1.82. The observing
operator will soon be able to judge of the strength of
the acid by its action on milk in mixing the two liquids
in the Babcock test bottles ; it is indeed remarkable
• what slight differences in the specific gravity of the
acid will make themselves apparent in working the test,
as regards the rapidity with which both the curdled
milk is dissolved and the mixture of acid and milk turns
black.

1 American Food Journal, 1907, No. 7, p. 28; Hoard's Dairyman, Nov.
8, 1907.

The Babcock Test. 67

76. Strength of sulfuric acid. The relation between
the strength of sulfuric acid and its specific gravity
will be seen from the following table:

Specific Gravity of Sulfuric Acid of Different Strength.

Specific Gravity Sulfuric Acid

(1PC, water U°C). (HZSOJ.

1.841 97 per cent.

1.840 96

1.839 95

1.837 94

1.834 93

1.830 92

1.825 91

1.820 %

1.815 89

1.808 88

It will be noticed that the sulfuric acid to be used in
the Babcock test should contain 90 to 92 per cent, of
acid (H2S04) ; slightly weaker or stronger acid than
this may, as previously stated, be used by varying the
quantity of acid taken for each test according to the
strength of the acid, but successful tests cannot, as a
rule, be made with acid weaker than 89 per cent, or
stronger than 95 per cent.

77. The Swedish acid tester is a small hydrometer, intended
to show whether the acid used in the Babcock test is of the cor-
rect strength. An examination of these testers will show that
they are practically useless for the purpose intended, from the
fact that they are not sufficiently sensitive; while the testers^
examined were found to sink to the line marked Correct on the
scale, when lowered into sulfuric acid of a specific gravity of
1.83, they would sink to a point much nearer the same mark,
than to the lines marked Too strong or Too weak, respectively,
when lowered into either too strong or too weak acid.

78. The color of the fat column an index to the
strength of the acid used. The strength of the acid
is indicated to a certain extent by the color of the fat

68 Testing Milk and Its Products.

which separates in the neck of the test bottle when milk
is tested. If the directions given for making the tests
are carefully followed, the fat separated out will be of
a golden yellow color. If the fat is light colored or
whitish, it generally indicates that the acid is too weak,
and a dark colored fat, with a layer of black material
beneath it, shows that the acid is too strong, provided
the temperature of both milk and acid is about 70°.
[For influence of temperature, see next paragraph.]
The acid used in the test is not of sufficient strength
to appreciably attack the fat at ordinary temperatures
of testing, but a variation in the strength of the acid
or in the temperature of the milk influences the in-
tensity of the action of the acid on the fat, as shown in
the color of the fat obtained.

The following experiment shows the relation between
the strength of the acid, the temperature of the milk,
and the color of the fat:

First: — From a sample of milk measure the usual quantity
for testing into each of three bottles, A, B and C. Place A in
iced water, and C in warm water, leaving bottle B at ordi-
nary temperature. After the bottles have been left for ten min-
utes under these conditions, add the normal quantity of acid
to each and proceed with the test in the ordinary manner.

Second: — Measure some of the same milk into three other
bottles, D, E and F. Into test bottle D pour the usual amount
of rather weak acid; add the same amount of acid of normal
strength (1.82-1.83) to bottle E, and add 17.5 cc. of a still
stronger acid (concentrated sulfuric acid, sp. gr. 1.84), in test
bottle F; complete the tests in the usual way.

On the completion of the preceding six tests the operator will
notice that the fat in the necks of test bottles A (cold milk)
and T> (weak acid) is much lighter colored than that in C (warm
milk) and F (strong acid), and that tho color of the fat in B
(normal temperature) and E (normal acid) is somewhere be-
tween that of these two series.

The Babcock Test. 69

79. Influence of temperature on the separation of
fat. The intensity of the action of the sulfuric acid
on the milk is influenced by the temperature of either
liquid; the higher the temperature, the more intense
will be the action of the acid on the solids of the milk.
It may be noticed that acid from the same carboy will
act differently on milk in summer than in winter time,
if the acid and the milk are not brought to a tempera-
ture of about 70° before testing during both seasons.
The temperature of the liquids may be as low as 40° F.
in winter and as high as 80° F. in summer. This dif-
ference of forty degrees will often have considerable
influence on»4he clearness of the fat separated, show-
ing white curdy substances and a light colored fat in
winter, or black flocculent specks, with a dark colored
column of fat in summer. Beth these defects can be
avoided, when the acid is of the proper strength, by
bringing the temperature of the milk and the acid to
about 70° F. before the milk is tested.

The operator should be particularly cautious against
over-heating either milk or acid, since the heat intensi-
fies the action of the acid and this may become so vio-
lent as to force the hot liquid out of the neck of the
test bottle when the acid is added to the milk, thus
spoiling the test and possibly causing an accident.

4.— WATER TO BE USED IN THE BABCOCK TEST.

80. Eain water, condensed steam, or soft water should
be used for the purpose of bringing the fat into the
neck of- the test bottles. The surface of the fat column
will then usually be' clear and distinct. The foam or

70 Testing Milk and Its Products.

bubbles that sometimes obscure the upper line (menis-
cus) of the fat, making indistinct the point from which
to measure it, is generally caused by the action of the
acid on the carbonates in hard water. The carbonic
acid gas liberated from such water by the sulfuric acid
is more or less held by the viscid fat and produces a
layer of foam on its surface. If clean soft water cannot
be obtained for this purpose, hard water may be used, by
adding a few drops of sulfuric acid to the water before
it is heated, thus causing the carbonic acid to be ex-
pelled. By simply boiling, many hard waters will be
rendered soft and adapted to use in the Babcock test,
as most of the carbonates which cause this foaming are
thereby precipitated.

If the test has been completed, and a layer of foam
appears over the fat, it may be destroyed by adding a
drop or two of alcohol. If this is done, the fat column
should be read at once after the alcohol is added, as
the latter will soon unite with the fat and increase its
volume.

81. Reservoir for water. When only a few tests are
made at one time, hot water can be added with the 17.6
cc. pipette. If many tests are made, the water is more
conveniently and quickly filled into the test bottles by
drawing it from a small copper reservoir or tin pail
suspended over the testing machine.1 The flow of water
through a rubber tube connected with the reservoir, is
regulated by means of a pinch cock. The water must
be hot when added to the test bottles so as to keep the

1 Ordinary tinware will soon rust when water is left standing in
it, and copper reservoirs are therefore more economical.

The Babcock Test.

t'at in a melted condition until the readings are taken.
Most turbine testers are now made with a very conven-
ient water reservoir attached to the tester (figs. 22-25).
The use of zinc or steel oilers, or perfection oil cans
has been suggested as a handy and rapid method of
adding hot water to the test bottles, but most operators
prefer to add water to the bottles by means of a
piece of rubber tubing connected with a reservoir, as
shown in the illustrations just referred to.

5. — MODIFICATIONS OF THE BABCOCK TEST.

82. The Russian milk test. The same chemical and me-
chanical principles applied in the regular Babcock test, are used
in the Russian milk
test, except that in
this case the machine
in which the bottles
are whirled, and the
bottles themselves, are
so constructed that
the latter can be filled
with hot water while
the machine is run-
ning, thus saving
time and the trouble
incident to the stop-
ping of the tester and
filling the bottles by means of a pipette. The milk-measuring
pipette (fig. 28) and the acid measure used in the Eussian test
are one-half of the ordinary size, and the test bottles are made
in two pieces with a detachable narrow graduated stem (see fig.
27). The machine is substantially made of cast iron; it is pro-
vided with a very satisfactory speed indicator which shows at
any time the number of revolutions at which the bottles are
being turned. The accompanying illustrations show the appa-

FIG. 26. The Russian test.

Testing Milk and Its Products.

ratus used in this test. When the directions for operating, the
test are followed closely, the results obtained are accurate and
very satisfactory

83. Barllett's modification. Bartlett1 proposed a modifi-
cation of the method of procedure in the Babcock test, which

aims to simplify the manipulations. 20
cc. of acid are added, instead of 17.5
cc., and the bottles filled with the milk-
acid mixture are left standing for not
less than five minutes and then filled
with hot water to within the scale; the
bottles are then whirled for five min-
utes at the regular rate (52).

83a Siegfeld's modification. The
German dairy chemist Siegfeld in
1899 proposed a modification of the
Babcock test (MolTcerei Ztg. 1899, p.

O51) using 2 cc. of amyl alcohol with
the sulfuric acid, and filling up with
dilute sulfuric acid (1:1, sp. gr. 1.5)

in one filling, in place of water after

the whirling. A clear separation of the
fat is facilitated by both these changes,
but when properly conducted there is
no difficulty whatever in obtaining a
clear fat column in the Babcock test as Pipette used
described in this book, and the modifica- ^an^es/^'^
tion will not therefore be likely to be
FIG. 27. generally introduced in American factories. It has,
used8 in the however, been adopted in many German creameries
Russian test. where the Babcock test is used.

84. Bausch and Lomb centrifuge. Fig. 29 shows a form of
hand centrifuge which may be used to advantage by physicians
of in pathological laboratories for the determination of fat in
milk. The centrifuge is especially designed for examination of
urine, sputum, blood, etc., but has been adapted to milk analysis
by the Leflfmann & Beam test, a special form of bottle (fig. 30)

FIG. 28.

Maine experiment station, bull. 81 (H. *.).

The Babcock Test.

having been constructed for this
purpose. The machine gives satis-
factory results by the Babcock test
as well, provided the acid used is
1.83-1.84, or if the bottles contain-
ing the acid-milk mixture be placed
in hot water for five or ten minutes
prior to the whirling. As the bottles
are calibrated for only 5 cc. of milk
and the neck of the
bottles, with scale, is
correspondingly fine,
testing milk with this
machine requires some
nicety of manipula-
tion not called for in
case of regular Bab-
cock testers constructed

FIG. 29. Physician's centri- for the use of farmers f^t tJhvsi-

ir»Q +Ko+ 1^0 IT Via 11 ttrtsl tr\ ,' ™ < I IT . V. J

FIG. 30.
Test bottle
pipette

fuge that may be used for milk
testing.

and dairymen.

clan's cen-
trifuge.

Questions.

1. Give a short description of the Babcock test.

2. State precautions to be observed in each of the following
operations: (a) Measuring the milk, (b) adding the acid, (c)
whirling the bottles, (d) adding the water, (e) measuring the fat.
If the fat separates clear, but the results come evidently too
low, what is the probable cause, and how can the correct test be
established?

3. To what extent does the temperature of the fat, when
read, influence the result?

4. Explain the graduations of the milk test bottle.

5. What is the capacity of the neck of a milk test bottle be-
tween the 0 and 10 marks, expressed in cc., and in grams?

6. If the graduations of a test bottle measure 2.3 cc. from
0 to 10%, what would be the correct test of a sample which reads
3.4% fat in this bottle?

74 Testing MUk and Its Products.

7. Describe three different methods of calibrating milk test
bottles.

8. Describe the proper construction of the milk-measuring
pipette; what weight of milk does it deliver?

9. What is a Swedish acid-bottle?

10. What speed is required for testers having a diameter of
8, 15, and 20 inches?

11. Write an order for one gallon of sulfuric acid to be used
in testing.

12. How can the strength of the acid be tested at the farm or
in a factory?

13. State precautions to be taken in using an acid that is
(a) too strong, (b) too weak.

14. What may the color of the fat indicate in regard to the
strength of the acid or temperature of either acid or milk?

15. What is the cause of foam above the fat column, and how
may it be prevented?

16. What causes white curd or black specks in the fat?

17. Describe a few modifications of the Babcock test.

18. In which two points does the Eussian milk test mainly
differ from the Babcock test?

CHAPTER IV.
CREAM TESTING.

85. Cream may be tested by the Babcock test in the
same manner as milk, and the results obtained are ac-
curate when the necessary care has been taken in sam-
pling the cream and measuring the fat. The composi-
tion of cream varies greatly according to the process of
creaming, the temperature of the milk during the cream-
ing, the quality and the composition of the milk, etc.
The cream met with in separator creameries will con-
tain from 25 to 40 per cent, of fat, or on the average
about 35 per cent. Cream from hand separators may
be as rich as this, but it often contains only 20 per cent.

FIG. 31.
Students testing dairy products

76 Testing Milk and Its Products.

of fat as delivered to creameries. An average grade of
market cream as retailed contains about 25 per cent, of
fat. If 18 grams of 25 per cent, cream is measured
into an ordinary Babcock test bottle, there will be
18 X -25=4.5 grams of pure butter fat in the bottle,
or, (since the specific gravity of butter fat is about .9)
i^ = 5 cc. It is shown that the space from 0 to 10
in the neck of these bottles holds exactly 2 cc. (44).
The neck of the milk test bottle is not large enough to
show the per cent, of fat in a sample of cream if 18
grams are taken for testing, and it is therefore neces-
sary to adopt special measures when cream is to be
tested.

86. Errors of measuring cream. Several factors
tend to render inaccurate the measuring of cream for
the Babcock test, and correct results can therefore only
be obtained by weighing the cream. If a 17.6 cc. pi-
pette is used in testing the cream, it will not deliver
18 grams of crgam, as it will of milk, for the following
reasons :

1. The specific gravity of cream is lower than that of
milk; if a certain quantity of milk weighs 1030 Ibs., the
same quantity of cream will weigh from 1020 Ibs. to
1000 Ibs. or less, the weight being determined by the
richness of the cream ; the more fat the cream contains,
the less a certain quantity of it, e. g., a gallon, will
weigh.1

2. Cream is thicker (more viscous) than milk at the
same temperature, and more of it will adhere to the
sides of the measuring pipette than in the case of milk.

* For specific gravity of cn-niii of ditTm-nt richness, s«-.- tsiblron p. 77.

Cream Testing. 11

This is of special importance in testing very rich or
sour cream.

3. In case of separator cream, more or less air will
become incorporated with the cream during the process
of separation. In the ripening of cream, the fermenta-
tion gases developed are held in the cream in the same
way as bread dough holds the gases generated by yeast.
In either case the weight of a certain measure of cream
is diminished.

87. As an illustration of the effect of the preceding
factors on the amount of cream measured out by a Bab-
cock 17.6 cc. pipette, the following weighings of sepa-
rator cream are given (column b.) Tha cream was in
all cases fresh from the separator; it was weighed as
delivered by the pipette into a cream test bottle (89),
and the test proceeded with at once ; the specific gravity
of the cream was determined by means of a picnometer
(248). The data given are in all cases averages of sev-
eral determinations; the samples of ci^am have been
grouped according to their average fat contents.1

Weight of fresh separator cream delivered by a 17.6 cc. pipette.

Per cent
of fat
in cream.

Specific gravity ( 17.5°C. }
(a)

Weight of cream deliv-
ered, grams,
(b)

1.023

17.9

1.012

17.7

1.008

17.3

1.002

17.2

.996

17.0

.980

16.4

.966

16.3

.950

16.2

.947

15.8

1 For Influence of condition of cream on the amount measured out
with a 17.6 cc. pipette, see also Bartlett, Maine exp. sta., bull. 31 (S.
S.); Jones, Vt. exp. sta., report 16, 101-6, and "Dean, Guelph (Ont.) agr.
college, report 1906, p. 125.

78 Testing Milk and Its Products.

The figures in the table show plainly the variations
in the specific gravity of cream of different richness
and the error of making tests of cream by measuring it
with a 17.6 cc. pipette, especially if the pipette is not
rinsed and the washings added to the test bottle ; if the
cream to be sampled is fresh separator cream testing
over 30 per cent., less than 17.0 grams of cream will be
delivered into the test bottle, and the results of the
reading will be at least one-eighteenth too low (since
the bottles are graduated for 18 grams), or about 1.6
per cent, too low in the case of a 30 per cent, cream. If
the cream is sour, the error will of course be still greater.

It should be remembered that the specific gravities
of the cream given in the table refer to fresh separator
cream only. Considerable air is incorporated during
the separation, and cream of this kind is therefore lighter
than gravity cream of corresponding fat contents.

88. Weighing cream for testing. For the reasons
stated in the preceding, accurate tests of cream can
only be made by weighing the cream into the Babcock
test bottles.1

The simplest method is to weigh 9 or 18 grams of the
sample on a small cream-weighing scale (see p. 80) into
one of the special forms of cream-test bottles.

Cream-test bottles. Special forms of bottles have
been devised for testing samples of cream by the Bab-
cock test by Winton, Bartlett, and by various manu-
facturers.

1 This is recognized by a law passed by the Wisconsin legislature of
1903, which requires cream to be weighed for testing where it is sold on
the basis of its fat content. (Chapter 43, laws of 1903, An act to pre-
scribe the standard measures for the use of the Babcock test in deter-
mining the per cent, of butter fat in milk or cream.)

Cream Testing. 79

89. The Winton cream bottle. The cream-test bot-
tle devised by "Winton,1 (fig. 32), has a neck of the
usual length, and of sufficient width to measure 30 per
cent, of fat. The scale of the neck is divided

into parts representing one-half of one per
cent, each, but readings of a quarter of a per
cent, can easily be estimated. Such readings
of cream tests are sufficiently exact for most
commercial purposes, e. g., in creameries.
This form of cream bottle will be found very
convenient in making tests of composite sam-
ples of cream.

Cream test bottles of a small bore are
greatly to be preferred to those with wide
necks (fig. 32), since they permit of accurate
readings to a quarter of a per cent.

Other forms of cream-test bottles which

will allow the testing of 50 or 55 per cent.

FIG 32.
cream have been placed on the market dur- Thewinton

ing late years by some manufacturers. These bottiem
bottles (so-called 9-inch bottles] have long necks and
require especially constructed, large and deep testers
(see fig. 25). These machines and accompanying bot-
tles have of late been adopted for cream testing in
many localities where farm separator cream is deliv-
ered to the creameries.

90. The bulb-necked cream bottles (fig. 33) allow the test-
ing of cream containing 23 or 25 per cent, of fat, when the
usual quantity of cream (18 grams) is taken. The neck is
graduated from 0 to 23 per cent., and in some cases to 25 per

i Connecticut experiment station (New Haven), bull. 117; report
1894, p. 224.

•80

Testing Milk and Its Products.

cent., the graduation extending both below and above the bulb.
This is sometimes an inconvenience, as the water must be added
carefully so that the lower end of the column of fat will always
come below the bulb, in the graduated part of the neck, and
not in the bulb itself. Beginners are especially apt to lose tests
when this bottle is first used, for the reason given. It is rec-
ommended to fill these bottles with the first portion
of hot water to just above the bulb, so that one
can see how much water to add the second time in
order to bring the fat within the scale.

Each division of the scale on these cream bottles
represents two-tenths of one per cent, of fat, as
in case of the milk test bottles. This form of bot-
tle is no longer used to any extent, as it has been
largely replaced by the Winton cream-bottle.

91. Scales for weighing the cream. When
a small, delicate balance is used, cream can
be weighed rapidly into the bottles. Either
of the scales shown in the accompanying il-
lustrations, (figs. 34-35), will be found suf-
ficiently accurate for this purpose; a small
scale of this kind is also convenient and help-
ful in testing cheese, butter and condensed
milk, in determining the strength of sulfuric
acid, and in testing the accuracy cf test bot-
tles and pipettes. In testing cream by
FIG. 38. .

The bulb- weight, the test bottle is first weighed empty,

necked cream . „ ,

test bottle, and again when 9 or 18 grams 01 cream have
been placed in it; the difference between the two weights
gives the weight of cream taken for the test. If the
cream contains less than 30 per cent, of fat, the regu-
lar milk test bottle can be used for testing the cream, if
not much more than 5 grams are weighed out ; if more
cream is taken, or if this is richer than 30 per cent., it
is advisable to use cream bottles.

Cream Testing.

The cream scale shown in fig. 34 permits the weighing
of six samples of cream on each pan with only one tar-

ing of the bottles, which
greatly facilitates the
work of testing the
cream.

The operator should be
careful in weighing the

FIG. 34. Scales used for weighing Cream not to Spill it On
cream, cheese, etc., In the Babcock ,, , . -. /, ,,

test. the outside 01 the test

bottle. If less than 18 grams of cream has been weighed

into the bottle, sufficient water is added to the bottle

to make the total volume about 18 cc. The usual quan-

tity of acid (17.5 cc.) is then added, and the test com-

pleted in the ordinary

manner. The reading of

the amount of fat in the

neck of the test bottle

will not show the correct

per cent, of fat in the

cream unless exactly 18

grams are weighed out.

If less than this weight

was taken the per cent,

oi rat in the cream tested

is obtained by multiplying the reading by 18, and di-

viding the product by the weight cf cream taken.

EXAMPLE: Weight of cream tested, 5.2 grams; reading of col-
umn of fat ^O.S, 2)9.7, average 9.75; per cent, of fat in the cream

FIG. 35. Torsion balance used for
weighing cream, butter, cheese, etc.,
in the Babcock test. Sensitive to .01

9.75X18
* 5.2

=33.75.

82 Testing Milk and Its Products.

It is very convenient to weigh out 18 grams of cream
(or a fraction thereof) so that the readings may be
taken directly from the neck of the bottle. The smaller
the quantity of cream taken for a sample, the greater
is the error introduced by inaccurate weighings or read-
ings. The result is rendered more accurate and certain
if two or three tests of a sample are made, and the
readings averaged.

92. Measuring cream for testing. Where a special
cream scale or a small balance is not available, fairly
satisfactory results may be obtained with cream of low
or average quality by measuring out the sample with
a 17.6 pipette and correcting the results as indicated
below. One cf the cream test bottles or a common milk
test bottle may be used for this purpose. The table
on p. 76 shews that a 17.6 cc. pipette, in the case of
cream fresh from the separator, containing less than
25 per cent, of fat, will deliver only 17.2 grams of
cream, that is, the results will bei**i5=l.l per cent, too
low. In the same way in case of 40 per cent, cream,
only 16.3 grams of cream would be delivered, and the
results therefore 3.8 per cent, too low. When the cream
has been ripened or is thick, less cream would be deliv-
ered than the amounts given, and the error introduced
by measuring out the samples correspondingly increased.
A table of correction for testing such cream by meas-
uring the samples has been prepared by Prof. Eckles,
formerly of Iowa experiment station.1

1 Press bull, dated August, 1901. Bonn1 croMim»rit>s boat tin- sam-
ples of en-am in a w:il«-r bath to about 110° K. brforo tin- test -;mipl«-s

Cream Testing. 83

Approximately correct results may be obtained in
testing thin cream by using an 18 cc. measuring pipette ;
to avoid the 'expense and trouble of using two different
pipettes, one for milk and one for cream, a pipette with
two marks on the stem, at 17.6 cc. and 18 cc., has been
placed on the market, the former mark being used when
milk is tested, and the latter for cream. It should be
borne in mind, however, that such pipettes can only be
used with fairly satisfactiry results in the case of sweet
cream of average richness.

93. Use of milk test bottles. Cream may be tested
by emptying a 17.6 cc. pipetteful of the sample into
two or more milk test bottles, dividing the amount about
equally between the bottles and filling the pipette with
water once or twice, which is then in turn divided about
equally between the test bottles ; the per cent, of fat in
the cream is found by adding the readings obtained in
each of the bottles. The cream and the water must be
mixed "before the acid is added.

This method does away with the error incident to the
adhesion of cream to the side of the pipette, but not
with that due to the low specific gravity of the cream,
and the results obtained will therefore be too low. The

are measured out by means of a 17.6 cc. pipette. This increases the fluid-
ity of the cream and causes less to adhere to the pipette. The Vermont
experiment station found in examining this method that it did not
yield satisfactory results in the case of cream of different richness
and recommends that cream be weighed when accurate tests are de-
sired. (See report 16, pp. 191-6.)

Professor Spillman, in Bull. 32 of Washington experimentlstation,
recommends the use of a 17.6 cc. pipette for testing cream, the results,
obtained being corrected by a certain per cent., as showrn in a table
given in the bulletin. The table is based on the figures given on p. 77
of this book, and is therefore only applicable to' fresh separator cream.

84 Testing Milk and Its Products.

dilution of the cream with water in the test bottles not
only makes it possible to bring into the bottle all the
cream measured out, but also insures a clear test. If
ordinary cream is mixed with the usual quantity
of sulfuric acid used in the Babcock test, a dark-colored
fat will generally be obtained, while the cream diluted
with an equal or twice its volume of water, when mixed
with the ordinary amount of acid, will give a light yel-
low, clear column of fat, which will allow of a very-
distinct and sharp reading.

The number of bottles to be used for testing a sam-
ple of cream by this method must be regulated by the
richness of the cream. If the sample probably contains
20 per cent, or more, a pipetteful should be divided
nearly equally between three milk test bottles, and two-
thirds of a pipetteful of water is added to each bottle.
If the cream contains less than 20 per cent, of fat, it
will only be necessary1 to use two milk test bottles, divid-
ing the pipetteful between these, and adding one-half
of a pipetteful of water to each bottle.

By using cream test bottles (89), more accurate tests
may be obtained in case of cream containing as much
as 25 per cent, of fat, by dividing one pipetteful be-
tween two bottles, rinsing half a pipette of water into
each one, than by adding all the cream to one bottle
without rinsing the pipette, for reasons apparent from
what has been said in the preceding.

94. Use of a 5 cc. pipette. When the cream is in good con.
dition for sampling, satisfactory results can also be obtained by
the use of a 5 cc. pipette, provided great care is taken in mix-
ing the cream before sampling; 5 cc. of cream are measured into

Cream Testing.

-d,

a milk test bottle, and two pipettefuls of water are added. In
this way all the cream in the pipette is easily rinsed into the
test bottle. The readings multiplied by ^=3.6 will give the
per cent, of fat in the cream. If the specific gravity of the
cream tested varies appreciably from 1, corrections should be
made accordingly; e. g., if the specific gravity is 1.02, the fac-
tor should read .^ —3.53; if .95, -Ji^. =3.79, etc.

95. Proper readings of cream tests. The accom-
panying illustration (fig. 36), shows the proper method
of reading the fat column in cream
tests; readings are taken from a to c,
not to & or to d, when readings are
made at 140° P.1

No special precautions other than
those required in testing milk have been
found necessary in testing cream, ex-
cept that it is sometimes advisable not
to whirl the test bottles in the centri-
fuge at once after mixing, but to let the
cream-acid mixture stand for a while,
until it turns dark colored. At first,
the mixture of cream and acid is much
lighter colored than that of milk and
acid, owing to the smaller proportion of

FIG. 36. Measur-

n solids not fat contained in the cream.

The liquid beneath the fat in a com-
pleted test of cream is sometimes milky
and the fat appears white and cloudy, making an exact

ins the6

cream bottle. Read-
ing should be made
from a to c, not to b
or to d.

1 The size of the meniscus is magnified in this cut. A study of the
meniscus formed in bottles with narrow or wide necks, and its bearing
on the results of cream tests is given in bulletin 58, Bur. An. Ind.,
U. S. Dept. of Agriculture, where a discussion of the influence of dif-
ferent temperatures on readings of cream tests will also be found
(see 96).

86 Testing Milk and Its Products.

reading difficult. Such defects can usually be over-
come by placing the test bottles in hot water for about
ten minutes previous to the whirling, or by allowing the
fat to crystallize (which is done by cooling the bottles
in cold water after the last whirling) and remelting
it by placing the bottles in hot water.

The error due to the expansion of the fat in case of
excessively hot turbine testers having no openings in
the cover as mentioned on p. 36, is especially noticeable
in cream testing, where it may amount to one per cent,
or more. In order to obtain correct results with such
testers, the hot cream test bottles must be placed in
water at about 140° F. for some minutes before the
results are read off.

96. The subject of different methods of reading
cream tests has been studied by Webster and Gray/
who conclude that correct results are obtained by
taking readings at 120° F., from the bottom to the ex-
treme top of the fat column, deducting four-fifths of
the depth of the meniscus from this result and adding
.2 per cent, to the figure thus obtained. The error due
to differences in the diameter of the necks of the test
bottles is thus done away with. In the case of tests of
9-gram samples, the reading is doubled before .2 per
cent, is added. While this method of reading does
away with the error "due to the varying depths of the
meniscus in bottles with narrow and wide necks, it re-
fers to reading the tests at a lower temperature than
is now generally practiced in factories, viz., at 120°, in-

1 Bull. 58, Bur. An. Ind., U. S. Dept. of Agriculture.

Cream Testing. 87

stead of 140° (see 41). Pending a similar investiga-
tion as that referred to above, for a temperature of
140°, it is well to read cream tests to the bottom of the
meniscus (at c, fig. 36) at this temperature, rather than
to 5 or d, as it is believed that more correct results will
be obtained by this method of reading.

1. Give three reasons for weighing cream for testing.

2. How does the richness of the cream influence its weight?

3. What will be the weight of one gallon of cream testing
10, 30, or 50% fat?

4. Describe at least three forms of cream test bottles.

5. What is the use of a bulb in the cream bottle.

6. Between what points should the cream fat column be read?

7. If cream was erroneously weighed into a test bottle as 9.3
gr. instead of 10 gr., what error would this cause on a sample
testing 33% fat?

8. Mention a few important points in the construction of a
cream test bottle.

9. If 12.5 gr. cream give a reading of 18.5, what is the cor-
rect test of the sample?

10. If 7.2 gr. of cream give a reading of 6.4, what is the cor-
rect test of the sample?

11. If the fat in a cream test is read as 28% at a temperature
of 180° P., what is the correct test?

12. If at the end of a full day's run 4,280 Ibs. of milk had
been received, testing 3.95 per cent., and 535 Ibs. of cream test-
ing 34.5 per cent, fat; how much fat (a) in the whole milk;
(b) in the cream; (c) in the skim milk? (d) what would be
the test of the skim milk, (e) how many pounds of skim milk
would there be; and (f) what would be the per cent, of cream
from the milk?

CHAPTER V.
BABCOCK TEST FOR OTHER MILK PRODUCTS.

97. Skim milk. Each division on the scale of the
neck of the regular Babcock test bottle represents two-
tenths of one per cent. (44). When a sample of skim
milk or butter milk containing less than this per cent,
of fat is tested, the estimated amount is expressed by
different operators as one-tenth, a trace, one-tenth trace,
or one- to five-hundredths of one per cent. Gravimetric
chemical analyses of skim milk have, however, shown
that samples which give only a few small drops of fat
floating on the water in the neck of the test bottle, or
adhering to the side of the neck, generally contain
one-tenth of one per cent, of fat, and often more. Sam-
ples of skim milk containing less than one-tenth of one
per cent, of fat are very rare, and it is doubtful whether
a sample of separator skim milk representing a run
of, say 5000 Ibs. of milk, has ever shown less than
five-hundredths of one per cent, of fat. Under ordi-
nary factory conditions, few separators will deliver
skim milk containing under one-tenth of one per cent,
of fat, when the sample is taken from the whole day's
run. This must be considered a most satisfactory sepa-
ration.1

1 For comparative analyses of separator skim milk by the gravi-
metric method and by the Babcock test, see Wis. exp. station bull. 52
and rep. XVII, p. 81; Conn. (Storrs) exp. station, bull. 40; Utah exp.
station, bull. 96. See also Woll, Testing skim milk by Babcock test, in
Country Gentleman, April 26, 1902. The results obtained by the use of
the Gottlieb method have shown that! ether-extraction methods, as

Babcock Test for other Milk Products. 89

98. The reason why the Babcock test fails to show all
the fat present in skim milk must be sought in one or
two causes: a trace of fat may be dissolved by the.sul-
furic acid, or owing to the minuteness of the fat glob-
ules of such milk they may not be brought together in
the neck of the bottles at the speed used with the Bab-
cock test. The latter cause is the more likely explana-
tion. If a drop of the dark liquid obtained in a Bab-
cock bottle from a test of whole milk be placed on a
slide under the microscope, it will be seen that a fair
number of very minute fat globules are found in the
liquid. These globules are not brought into the column
of fat in the neck of the bottle by the centrifugal force
exerted in the Babcock test, even if the bottles are
whirled in a turbine tester in which they are heated
to 200° F. or higher (see 71) ; the loss of the fat con-
tained in these fine globules is compensated for, in the
testing of whole milk, by a liberal reading of the fat
column, the reading being taken from the bottom of
the fat to the top of the upper meniscus (see p. 35) ;
in some separator skim milk, on the other hand, not
enough fat remains to completely fill the neck, and the
reading must therefore be increased by from five-hun-
dredths to one-tenth of one per cent.

It follows from what has been said that tests of skim
milk showing no fat in the neck of the test bottles on
completion of the test, generally indicate inefficient
work of the centrifugal tester or of the operator, or of

well as the Babcock test, give too low results with dairy by-products
low in fat, like skim milk, butter-milk, etc. The Gottlieb method for
this reason has been adopted as a standard for analysis of these prod-
ucts by European chemists. (See 254)

Testing Milk and Its Products.

both. The test should be repeated in such cases, using
more acid and whirling for full five minutes. Sepa-
rator skim milk should be allowed to stand 10 to 15 min-
utes for the air to escape before the sample is taken.

In order to bring as much fat as possible into the
neck of the bottles in testing skim milk, it is advisable
to add somewhat more acid than when
whole milk is tested, viz., about 20 cc.,
and to whirl the bottles at full speed for
at least five minutes, keeping the tester as
hot as possible the whole time.1 The read-
ings must be taken as soon as the whirl-
ing is completed, as owing to the contrac-
tion of the liquid by cooling, the fat oth-
erwise adheres to the inside of the neck
of the test bottle as a film of grease which
cannot be measured by the scale.

99. The double-necked test bottle,
(fig. 37), suggested by one of us,2 is made
especially for measuring small quantities
of fat and gives fairly satisfactory results
in testing skim milk and butter milk.
Each division of the scale in these bottles
represents five-hundredths of one per

FlG.

The

/» ,, , double-necked

cent, and the marks are so far apart that skim miik bot-

., . th> (sometimes

the small fat column can be easily esti- called the ohi-

son or B. & W.

mated to single hundredths of one per bottle.)

cent. In the first forms, now out of use, the neck was

graduated to hundredths of one per cent.

1 See Wis. exp. station, report XVII, p. 81.

2 First constructed by Mr* J. J. Nussbaurner, of Illinois; now man-
ufactured by various firms.

Babcock Test for other Milk Products. 91

The value of the divisions of the scale on the double-
necked test bottles has been a subject of considerable
discussion, and various opinions have been expressed
whether they show one-tenth or one-twentieth (.05) of
one per cent, of fat. By calibration with mercury the
value of the divisions will be found to be .05, or one-
twentieth, of one per cent., but as shown above, the re-
sults obtained in using the bottles for separator skim
milk generally come at least .05 per cent, too low, so
that, practically speaking, each division may be taken
to show one-tenth of one per cent., if the fat fills only
one division of the scale or less.1

The double-necked bottle is very convenient for the
testing of separator skim milk, thin butter milk and
whey. The milk, acid and water are added to the bottle
through the large side-tube ; the mixing of milk and acid
must be done with great care, so that none of the con-
tents is forced into the fine measuring tube and lost; it
is best to add half of the acid first and mix it with the
milk, and then add the rest. When the fat is in the
lower end of the measuring tube, it can be forced into
the scale by pressing with the finger on the top of the
side tube.

In placing the double-necked bottles in the tester they
should be put with the filling tube toward the center so
as to avoid any of the fat being caught between this
tube and the side of the bottle when it resumes a verti-
cal position.

This test bottle is more fragile and expensive than
the ordinary Babcock bottles, and must be carefully

1 Wis. exp. station, bull. 52; Penna. exp. station," report 1896, p. 221.

Testing Milk and Its Products.

handled ; it has recently been made of heavier glass and
this form is to be highly recommended.1

100. The double-sized skim milk bottle, which was the
first one recommended for the testing of skim milk, is of no
particular value. It is difficult to obtain a thorough mixture of
the milk and the acid in these bottles, and the tests invariably
come too low, more so than with the regular Babcock bottles or
the double-necked skim milk bottles, for reasons
that are readily seen.

101. Buttermilk and whey. The
testing of buttermilk or whey by the
Babcock test offers no special difficul-
ties, and what has been said in regard
to tests of separator skim milk is equally
true in case of these by-products. Whey
contains only a small quantity of solids
not fat, viz., less than 7 per cent. (27),
and the mixing with acid and the solu-
tion of the whey solids therein is there-
fore readily accomplished; the acid so-
lution is of a light reddish color, turn-
ing black but very slowly.

TOiz Riitt^r "Rntfpr i<a not «sn pasi'lv^0-88' Tbe Wagner

102. Duner. cutter is LOI so easily sklm mllk Bottle,
tested as other dairy products, both because of the dif-
ficulties in obtaining a fair sample, and on account of
the high percentage of fat it contains. Butter is a me-
chanical mixture of water, curd, and salt, with butter-
fat; and the water or brine is so easily pressed out that
great care must be taken to get the same amount of

1 A double-necked copper test bottle with a detachable graduated
glass neck was designed and tried by one of us a few years ago, but It
was not found to possess any special advantages over the glass bottle.

WAGNERS,
OUBLE BOR'
KiMMED MILI|

TESTING BOTTU

Babcock Test f<

water in the small portion to be" LUSltHl l<\& exists in the
lot of butter sampled.

Sampling butter. Small portions of butter are taken
with a butter trier or a knife from different parts of
the tub, package, or churning of butter to be tested.
These small portions are placed in a wide-necked bottle
or jar which is securely stoppered and placed in warm
water until the butter melts. The jar is then shaken
vigorously in order to obtain a thorough mixing of the
various components of the butter, and placed in cold
water. As the butter cools, the jar must be shaken re-
peatedly until the butter either solidifies or becomes of
a thick creamy consistency. From this sample small
portions may be taken for testing.

It is not always necessary to prepare a sample of
butter for testing in the manner described. If the but-
ter contains no loose drops of brine on the freshly-cut
surface, a sample for testing can be taken directly from
the package. The operator must use his judgment in
regard to the necessity of preparing a special sample in
each case.

Scales for weighing butter. In testing butter it is
necessary to weigh the amount taken for a test with
great accuracy. Scales sensitive to less than .05 should
be used, as a difference of .1 gram in weight has a value
of 1.0 per cent, in the result when 10 grams of butter
are tested. Slow-working scales with bearings that will
rust are worthless for testing butter. The scales should
always be balanced before being used and the weights
kept bright and clean.

94 Testing Milk and Its Products.

Carelessness in weighing may be the cause of very
inaccurate results, and the importance of a sensitive
scale cannot be over-estimated. Scales with a graduated
side beam are preferable to those that require the use
of small weights. It is ,now possible to get a scale that
is sensitive to .01 gram on the side beam, and permits
of 20 to 50 grams of butter being weighed out for
testing.1

103. Fat in butter. The Babcock test can be used
with a fair degree of accuracy for estimating the per
cent, of fat in butter, by weighing 9 grams of butter
into a test bottle graduated to measure 50 per cent. fat.
About 10 cc. of hot water is added to the butter, and
17.5 cc. of sulfuric acid of one-half the strength used in
milk testing. Mix the butter and acid until the curd
is all dissolved, add hot water to bring the fat into
the neck of the test bottle and whirl in a centrifuge.
When a clear separation of the fat is obtained the test
bottle is placed in water of 140° F. up to near the top
of the neck and after standing a few minutes in this
water the fat column is read off ; the reading multiplied
by 2 gives the per cent, of fat.

Accurate results can only be obtained by taking great
care in all the manipulations, especially in weighing the
butter and in reading the fat at the proper tempera-
ture. Small errors in making tests have a great influ-
ence on the results, because the butter fat is such a

1 See bull. 154, Wisconsin exp. sta., p. 10.

Babcock Test for other Milk Products. 95

large per cent, of the butter. Tests should always be
made in duplicate.1

104. Cheese. Cheese can be easily tested by the Bab-
cock test if a small scale (fig. 34) is at hand for weigh-
ing the sample; the results obtained will furnish accu-
rate information as to the amount of fat in the cheese,
provided good judgment and exactness are used in
sampling and weighing the cheese. The following
method of sampling cheese is recommended :2

" Where the cheese can be cut, a narrow wedge reaching from
the edge to the center of the cheese will more nearly represent
the average composition of the cheese than any other sample.
This may be cut quite fine, with care to avoid evaporation of
water, and the portion for analysis taken from the mixed mass.
When the sample is taken with a cheese trier, a plug taken per-
pendicular to the surface, one-third of the distance from the
edge to the center of the cheese, will more nearly represent the
average composition than any other. The plug should either
reach entirely through or only half way through the cheese.

"For inspection purposes the rind may be rejected, but for
investigations, where the -absolute quantity of fat in the cheese
is required, the rind should be included in the sample. It is
well, when admissible, to take two or three plugs on different
sides of the cheese and after splitting them lengthwise with a
sharp knife, take portions of each for the test."

105. When a satisfactory sample of the cheese has
been obtained, about 5 grams are weighed into a milk
test bottle, or a larger quantity may be used with a
cream test bottle. The test bottle is first weighed empty,
and again after the pieces of cheese have been added.

1 Special bottles for testing butter for its fat content have been put
on the market, e. g., the Wagner Butter Test Bottle and the form sug-
gested by H. R. Wright, given in the 18th report of the Iowa State
Dairy Commissioner, 1904, p. 40.

2 U. 8. Dept. of Agriculture, Chemical Division, bull. 46, p. 37.

96 Testing Milk and Its Products.

About 15 cc. of warm water is added to the cheese in
the test bottle, and this is shaken occasionally until the
cheese softens and forms a creamy emulsion with the
water. A few cc. of acid will aid in this mixing and
disintegration, the process being hastened by placing
the bottles in tepid water. When all lumps of cheese
have disappeared in the liquid, the full amount of acid
is added, and the test completed in the ordinary man-
ner.

The per cent, of fat in the cheese is obtained by mul-
tiplying the reading of the fat column by 18 and divid-
ing the product by the weight of cheese. The weighing
of the cheese and the reading of the fat must be done
with great care, since any error introduced is more than
trebled in calculating the per cent, of fat in the cheese.

106. Condensed milk. The per cent, of fat in un-
sweetened condensed milk can be obtained by weighing
about 8 grams into a test bottle and proceeding in ex-
actly the same way as given under testing of cheese.
It is not necessary to warm the condensed milk in the
test bottles, since the solution of this in water is readily
effected. Enough water should be added to make the
total volume of liquid in the bottles 15 to 18 cc.

If a scale is not available for weighing the sample,
fairly accurate results may be obtained by diluting the
condensed milk with water (1:3), and completing the
test in the ordinary manner. When this is done, the
results must be corrected" for the dilution which the
sample received.

107: Sweetened condensed milk. The testing of
sweetened condensed milk presents peculiar difficulties,

Babcock Test for other Milk Products. 97

whether it is to be tested by the Babcock test or by
chemical analysis. It may, however, be readily tested
by the Babcock test by introducing certain changes in
the manipulation of the test, as worked out by one of
us.1 A brief description of the manipulations adopted
is here given.

About sixty grams of condensed milk are weighed
into a 200 cc. graduated flask, to this 100 cc. of water
are added and the solution of the condensed milk ef-
fected. The flask is then filled to the mark with water
and after mixing thoroughly, a 17.6 cc. pipette full is
measured into a Babcock test bottle. About three cc.
of the sulfuric acid commonly used for testing milk are
then added and the milk and acid mixed by shaking the
bottle vigorously. The milk is curdled by the acid, and
the curd and whey separated somewhat. In order to
make this separation complete and to compact the curd
into a firm lump, the test bottle is whirled for about six
minutes at a rather high speed (1,000 rev.) in a steam-
heated turbine centrifuge.

The chamber in which the bottles are whirled ought
to be heated to about 200° F. This can be done either
by the turbine exhaust steam which leaks into the test-
bottle chamber of some machines, or by means of a
valve and pipe which will allow steam to be turned di-
rectly into the test bottle chamber. After this first
whirling the test bottles are taken from the centrifuge
and by being careful not to break the lump of curd
nearly all the whey or sugar solution can be poured out
of the neck. Ten cc. of water are then poured into the

1 Wis. exp. station, report XVII, pp.
7

98 Testing Milk and Its Products.

test bottle and the curd is shaken up with it so as to
wash out more of the sugar. Three cc. of acid are now
added as before and the test bottle whirled a second
time in the centrifuge. The whey is decanted again
and this second washing removes so much of the sugar
that what remains will not interfere with testing in the
usual way. The curd remaining in the bottle after the
second washing is shaken up with ten cc. of water; the
water-emulsion of the curd is then cooled ; the usual
amount, 17.5 cc., of sulfuric acid is added, and the test
completed in the same way as when milk is tested. The
amount of fat obtained in the neck of the test bottle is
calculated to the weight of condensed milk taken.1

108. Ice cream. Methods for determining the per
cent, of fat in ice cream have recently been worked out
by Holm2 and Howard.3 The former recommends the
use of a mixture of equal parts of hydrochloric and
glacial acetic acid, in the place of sulfuric acid, as the
latter is likely to char the sugar in the ice cream, thus
giving difficulty in reading the results. Nine grams of
the sample are weighed into a Babccck milk bottle,
which is then filled almost to the neck with the mixture
of the two acids given. This is then heated for a few
minutes until black, when the bottle is whirled in the
tester and water added to bring the fat column within
the graduations of the neck, as in the regular Babcock
test. The reading multiplied by two gives the per cent,
of fat in the ice cream.

1 The Gottlieb method gives very satisfactory results with both
cheese and condensed milk (see 2f>i).

2 Report Dept. of Health, City of Chicago, 1006, p. 50.

3 Journ. Am. Ohem. Soc., 1907, p. 16.

Babcock Test for other Milk Products. 99

Questions.

1. Why is it difficult to get accurate tests of skim milk by
the Babcock test?

2. Mention at least three precautions that should be taken
in testing skim milk.

3. Should more acid be used for full milk than for skim
milk, or more for skim milk than for whey? Why?

4. How much fat is probably present in a sample of skim
milk which shows no fat on being tested in a skim milk bottle?

5. What per cent, of fat does each division of a double-
necked skimmilk test bottle represent?

6. How can (a) butter, (b) cheese, (c) condensed milk be
tested with the Babcock test?

7. If 8.4 gr. cheese give a reading of 12.2% on the neck of a
test bottle, what per cent, of fat does the cheese contain?

8. What is the per cent, of fat in a sample of cheese, of
which 4.2 grams contained enough fat to fill the space in the
neck of a Babcock milk test bottle from 1.7 to 9.5 mark!

9. How can the per cent, of fat in ice cream be determined?

CHAPTER VI.

•

THE LACTOMETER AND ITS APPLICATION.

109. The lactometer is used for determining the spe-
cific gravity of milk. The term specific gravity means
the weight of a certain volume of a solid or a liquid
substance compared with the weight of the same vol-
ume of water at 4° C. (39.2° Fahr.) ; for gases the
standard of comparison is air or hydrogen. If the milk
which a can will hold weighs exactly 103.2 Ibs., this can
will hold a smaller weight of water, say 100 Ibs., as milk
is heavier than water; the specific gravity of this milk
will then be 1^=1.032.

The specific gravity of normal cow's milk will vary
in different samples between 1.029 and 1.035 at 60° F.,
the average being about 1.032. The specific gravity of
skim milk is about 1.036-1.038, and of sweet cream 1.01
to .95, according to the per cent, of fat contained there-
in; average specific gravity 1.0 (see p. 76). 1

The lactometer enables us to determine rapidly the
relative weight of milk and water. Its application rests
on well-known laws of physics : When a body floats in
a liquid, the weight of the amount of liquid which it
replaces is equal to the weight of the body. It will sink
further into a light liquid than into a heavy one. be-

1 Since 1 gallon of water weighs 8.34 Ibs., 1 prnl. milk will wi-iirh *.:',!
XI. 032 or 8.6 Ibs. ; 1 gal. of skim milk, 8.7 Ibs., and 1 gal. of cream from s
to 8.4 Ibs., according to its richness.

The Lactometer and Its Application.

101

cause a larger volume of the former will
be required to equal the weight of the
body. A lactometer will therefore sink
deeper into milk of a low specific grav-
ity than into milk of a high specific
gravity.

no. The Quevenne lactometer.
This instrument (fig. 39), consists of
a hollow cylinder weighted by means of
mercury or fine shot so that it will float
in milk in an upright position, and pro-
vided with a narrow stem at its upper
end, inside of which is found a gradu-
ated paper scale. In the better forms,
like the Quevenne lactometer shown in
the figure, a thermometer is melted into
the cylinder, with its bulb at the lower
end of the lactometer and its stem ris-
ing above the lactometer scale.

The scale of tne Quevenne lactometer
is marked at 15 and 40, and divided into
25 equal parts, with figures at each five
divisions of the scale. The single divis-
ions are called degrees. The 15-degree
mark is placed at the point to which the
lactometer will sink when lowered into
a liquid of a specific gravity of 1.015,
and the 40-degree mark at the point to
which it will sink when placed in a
liquid of a specific gravity of 1.040.

d£ai5)?tln °ylin"

102 Testing. Milk and Its Products.

The specific gravity is changed to lactometer degrees
by multiplying by 1000 and subtracting 1000 from the
product.

EXAMPLE: Given, the specific gravity of a sample of milk,
1.0345; corresponding lactometer degree, 1.0345X1000 — 1000=
34.5.

Conversely, if the lactometer degree is known, the
corresponding specific gravity is found by dividing by
1000 and adding 1 to the quotient (34.5-r-1000=0345;
.0345+1=1.0345).

in. Influence of temperature. Like most liquids,
milk will expand on being warmed, and the same vol-
ume will, therefore, weigh less when warm than before ;
that is, its specific gravity will be decreased. It follows
then that a lactometer is only correct for the tempera-
ture at which it is standardized. If a lactometer sinks
to the 32-mark in a sample of milk of a temperature of
60° F., it will only sink to, say 33, if the temperature
of the milk is 50° F., and will sink farther down, e. g.,
to 31, if the temperature is 70° F. Lactometers on the
market at present are generally standardized at 60° F.,
and to show the correct specific gravity the milk to be
tested should first be warmed (or cooled, as the case
may be) to exactly 60° F. As this is a somewhat slow
process, tables have been constructed for correcting the
results for errors due to differences in temperature (see
Appendix, Table V).

112. As the fat content of a sample of milk has a
marked influence on its specific gravity at different
temperatures, the co-efficient of expansion of fat differ-
ing greatly from that of the milk serum, the table can-

The Lactometer and Its Application. 103

not give absolutely accurate corrections for all kinds of
milk, whether rich or poor. But the error introduced
by the use of one table for any kind of whole milk
within a comparatively small range of temperature, like
ten degrees above or belcw 60°, is too small to have any
importance outside of exact scientific work, and in such,
the specific gravity is always determined by means of a
picnometer or a specific-gravity bottle (248), at the exact
temperature at which this has been calibrated. In tak-
ing the specific gravity of a sample of milk by means
of a lactometer, the milk is always warmed or cooled
so that its temperature does not vary ten degrees either
way from 60° F.

113. The temperature correction table for whole milk,
given in the Appendix shows that if, e. g., the specific
gravity of a sample of milk taken at 68° F. was found
to be 1.034, its specific gravity would be 1.0352 if the
milk was cooled down to 60°. If the specific gravity
given was found at a temperature of 51°, the corrected
specific gravity of the milk would be 1.0329.

In practical work in factories or at the farm, suffi-
ciently accurate temperature correcticns may generally
be made by adding .1 to the lactometer reading for
each degree above 60° F., and subtracting .1 for each
degree below 60° ; e. g., if the reading at 64° is 29.5.
it will be about 29.5+.4=29.9 at 60° F. ; and 34.0 at
52° F. will be about 34.0— .8=33.2 at 60° F. The table
in the Appendix gives 33.0 as the corrected figure in
both cases.

The scale of the thermometer in the .lactometer should
be placed above the lactometer scale so that the tern-

104 Testing Milk and Its Products.

perature may be read without taking the lactometer out
of the milk; this will give more correct results, will
facilitate the reading and save time.

114. N. Y. Board of Health lactometer. In the East, and
among city milk inspectors generally, the so-called New York
Board of Health lactometer is often used. This does not give
the specific gravity of the milk directly, as is the case with the
Quevenne lactometer; but the scale is divided into 120 equal
parts, known as Board of Health degrees, the mark 100 being
placed at the point to which the lactometer sinks when lowered
into milk of a specific gravity of 1.029 (at 60° F.) ; this is con-
sidered the lowest limit for the specific gravity of normal cow's
milk. The zero mark on the scale shows the point to which the
lactometer will sink in water; the distance between these two
marks is divided into 100 equal parts, and the scale is contin-
ued below the 100 mark to 120. As 100° on the Board of Health
lactometer corresponds to 29° on the Quevenne lactometer, the
zero mark showing in either case a specific gravity of 1, the
degrees on the former lactometer may easily be changed into
Quevenne lactometer degrees by multiplying by .29. To fur-
ther aid in this transposition, Table III is given in the Appen-
dix, showing the readings of the two scales between 60° and
120° on the Board of Health lactometer.

115. Reading the lactometer. For determining the
specific gravity of milk in factories or private dairies,
tin cylinders, l1/^ inches in diameter and 10 inches
high, with a base about four inches in diameter, are
recommended (see fig. 39) ; another form of specific-
gravity cylinder, in use in chemical laboratories, is
shown in fig. 40. The cylinder is filled with milk of a
temperature ranging between 50° and 70° F., to within
an inch of the top, and the lactometer is slowly lowered
therein until it floats; it is left in the milk for about
half a minute before lactometer and thermometer read-

The Lactometer and Its Application. 105

•
ings are taken, both to allow the escape of air which

has been mixed with the milk in pouring it, prepara-
tory to the specific-gravity determination, and to allow
the thermometer to adjust itself to the tem-
perature of the milk. The lactometer should
not be left in the milk more than a minute
before reading is taken, as cream will soon
begin to rise on the milk, and the reading,
if taken later, will be too high, as the bulb
of the lactometer will be floating in partially
skimmed milk (23). In reading the lacto-
meter degree, the mark on the scale plainly
visible through the upper portion of the
meniscus of the milk should be noted. Ow-
ing to surface tension the milk in immediate
contact, with the lactometer stem will rise
above the level of the surface in the cylinder, cylinder-
and this must be taken into consideration in reading
the degrees. It is not necessary to read closer than one-
half of a lactometer degree in the practical work of a
factory or a dairy.

116. Time of taking lactometer readings. The spe-
cific gravity of milk should not be determined until an
hour or two after the milk has been drawn from the
udder, as too low results are otherwise obtained (Reck-
nagel's phenomenon).1 The cause of this phenomenon
is not definitely understood; it may come from the es-
cape of gases in the milk, or from changes occurring in
the mechanical condition of the nitrogenous compo-

1 Milchztg. 1883, 419; bull. 43,Ohem. Div., U.S. Dept. of Agriculture,
p. 191; Analyst, 1894, p. 76.

106 Testing Milk and Its Products.

nents of the milk. The results obtained after a couple
of hours will, as a rule, come about one degree higher
than when the milk is cooled down directly after milk-
ing and its specific gravity then determined.

117. Influence of solid preservatives on lactome-

•*
ter readings. When potassium bi-chromate, corrosive

sublimate, etc., is added to milk samples to preserve
them from souring (190), the specific gravity of the
milk will be increased ; with the quantity usually added
(% g^am to a pint of milk) the increase amounts to
about 1 lactometer degree, and this correction of lacto-
meter readings should be made with milk samples pre-
served in this manner. To avoid this error, Dr. Eich-
loff1 recommends the use of a solution of potassium bi-
chromate in water (43 grams to 1 liter), the specific
gravity of which is 1.032, or similar to that of average
milk; 5 cc. of this solution is required for a pint of
milk. No correction is necessary for the dilution with
this small amount of liquid preservative.

118. Cleaning of lactometer. The lactometer should
be cleaned directly after using, by rinsing with cold
water; it is then wiped dry with a clean cloth and
placed in the case. *

n8a. Testing the accuracy of lactometers. The
correctness of lactometers may be determined with a
fair degree of accuracy by placing them in different
salt solutions prepared by dissolving exactly 3, 4, and 5
grams of pure dairy salt in 100 grams (cc.) of water.
The specific gravities at 60° F. of solutions thus (>b-

1 'IVrlmik <!«•!• MNrhpriifiintr. p. 98.

The Lactometer and Its Application. 107

tained are 1.022, 1.029, and 1.036, for 3, 4, and 5 per
cent, solutions, respectively.

CALCULATION OF MILK SOLIDS.

1 19** A number of chemists have prepared formulas
for the calculation of milk solids when the fat content,
and the specific gravity (lactometer reading) of the
milk are known. By careful work with milk tester and
lactometer it is possible by means of these formulas to
determine the compcsition of samples of milk with con-
siderable accuracy both outside of and in chemical lab-
oratories. As the .complete formulas given by various
chemists (Behrend and Morgen, Clausnitzer and Mayer,
Fleischmann, Hehner and Eichmond, Eichmond, Bab-
cock)1 are very involved, and require rather lengthy
calculations, tables facilitating the figuring have been
prepared. The formulas in use at the present time, in
this country and abroad, are those proposed by Fleisch-
mann, Hehner and Eichmond, or Babcock. Babcock's
formula is the one generally taught in American dairy
schools and is therefore given here; it forms the foun-
dation for Table VI in the Appendix for calculation of
solids not fat.

By the use of these tables the percents of solids not
fat may be found, corresponding to lactometer read-
ings from 26 to 36, and to fat contents from 0 to 6
per cent. The formula, as amended in 1895,2 is as fol-
lows, 8 being the specific gravity and / the per cent, of
fat in the milk.

1 Agricultural Science, vol. Ill, p. 139.

2 Wisconsin experiment station, twelfth report, page 120.

108 Testing Milk and Its Products.

SolSdB not fat=(IJ^fgf-l)(100-f) 2.5

The derivation of this formula is explained in the re-
port referred to.

120. Short formulas. The tables made up from this
formula, giving the percentages of solids not fat corre-
sponding to certain per cents, of fat and lactometer
readings, are given in the Appendix. A careful exam-
ination of the tables will disclose the fact that the per
cent, of solids not fat increases uniformly at the rate
of .25, or one-fourth of a per cent, for each lactometer
degree, and .02 per cent, for each tenth of a per cent, of
fat. This relation is expressed by the following simple
formulas :

Solids not f at=% L -f .2 f
Total solids=% L + 1.2 f,

L being the lactometer reading at 60° F. (specific gravity
X 1000 — 1000), and f the per cent, or fat in the milk.

Eule: a, To -find the per cent, of solids not fat in milk, add
two-tenths of the per cent, of fat to one- fourth of the lacto-
meter reading, and

b, To find the per cent, of total solids in millc, add one and
two-tenths times the per cent, of fat to one-fourth of the lacto-
meter reading.

These formulas and rules are easily remembered and
can be quickly applied without the use of tables. The
results obtained by using them do not differ more than
.04 per cent, from those of the complete formula for
milks containing up to 6 per cent, of fat, and may be
safely relied upon in practical work.

The English dairy chemist Droop Richmond has
constructed an ingenious sliding "milk scale'7 which en-
ables one to readily find the percentages of total solids

The Lactometer and Its Application. 109

corresponding to different lactometer readings and fat
contents, or the percentage cf fat from total solids and
lactometer readings.1

ADULTERATION OF MILK.

121. Methods of adulteration. The problem of de-
termining whether or not a sample of milk is adulter-
ated becomes an important one in the work of milk in-
spectors and dairy and food chemists. Managers of
creameries and cheese factories are also sometimes in-
terested in ascertaining possible adulterations in the
case of some patron's milk, although at present, since
the general introduction of the Babcock test in factories
and the payment for the milk on the basis of the amount
of butter fat delivered, the temptation to water or skim
the milk has been largely removed. In the city milk
trade, especially in our larger cities, watered or skimmed
milk is still frequently met with, in spite of the vigi-
lance of their milk inspectors or the officers of the city
boards of health.

When the origin of a suspected sample of milk is
known, a second sample should always be taken on the
premises, if possible, by or in the presence of the in-
spector, and the composition of the two samples com-
pared. If the suspected sample is considerably lower
in fat content than the second, so-called control-sample,
and has a normal per cent, of solids not fat, it is
skimmed; if the solids not fat are below normal, it is
watered; and if both these percentages are abnormally
low, the sample is most likely both watered and
skimmed (126).

1 Dairy;Ohemistry,*page 61.

110 Testing Milk and Its Products.

122. Latitude of variation. In order to determine
whether or not a sample of milk is skimmed or watered,
or both skimmed and watered, the per cents, of fat and
of solids not fat in the sample must be ascertained, and
if a control-sample can be secured, these determina-
tions for both samples compared. The proper latitude
to be allowed for the natural variation in the com
tion of milk differs according to the origin of the milk ;
in case of milk from single cows, the variations in fat
content from day to day may exceed one per cent., al-
though under ordinary conditions the per cent, of fat
in most cow's milk will not vary that much. The con-
tent of solids not fat is more constant, and rarely va-
ries one-half of one per cent, from day to day with
single cows. Cows in heat or sick cows may give milk dif-
fering considerably in composition from normal milk^X

123. Mixed herd milk is of comparatively uniform *
composition on consecutive days, and as most milk of-
fered for sale or delivered to factories is of this kind,
the task of the milk inspector is made considerably
easier and more certain on this account. Daily varia-
tions in herd milk beyond one per cent, of fat and one-
half per cent, of solids not fat, are suspicious and may

be taken as fairly conclusive evidence of adulteration.
This is especially true in case the control -sample sho ws n
comparatively low content of fat or solids not fat (159).

124. Legal standards. Where a control-sample can-
not be taken, the legal standards of the various states
for fat or solids in milk are used as a basis for calculat-

1 Blythe, Foods, their Composition and Analysis, London, 1903, p.
250 et seq.

The Lactometer and Its Application. Ill

ing the extent of adulteration of a sample of milk. A
list of legal standards for milk in this country and
abroad is given in the Appendix. These standards de-
termine the limits below which the milk offered for sale
within the respective states must not fall. Legally it
matters not whether a sample of milk offered for sale
has beo^l skimmed or watered by the dealer or by the-
cow ; i^ the latter case, the cows producing the milk are
of a breed or a strain that has been bred persistently
for quantity of milk, without regard to its quality. In
most states the legal standard for the fat content of
milk is 3 per cent., and for solids not fat 9 per cent.
There are, however, cows which at times produce milk
containing only 2.5 to 2.8 per cent, of fat, and less than
8.5 per cent, solids not fat. Such milk cannot therefore
j be legally sold in most states in the Union, and the far-
f mer offering such milk for sale, even if he does not
know the composition of the milk produced by his cows
is as liable to prosecution as if he had directly watered
the milk. By mixing the milk of several cows, the
chances are that the mixed milk will contain more fat
and solids not fat than called for by the legal standard ;
if such should not be the case, cows producing richer
milk must be added to the herd so as to raise the qual-
ity of the herd milk up to the legal standard, or the
cows giving very thin milk must be disposed of.

125. The specific gravity of the milk solids. A calcula-
tion of the specific gravity of the milk solids is of considerable
assistance in interpreting the results of analyses of ' suspected
milk samples. The milk solids vary but slightly in specific
gravity, viz., between 1.25 and 1.34, the richer milks having sol-
ids of low specific gravities. The specific gravity of the milk
solids is calculated by means of Fleischmann 's formula

112 Testing Milk and Its Products.

~t 100 s-100

S being the sp. gr. of the milk solids, s that of the milk and t
the total solids of the milk.

Example: A sample of milk has been found to contain 13.0
per cent, of solids, sp. gr. 1.032; then a ° °^-||~1-^=3.101;
13.0—3.101=9.899; -1-^°- =1.31r=the specific fltvity ol the milk

9-899 ^

solids.

The specific gravity of the solids does not change if ^he milk
is watered, while it is increased when the milk is skimmed. If *a
sample of milk of the composition given in the preceding e^.-
ample had been watered so as to reduce the solids to 11.7 per
cent, and .the specific gravity to 1.0291 (as would be the case
when 10 per cent, of water was added), we would again have,
by calculation as above, S=1.31. If, on the other hand, the
milk was skimmed so as to reduce the solids to 11.7 per cent.,
thereby increasing the specific gravity of the milk to, say 1.035,
we would have by substituting these values in the preceding
formula, S=1.41, showing conclusively that the milk had been
skimmed.

An addition of skim milk to whole milk would have the same
effect as skimming, as regards the composition of the latter, and
the specific gravity of its solids.

The specific gravity of pure butter fat at 60° F. is .93, and
of the fat-free milk solids, 1.5847 (Fleischmann). The solids of
skim milk have a specific gravity of 1.56. Samples of whole
milk, the solids of which have a specific gravity above 1.34 are
suspicious, and a specific gravity over 1.40 is conclusive evidence
of skimming.

To facilitate the calculation of the specific gravity of milk
solids, Table IV is given in the Appendix, showing at a glance
the value of 1 ° ° 8~ 1 ° ° for specific gravities between 1.019 and
1.0369. An example will readily illustrate the use of the table.

Example: A* sample of milk has a specific gravity of 1.0343
and contains 12.25 per cent, solids. In Table IV, we find in the
horizontal line beginning with 1.034 under the column headed
0.0003, the figure 3.316, which is the value for 10°8~100 when

The Lactometer and Its Application. 113

s=1.0343. Introducing this value and that of the total solids
in the formula, the calculation is 12.25—3.316=8.934; 12.25-^
8.934=1.37, which is the specific gravity of the solids in this
case.

126. To recapitulate. Adulteration of milk by water-
ing or skimming or bcth may be established by a com-
parison of the composition of the suspected sample with
that of a control-sample, or if none such can be ob-
tained, with the legal standards. If the composition of
the two samples varies appreciably, the milk has been
adulterated, and the character of the adulteration is
shown from the following statement :

If the analysis of the suspected sample
shows

sp. gr. of milk ) , ]

fat and solids not fat ,. / > watered

gr. of solids \ ., . ._._._ normal )

sp. gr. of milk and of solids ) » . * * 1

solids not f at \ m££| L skimmed

J:at and solids JcJK — J

~"sp\gr. °f milk "*. normal v J watered

sp.'gr. of solids normal or high > and

fat and solids not fat low ) skimmed

The extent»of the adulteration is determined as given
below. k •

127. ^fcWation of extent of adulteration.1 In the

following fyPffil*w percentages found in the control-
samples, if sucrHfrfc at hand, are always substituted for
the legal standarcfe,

a. Skimming. — 1. If a sample of milk has been
skimmed, the following formula will give^he number
cf pounds cf f at *abstr acted from lOO^il^V^f milk:

Fat abstracted=legal standard for fat — f, . . (I)
f being the per cent, of fat in the suspected sample.

1 Well, Handbook for Farmers and Dairymen, New York, 1907, pp.

267-8.

114 Testing Milk and Its Products.

2. The following formula will give the per cent, of
fat abstracted, calculated on the total quantity of fat
originally found in the milk:

x=100 fxioo n

legal standard for fat

b. Watering.— If a sample is watered, the calcula-
tions are mcst conveniently based on the percentage of
solids not fat in the milk. The percentage adulteration
may be expressed either on basis of the amount of
water present in the adulterated milk, or the amount of
water added to the original milk:

1. Percent, of foreign (extraneous) water in the adul-

, , , .„ ln, sxioo

terated milk=10Q—^ — r— — ^ — T~S ?T3 — , n . (Ill)

legal standard tor solids not tat

S being the per cent, of solids not fat in the suspected
sample.

Example: A sfiple of milk contains 7.5 per cent, solids not
fat; if the legal standard for solids not fat is 9 per cent., then
100 — 7.5*1 ^-=16.7,' shows the per cent, of extraneous water
in the milk.

2. Watering of milk may also be expressed in per
cent, of water added to the original milk, by "formula IV :

Per cent, of water added to the o

100 X leg. stand, for sol. dfi
=- -g- -^--100 (IV)

%*"
In the example given above, l™^?— 100=20 percent.

of water was added to the original milk.

c. Watering and skimming. — If a Cample has been
both watered f*nd skimmed, the extent of watering is
ascertained by means of formula (III) or (IV), and
the fat abstracted found according to the following
formula :

The Lactometer and Its Application. 115

Per cent, fat abstracted=

leg. stand, for sol. not fat
leg. stand, for fat — ^ — — Xf. . . (V)

Example: A sample of milk contains 2.4 per cent, of fat and
8.1 per cent, solids not fat; then

Extraneous water in milk=100- 8- lx^ ° °:=10 per cent.

Fat abstracted=3— ^|^=33 per cent.

100 Ibs. of the milk contained 10 Ibs. of extraneous water and
.33 Ib. of fat had been skimmed from it.

For methods of detection of other adulterations and
of preservatives in dairy products, see Chap. X, 299,
et seq.

Questions.

1. What is the weight of 1000 cc. of (a) water; (b) skim
milk; (c) whole milk; (d) cream testing 30% fat; (e) whey;
(f) butter fat? ^

2. If the sp. gr. of a sample of milk is 1.0325 at 68° F.,
what is the lactometer reading at 60°?

3. What effect on the sp. gr. has 1.0% solids not fat and
1.0% fat?

4. How can the accuracy of a lactometer be tested?

5. If a sample of milk has a sp. gr. of 1.032 and 13.0% sol-
ids, what is the sp. gr. of the milk solids?

6. How can (a) skimmed milk, (b) watered milk, (c)
skimmed and watered milk be detected?

7. Give lactometer readings and percentages of fat in sam-
ples showing (a) watering, (b) skimming, (c) watering and
skimming.

8. If one quart of water is added to one quart of milk, what
per cent, of water is added, and what per cent, extraneous water
does the mixture contain?

116 Testing Milk and Its Products.

9. How many pounds of fat have been removed from a sam-
ple of milk testing 2.6%, and what per cent, of the fat was re-
moved?

10. If a sample of milk contains 7.0% solids not fat, what
per cent, water was added and how much extraneous water did
the sample contain?

11. What has probably been done to each of- the following
samples of milk, that were found to contain (a) 7.2 per cent,
solids not fat, 2.6 per cent, fat; (b) 9.0 per cent, solids not fat,
2.5 per cent, fat; (c) 6.5 per cent, solids not fat, 2.4% fat?

12. What is the per cent, solids not fat and what is the con
dition of each of the following samples of milk:

Per Cent. Fat.

4.0
2.5
3.5
2.5
2.4

Lactometer

Beading.

(a)

58°

(b)

56°

(c)

63°

(d)

54°

(e)

69°

CHAPTER VII.
TESTING THE ACIDITY OF MILK AND CREAM.

128. Cause of acidity in milk. Even directly after
milk is drawn from the udder it will be found to have
an acid reaction, when phenolphtalein is used as an in-
dicator.1 The acidity of fresh milk is not due to the
presence of free organic acids in the milk, like lactic
or citric acid, but to acid phosphates, and possibly also
in part to free carbonic acid gas in the milk or to the
acid reaction of casein. Even in case of so-called sweet
milk, nearly fresh from the cow, a certain amount of
acidity, viz., on the average about .07 per cent., is there-
fore found. When the milk is received at the factory
it will rarely test less than .10 per cent, of acid, calcu-
lated as lactid acid; some patrons bring milk day after
day that does not test over .15 per cent, of acid; that
of others tests from .20 to .25 per cent., and some lots,
although very rarely, will test as high as .3 of one per
cent, of acid. It has been found that milk will not
usually smell or taste sour or "turned," until it con-
tains .30 to .35 per cent, of acid.

129. The acidity in excess of that found normally in
milk as drawn from the udder, is due to other causes
than those described. Bacteriological examinations of
milk from different sources and of milk of the same
origin at different times have shown that there is, roughly
speaking, a direct relation between the bacteria found

1 Freshly drawn milk shows an amphoteric reaction to litmus, i. e.,
it colors blue litmus paper red, and red litmus paper faintly blue.

118 Testing Milk and Its Products.

in normal milk, and its acidity; the larger the number
of bacteria per unit of milk, the higher is, in general,
the acidity of the milk. The increase in the acidity
of milk on standing is caused by the breaking-
down of milk sugar into lactic, acid through the activi-
ties of acid-forming bacteria. Since the bacteria get
into the milk through a lack of cleanliness during the
milking, or careless handling of the milk after the
milking, or both, it follows that an acidity test of new
milk will give a good clue to the care bestowed in hand-
ling the milk. Such tests will show which patrons take
good care of their milk and which do not wash their
cans clean, or their hands and the udders of the cows
before milking, and have, in general, dirty ways in milk-
ing and caring for the milk. The acidity test is always
higher in summer than in winter, and is generally high
in the case of milk kept for more than a day (Monday
milk), or delivered after a warm, sultry day or night.
The bacteria have had a good chance to multiply enor-
mously in such milk, even if it be kept cooled down to
40° -50° F., and as a result considerable quantities of
lactic acid have been formed. The determination of the
acidity of fresh milk is explained in detail below (143).
130. Method of testing acidity. Methods of meas-
uring the acidity or alkalinity of liquids by means of
certain chemicals giving characteristic color reactions in
the presence of acid or alkaline solutions (so-called
volumetric methods of analysis) have been in use for
many years in chemical laboratories. They were applied
to milk as early as 1872 by Soxhlet,1 and the method
worked out by Soxhlet and Henkel has since been in

1 Jour. f. prukt. Ohemle, 1872, p. 6, 19.

Testing the Acidity of Milk and Cream. 119

general use by European chemists. They measured out
50 cc. of milk to which was added 2 cc. of a 2 per cent,
alcoholic solution of phenolphtalein, and this was ti-
trated with a one-fourth normal soda solution1 (see
below) . In this country, Dr. A. G. Manns in 1890 pub-
lished the results of work done in the line of testing
the acidity of milk and cream,2 and the method of pro-
cedure and apparatus proposed by him has become
known under the name of Manns' test, and is being
advertised as such by dealers in dairy supplies.

131. Manns' test. The acid in milk or cream is
measured by using an alkali solution of certain strength,
with an indicator which shows by a change of color in
the milk when all its acid has been neutralized. Any of
the alkalies, soda, potash, ammonia, or lime can be used
for making the standard solution, but it requires the
skill and apparatus of a chemist to prepare it of the
proper strength. A tenth-normal solution3 of caustic
soda is the alkali solution used most frequently in de-
termining the acidity of milk, and is the solution labeled
Neutralizer of the Manns' test.

1 Fleischmann, Lehrb. d. Milchwirtschaft, 3rd ed., p. 57.

2 Illinois experiment station, bulletin 9..

3 Normal solutions, as a general rule, are prepared so that one liter
shall contain the hydrogen equivalent of the active reagent weighed
in grams (Button). Caustic soda (NaOH) is made up of an atom each
of sodium (Na), oxygen (O), and hydrogen (H); its molecular weight is
therefore

23+16+1=40

Na O H

A normal soda solution then is made by dissolving 40 grams of
soda in water, making up the volume to 1000 cc. ; a one-tenth normal
solution will contain one-tenth of this amount of soda, or 4 grams dis-
solved in one liter. One cubic centimeter of the latter solution will
contain .001 gram of soda, and will neutralize .009 gram of lactic acid.
The formula for lactic acid is 03H6O3 (see page 00), and its molecular
weight is therefore 3X12+6X1+3X16=90. A tenth-normal solution of .
lactic acid contains 9 grams per liter, and .009 gram per cubic centimeter. /

120 Testing Milk and Its Products.

The indicator used is a solution of phenolphtalein, a
light yellowish powder; its compounds with alkalies are
red, in weak alkaline solutions pink colored, while its
acid compounds are colorless. The phenolphtalein solu-
tion used is prepared by dissolving 10 grams in 300 cc.
of 90 per cent, alcohol (Mohr).

132. In testing the acidity of either milk or cream it
is necessary to measure out with exactness the quantity
of liquid to be tested; Manns recommended using a 50
cc. pipette. This amount of milk or cream is measured
into a clean tin, porcelain or glass cup, a few drops of
the phenolphtalein solution are added, and the Neutral-
izer (or alkali solution) is cautiously dropped in from
a burette, the point at which the solution stands before
any is drawn off being noted. By constant stirring
during this operation it will be noticed that the pink
color formed by the addition of even a drop of alkali
solution will at first entirely disappear, but as more and
more of the acid in the sample becomes neutralized, the
color will disappear more slowly, until finally a point
is reached when the pink color remains permanent for a
time. No more alkali should be added after the first
appearance of a uniform pink color in the sample. This
color will "fade and gradually disappear again on stand-
ing, owing to the effect of the carbonic acid of the air,
to which phenolphtalein is very sensitive. The amount
of the alkali solution used for the test is then obtained
from the reading on the scale of the burette. The per
cent, of acid in the sample is calculated by multiplying
the number of cc. of alkali solution used, by .009 and
dividing the predict hy the rmilTher of eo. of the sample
tested, the quotient being multiplied by 100.

Testing the Acidity of MUk and Cream. 121

e. c. alkaliX.009 v

Per cent. acidity= — — rXlOO

c. c. sample tested

If 50 cc. of cream required 32 cc. of alkali solution to
produce a permanent pink color, the per cent, of acid in

the cream would be 32*;OQ9-XlOO=.58 per cent A

part of this calculation may be saved by using a factor
for multiplying the number of cc. of alkali added in
each test. This factor is obtained by dividing .009 (the
number of grams of lactic acid neutralized by one cc.
of alkali solution) by the number of cc. of sample
tested, and multiplying the quotient by 100. If a 50
cc. pipette is used for measuring the sample to be tested,
the factor will be (.009-=-50)X 100=^.018; if a 25 cc.
pipette is used, the factor will be (.009-f-25)XlOO=
.036; and if a 20 cc. pipette is used, (.009-1-20) X 100=
.045 will be the factor to be applied in calculating the
per cent, of acidity, the number of cc. of alkali used
being in all cases multiplied by the particular factor
corresponding to the volume of the sample tested.

133. If a Babcock milk test pipette is used for measr-
uring the milk or cream to be tested for acidity, the
factor will be (.009^-17.6) XlOO=.051. This is so nearly
.05 that sufficiently accurate results may be obtained by
simply dividing the number of cc. used by two ; the re-
sult will be the tenths of per cent, of acid in the sample
tested, e. g., if 17.6 cc. of cream required 12 cc. of one-
.tenth normal alkali to give a pink color, then the per
cent, of acid is 12-^2=.6 per cent. If one-fifth normal
alkali is used for testing, the per cent, of acidity is
shown directly by the number of cc. used (Vivian).1

1 Van Norman recommends the use of a 50th normal solution for
testing cream (see Purdue exp..sta., bull. 104). 37 cc. of a normal soda

122

Testing Milk and Its Products.

134. Manns' testing outfit. The appa-
ratus (see fig. 41) and chemicals needed for
testing the acidity of milk or cream by the
so-called Manns ' test include one gallon of a
one-tenth normal alkali solution; four ounces
of an alcoholic solution of phenolphtalein, a
50 cc. glass burette provided with a pinch-
cock, a burette stand, and a pipette for meas-
uring the sample. This outfit will make about
100 tests and is sold for $5.00.1

135. The alkaline tablet test. Solid
alkaline tablets were proposed by Far-
rington in 1894, as a substitute for the
liquid used in the Manns ' test.2 It was
found possible to mix a solid alkali car-
bonate and coloring matter, and com-
press the mixture into a small tablet,
which would contain an exact amount
of alkali. The advantage of the tablets
lies in the fact that they will keep far

better than a standard alkali solu-
tion, and they can be easily and
safely sent by mail; they also re-
4uire less apparatus and are con-
FlG'tnMtnnt'rattests.used siderably cheaper than standard
alkali solutions; 1000 of these tablets, costing $2 00, will

solution is diluted to 1850 cc. in a two-quart bottle, such as is used for
mineral waters. Each cc. of this solution represents .01 cc. of acidity
when 17.6 cc. of cream is measured off. The titration is made in tin'
usual manner, using phenolphtalein as an indicator.

1 Devarda's acidimetcr (Milch/eitung, 1896, p. 785) is based on tin-
s;nno principle as Manns' t«ist: one-tenth soda solution is added to 100
cc. of milk in :i glass-stoppered graduated flask, 2 cc. of a 4 per cent,
phenolphtalein solution being used as an indicator. The graduations
on the neck of the flask give the "degrees acidity" directly.

2 Illinois exp, •riinont station, bulletin 32, April, 1894.

Testing the Acidity of Milk and Cream. 123

make about 400 tests.1 Similar alkaline tablets were
placed on the market in Europe at about the same time,
viz., Stokes' Acidity Pelletts in 1893, and Eichler's
Saurepillen (acid pills) in 1895.2

Two methods of using the tablets have been proposed,
one, for the titration (determination of acidity) of rip-
ening cream in the manufacture of sour-cream butter;
and the other, for determining the approximate acidity
of different lots of apparently
sweet milk or cream.

136. Determination of acidity
in sour cream. The method is
equally applicable for the deter-
mination of the acidity of sour

(2>y hndei»

of «

FIG . 42. Apparatus used for determining the acidity of cream or milk.

cream, sour milk and buttermilk, but is most frequently
employed in testing the acidity of ripening cream, to
examine whether or not the ripening process has
reached the proper stage for churning the cream. The
apparatus used (see fig. 42) is as follows :

1 The tablets are sold by dealers in dairy supplies.

2 Milchzeitung, 1895, pp. 513-16.

124 Testing Milk and Its Products.

1 Babcock 17.6 cc. pipette.
1 white cup.

100 cc. graduated cylinders; it is well to provide two
or three of these, although only one is strictly necessary.

137. Preparation of the solution. The tablet solu-
tion formerly used was prepared by dissolving five tab-
lets in 50 cc. of water; with 20 cc. of cream each cubic
centimeter of this solution represents .017 per cent, of
acid (lactic acid) in the sample tested. The amount of
acid in a given sample is then obtained by multiplying
the number of cubic centimeters of the tablet solution
used, by .017.

138. According to a suggestion made by Mr. C. L.
Pitch/ the strength of the solution was changed in such
a manner that the percentages of acidity are indicated
directly by the number of cubic centimeters of tablet
solution used in each test.

The 17.6 cc. Babcock milk test pipette may be used
for measuring the sample for acidity testing, and the
results read directly from the graduated cylinder, if
the tablet solution is prepared by taking one tablet for
every 19.5 cc. of water; five tablets are therefore dis-
solved in 97 cc. of water.

139. As cream during its ripening process under the
conditions present in this country generally has from
.5 to ,6 per cent, of acid before it is ready to be churned,
a 50 cc. cylinderful of tablet solution of this strength
will not be sufficient to make a test of cream containing
over .5 per cent, of acid, although it is enough for test-

1 Hoard's Dairyman, Sept. 8, 1897.

Testing the Acidity of Milk and Cream. 125

ing the cream up to this point during the ripening pro-
cess. The acid-testing outfit should therefore contain a
100 cc. graduated cylinder, instead of one of 50 cc. capa-
city, so that cream of any amount of acidity up to 1
per cent, can be tested. A tablet solution of the strength
given has not only the advantage over the solution pre-
viously recommended (5 tablets to 50 cc. of water)1
of showing the per cent, of acidity directly, without
tables or calculations, but being weaker, the unavoid-
able errors of determination are decreased by its use.

Since a 17.6 cc. pipette is found in creameries and
dairies with the Babcock test outfit, no new apparatus is
necessary for making the acidity test in the manner
given.

140. The preparation of the standard solution is as
follows: Five tablets are placed in the 100 cc. cylinder
which is filled to the 97 cc. mark with, clean soft water.2
The cylinder is tightly corked, shaken and laid on its
side, as the tablets dissolve more quickly when the cyl-
inder is placed in this position than when left upright
with the tablets at the bottom. Several cylinders con-
taining the tablet solution may be prepared at a time;
as scon as one is emptied, tablets and water are again
added, and the cylinder is corked and placed in a hori-
zontal position. In this way fresh solutions ready for
testing are always at hand. The cylinder is kept tightly
corked while the tablets are dissolving, so that none of

1 Illinois experiment station, bulletin 32; Wisconsin experiment
station, bulletin 52.

2 Condensed steam or rain water should be used, and not hard or
alkali water, since the impurities in these affect the strength of the
tablet solution.

126 Testing Milk and Its Products.

the liquid is lost by the shaking. It is well to put the
tablets in the cylinder with water at night; the solution
will then be ready for use in the morning. Excepting
a flocculent residue of inert matter, " settlings/7 which
will not dissolve, the tablets must all disappear in the
solution before this is used. The strength of the tablet
solution does not change perceptibly by standing, at
least for one week. The only precaution necessary is
to avoid evaporation of the solution by keeping the cyl-
inders tightly corked. The solid tablets will not change
if kept dry, any more than dry salt changes by age.

141. Accuracy of the tablets. The tablets have been
repeatedly tested by chemists and found to be accurate
and very uniform in composition. Tests made with the
tablets according to the directions here given can there-
fore be relied on as correct. The alkali solution is very
sensitive, however, and should not be measured in a cyl-
inder which has been previously used for measuring
sulfuric acid, as the smallest drop or film of acid from
a dish or from the operator's fingers will change the
standard strength of the tablet solution. Of late pow-
dered sodium carbonate weighed out exactly in the
quantity required for making a gallon of tenth normal
solution has been placed on the market; these "test pow-
ders " are cheaper than alkaline tablets and when put
out by a reliable firm are equally accurate as these.

142. Making the test. The cream to be tested is
thoroughly mixed, and 17.6 cc. are measured into the
cup. The pipette is rinsed once with water, and the
rinsings added to the cream in the cup. A few cc. of
the tablet solution prepared as given above are now

Testing the Acidity of Milk and Cream. 127

poured from the cylinder into the cream and mixed
thoroughly with it by giving the cup a gentle rotary
motion. The tablet solution is added in small quanti-
ties until a permanent pink color appears in the sam-
ple. The number of cc. of tablet solution which has
been used to color the cream is now read off on the
scale of the cylinder.

In comparing the results of one test with another, the
same shade of color should always be adopted.1 The
most delicate point is the first change from pure white
or cream color to a uniform pink which the sample
shows when the acid contained therein has been neu-
tralized. This shade of color is easily recognized with
a little practice. The pink color is 'not permanent un-
less a large excess of the alkaline solution has been
added, on account of the influence of the carbonic acid
of the air (132), and the operator should not therefore
be led to believe by the reappearance of the white color
after a time, that the point of neutralization was not
already reached when the first uniform shade of pink
was observed.

143. Acidity of cream. 17.6 cc. of sweet cream is
generally neutralized by 15 to 20 cc. of this tablet solu-
tion, representing from .15 to .20 per cent, of acid. A
mildly sour cream is colored by 35 cc. tablet solution, and
a sour cream ready for churning by about 50 to 60 cc.

1 A helpful suggestion has been made by the Danish State Dairy In-
structor, Dr. G. Ellbrecht, for obtaining a uniform color in all acidity
tests. Strips of pink paper are attached to the cup or glass in which
the titration is made, and alkali solution is added, until the color of the
milk or cream corresponds to that of the strips.

128 Testing Milk and Its Products.

tablet solution. As the cream ripens, its acidity in-
creases. The rate of ripening depends largely on the
temperature at which the cream is kept. Cream con-
taining .5 to .6 per cent, of acid will make such butter
as our American market demands at the present time.
Cream showing an acid test of .55 per cent, may not be
too sour, but .65 per cent, of acid is very near, if not
on the danger line, since such cream is likely to make
strong flavored, almost rancid butter. Each lot of cream
should be tested as soon as it is ready for ripening, and
the result of the test will show whether the cream should
be warmed or cooled in order to have it ready for churn-
ing at the time desired. Later tests will show the rate
at which the ripening is progressing, and the time when
the cream has reached the proper acidity for churning.
144. The influence of the richness of cream on the
acid test has been studied by Professor Spillman,1 and
others.2 Since the acidity develops in the cream serum,
it follows that an acidity of, say .5 per cent, in a 40
per cent, cream represents a larger acidity than in 20
per cent, of cream, e. g. ; in the former case we have .5
gram of acid in 60 grams of serum (=.83 per cent, of
the serum) ; in the latter case .5 gram acid is found in
80 grams serum (=.63 per cent, of the serum). There-
fore, rich cream need not be ripened to as high a degree
of acidity as thin cream. A table is given in the Iowa
bulletin referred to, showing the relation between the
richness and the acidity of cream.

1 Washington experiment station, bulletin :$!?.

2 Chicago Dairy Produce, April '21, 1(.KX), p. 80; Town <>.\pt. stn., bull. 5*2.

Testing the Acidity of Milk and Cream. 129

(45. Spillman's cylinder. The graduated cylinder shown in
fig. 43 was devised by Professor Spillman for use in testing the
acidity of milk and cream with Farrington's alkaline tablets.
The following directions are given for making
tests with this piece of apparatus:1

"All that is needed in addition to the acid-test
graduate shown in the accompanying illustration,
is a common prescription bottle of six or eight
ounce capacity, and a package of Farrington's
alkaline tablets. Fill the bottle with water and
add one tablet for each ounce of water in the
bottle. Shake the bottle frequently to aid in dis-
solving, the tablets.

"Making the test. In making the test, the
acid-test graduate is filled to the zero mark with
the milk or cream to be tested. The tablet solu-
tion is then added, a little at a time, and the
graduate shaken after each addition, in order to
t thoroughly mix the milk and the tablet solution.

In snaking the graduate, give it a rotary motion
FIG. 43. Spill- . .,,. „ .. ,. .» • , Vi

man's cylinder, to prevent spilling any of the liquid. Continue

mfifln^theaclci- adding tne tablet solution until a permanent pink
ity of cream or color can be detected in the milk. The level of
the liquid in the graduate, measured by the scale
on the graduate, will then show the per cent, of the acidity of the
milk. It is best to stand the graduate on a piece of white paper,
so that the first pink coloration of the milk may be easily de-
tected. ' '

146. The Marschall acid test (see fig. 44) is a con-
venient apparatus for determining the acidity of milk,
cream, or whey.2 It is used with tenth-normal alkaline
solution ("Nentralizer"), 9 cc. of milk, cream, etc.,
being measured out for the test, and alkali solution
added from the combined burette and bottle, the former
being graduated to two-tenths of one cc. With the

1 Washington experiment station, bulletin 24.

2 See Wis. exp. sta. bull. 129.

130 Testing Milk and Its Products.

quantity of milk given, the readings obtained represent
per cent, of acidity direct.

147. Rapid estimation of the acidity of apparently
sweet milk or cream, a, Milk. The alkaline tablet
method offers a ready means of estimating the acidity
of milk or cream that
is still sweet to the
taste. The selection of
the best kinds of milk
is especially important
in pasteurizing milk
or cream. As pre-
viously noted, milk
which gives the high-
est acid test contains,
as a rule, a larger
number of bacteria
and spores not de-
stroyed by pasteuriza-
tion than does milk
giving a low acid test
(129) ; the acidity test
may therefore be used

to advantage for the FIG" 44' T^ Mamchaii add test,
purpose of selecting milk best adapted for pasteuriza-
tion, as well as such as is to be retailed or used in the
manufacture of high-grade butter and cheese.

In distinguishing milk fit for pasteurization purposes
from that which is doubtful, an arbitrary standard of
two-tenths of one per cent, of acid may be taken as the

Testing the Acidity of Milk and Cream. 131

upper limit for milk of the former kind. The appara-
tus used in making this test is shown in the accompany-
ing illustration (fig. 45), and consists of a white tea-
cup; a four-, six-, or eight-ounce bottle, and a No. 10
brass cartridge shell, or a similar measure. A solution
of the tablets in water is first prepared, one tablet being
always added to each ounce of water: four tablets in a

k "Measure

FIG. 45. Apparatus used for rapid estimation of the acidity of ap-
parently sweet milk or cream.

four-ounce bottle; six, in a six-ounce bottle, etc., the
amount of tablet solution prepared depending on the
number of tests to be made at a time. The bottle is filled
up to its neck with clean, soft water, and the solution
prepared in the manner previously given (140).

148. Operating the test. As each lot of milk is
brought to the creamery in the morning and poured into
the weigh can, a cartridge-shell dipper is filled with

132 Testing Milk and Its Products.

milk and this is poured into the white cup. The same or
another No. 10 shell is now filled twice with the the tab-
let solution and emptied into the milk in the cup. In-
stead of dipping twice with one measure or a No. 10
shell, a tin measure can be made holding as much as two
No. 10 shells, or the tablet solution may be made of
double strength ; that is, two tablets to each ounce of
water and the same sized measure used for both the milk
and the tablet solution. The liquids are then mixed in
the cup by giving this a quick, rotary motion, and the
color of the mixture noticed. If the milk remains white
it contains more than two-tenths of one per cent, of acid
and should not be used for pasteurization. If it is col-
ored after having been thoroughly mixed with two
measures of tablet solution, it contains less than this
amount of acid and may, as far as acidity goes, be safely
used for pasteurization or for any other purpose which
requires thoroughly sweet milk. The shade of color ob-
tained will vary with different lots of milk; the sweet-
est milk will be most highly colored, but a milk retain-
ing even a faint pink color with two measures of tablet
solution, or one measure of the double strength solution
to one measure of milk, contains less than .2 per cent,
of acid.

By proceeding in the manner described, the man re-
ceiving and inspecting the milk at the factory weigh-can *
is able to test the acidity of the milk delivered nearly as
quickly as he can weigh it ; and according to the results
of the test he can send the milk to the general delivery
vat or to the pasteurization vat, as the weigh-can may
be provided with two conductor spouts.

Testing the Purity of Milk. 133

149. Size of measure necessary. It is not necessary
to use a No. 10 shell for a measure in working the pre-
ceding method; one of any convenient size that can be
filled accurately and quickly, will answer the purpose
equally well, if a measure of the same size is used for
both the sample and the tablet solution. Each measure-
ful of tablet solution made up as directed, will in this
case represent one-tenth per cent, of acid in the sam-
ple tested.1

150. b, Cream. Cream can be tested in the way al-
ready described for testing the acidity of fresh milk, by
adding to one measureful of cream in the cup as many
measures of tablet solution as are necessary to change
the color of the cream when the two liquids are thor-
oughly mixed. If one measure of tablet solution colors
one measure of cream, this contains less than .1 per
cent, acid; if five measures of tablet solution are re-
quired, the cream contains about .5 per cent, acid, etc.
By proceeding in the manner described, the operator
can estimate the acidity to within .05 per cent, of acid,
if half measures of tablet solution are added. The re-
sults thus obtained are sufficiently delicate for all prac-
tical purposes.

151. Detection of boracic-acid preservatives in milk. The

application of the alkaline tablet test for detecting boracic acid in
milk was first discussed in bulletin No. 52 of Wisconsin experi-
ment station. The acidity of the milk is increased by the addi-
tion of boracic acid, but neither the odor nor the taste of the
milk is affected thereby. By adding to sweet milk the amount

1 In European creameries and city milk depots the alcohol test is
often applied to every can of milk received; milk that is sufficiently
sour to be noticed by the taste, will coagulate when mixed with an
equal volume of 70% alcohol.

134 Testing Milk and Its Products.

of boracic acid which will keep it sweet 36 hours, its acidity may
be increased to .35 per cent., in a sample of milk which pre-
viously tested perhaps only .15 per cent. acid.

As before stated, unadulterated milk will usually smell or
taste sour or " turned, " when it contains .30-. 35 per cent, acid
(121) • milk testing as high as this limit, which neither smells
nor tastes sour in any way, is therefore in all probability adul-
terated with some preparation containing boracic acid or a simi-
lar compound.

152. "Alkaline tabs." These are not the alkaline tablets,
but a substitute which was put on the market by a New York
firm. The outfit furnished consisted of four packages of paper
discs made of filter paper, each of about the size of an old-style
copper cent; two packages of square paper; one glass of about
10 cc. capacity, and one small glass bottle. An investigation of
these "Tabs" soon disclosed the fact that they were entirely
inaccurate, and that no dependence could therefore be placed on
the results obtained by their use.

Questions.

1. What is the meaning of a one-tenth normal alkali solu-
tion?

2. How are the results expressed in testing cream by the
Manns7 test?

3. What per cent, acidity is indicated by 35 cc. & alkali?

4. If 20 cc. cream require 12 cc. *T*J alkali for neutralization,
what per cent, acid in the sample?

5. If 1 cc. NJ alkali neutralize .009 gram lactic acid, what is
the per cent, of acid in a sample of cream, which required 12 cc.
alkali for 25 cc. of cream?

6. What apparatus and strength of solution must be taken
to show per cent, acidity directly from cc. alkali used with Far-
rington's alkaline tablets?

7. If cream testing 20% fat has an acidity of .6%, what will
be the corresponding acidity of cream testing 40% fat?

8. Describe the rapid method of testing acidity of samples of
milk or cream by the alkaline tablet solution.

9. What is the per cent, acidity in a sample that requires
2 oz. of standard tablet solution to give a pink color in 1 oz. of
milk?

CHAPTER VIII.
TESTING THE PURITY OF MILK.

153. The Wisconsin curd test. Cheese makers are
often troubled with so-called floating or gassy curds
which produce cheese defective in flavor and texture.
These faults are usually caused by some particular lot
of milk containing impurities that cannot be detected
by ordinary means of inspection. The Wisconsin curd
test is used to detect the source of these defects and
thus enable the cheese maker to exclude the milk from
the particular farm or cow to which the trouble is
traced. This test is similar in principle to tests that
have for many years past been in use in cheese-making
districts in Europe, notably in Switzerland,1 but was
worked out independently at the Wisconsin Dairy
School in 1895 and is now generally known as the "Wis-
consin Curd Test."2

154. Method of making the test. Pint glass jars,
thoroughly cleaned and sterilized with live steam, are
provided; they are plainly numbered or tagged, one
jar being provided for each lot of milk to be tested. The
jars are filled about two-thirds full with milk from the
various sources; it is not necessary to take an exact

* Herz, Unters. d. Kuhmilch, Berlin, 1889, p. 87; Slats, Unters.
landw. wicht. Stoffe, 1903, p. 140.

2 Wisconsin experiment station, twelfth report, p. 148. The appar-
atus used for the test was greatly improved in 1898, and a description
of the improved test is given in bulletin No. 67 and the annual report
of the Station for 1898 (fifteenth report, p. 47-53), from which source the
accompanying illustration is taken (see fig. 46).

136

Testing Milk and Its Products.

quantity; they are then placed in a water tank, the
water of which is he'ated until the milk in the jars has
a temperature of 98° F. In transferring the thermom-
eter used from one jar to another, special care must be
taken to clean it each time in order to prevent contami-
nation of pure lots of milk by impure ones.

When the milk has reached a temperature of 98°,
add to each sample ten drops of rennet extract, and mix
by giving the jar a rotary motion. The milk is thus
curdled, and the curd allowed to stand for about twenty

FIG. 46. Gross-section of the Wisconsin curd test. T J-TJ", testing
jars showing different stages of test ; WL, water line ; M, milk ; F, frame ;
WS, stand to support cover; AI, drain holes; WO, water outlet; hi'-
drain pail.

minutes until it is firm. It is then cut fine with a case
knife, and stirred at intervals for one-half to three-
quarters of an hour sufficiently to keep the curd from
matting under the whey. When the cubes are quite firm
the whey is poured off and the curd left to mat at the
bottom of the bottles if the old form of apparatus is
used. The best tests are made when the separation of
the whey is most complete. By allowing the samples to
stand for a short time, more whey can be poured off,
and the curd thereby rendered firmer. The water around
the jars is kept at a temperature of 98°, the vat is cov-
ered, and the curds allowed to ferment in the sample
jars for six to twelve hours.

Testing the

During this time the
sample will cause gases to be develop 6(1 ill tluTcurds so
that by examining these, by smelling of them and cut-
ting them with a sharp knife, those having a bad flavor,
or a spongy or in any way abnormal texture may be
easily detected, and thus traced to the milk causing the
trouble.

Since the curd test was first described, several modi-
fications have been made in the apparatus. In one of
these the bottles are held in a covered metal frame so
that all of them can be drained at once by inverting the
frame.

155. By proceeding in the way described with the
milk from the different cows in a herd, the mixed milk
of which produced abnormal curds, the source of con-
tamination in the herd may be located. Very often the
trouble will be found to come from the cows' drinking
foul stagnant water or from fermenting matter in the
stable. In the former case the pond or marsh must be
fenced off, or the cows kept away from it in other ways ;
in the latter, a thorough cleaning and disinfection of
the premises are required. If the milk of a single cow
is the source of contamination, it must be kept by itself,
until the milk is again normal; under such conditions
the milk from the healthy cows may, of course, safely
be sent to the factory.

156. The fermentation test. The Gerber fermentation
test (see fig. 47) also furnishes a convenient method for
examining the purity of different lots of milk. The test consists
of a tin tank which can be heated by means of a small lamp,

138

Testing Milk and Its Products.

and into which a rack fits, holding a certain number of cylin-
drical glass tubes; these are all numbered and provided with a
mark and a tin cover.
In making the test, the
tubes are filled to the
mark with milk, the num-
ber of each tube being
recorded in a note book,
opposite the name of the
particular patron whose
milk was placed therein.
The tubes in the rack are
put in the tank, which is
two-thirds full of water; FlG- 47- The Gerber fermentation test,
the temperature of the water is kept at 104-106° F., for
six hours, when the rack is taken out, the tubes gently shaken,
and the appearance of the milk, its odor, taste, etc., carefully
noted in each case.

The tubes are then again heated in the tank at the same tem-
perature as before, for another six hours, when observations of
the appearence of the milk in each tube are once more taken. The
tainted milk may then easily be discovered by the abnormal
coagulation of the sample. According to Gerber,1 good and prop-
erly handled milk should not coagulate in less than twelve hours,
when kept under the conditions described, nor show anything
abnormal when coagulated. Milk from sick cows and from cows
in heat, or with diseased udders, will always coagulate in less
than twelve hours. If the milk does not curdle within a day or
two, it should be tested for preservatives (299).

157. The Monrad rennet test is used by cheese mak-
ers for determining the ripeness of milk. Fig. 48 shows
the apparatus used in the test. 5 cc. of rennet extract
is measured into a 50 cc. flask by means of a pipette;
the pipette is rinsed with water, and the flask filled to
the mark with water. 160 cc. of milk is now measured
into the tin basin from the cylinder and slowly heated
to exactly 86° F. 5 cc. of the dilute rennet solution is

Die praktische Milchpriifung, p. 85.

Testing the Purity of Milk.

139

quickly added to the warm milk and the time
rfequired for coagulation
noted.1 Milk sufficiently ripe
for cheddar cheese making
will coagulate in 30 to 60
seconds, according to the
strength of the rennet ex-
tract used.

158. The Marschall ren-
net test is used for the same
purpose as the Monrad test.
The directions for this test
are as follows : Fill the small
glass with pure water to
the mark, pour into it one
cc. of rennet extract and
rinse the pipette in the same

FIG. 48. The Monrad rennet test. water< Fm ^ cup ^^

•milk to the zero mark, add the rennet, mix thoroughly
and allow it to stand. The sweeter the milk is, the
longer it will take to
coagulate, and the more
milk will run out of the
cup before the point of
coagulation is reached,
when the flow of milk
will cease. The time re-
quired for coagulating tj
the milk is shown di- ^

rectly by a Scale On the FIG- 49- Tne Marsphall rennet test.

inside wall of the cup (see fig. 49).

1 Decker, Cheese Making, 1900, p. 36.

CHAPTER IX.
TESTING MILK ON THE FARM.

159. Variations in milk of single cows. The varia-
tions in the tests of milk of single cows from milking to
milking or from day to day, are greater than many
cow-owners suspect. There seems to be no uniformity
in this variation, except that the quality of the milk
produced generally improves with the progress of .the
period of lactation; even this may not be noticeable,
however, except when the averages of a number of tests
made at different stages during the lactation period are
compared with each other. When a cow gives her maxi-
mum quantity of milk, shortly after calving, the qual-
ity of her milk is generally poorer (by one per cent, of
fat or less) than when she is drying off. Strippers'
milk is therefore, as a rule, richer in fat than the milk
of fresh cows.

160. By testing separately every milking of a number
of cows through their whole period of lactation, the
results obtained have seemed to warrant the following
conclusions in regard to the variations in the test of tbo
milk from single cows, and it is believed that these con-
clusions allow of generalization.1

1. Some cows yield milk that tests about the same at
every milking, and generally give a uniform (jiinntity
of milk from day to day.

1 Illinois experiment station, bulletin sM.

Testing Milk on the Farm. 141

2. Other cows give milk that varies in an unexplain-
able way from one milking to another. Neither the
morning nor the evening milking is always the richer,
and even if the interval between the two milkings is
exactly the same, the quality as well as the quantity of
milk produced will vary considerably. Such cows are
generally of a nervous, excitable temperament, and are
easily affected by changes in feed, drink, or surround-
ing conditions.

3. The milk of a sick cow, or of a cow in heat, as a
rule, tests higher than when the cow is in normal con-
dition; the milk yield generally decreases under such
conditions; marked exceptions to this rule have, how-
ever, been observed.

4. Half-starved or underfed cows may give a small
yield of milk testing higher than when the cows are
properly nourished, probably on account of an accom-
panying feverish condition of the animal. The milk is,
however, more generally of an abnormally low fat con-
tent, which may be readily increased to the normal per
cent, of fat by liberal feeding.

5. Fat is the most variable constituent of milk, while
the solids not fat vary within comparatively narrow
limits. The summary of the analyses of more than 2400
samples of American milk calculated by Cooke1 shows
that while the fat content varies from 3.07 to 6.00 per
cent., that of casein and albumen varies only from 2.92
to 4.30 per cent., or less than one and one-half per cent.,

1 Vermont experiment station, report for 1890, p. 97.

142 Testing Milk and Its Products.

and the milk sugar and ash content increases but little
(about .69 per cent.) within the range given.

6. A test of only one milking may give a very erro-
neous impression of the average quality of a certain
cow's milk. A composite sample (see 179) taken from
four or more successive milkings will represent the
average quality of the milk which a cow produces at
the time of sampling.

161. The variations that may occur in testing the
milk of single cows, are illustrated by the following fig-
ures obtained in an experiment made at the Illinois ex-
periment station,1 in which the milk of each of six cows
was weighed and analyzed daily during the whole period
of lactation. Among the cows were pure-bred Jerseys,
Shorthorns and Holsteins, the cows being from three to
eight years of age and varying in weight from 850 to
1350 Ibs. During a period of two months of the year,
the cows were fed a heavy grain ration consisting of
twelve Ibs. of corn and cob meal, six Ibs. of wheat bran,
and six Ibs. of linseed meal, per day per head. This sys-
tem of feeding was tried for the purpose of increasing,
if possible, the richness of the milk. The influence of this
heavy grain feed, as well as that of the first pasture
grass feed, on the quality and the quantity of the milk
produced is shown in the following table, which gives
the complete average data for one of the cows (No. 3).
The records of the other cows are given in the publica-
tion referred to ; they were similar to the one here given
in so far as variations in quality are concerned.

1 Bulletin 24.

Testing Milk on the Farm.

143

Average results obtained in weighing and testing a cow's
milk daily during one period of lactation.

MONTH

3S
P

Daily milk
yield

Test of one day's
milk

Yield of fat per
day

8 «J

16.0
17.7
17.7
16.0
16.5
17.2
14.0
12.2
9.3

o>"o

is'
°l

<t>

1 .

.34

.44
.51

.50
.46
.44
.35

.27
.16

December. .
January ....
February. ..
March
April .

920
927
1035
1047
1054
1079
1105
1180
1130

12.1
16.0
16.1
14.3
13.8
14.5
12.1
9.3
6.4

10.0
14.0
13.5
12.5
11.5
10.0
9.2
6.0
3.5

3.8
3.7
3.6
3.8
4.0
3.8
3.9
4.2
4.7

4.9
4.6

5.8
4.7
5.8
4.6
4.6
6 2
7.9

3.0

2.7
3.2
3.4
3.0
3.4
3.2
2.8
2.9

.46
.59
.58
.54
.55
.55
.47
.39
.30

.60
.76

.84
.61
.72

157
.60
.50

May
June
July.

August

162. The average test of this cow's milk for her whole
period of lactation was 3.8 per cent, of fat (i. e., the
total quantity of fat produced -4- total milk yield X
100) ; twice during this time the milk of the cow tested
as high as 5.8 per cent., and once as low as 2.7 per cent.
The average weight of milk produced per day by the
cow was 14 Ibs. ; this multiplied by her average test,
3.8, shows that she produced on the average .53 lb., or
about one-half of a pound, of butter fat per day during
her lactation period. If, however, her butter-producing
capacity had been judged by the test of her milk for
one day only, this test might have been made either on
the day when her milk tested 5.8 per cent., or when it
was as low as 2.7 per cent. Both of these tests were
made in mid-winter when the cow gave about 16 Ibs. of
milk a day. Multiplying this quantity by .058 gives .93
lb. of fat, and by .027 gives .43 lb. of fat. Either

144 Testing Milk and Its Products.

result would show the butter fat produced by the cow on
certain days, but neither gives a correct record of her
actual average daily performance for this lactation
period.

A sufficient number and variety of tests of the milk
of many cows have been made to prove that there is
no definite regularity in the daily variations in the
richness of the milk of single cows. The only change in
the quality of milk common to all cows is, as stated,
the natural increase in fat content as the cows are dry-
ing off, and even in this case the improvement in the
quality of the milk sometimes does not occur until the
milk yield has dwindled down very materially.

163. Causes of variations in fat content. The qual-
ity of a cow's milk is, as a rule, decidedly influenced by
the following conditions:

Length of interval between milkings.

Change cf feed.

Change of milkers.

Rapidity of milking.

Exposure to rain or bad weather.

Rough treatment.

Unusual excitement or sickness.

164. Disturbances like those enumerated frequently
increase the richness of the milk for one, and some-
times for several milkings, but a decrease in quality fol-
lows during the gradual return to normal conditions,
and taken as a whole there is a considerable falling off
in the total production of milk and butter fat by the
cow, on account of the nervous excitement which she
has gone through. Aside from changes due to well-

Testing Milk on the Farm. 145

definable causes like those given above, the quality of
some cows' milk will often change considerably without
any apparent cause. The dairyman who is in the habit
of making tests of the milk of his individual cows at
regular intervals will have abundant material for study
in the results obtained, and he will soon be able to tell
from the tests made, if these are continued for several
days, whether or not the cows are in a normal healthy
condition or have been subjected to excitement or abuse
in any way.

165. Number of tests required during a period of
lactation in testing cows. The daily records of the
six cows referred to on page 142 furnish data for com-
paring their total production of milk and butter fat dur-
ing one period of lactation, as found from the daily
weights and tests of their milk, with the total amount
calculated from weights and tests made at intervals of
7, 10, 15 or 30 days. The averages of all results ob-
tained with each of the six cows show that weighing and
testing the milk of a cow every seventh day gave 98 per
cent, of the total milk and butter fat, which according
to her daily record was the total product. Tests made
once in two weeks gave 97.6 per cent, of the total milk,
and 98.5 per cent, of the total butter fat, and tests made
once a month, or only ten times during the period of
lactation, gave 96.4 per cent, of the total milk, and 97
per cent, of the total production of butter fat.

166. The record of one of the cows will show how
these calculations are made: It was found from the
daily weights and tests that cow No. 1, in one lactation

period of 307 days, gave 5,044 Ibs. of milk which con-
10

146

Testing Milk and Its Products.

tained 254 Ibs. of butter fat. Selecting every thirtieth
day of her record as testing day, the total production of
milk and fat is shown to be as follows:

Production of milk and butter fat per day.

Testing day

Weight of Milk

Test of Milk"

Yield of butter fat

Nov. 4

R>8.

20 5

per cent.

4 7

Ibs.
96

Dec. 4

18 7

4 6

Jan. 3

17.7

4 9

Feb. 2

20.0

4 5

Mar. 3

18 2

4 7

April 2

19 5

4 4

May 2

17.7

4 8

June 1

13.1

5 5

July 1

12.2

6.2

July 31 . .

3 2

7 2

Total

160.8 Ibs.

7 81 Ibs.

Average per day.

16.08 Ibs.

4.85

.78 ft).

The average daily production of the cow, according
to the figures given in the preceding table, was about
16 Ibs. of milk, containing .78 Ib. of butter fat. Multi-
plying these figures by 307, the number of days during
which the cow was milked, gives 4,912 Ibs. of milk and
240 Ibs. of fat. This is 132 Ibs. of milk and 14 Ibs. of
fat less than the total weights of milk and butter fat, as
found by the daily weights and tests, or 2.8 and 5.5 per
cent, less, for milk- and fat production, respectively.
This is, however, calculated from only ten single weights
and tests, while it required over 600 weighings and 300
tests of the milk to obtain the exact amount.

Similar calculations from the records of the other
cows gave fully as close results, showing that quite sat-

Testing Milk on the Farm. 147

is factory data as to the total production of milk and
butter fat of a cow may be obtained by making correct
weighings and tests of her full day's milk once every
thirty days.

167. When to test a cow. The Vermont experi-
ment station for several years made a special study of
the question when a cow should be tested in order to
give a correct idea of the whole year's production, when
only one or two tests are to be made during the lacta-
tion period.1 The results obtained may be briefly sum-
marized as follows:

a. As to quality of milk produced. If two tests of
each cow ?s milk are to be made during the same lacta-
tion period, it is recommended to take composite sam-
ples at the intervals given below.

KIKST S A MPLS

SEC'' N 1AX t'LK

For spring

For summer • '
For fall "

ks after calving

0 41 44 <(

8-10"

6J-71 mos. after calving
6-7
5J-7 •' " "

If only one test is to be made, approximately correct
- Its may be obtained by testing the milk during the
h month from calving, in case of spring cows ; dur-
ing the third to fifth month in case of summer-calving
3, and during the fifth to seventh month for fall-
calving cows.

In all cases composite samples of the milk for at least
four days should be taken (169). "The test of a single
sample, drawn from a single milking or day, will not of
necessity, or indeed usually, give trustworthy results."

1 Sixth report, 1S81>. p. lOtf: Ninth report. 1886, p. 17&

148 Testing Milk and Its Products.

b. As to quantity of milk produced. The milk may
be weighed for four days in the middle of the month,
and the entire month's yield obtained with considerable
accuracy (barring sickness and drying off),
by multiplying the sum by 7, iy2 or 7%,
according to the number of days in the dif-
ferent months. The weighing is most read-
ily done by means of a spring balance, the
hand of which is set back so that the empty
pail brings it to zero (fig. 50). If several
pails are to be used, they should first be
made to weigh the same by putting a little
solder on the lighter pails. Milk scales
which weigh and automatically register the
yield of milk from twenty cows have been
placed on the market, but so far as known
FlG'ScaieMllk have not proved satisfactory.1

168. Sampling milk of single cows. In sampling
the milk, of single cows, all the milk obtained at the
milking must be carefully mixed, by pouring it from
one vessel to another a few times, or stirring it thor-
oughly by means of a dipper moved up and down, as
well as horizontally, in the pail or can in which it is
held; a sample for testing purposes is then taken at
once. A correct sample of a cow's milk cannot be ob-
tained by milking directly into a small bottle from one

1 The various state experiment stations now conduct official /r.v/.v of
dairy cows for breeders and dairy fiirmors, by which the production of
milk and butter fat by cows is determined accurately by representa-
tives of the stations. Information concerning these tests may be had
by writing to the director of the nearest experiment station.

Testing Mttk on the Farm. 149

teat, or by filling the bottle with a little milk from each
teat, or by taking some of the first, middle and last milk
drawn from the udder. Such samples cannot possibly
represent the average quality of the milk of one entire
milking, since there is as much difference between the
first and the last portions of a milking, as between milk
and cream.1 Lack of care in taking a fair sample is
the cause of many surprising results obtained in testing
the milk of single cows.

169. Composite samples. When a cow is to be tested,
she should be milked dry the last milking previous to
the day when the test is to be made. The entire quan-
tity of milk obtained at each milking is mixed and
sampled separately. On account of the variation in the
composition of the milk, a number of tests of successive
milkings must be made. As this involves considerable
labor, the plan of taking composite samples is prefer-
able; the method of composite sampling and testing is
explained in detail under the second subdivision of
Chapter X (180) ; suffice it here to say that the method
followed in the case of single cow's or herd milk is to
take about an ounce of the thoroughly mixed milk of
each milking; this is placed in a pint or quart glass jar
containing a small quantity of some preservative, prefer-
ably about one-half a gram (8 grains) of powdered
potassium bi-chromate. If a number of composite sam-
ples of the milk of single cows are taken, each jar should
be labeled with the number or name of the particular

1 Woll, Handbook for Farmers and Dairymen, p. 249; Agricultural
Science, 6, pp. 540-42.

150 Testing Milk and Its Products.

cow. Composite tests are generally taken for four days
or for a week. If continued for a week, the jars will
contain at the end of this time a mixture of the milk
of fourteen milkings. The composite sample is then
carefully mixed by pouring it gently a few times from
one jar to another, and is tested in the ordinary man-
ner. The result of this test shows the average quality
of the milk produced by the cow during the time the
milk was sampled.

As the amounts as well as the quality of the milk pro-
duced by single cows vary somewhat from day to day
and from milking to milking, it is desirable in testing
single cows, especially when the test includes only a few
days, to take a proportionate part (an aliquot) of each
milking for the composite test sample. This is easily
done by means of a Scovell sampling tube, the use of
which is explained in another place (183), or by a 25 cc.
pipette divided into -fa cc. ; in using the latter appara-
tus as many cubic centimeters and tenths of a cubic
centimeter of milk are conveniently taken each time for
the composite sample as the weight of milk in pounds
and tenths of a pound produced by the cow.1

170. The opinion is sometimes expressed that a con-
siderable error is introduced by measuring out milk
warm from the cow for the Babcock test, since milk ex-
pands on being warmed, and a too small quantity is
obtained in this manner. By calculation of the expan-
sion of milk between different temperatures it is found
that 1 cc. of milk at 17.5° C. (room temperature) will

i Decker, Wls. experiment station, report XVI, 155.

Testing Milk on the Farm. 151

have a volume of 1.006289 cc. at 37° C. (blood-heat),
i. e., an error of less than .03 per cent, is introduced by
measuring out milk of ordinary quality at the latter
temperature. While the temperature has therefore prac-
tically no importance, the air incorporated in the milk
during the milking process will introduce an appreci-
able error in the testing, and samples of milk should
therefore be left for an hour or more after milking be-
fore the milk is measured into the test bottles. By this
time the specific gravity of the samples can also be cor-
rectly determined (113).

171. Size of the testing sample. Four ounces is a
sufficient quantity for a sample of milk if it is desired
to determine its per cent, of fat only ; if the milk is to
be tested with a lactometer, when adulteration is sus-
pected, a pint sample is needed. If this sample of milk
is put into a bottle and carried or sent away from the
farm to be tested, the bottle should be filled with milk
clear up to the neck to prevent a partial churning of
butter in the sample during transportation (30).

172. Variations in herd milk. While considerable
variations in the quality of the milk of single cows are
often met with, a mixture of the milk of several cows,
or of a whole herd, is comparatively uniform from day
to day; the individual differences tend to balance each
other so that variations, when they do occur, are less
marked than in case of milk of single cows. There are,
however, at times marked variations also in the test of
herd milk on successive days ; the following figures from
the dairy tests conducted at the World's Columbian Ex-
position in Chicago in 1893 illustrate the correctness of

152

Testing Milk and Its Products.

this statement. The tests included twenty-five Jersey
and Guernesey cows each and twenty-four Shorthorn
cows.

Tests of herd milk on successive days.

DATE

Jersey

Guernsey

Shorthorn

July 16, 1893..

4 8 per cent

4 6 per cent

3 8 per cent

July 17, 1893

5.0

45 "

38 "

July 18, 1893

4.7 "

4.4 "

38 "

Jnly 19, 1893

4.6

July 20, 1893

38 "

On July 17, 1893, the mixed milk of the Jersey cows
tested two-tenths of one per cent, higher than on the
preceding day ; the Guernsey herd milk tested one-tenth
of one per cent, lower, while the Shorthorn milk did not
change in composition; comparing the tests on July 19
and 20, we find that the Jersey and Shorthorn milk
tested four-tenths and one-tenth of one per cent, higher,
respectively, on the latter day than on the former, and
the Guernsey milk tested one-tenth of one per cent,
lower.

173. Ranges in variations of herd milk. According
to Fleischmann,1 the composition of herd milk may on
single days vary from the average values for the year,
expressed in per cent, of the latter, as follows:

The specific gravity (expressed in degrees) may go above or
below the yearly average by more than 10 per cent.

The per cent, of fat may go above or below the yearly aver-
age by more than 30 per cent.

The per cent, of total solids may go above or below the yearly
average by more than 14 per cent.

1 Book of the Dairy, p. 32.'

Testing Milk on the Farm. 153

The per cent, of solids not fat may go above or below the
yearly average by more than 10 per cent.

To illustrate, if the average test of a herd during a whole
period of lactation is 4.0 per cent., the test on a single day may
exceed 4.0+30 X 4.0=5.2, or may go below 2.8 per cent, (viz.,
4.0 — so X4.0) ; if thei average specific gravity is 1.031 (lacto-
meter degrees, 31 )J the specific gravity of the milk on a single
day may vary between 1.0279 and 1.0341 (31+^X31=34.1;
31-^X31=27.9).

174. Influence of heavy grain-feeding on the qual-
ity of milk. If cows are not half-starved or underfed,
an increase in the feeding ration will not materially
change the richness of the milk produced, as has been
shown by numerous careful feeding experiments con-
ducted under a great variety of conditions and in many
countries. Good dairy cows will almost invariably give
more milk when their rations are increased, so long as
they are not overfed, but the milk will remain of about
the same quality after the first few days are passed as
before this time, provided the cows are in good health
and under normal conditions. Any change in the feed
of cows will usually bring about an immediate change
in the fat content of the milk, as a rule increasing it to
some extent, but in the course of a few days, when the
cows have become accustomed to their new feed, the fat
content will again return to its normal amount.

175. The records of the cows included in the feeding
experiment at the Illinois station, to which reference
has been made on p. 142, furnish illustrations as to the
effect of heavy feeding on the quality of milk. The
feed, as well as the milk of the cows, was weighed each
day of the experiment. During the month of December

i See page 101.

154 Testing Milk and Its Products.

each cow was fed a daily ration consisting of 10 Ibs. of
timothy hay, 20 Ibs. of corn silage and 2 Ibs. of oil meal ;
the table on p. 143 shows that cow No. 3 produced on
this feed an average of 12.1 Ibs. of milk, testing 3.8 per
cent, of fat. In January the grain feed was gradually
increased until the ration consisted of 12 Ibs. of timothy
hay, 8 Ibs. of corn and cob meal, 4 Ibs. of wheat bran,
and 4 Ibs. of oil meal. All the cows gained in milk on
this feed ; cow No. 3 thus gave an average of 4 Ibs. more
milk per day in January than in December, but the
average test of her milk was 3.7 per cent., or one-tenth
of one per cent, lower than during the preceding month.
The heavy grain-feeding was continued through Febru-
ary and March, when it reached 12 Ibs. of timothy hay,
12 Ibs. of corn and cob meal, 6 Ibs. of wheat bran and
6 Ibs. of oil meal per day. The records show that the
flow of milk kept up to 16 Ibs. per day in February in
case of this cow, but fell to 14 Ibs. in March and April,
the average test of the milk being, in February 3.6, in
March 3.8, and in April 4.0 per cent. The milk was,
therefore, somewhat richer in April than in December,
but not more so than is found normally, owing to the
progress of the period of lactation.

176. Influence of pasture on the quality of milk.
On May 1, the cows were given luxuriant pasture feed
and no grain ; a slight increase in the average amount of
milk produced per day followed, with a reduction in
the test, this being 3.8 per cent., the same as in De-
cember.

During all these changes of feed there was, therefore,
not much change in the richness of the milk, while the

Testing Milk on the Farm. 155

flow of milk was increased by the heavy grain feeding
for several months, as well as by the change from grain-
feeding in the barn to pasture feed with no grain.1 As
a general rule, the test of the milk will be increased by
a few tenths of a per cent, during the first couple of
weeks after the cows have been turned out to pasture
in the spring. The increase is perhaps due as much to
the stimulating influence of out-door life after the con-
finement in the stable during the winter and spring, as
to the change in the feed of the cows. After a brief
period the milk will again change back to its normal fat
content.

177. The increase which has often been observed in
the amount of butter produced by a cow, as a result of
a change in feed, doubtless as a rule comes from the
fact that more, but not richer milk is produced. The
quality of milk which a cow produces is as natural to
her as is the color of her hair and is not materially
changed by any special system of normal feeding.2

* For further data on this point, see Cornell (N. Y.) exp. sta., bulle-
tins 13, 22, 36 and 49; N. D. exp sta., bull. 16; Kansas exp. sta., report,
1888; Hoard's Dairyman, 1896, pp. 924-5, W. Va. exp. sta., b. 109.

2 On this point numerous discussions have in recent years taken
place in the agricultural press of this and foreign countries, and the
subject has been under debate at nearly every gathering of farmers
where feeding problems have been considered. Many farmers are firm
in their belief that butter fat can be "fed into" the milk of a cow, and
would take exception to the conclusion drawn in the preceding. The
results of careful investigations by our best dairy authorities point con-
clusively, however, in the direction stated, and the evidence on this
point is overwhelmingly against the opinion that the fat content of the
milk can be materially and for any length of time increased by changes
in the system of feeding. The most conclusive evidence in this line is
perhaps the Danish co-operative cow-feeding experiments, conducted
during the nineties with over 2,000 cows in all. The conclusion arrived
at by the Copenhagen experiment station, uuder whose supervision the
experiments have been conducted, is: that the changes of feed made in

156 Testing Milk and Its Products.

178. Method of improving the quality of milk.

The quality of the milk produced by a herd can gener-
ally be improved by selection and breeding, i. e., by dis-
posing of the cows giving poor milk, say below 3 per
cent, of fat, and by breeding to a pure-bred bull of a
strain that is known to produce rich milk. This method
cannot work wonders in a day, or even in a year, but it
• is the only certain way we have of improving the qual-
ity of the milk produced by our cows.

It may be well in this connection to call attention to
the fact that the quality of the milk which a cow pro-
duces is only one side of the question; the quantity is
another, and an equally important one. Much less dis-
satisfaction and grumbling about low tests among pat-
rons of creameries and cheese factories would arise if
this fact was more generally kept in mind. A cow giv-
ing 3 per cent, milk should not be condemned because
her milk does not test 5 per cent. ; she may give twice
as much milk per day as a 5 per cent cow, and will
therefore produce considerably more butter fat. The
point whether or not a cow is a persistent milker is also
of primary importance ; a production of 300 Ibs. of but-
ter fat during a whole period of lactation is a rather
high dairy standard, but one reached by many herds,
even as the average for all mature cows in the herd.

the different lots of cows included on the experiments had prm-t it-ally
no influence on the chemical composition (the fat content) of the milk
produced. In these experiments grain feeds were fed against roots,
against oil cake, and against wheat bran or shorts; trnmi ;md oil rak<-
were furthermore fed against roots, and roots wen- yivcn as nn addi-
tional feed to the standard rations tried,— in all cases with prm-t ically
negative results so far as changes in the fat contents of the milk pro-
duced are concerned.

Testing Milk on the Farm. 157

It should be remembered that a high production of but-
ter fat in the course of the whole period of lactation is
of more importance than a very high test.

1. How does the test of the milk yielded by a cow generally
change with the advance of the. period of lactation?

2. Mention at least six causes of variations in the test of a
cow's milk.

3. How is an accurate sample taken of a cow's milk?

4. Between which limits is the test of milk of single cows
and of a herd likely to vary?

5. Will it introduce any error in the! test of a cow's milk to
measure out the sample directly after milking ?If so, how much?

6. How many times should the milk of a cow be weighed and
tested to calculate! the total production of milk and butter fat
by the cow during a whole period of lactation?

7. What is an official test of a cow?

8. How does the test, as a general rule, change during the
first couple of wc^eks after the cows are let out on pasture in the
the spring?

9. How do changes in the feed of a cow influence the quan-
tity and the quality of her milk?

CHAPTER X.

COMPOSITE SAMPLES OF MILK.

179. Shortly after milk testing had been introduced
to some extent in creameries and cheese factories, it was
suggested by Patrick, then of the Iowa experiment sta-
tion,1 that a great saving in labor, without affecting

the accuracy of the
results, could be ob-
tained by testing a
mixture of the daily
samples of milk from
one source, instead of
each one of these
samples. Such a mix-
ture is called a com-
posite sample. The
usual methods of tak-
ing such samples at
creameries and cheese
factories are as fol-
lows:

180. Methods of
taking composite

FIG. 51. Taking test samples at in-take. samples. a. Use of

tin dipper. Either pint or quart fruit jars, or milk bot-
tles provided with a cover, are used for receiving the
daily samples. One of these jars is supplied for each

l Bulletin 9. May 1890.

Composite Samples of Milk. 159

patron of the factory and is labeled with his name or
number. A small quantity of preservative (bi-chromate
of potash, corrosive sublimate, etc., see 190) is added to
each jar; these are placed on shelves or somewhere
within easy reach of the operator who inspects and
weighs the milk as it is received at the factory. When
all the milk delivered by a patron is poured into the
weighing can and weighed, a small portion thereof,
usually about an ounce, is put into the jar labeled with
the name or number of the patron. The samples are
conveniently taken by means of a small tin dipper hold-
ing >about an ounce. This sampling is continued for a
week, ten days, or sometimes two weeks, a portion of
each patron's milk being added to his particular jar
every time he delivers milk. A test of these composite
samples takes the place of separate daily tests and gives
accurate information regarding the average quality of
the milk delivered by each patron during the period of
sampling. The weight of butter fat which each patron
brought to the factory in his milk during this time, is
obtained by multiplying the total weight of milk deliv-
ered during the sampling period by the test of the com-
posite sample, dividing the product by 100.

181. This method of taking composite samples has
been proved to be practically correct. It is absolutely
correct only when the same weight of milk is delivered
daily by the patron. If this is not the case, the size of
the various small samples should bear a definite relation
to the milk delivered; one sixteen-hundredth, or one
two-thousandth of the amount of milk furnished should,
for instance, be taken for the composite sample from

160 Testing Milk and Its Products.

each lot of milk. This can easily be done by means of
special sampling devices (see 182 et seq.). As the quan-
tities of the milk delivered from day to day by each
patron vary but little, perhaps not exceeding 10 per
cent, of the milk delivered, the error introduced by
taking a uniform sample, e. g., an ounce of milk, each
time is, however, small and it may not be necessary to
take cognizance of it in factory work. This method of
composite sampling described is quite generally adopted
in separator creameries and cheese factories, where the
payment for the milk is based on its quality.

In order to obtain reliable results by composite sam-
pling it is essential that each lot of milk sampled shall
be sweet and in good condition, containing no lumps of
curdled milk or butter granules. The milk should of
course always be evenly mixed before the sample is
taken.

182. b. Drip sample. Composite samples are some-
times taken at creameries and cheese factories by col-
lecting in a small dish the milk that, drips through a
fine hole in the bottom of the conductor spout through
which the milk runs from the weighing can to the re-
ceiving vat or tank. A small portion of the drip col-
lected each day is placed in the composite sample jar,
or the quantity of drip is regulated so that all of it
may be taken. In the latter case the quantity of milk
delivered will enter into the composite sampling as well
as its quality and the sample from, say 200 Ibs. of milk,
will be twice as large as the sample from 100 Ibs. of milk.

Where it is desired to vary the size of samples accord-
ing to the quantity of milk delivered from day to day.

Composite Samples of Milk. 161

it is necessary to adopt the method of collecting drip
samples, just explained, or to make use of special sam-
pling devices, like the "milk thief," the Scovell, Equity,
McKay, and Michels sampling tubes.1 The
principle of these tubes is the same, and it will
be sufficient to describe here only a few of them.
183. c. The Scovell sampling tube. This
convenient device for sampling milk2 (fig. 52)
consists of a drawn copper or brass tube, one-
half to one inch in diameter; it is open at both
ends, the lower end sliding snugly in a cap pro-
vided with three elliptical openings at the side,
through which the milk is admitted. The milk
to be sampled is poured into a cylindrical pail,
or the factory weighing can, and the tube, with
the cap set so that the apertures are left open,
is lowered into the milk until it touches the
bottom of the can. The tube will be filled in-
stantly to the level of the milk in the can and
is then pushed down against the bottom of the
can, thereby closing the apertures of the cap
FIG. 52. and confining within the tube a column of milk

SCOVel

milk representing exactly the quality of the milk

sampling

tube, in the can and forming an aliquot part thereof.
The milk in the sampling tube is then emptied into the
composite sample jar by turning the tube upside down.

1 A recent Wisconsin law (Chap. 99, laws of 1907) provides that in
sampling cream or milk from which composite tests arc to be made to
determine the per cent of butter fat therein, no such sampling shall be
lawful, unless a sample be taken from each weighing, and the quantity
thus used shall be proportioned to the total weight of cream or milk
tested.

2 Kentucky experiment station, 8th report, pp. xxvi-xxvii.

162 Testing Milk and Its Products.

184. If the diameter of the sampling pail used is 8
inches, and that of the sampling tube ^ inch, the quan-
tity of milk secured in the tube will always stand in the
ratio to that of the milk in the pail, of (1/2) 2 to 82,1
that is, as 1 to 256, no matter how much or how little
milk there is in the pail, the sample will represent ^6
part of the milk. For composite sampling of the milk
of single cows, this proportion will prove about right;
if more milk is wanted for a sub-sample, dip twice, or
pour the milk to be sampled into a can of smaller diam-
eter. If the mixed milk from a number of cows is to
be sampled, a wider sampling can may be used. By ad-
justing the diameters of the tube and the can, any de-
sired proportion of milk can be obtained in the sample.

For factory sampling, with a weighing can 26 inches
in diameter, a tube three-quarters of an inch in diameter
will be found of proper dimensions.

In using these tubes, the milk or cream must in all
cases be in cylindrical cans when the sample is drawn.

The sampling tube will furnish a correct sample of
the milk in the can, even if this has been left standing
for some time; it is better, however, to take out the
sample soon after the milk has been poured into the can,
as the possible error of cream adhering to the sides of
the sampling tube is then avoided.

185. The accuracy of the sampling of milk by means
of the Scovell tube was proved beyond dispute in the
breed tests conducted at the World's Columbian Expo-
sition in 1893, in which tests this method was adopted

1 The contents of a cylinder are represented by the formula Tfr^h, r
being the radius of the cylinder, and h its height. The relation brtwrei)
two cylinders of the same height, the radii of which are 7\* and r. Is
therefore as 7TR2h to 7Tr2h, or as R2 to r2.

Composite Samples of Milk.

163

for sampling the milk produced by the single cows and
the different herds.1 The data obtained in these breed
tests also furnish abundant proof of the accuracy of the
Babcock test.

186. d. The McKay sampler (fig. 53), constructed by
Professor G-. L. McKay, of Iowa experiment station,

consists of two nickel-plated brass

tubes that telescope one within the

other; both have a milled slot so

made that when

the handles stand

together the slot

is open: by turn-
ing the handles

at right angles

the slot is closed.

The sampler is

made in two

lengths, 21 and

18 inches, and

has been found

very convenient

for sampling
either milk or cream.

i86a. e. Michels' cream-sampling
tube. Pig. 54 shows a section through
a modified Scovell sampler in a tin
heater recently invented by Prof.
John Michels of North Carolina agricultural college.

1 Kentucky experiment station, 8th report, pp. xxx-xxxi. Another
form of a milk sampling tube in use at the Iowa experiment station was
described and illustrated by Mr. Eckles in Breeder's Gazette, May 19,
1897.

FIG. 53. The McKay
sampler.

FIG. 54. Michels'

cream sampling

tube.

164 Testing Milk and Its Products.

This sampler renders possible an accurate and rapid
sampling of any cream, regardless of its richness and
acidity, without stirring the cream. The following is a
description of this sampler, with directions for using it :

A is a steam and hot water reservoir with an inlet at B. The
steam and hot water discharge through a circle of small openings
at D. The condensed steam finds exit at C. E is a Scovell sam-
pler provided with a handle G, and a circular piece of heavy tin
K, which holds the sampler in position and prevents the escape
of steam. F is a strong wire attached to the cap which opens
and closes the sampler. The wire ends at the top in a right
angle turn, H, which rests across the top of the sampler when
the lattei^ is open. The construction of the heater prevents the
entrance of water into the sampler and necessitates the use of
but a very small amount of steam, which is admitted through
the steam hose, I. The latter connects with J leading to the
boiler.

When ready to sample, remove the sampler from the heater,
plunge at once to thei bottom of the can of cream to be sampled,
and remove quickly. While holding the composite sample jar in
the left hand, discharge the contents of the sampler into it by
pressing down on H with the thumb of the hand holding the
sampler. Owing to the heated condition of the sampler, the
cream discharges instantly and, what is equally important, all of
it discharges.

The sampler is pronounced accurate, quick, conven-
ient and simple, and makes the sampling of heavy, rich
cream, or thick, sour cream, no more difficult than that
of milk.

187. f. Composite sampling with a "one-third sample
pipette." Milk is sometimes sampled directly from the weighing
can into the Babcock test bottle by means of a pipette holding
5.87 cc., which is one-third the size of the regular pipetto. This
quantity is measured into the test bottle from three success! vi-
le ts of milk from thei same patron and the test then made in the
ordinary manner. In this way one test shows the average com-
position of the milk delivered during three successive days or,
deliveries. When this method is adopted, as many test bottles

Composite Samples of Milk.

165

are provided as there are patrons; there is no need of using any
preservatives for milk in this case. Fig. 55 shows a convenient
rack for holding the test bottles used in composite sampling with
a * ' one-third sample pipette. ' '

Accurate results can be obtained by this method of sampling,
if care is taken in measuring out the milk, and if it is not frozen
or contains lumps of cream.
It is doubtful if the method
has any advantage over the
usual method of composite
sampling. If milk is deliv-
ered daily and each lot is
sampled with the one-third
pipette, twice or three times
the number of tests are re-
quired as when composite
samples are taken in jars
and tested once every week
or ten days. This method
furthermore takes a little
more time in the daily sam-
pling than the other, as the
quantity of milk must be
measured out accurately each
time. If a test bottle is accidently broken or some milk spilled,
the opportunity of ascertaining the fat content of the milk de-
livered during the three days is lost; if a similar accident should
occur in testing composite samples collected in jars, another test
can readily be made.

188. Accuracy of the described methods of sam-
pling. An experiment made at the Wisconsin Dairy
School may here be cited, showing that concordant re-
sults willl be obtained by the use of the drip sampling
method and the Scovell tube. Two composite samples
were taken from fifty different lots of milk, amounting
to about 6,000 Ibs. in the aggregate. One sample was
taken of the drip from a hole in the conductor spout

FIG. 55. Test-bottle rack for use in
crenmeries and cheese factories.

166 Testing Milk and Its Products.

through which the milk passed from the weighing can;
the other was taken from the weighing can by means
of a Scovell sampling tube. The following percentages
of fat were found in each of these samples r1

Babcock test

Gravimetric
analysis

Drip composite sample

4 0 per cent

' 4 04 percent

Scovell tube composite sample..

4.0 per cent.

4. 06 per cent.

PRESERVATIVES FOR COMPOSITE SAMPLES.

189. When milk is kept for any length of time under
ordinary conditions, it will soon turn sour and become
loppered, and further decomposition shortly sets in,
which renders the sampling of the milk both difficult
and unsatisfactory (19). The period during which milk
will remain in an apparently sweet or fresh condition
varies with the temperature at which it is kept, and
with the cleanliness of the milk. It will not generally
remain sweet longer than two days at the outside, at
ordinary summer or room temperature.

In order to preserve composite samples of milk in a
proper condition for testing, some chemical which will
check or prevent the fermentation of the milk must be
added to it. A number of substances have been pro-
posed for this purpose.

190. Bi-chromate of potash. This preservative is
preferred by many because it is relatively harmless,
cheap and efficient. The bi-chromate method for pre-
serving samples of milk was proposed by Mr. J. A.
Alen, city chemist of Gothenburg, Sweden, in 1892,2

1 See also 199 et seq.

2 Biedermann's Oentralblatt, 1892, p. 549.

Composite Samples of ]\iilk. 167

and has been generally adopted in dairy regions in this
country and abrcad. While not perfectly harmless, the
bi-chromate is not a violent poison like other chemicals
proposed for this purpose, and no accidents are liable
to result from its use.

191. The quantity cf bi-chromate necessary for pre-
serving half a pint to a pint of milk for a period of
one or two weeks is abcut one-half gram (nearly 8
grains).

According to Winton and Ogden,1 a .22-inch pistol
cartridge shell % inch long, cr a .32-inch caliber shell
1/4 inch long, when loosely filled, will hold enough pow-
dered bi-chromate to preserve y2 pint, and a .32-inch
caliber shell % inch long will hold enough to preserve
one pint. These shells may be conveniently handled
by soldering to them a piece of stiff wire which serves
as a handle. The amount of bi-chromate placed in
each composite sample jar would fill about half the
space representing one per cent, in the neck of a Bab-
cock milk test bottle.

192. The first portions of milk added to the com-
posite sample jars containing the specified amount of
bi-chromate will be colored almost red, but as more
milk is added day by day, its color will become lighter
yellow. The complete sample should have a light straw
color; such samples are most easily mixed with acid
when tested. If more bi-chromate is used, the solution
of the casein in the acid is rendered difficult and re-
quires persistent shaking. Bi-chromnte can be bought

1 Connecticut experiment station, report for 1884, p. W2.

168 Testing Milk and Its Products.

at drug stores or from dairy supply dealers at about 30
cents a pound. Powdered bi-chromate of potash should
be ordered, and not crystals, as the latter dissolve only
slowly in the milk. Bi-chromate tablets contain the
correct quantity of preservative for a quart sample, and
will be found convenient.

193. Other preservatives for composite samples.
Among other substances recommended for use in butter
or cheese factories as milk preservatives for composite
samples are formalin, boracic-acid compounds, chloro-
form, carbon bi-sulfid,1 copper ammonium sulfate, so-
dium fluorid, ammonia glycerin (sp. gr., 1.031), and
mixtures containing mercuric chlorid (corrosive sub-
limate) with anilin color (rosanilin).2 The coloring
matter in the latter compounds is added to give a rose
color to the sample preserved, thus showing that the
milk is not fit for consumption; the bi-chromate giving
naturally a yellow color to the milk, renders unneces-
sary the addition of any special coloring matter.

The compounds containing corrosive sublimate are
violent poise ns and must always be handled with the
greatest care, lest they get into the hands of children or
persons not familiar with their poisonous properties;
they will preserve the milk longer than bi-chromate
when applied in sufficient quantities. During late years
corrosive sublimate tablets have come into general use
in factories.

1 Delaware experiment station, eight li report, IS<M>, which also sec for
trials with a lar^e number of dilTerent preservat i\ ••>.

2 Iowa experiment station, bulletins (.», 11, iW.

Composite Samples of Milk. 169

194. Care of composite samples. The composite
sample jars should be kept covered to prevent loss by
evaporation, and in a cool, dark place, or at least out
of direct sunlight when bi-chromate of potash is used
as a preservative; the chromic acid formed by the re-
ducing influence of light on chromate solutions pro-
duces a leathery cream which is difficult to dissolve in
sulfuric acid.

A coating of white shellac has been suggested to pro-
tect the labels of the composite sample jars. The shel-
lac is applied after the names of the patrons have been
written on the labels, and when these have been put on
the jars. Gummed labels, 1x2% inches, answer this
purpose well.

Numbers are sometimes ground on the sample jar or
stamped on brass tags attached to the jars by a wire.

In keeping the milk from day to day, care should be
taken that the cream forming on the milk does not stick
to the sides of the jars in patches above the level of the
milk. Unless the daily handling of the jars and the
addition of fresh portions of milk be done with suffi-
cient care, the cream will become lumpy and will dry
on the sides of the jars. In some cases it is nearly im-
possible to evenly distribute this dried cream through
the entire sample at testing time so as to make the com-
posite sample a true representative of the different lots
of milk from which it has been taken.

195. Every time a new portion of milk is added to
the jar this should be given a gentle horizontal rotary

170 Testing Milk and Its Products.

motion, thereby mixing the cream already formed in
the jar with the milk and loosening the cream stick-
ing to its side. This manipulation also prevents the
surface of the milk from becoming covered with a layer
of partially dried leathery cream.

Composite samples having patches of dried cream on
the inside of the jar are the result of carelessness or
ignorance on the part of the operator. If proper at-
tention is given to the daily handling of the composite
samples, the cream formed in the jars can again be
evenly mixed with the milk without difficulty.

196. Fallacy of averaging percentages. A composite
sample of milk should represent the average quality
of the various lots of milk of which it is made up. This
will be true if a definite aliquot portion* or fraction of
the different lots of milk is taken. If the weights of,
say ten different lots of milk, are added together and
the sum divided by ten, the quotient will represent the
average weight per lot of milk, but an average of the
tests of the different lots obtained in this way may not
be the correct average test of the entire quantity of
milk. The accuracy of such an average figure will de-
pend on the uniformity in the composition and weights
of the ten lots of milk. When there is no uniformity,
the weights of the different lots of milk as well as their
tests must be considered. The following example will
illustrate the difference between the arithmetical aver-
age of a number of single tests and the true average test
of the various lots.

Composite Samples of Milk. 171

Methods of calculating average percentages.

I. Milk varying in weights and tests.

II. Milk of uniform weights and tests.

LOT.

Weight
of milk.

Test
of milk.

Weight
of fat.

LOT.

Weight
of milk.

Test
of milk.

Weight
of fat.

Ibs.

120
570
360
55

per ct.

3.5
5.0
5.2
3.0
4.0

Ibs.

4.2
28.5
18.7
1.6
3.2

Ibs.

250
225
240
238
234

per ct.

4.2
4.0
4.3
4.1
4.4

Ibs.

10.5
9.0
10.3
9.7
10.3

II ..
Ill ..

III ..

Total

1187
237

56.2
11.24

1187
237

49.8
10.0

Average..

True aver-
age test...

4.14
4.73*

Average

True average
test

4.20
4 22+

*56. 2X100
1187

=4.73.

+49.8X100
1187

197. The figures given in the table show that when
the different lots of milk vary in test and weight, as in
the first case, the correct average test of the 1187 Ibs.
of milk is not found by dividing the sum of these tests
by five, which would give 4.14 per cent. ; but the per-
centage which 56.2 (the total amount of fat in the
mixed milk) is of 1187 (the total amount of milk), is
4.73, and this is the correct average test of the mixed
milk made up of the five different lots.

In the second case, the variations in both the weights
of the different lots of milk and their tests, are com-
paratively small, and both methods of calculation give
therefore practically the same average test; but also in
this case, the correct average test is found by dividing
the total amount of fat by the total quantity of milk,
making 4.22 per cent., instead of 4.20 per cent., wnich is

172 Testing Milk and Its Products.

the arithmetical mean of the five tests. The quantities
of milk in the various lots do not enter into the calcula-
tion of the latter.1

198. The second example represents more nearly
than the first one the actual conditions met with at
creameries and cheese factories. As a rule, the mixed
milk from a herd of cows does not vary more in total
weight or tests, within a short period of time like one
to two weeks, than the figures given in this example.
On account of this fact, samples taken, for instance,
with a small dipper may give perfectly satisfactory re-
sults to all parties concerned. If the different lots of
milk varied in weight and test from day to day, as
shown in the first case, it would be necessary to use a
"milk thief" or one of the sampling tubes for taking
the composite samples; the size of each of the samples
taken would then represent an exact aliquot portion of
the various lots of milk (182).

199. A patron's dilemma. The following incident will fur-
ther explain the difficulties met with in calculating the average
tests of different lots of milk.

Thel weekly composite sample of the milk supplied by a cream-
ery patron from his herd of 21 cows tested 4.0 per cent. fat.
One day the farmer brought to the creamery a sample of the
morning's milk from each of his cows, and had thorn tested;
after adding the tests together and dividing the sum by 21, he
obtained an average figure of 5.1 per cent, of fat. From this
he concluded that the average test of the milk from his cows
ought to be 5.1, instead of 4.0, and naturally asked for an ei
planation.

1 In the experiment Driven on p. 146, the arithmetical nn-jin of tin-
tests Is 5.15 per cent., while the true average fat content of milk is
4.85 per cent.

Composite Sa

The first thing done was to show him that while 5.1 was the
correct average of the figures representing the tests of his
twenty-one cows, it was not a correct average test of the mixed
milk from all his cows, as he had not considered, in calculating
this average, the quantities of milk yielded by each cow; the
following illustration was used:

Cow No. 1, yield 25 Ibs. of milk, test 3.6 per cent.=0.9 Ib.of butter fat.
Cow No. 2, yield 6 Ibs. of milk, test 5.0 per cent. =0.3 Ib. of butter fat.

Total ....... 31 Ibs. 2)8.6 1.2 Ibs.

4.3 per cent.

The two cows gave 31 Ibs. of milk containing 1.2 Ibs. of fat;
the test of the mixed milk would therefore not be 4.3 per cent.
/3.65.0\ but 1.2X100 =3tg7 per cent If the fat in th

t per

milk was calculated by the average figure 4.3 per cent., 1.33 Ibs.
of fat would be obtained, i. e., 0.13 Ib. more than the cows pro-
duced.

In order to further demonstrate the actual composition of the
mixed milk of the twenty-one cows, the milk of each cow was
weighed and tested at each of the two niilkings of one day. The
weights and tests showed that the cows produced the following
total number of pounds of milk and of fat:

Morning milking, 113.3 Ibs. of milk, containing 5.17 Ibs. of fat.
Night milking, 130 9 Ibs. of milk, containing 4.98 Ibs. of fat.

The morning milk therefore contained 5- 7X*°°:=:4.56 per cent.

1 13 . 3

of fat, and the night milk, 4-^^°°=3.80 per cent, of fat.

The sum of the morning and night milkings gave: milk, 244.2
Ibs., fat 10.15 Ibs. The mixed morning and night milk, there-
fore, contained 10-^4X*00 = 4.1 per cent, of fat. This is the true
average test of the morning and night milkings of these twenty-
one cows, as found by weighing and testing separately the milk
of each cow at both milkings.

The total milk was strained into a large can at the farm, both
in the morning and in the evening. A sample of the mixed milk
was in each case taken with a long-handled dipper as soon as
the milkings were finished. When the cans of milk were deliv-

174

Testing Milk and Its Products.

ered at the creamery, a sample of each was taketn with a Scovell
sampling tube. The tests of these four samples are given below,
together with the results of the individual tests:

Morning Milk.

Night Milk.

Sample taken at the farm, with dipper. .
Sample taken at creamery with Scovell
tube

4.4 per ct.
4.5 "

3.8 per ct.
3.7 "

Calculated from weights and tests of
milk from each cow

45 "

3.8 "

The figures given show that practically uniform tests were ob-
tained by the different methods of sampling.

Questions.

1. What is a composite sample of milk?

2. Describe the proper care of composite samples.

3. Give an example showing that composite samples of milk
may be inaccurate when taken with a small dipper.

4. Describe the construction of the following methods of sam-
pling milk or cream, by (a) drip sample, (b) the Scovell, (c)
the McKay, and (d) the Michels' sampling tubes.

5. What is the purpose of adding preservatives to milk or
cream samples? Mefntion the more common preservatives used
and quantities to be added.

CHAPTER XI.
CREAM TESTING AT CREAMERIES.

. 200. The cream delivered at gathered-cream factories
is now in many localities tested by the Babcock test, and
this has been adopted as a basis of paying for the cream
in the same manner as milk is paid for at separator
creameries. It has been found to be more satisfactory
to both cream buyer and seller than either the oil-test
churn or the space (or gauge) systems which have been
used for this purpose in the past.

The details of the application of the Babcock test to
the practical work at cream-gathering creameries have
been carefully investigated by Winton and Ogden in
Connecticut,1 Bartlett in Maine,2 and Lindsey in Massa-
chusetts,3 and we also owe to the labors of these chem-
ists much information concerning the present workings
of other systems of paying for the cream delivered at
creameries.

201. The space system. Numerous tests have shown
that one space or gauge of cream does not contain a
definite, uniform amount of fat. In over 100 compari-
sons made by Winton it was found that one space of
cream4 contained from .072 to .170 Ib. of butter fat, or

1 Conn, experiment station (New Haven), bull. 108 and 119; report
1894, pp. 214-244.

2 Maine experiment station, bull. 3 and 4 (S. S.)

3 Hatch experiment station, report 1894, pp. 92-103; 1895, pp. 67-70.

4 The space is the volume of a cylinder, 8% inches in diameter and
AS of an inch high. The number of spaces in each can of milk is read off
before skimming by means of a scale marked on a strip of glass in the
side of the can (Conn. exp. sta., bull. 119).

176

Testing Milk and Its Products.

on the average .13 lb., and the number of spaces re-
quired to make one pound of butter varied from 5.01 to
11.72. It is also claimed that in the winter season when
the cream is gathered at long intervals, like once a week,
it is necessary for the buyer to accept the seller's state-
ment of the record of the number of cream spaces which
he furnishes, since the cream cannot be left in the
creaming can for so long a time. These objections to
the space system apply only to the method of paying
for the cream, and not to the manner in which the
cream is obtained.

202. The oil-test churn. As stated in the introduc-
tion, the oil-test churn (fig. 56) has been used quite ex-
tensively among gath-
ered-cream factories ;
this system is based on
the number of inches
of cream which the
various patrons deliver
to the factory; a
creamery inch is the
quantity of cream
which will fill a can
twelve inches wide, one
inch high ; it contains
113 cubic inches.1 This
quantity was supposed to make one pound of butter.
In using this method the driver pours the patron's
cream into his 12-inch gathering pail, measures it with

1 A layer of two inches in an 8-inch pail contains 101 >.">:; i rul>ir inches.
two inches In a8%-inch pail 110.18 cubic inches and 2 inches in a 8%-im'li
pail 113.49 cubic inches.

FIG. 56. The oil-test churn.

Cream Testing at Creameries.

Ill

his rule and records the depth of the cream in the can,
in inches anol tenths of an inch. The cream is then
stirred thoroughly with a ladle or a stout dipper, and
sampled by filling a test tube to the graduation mark
by means of a small conical dipper provided with a
lip. A driver's case contains either two or three
"cards," holding fifteen test tubes each (see fig. 57).
The tubes as filled are
placed in the case and
the corresponding num-
ber in each instance re-
corded in front of the
patron's name, together
with the number of
inches of cream fur-
nished by him.

On the arrival at the

. . FIG. 57. Cream-gatherer's

nunnery the tin cards sample case,

holding the tubes are p]aced in a vessel filled with
water of the temperature wanted for churning (say, 60°
in summer and 65° to 70° in winter). When ready for
churning they are placed in the oil-test churn, the cover
of the churn put on, and the samples of cream churned
to butter. On the completion of the churning, the cards
are transferred to water of 175-190° Fahr., where they
are left for at least ten minutes to melt the butter and
"cook the butter milk into a curd." The oil will now
be seen mixing through the mass. The test tubes are
then warmed to churning temperature and churned
again, by which process the curd is broken into fine

178 Testing Milk and Its Products.

particles, which, when the butter is re-melted, will set-
tle to the bottom. The butter is melted after the sec-
ond churning by placing the tubes in water at 150-175°
F., allowing them to remain therein for at least twenty
minutes. 'Some samples must be churned three or four
times before a gcod separation of oil is obtained. A
clear separation of oil is often facilitated by adding a
little sulfuric acid to the tubes.

The length of the column of liquid butter fat is de-
termined by means of a special rule for measuring the
butter oil ; this rule shows the number of pounds and
tenths of a pound of butter which an inch of cream will
make; the first tenth of a pound on the rule is divided
into five equal parts, so that measurements may be made
to two-hundredths of a pound. The melted fat is meas-
ured with the rule, by raising the tin card holding the
bottles, to about the height of the eye ; the reading is
recorded on the driver's tablet under Test per incli, op-
posite the number of the particular patron. The test
per inch multiplied by the inches and tenths of an inch
of cream supplied will give the butter yield in pounds,
with which the patron will be credited on the books of
the creamery.

203. The objection to this system of ascertaining the
quality cf cream delivered by different patrons lies in
the fact that it determines the churnable fat, and n<>1
the total fat of the cream; the amount of the former
obtained depends on many conditions beyond the con-
trol of the patron, viz., the consistency, acidity and tem-
perature of the cream, the size of the churn or churn

Cream Testing at Creameries. 179

ing vessel, etc.1 The same reasons which caused the
churn to be replaced by methods of determining the
total fat of the milk, in the testing of cows among dairy-
men and breeders, have gradually brought about the
abandonment of the oil test in creameries and the adop-
tion of the Babcock test in its place. It may be said,
en the other hand, in favor of the use of the oil test in
creameries that it is a considerably cheaper method
than any fat test, and -calls for an expenditure of less
labor and time on the part of the operators than do the
latter methods.

204. The Babcock test for cream. Both the space
system and the oil-test churn used for estimating the
quality of cream at creameries have now largely been
replaced by the Babcock test in the more progressive
creameries in this country, and composite samples of
cream are collected and tested in a similar manner as
is done with milk at separator creameries and cheese
factories.

A very satisfactory method of arrangements for
working the Babcock test, in use in many eastern cream-
eries, is described by Winton and Ogden in the Con-
necticut report previously referred to. The cream
gatherer who collects the cream in large cream cans is
supplied with a spring balance (1, see fig. 58), pail for
sampling and weighing the cream (2), sampling tube
(3), and collecting bottles (5). At each patron's farm
he takes from his wagon the sampling pail and tube,

1 It follows from this that there can be no definite relation between
the results obtained by the Rabcock test and the oil-test readings; or-
dinarily a reading of 100 In the oil-test Is equlvelant to about 23 per
cent, of butter fat in the cream.

180

Testing Milk and Its Products.

the scales, and one small collecting bottle. He should
find in the dairy of the patron the cans of perfectly
sweet cream, kept at a temperature of 40° to 50° F.,

and protected from dirt
and bad odors. Either sour
or frozen cream must be
rejected. The patron's
number should be painted
in some conspicuous place
nfcar the cream cans in his
dairy house. The gatherer
hangs the scale on a hook
near the cream to be col-
lected; the scale should be
made so that the hand of

FIG. 58. Outfit for cream testing f>,0 /JiQl ™71*n etanrl at -/o^n
by the Babcock test at gathered- tne Cial Wl11 stana at zei

when the empty pail is

hung on it. The cream is then poured at least twice
from one can to another in order to mix it thoroughly.1

205. When properly mixed, the cream is poured into
the weighing pail and is weighed and sampled. The
authors give the following description of the cream
sampling tube used, and directions for sampling and
weighing the cream.

"Sampling Tube. — This tube is of stout brass, about .^ :>f an
inch thin-k. and a few inches longer than the weighing pail which

1 The necessity of care In mixing: the cream is shown l>y t In- follow-
ing illustration given by the authors referred to.

Per cent of fat in cream which stood for ."/ ?nmr*.

Sample dr;i\vn
Surface. Bottom. with sampling tube.

Not mixed 28.00 5.00 19.25

Poured once 28.75 22.00 22.50

Poured twice... ».»

Testing Cream at Creameries. 181

is used with it. On the upper end, a small brass stop-cock of
the same bore is fastened. It should be nickel plated inside and
out, to keep the metal smooth and free from corrosion. These
tubes may be obtained from less than T\ to over % inch bore.
The greater the diameter of the weighing pail, the wider should
be the bore of the tube. For use with pails 8 inches in diameter,
a -,83 inch bore sampling tube will serve the purpose, but when
the pail has a diameter of 9 or more inches, a tube with a bore
of ^4 inch or more should be used. It must be borne in mind
that doubling the diametetr of the pail, or of the sampling tube,
increases its capacity fourfold.

" The tube when not in use should be kept in an upright posi-
tion to permit draining.

"Sampling and Weighing. — Lower the sampling tube, cock
end up, with the cock open, to the bottom of the weighing pail
which holds the mixed cream. When it is filled raise it out of
the liquid and allow it to drain for a few seconds. By this
means the tube is rinsed with the cream to be1 sampled and any
traces of cream adhering to the tube from previous use are re-
moved. With the cock still open, slowly lower the sampling tube
to the bottom of the cream pail. After allowing a moment for
the cream to rise in the tube to the same height as in the pail,
close the cock and raise the sampler carefully out of the cream.
As long as the cock is closed, the cream in the tube will not
flow out, unless the tube is strongly jarred. Allow the cream
adhering to the outside) of the tube to drain off for a few sec-
onds, then put the lower end into the 1 to 1% oz. wide-mouth
glass collecting bottle which bears the patron 's . number on its
cork, and open the cock. The cream will then flow out of the
sampler into the bottle, which is afterwards securely corked and
put into the cream gatherer's case. Immediately weigh the
cream in the cream pail to the quarter or half pound, as may
be judged expedient, and record the weight.

"If the patron has more than one pailful, repeat with each
pailful the operation of sampling and weighing, putting all the
samples in one/ and the same bottle. Weigh all cream collected
in one and the same sampling pail and draw a sample from each
separate portion weighed."

182 Testing Milk and Its Products.

206. After sampling and weighing each patron's
cream it is poured into the driver's large can, and the
sample bottles are carried in a case to the creamery
where the contents of each bottle is poured into the
composite sample jar of the particular patron. The
samples of cream in the small bottles, besides furnish-
ing the means of testing the richness of the cream, give
the creamery man an opportunity to inspect the flavor
of each lot of cream, and the condition in which it has
been kept by the various patrons. Some preservative,
usually corrosive sublimate tablets, is placed in the com-
posite sample jars, and these are cared for and tested
in the same manner as composite samples of milk (194).

207. The collecting bottles should be cleaned with
cold, and afterwards with hot water, as soon as they are
emptied, and before a film of cream dries on them.
When washed and dried, these bottles are placed in the
cases, ready for the next collecting trip. There can be
no confusion of bottles since the corks and not the bot-
tles are marked with the numbers of the respective
patrons.

208. When this system of testing composite samples
is adopted, the patrons are paid for the number of
pounds of butter fat contained in their cream, in ex-
actly the same way as milk is paid for at separator
creameries. It makes no difference how thick or how
thin the cream may be, or how much skim milk is left
in the cream when brought to the factory. Eighty
pounds of cream containing 15 per cent, of fat is worth
no more or less than 48 pounds of cream testing 25 per
cent.; in either case 12 pounds of pure butter fat is

Testing Cream at Creameries. 183

delivered. This will make the same amount of butter
in either case, viz., toward 14 Ibs., and both patrons
should therefore receive the same amount of money.

There is a small difference in the value of the two
lots of cream to the creamery owner or the butter maker,
in favor of the richer cream, both because its smaller
bulk makes the transportation and handling expenses
lighter, and because slightly less butter fat will be lost

in the butter milk, a smaller quantity of this being ob-

tained from the richer cream. But it is doubtful if the
differences thus occurring are of sufficient importance
to be noticed under ordinary creamery conditions; the
example selected presents an extreme case of variation
in the fat content of cream. A trial of this system at
five Connecticut creameries, supplied mostly with Cooley
cream, by over 175 patrons, showed that the average
composition of the cream from the different patrons
varied only from 16.9 to 19.8 per cent, of fat. The cream
of some patrons on certain days contained only 9.5 per
cent, of fat, and other patrons at times had as high a
test as 30 per cent., but these great differences largely
disappeared when the average quality of the cream
delivered during a period of time, like a month or more,
was considered.

209. Smaller differences in the composition of cream
will, however, always occur, even if the same system of
setting the milk, like the cold deep-setting process, is
used and the water is kept at the same temperature at
all times. This is due to differences in the composition
of the milk and its creaming quality; whether largely
from fresh cows or from late milkers; whether kept

184 Testing Cream and Its Products.

standing fcr a time before being set, or submerged in
the creamer immediately after milking and straining,
diameter of creaming cans, etc. Bartlett states1 that
the percentage of fat in the cream from the same cows
may be increased ten per cent, or more by keeping the
water at 70° instead of at 40° F. The higher tempera-
ture will give the richer cream, but the separation will
not be so complete, since a richer skim milk is obtained
from the milk set at this temperature. Separator cream
is not materially influenced by the conditions mentioned,
as the separator can be regulated to deliver cream of
nearly uniform richness from all kinds of sweet milk.

210. At creameries where both milk and cream are
delivered, somewhat of an injustice is done to patrons de-
livering cream, by paying for the amounts of butter fat
furnished by the different patrons. By multiplying the
cream fat by 1.03,2 the value of his products to the
creamery is taken into proper account, and justice is
done to all parties concerned3 (239).

211. Gathering and sampling hand-separator
cream. On account of the great variation in both the
richness and the purity of farm separator cream it has
been found in practice that composite samples of cream
are not so satisfactory to either buyer or seller as the
testing of a sample taken from each lot of cream gath-
ered. A still more satisfactory method is to provide
separate cans for each patron, the cream gatherer leav-

1 Bull. 8 (8. 8.), Maine experiment station.

2 Splllman (Dairy and Creamery, Chicago, April 1, 1899) recommends
the use of the factor 1.044.

3 This subject Is discussed in detail In the 17h annual report of Wls.
experiment station, pp. 90-92; see also the 20th report of this Station,
pp. 130-31.

Testing Cream at Creameries. 185

ing an empty, clean can at each farm and taking a full
or partially filled can of cream from the farm to the
factory. This makes it necessary for the cream gath-
erer to carry as many cans as he has patrons to gather
cream from, but it gives the factory receiving the cream
a chance to inspect, weigh and sample the cream from
each farm and relieves the cream gatherer of all these
details which are often the cause of dissatisfaction.

Questions.

1. In what ways do the results obtained with the oil- test
churn differ from those obtained with the Babcock test?

2. Describe the method of testing cream by the Babcock test
at gathered- cream factories.

3. What advantages has. the gathering of cream in separate
cans over mixing the cream from all the patrons of one route?

CHAPTER XII.
CALCULATION OF BUTTER- AND CHEESE VIELD

A.— CALCULATION OF YIELD OF BUTTER.

212. Butter-fat test and yield of butter. The Bab-
cock test shows the amount of pure butter fat contained
in a sample of milk, cream or other dairy products.
The butter obtained by churning cream or milk con-
tains, in addition to pure butter fat, a certain amount
of water, salt and curd. While an accurate milk test
gives the total quantity of butter fat found in the sam-
ple of milk or cream tested, the churn cannot be de-
pended upon either to leave the same amount of butter
fat in the butter milk or to include the same amount of
water, salt and curd in the butter at each churning.

If a quantity of milk, say 3,000 Ibs., be thoroughly
mixed in a vat, and then divided into half a dozen equal
portions, a Babcock test of the different lots will show
the same percentage of butter fat in each portion. If,
on the other hand, each of these lots be skimmed, and
the cream ripened in different vats and churned sepa-
rately, the same weight of butter from each lot of 500
Ibs. of milk will not be obtained, even by the most expert
butter maker, or if all the operations of skimming, cream
ripening, churning, salting and butter-working were
made as nearly uniform as possible. Careful operators
can handle the milk and cream so that very nearly the
same proportion of fat contained in the milk is re-

Calculation of Butter- and Cheese Yield. 187

covered in the butter in different churnings, but since
the water and salt in butter are held mechanically and
are not chemically combined with it, the amounts re-
tained by the butter are quite variable in different
churnings, especially since the laws governing the reten-
tion of water in butter are but imperfectly understood.
213. Variations in the composition of butter. As
an illustration of the variations in the composition of
butter that usually occur, the analyses made in the
breed tests at the World's Fair in 1893 may be here
cited; the butter was in all cases made by as nearly
identical methods and under as uniform conditions as
could possibly be obtained by the skilled operators hav-
ing this work in charge ; the average composition of 350
samples of this butter, with upper and lower limits,
was as shown in the following table :

Composition of samples of butter, World's Fair, 1893.

Sum of

Water.

Fat.

Ourd.

Salt and
ash.

water,c'rd
salt and

ash,

Per cent.

Average of 350

analyses

11.57

84.70

.95

2.78

15.30

Lower and up-

per limits

8.63-15.00

76.53-88.26

.50-2.14

1.01-8.58

Analyses of fifty samples of creamery butter taken in
1896, from the tubs ready for market at as many Wis-
consin creameries, showed that no two of them were ex-
actly alike in composition, but varied within the limits
given below:1

1 Wisconsin experiment station, bull. 56.

188 Testing Milk and Its Products.

Summary of analyses of Wisconsin creamery butter.

Water.

Fat.

Curd.

Salt and
ash.

Sum of
water, curd,
salt and
ash.

Highest

Per cent.

17 03

Per cent.

87 50

Per cent.
2 45

Per cent.
4 73

Per cent.
22 95

Lowest

9 18

77 07

1 30

12 50

Average

12.77

83.08

1 28

2 87

16 92

The preceding analyses show the composition of but-
ter made at one place where every possible effort was
taken to produce a uniform product, and of butter made
at fifty different creameries, where there was more or
less variation in the different operations of manufacture
and in the appliances and machinery used. The ma-
jority of thesamples of butter analyzed, in either case,
were very near the average composition given, but since
there are such wide variations in the composition of the
butter made by the uniform methods adopted in the
World's Fair breed tests, butter of a more uniform com-
position cannot be expected from the thousands of dif-
ferent creameries and private dairies which supply the
general market with butter.

The analyses of the fifty samples of creamery butter,
given above, show that the content of the butter fat
varied from 77 to over 87.5 per cent., and according to
the average of the analyses, 83 pounds of butter fat was
contained in, or made, 100 Ibs. of butter. There was,
therefore, in this case produced 20.5 per cent, more
butter than there was butter fat, since
83 : 100 : : 100 : x ; therefore
100X100

- = 120.5.

Calculation of Butter- and Cheese Yield. 189

214. "Overrun" of churn over test. The yield of
butter is not, however, as a rule compared with the
amount of butter fat contained in the butter, but with
the total butter fat of the, whole milk or cream from
which it was made. This "increase of the churn over
the test" is what is generally called overrun in cream-
eries.

The overrun obtained in different creameries, or even
in the same creameries at different times, will be found
to vary considerably. When the milk is accurately
tested and the butter well worked, this overrun will vary
from 10 to 16 per cent. ; that is, if a quantity of milk
contains exactly 100 Ibs of butter fat, as found by the
Babcock test or any other accurate method of milk test-
ing, from 110 to 116 Ibs. of butter ready for market may
be obtained from it. The overrun from cream will be
somewhat larger, 18 to 22 per cent., but will never ex-
ceed 25 per cent., unless the butter contains less than
80 per cent, fat (217).

215. Factors influencing the overrun from milk.
Even under the very best of care and attention to de-
tails, variations will occur in the speed of the separator,
in the conduct of the ripening and churning processes,
and in the condition of the butter when the churn is
stopped ; hence absolutely uniform losses of fat in skim
milk and butter milk, or the same water- and salt con-
tents of the butter, cannot be expected.

The overrun in separator creameries is influenced by
two legitimate factors : first, the losses of butter fat sus-
tained in separating the milk and churning the cream,
and second, the gain due to the admixture of water,

190 Testing Milk and Its Products.

salt, etc., in the manufacture of butter. Considering
first the losses of fat in skim milk and butter milk, the
separator will usually, when run at normal speed and
capacity, leave the same per cent, of fat in skim milk,
whether rich or poor milk is skimmed. An exception
to this may be found in separating rich milk having
large fat globules, or milk from fresh milkers, in either
of which cases the large size of the fat globules occa-
sions a more complete separation of fat by the centri-
fugal force. But generally speaking, the statement
holds good that the total loss of fat in separator skim
milk is a factor of the quantity of milk run through the
separator, rather than of its quality. It follows from
this, however, that the relative losses of fat in skim milk
will vary to some extent according to the quality of the
milk separated. Selecting two extremes in the quality
of milk, 2.5 and 6.0 per cent, of fat, there will be found,
say .1 per cent, of fat in the skim milk from either lot,
provided the separator is not unduly crowded, and the
separation is conducted under normal conditions in each
case. But .1 per cent, fat makes 4 per cent, of the total
fat in the poor milk ( ii^| - =4) , and only 1.7 per cent,
of that in the rich milk. It takes 4000 Ibs. of the 2.5
per cent, milk to furnish 100 Ibs. of fat, and only 1666
Ibs. cf the 6 per cent, milk ; in skimming the poor milk,
a less of .1 per cent, of fat is sustained in the skim milk
from 4000 Ibs. of milk (3.4 Ibs. fat), while in the rich
milk n similar loss is sustained in the skim milk from
only 1666 Ibs. of milk (1.4 Ibs. fat).

Calculation of Butter- and Cheese Yield. 191

The example gives an extreme case, and one not likely
to be met with in practice. The range of the richness of
the milk delivered by different patrons at the factory is
usually within one-half or one per cent, of fat. In such
cases the proportion cf fat lost in skimming does not
vary much, e. g., in case of milk containing 3.5 and 4.0
per cent, of fat, and variations in the overrun occurring
when the proper care in skimming, ripening and churn-
ing is taken, are due, therefore, primarily to differences
in the water and salt contents of the butter made (204).

216. The losses from poor, rich and average milk, as
received at creameries and cheese factories, can be traced
from the following statement ; this gives the quantities
of fat lost in' handling milk of four grades, viz. : 2.5,
3.5, 4.0 and 6.0 per cent., in case of each grade calcu-
lated to a standard of 100 Ibs. of fat in the milk.

To supply 100 Ibs. of fat would require the following
amounts cf the different grades of milk:

4000 Ibs. of milk testing 2.5 per cent, will contain 100 Ibs. of fat.

2857 " " " 3.5 " . " " 100 <4 " "

2500 " " " 4.0 " " " 100 " " "

1666 " " il 6.0 " " " 100 " " "

Assuming that the skim milk contains .1 per cent, of
fat and makes up 85 per cent, of the whole milk, and
that the butter milk tests .3 per cent., and forms 10
per cent, of the whole milk, the butter-fat record of
the quantities of different grades of milk containing 100
Ibs. of fat will be as given in the following table. Cer-
tain mechanical losses are unavoidable in the cream-
ery, as in all other factory operations, viz., milk and
cream remaining in vats and separators, butter sticking

192

Testing Milk and Its Products.

to the walls of the churn, etc. These losses have been
found to average about 3 per cent, of the total fat in
the milk handled, under normal conditions and under
good management (219).

Fat available for butter in different grades of milk.

Grade of milk.

Whole
milk.

Skim
milk.

Butter
milk.

Waste

Total
loss.

Fat.

availa-
ble for
butter.

2.5 percent

4000 Ibs.
2.5 per ct.

3400 Ibs.
.1 per ct.

400 Ibs.
.3 per ct.

Ibs.

Per ct.

Fat

100 Ibs.

3.4 Ibs.

1.2 Ibs.

3.0

7.6

92.4

3.5 per cent

2857 Ibs.
3.5 per ct.

2429 Ibs.
.1 per ct.

286 Ibs.
.3 per ct.

Fat...

100 Ibs.

2.4 Ibs.

.91b.

3.0

6.3

93.7

4.0 per cent

2500 Ibs.
4 per ct.

2125 Ibs.
.1 per ct.

250 Ibs.
.3 per ct.

Fat...

100 Ibs.

2.1 Ibs.

.7 Ib.

3.0

5.8

94.2

6.0 per cent

1666% Ibs.
6 per ct.

1417 Ibs.
.1 per ct.

167 Ibs.
.3 per ct.

Fat

100 Ibs.

1.4 Ibs.

.5 Ib.

3.0

4.9

95.1

The table shows that with 2.5 per cent.-milk, there is
a loss of 3.4 Ibs. of fat in the skim milk, a loss of 1.2
Ibs. of fat in the butter milk, and of 3.0 Ibs. in the
creamery waste, for every 100 Ibs. of fat in the whole
milk, or a total loss of 7.6 Ibs. from these sources. In
case of 6 per cent, milk these losses are 1.4 Ibs., .5 Ib.
and 3.0 Ibs. for skim milk, butter milk and waste re-
spectively; a total loss of 4.9 Ibs., or 2.7 Ibs. less than
the losses with poor milk. This difference in the losses
shrinks to only .5 pound of fat in case of 3.5 and 4.0
per cent.-milk, when a quantity containing 100 Ibs. of
fat is handled in both cases.

Calculation of Butter- and Cheese Yield. 193

The overrun from each of the four grades of milk can
be calculated for butter containing a certain per cent,
of fat. Assuming the fat content of butter to be 83 per
cent, on the average (213), the quantity of butter ob-
tained from the 100 Ibs. of fat, or rather from the por-
tion thereof which is available for butter, in each ease
will be as follows :

100 fts. of fat from Available Butter cont.^ Overrun

4,000 ft s. of 2.5 per cent. milk. . . . 92.4 fts.= 111.3 fts. 11.3

2,857 fts. of 3.5 per cent, milk 93.7 fts.= 113.0 fts. 13.0

2,500 fts. of 4.0 per cent, milk 94.2 fts.= 113.5 fts. 13.5

1,666 Ibs. of 6.0 per cent, milk 95.1 fts.= 114.6 fts. 14.6

All butter makers should obtain more butter from a
certain quantity of milk than the Babcock test shows it
to contain butter fat, but it is impossible to know ex-
actly, except by chemical analysis, how much butter fat
is lost in the skim milk and the butter milk, and how
much water, salt and curd the butter will contain.

217. Overrun from cream. The overrun from cream
is, as already stated, larger than from milk because
there is no loss of fat in the skim milk to be consid-
ered. Rich cream will give a somewhat greater over-
run than thin cream, for the same reasons as have been
shown in the calculations of overrun from milk. If
similar calculations are made from cream of different
richness as these given for milk (216), the fat available
for butter-making and the yield of butter per 100 pounds
of fat in the cream will be as shown below. A loss
through waste in the process of butter-making amount-
ing to 2 per cent, has been assumed in these calcula-
tions :

194

Testing Milk and its Products.

100 Ibs. fat in

Available fat,

Butter of

QQC/f, fni

Overrun,

cream

Ibs.

per cent.

20%

96.8

116.6

16.6

30%

97.3

117.2

17.2

40%

97.6

117.6

17.6

We note that the overrun for cream of different qual-
ity under the conditions given ranges from 16.6 to 20-
per cent, cream to 17.6 for 40-per cent, cream. A some-
what larger overrun would be obtained when the butter
made contains less fat and more water than assumed.

Assuming that the butter contains the maximum
amount of water allowed by law (16 per cent.) and
nearly 80 per cent, fat, the overrun for both milk and
cream would be somewhat larger than already given, as
shown by the following figures:

Maximum overrun from milk Maximum overrun from cream

2 5%

15 5

20%

21.0

3.5%

17.1

30%

21.6

4.0%
6.0%. ../..

17.8
18.9

40 %

22.0

This table shows the highest overruns that are likely
to be obtained when the cream is to contain no more
than the maximum amount of water allowed by law.
Larger overruns can only be obtained by reducing the
losses of manufacture (which will give but slightly
higher figures) or, fraudulently, by inaccurate weigh-
ing or testing of the milk, cream or butter.

218. Calculation of overrun. The overrun is calcu-
lated by subtracting the amount of butter fat contained
in a certain quantity of milk or cream, from the amount

Calculation of Butti^and Cheese Yield.

of butter made from it, and iindmg ^fiat^ter. cent, this
difference is of the amount of butter fat in the milk.

Example 1 : 8000 Ibs. of milk is received at the creamery on
a certain day; the average test of the milk is 3.8 per cent. By
a simple multiplication we find that thd milk contained 8000 X
.038=304 Ibs. of butter fat. 340 Ibs. of butter was made from
this milk, as shown by the weights of the packed tubs. The dif-
ference between the weight of butter and butter fat is, therefore,
36 Ibs.; 36 is 36tX100 =11.8 per cent, of the quantity of butter
fat in the milk; that is, the overrun for the day considered was
11.8 per cent.

The formula for the overrun is as follows :
v_(b— f) 100

~T~ -r.aaa

b and / designating the quantities of butter and butter

fat, respectively, made from or contained in a certain
quantity of milk. In the preceding example, the calcu-
lation would be as follows: (340-aoi)xioo=ii<8 per cent.

804

Example 2: 1000 Ibs. of cream testing 25 per cent, fat con-
tains 1000 X. 25=250 Ibs. butter fat. If 304 Ibs. of butter is
made, the overrun may be calcullated by subtracting the butter
fat from the butter, 304—250=54 Ibs., 'then divide this by the

fat in the cream and multiply by 100; or ^2^=18 per cent.,

oOO

which is the cream overrun.

219. Conversion factor for butter fat. A committee
of the Association of American Agricultural Colleges
and Experiment Stations at the ninth annual convention
of the Association reported that "in the ninety-day
Columbian Dairy Test, 96.67 per cent, of the fat in the
whole milk was recovered in the butter. This butter, on
the average, contained 82.37 per cent, butter fat; in
other words, 117.3 pounds of butter were made from
each 100 pounds of butter fat in the whole milk.1 The

1 When 82.37 Ibs. of butter fat will make 100 lt>s. of butter, how much
butter will 96.«7 tt>s. of butter fat make? 82.37:96.67: : 100 :x, x= 117.3.

196 Testing Milk and Its Products.

exact conversion factor would be 1.173. As this is an
awkward number to use, and as 1% is so nearly the
same ... it has seemed best to recommend that the
latter be used as the conversion f actor, "

A resolution was adopted by this Association recom-
mending that the approximate equivalent of butter be
computed by multiplying the amount of butter fat
by 1%, and this figure has been generally accepted for
computing the yield of butter from a certain amount of
butter fat.

The figures given are the result of more than ordinary
care in skimming, churning and testing, and probably
represent the minimum losses of fat in the manufactur-
ing processes. The increase of churn over test repre-
sented by one-sixth, or 16 per cent., may therefore be
taken as a maximum "overrun" for milk under ordi-
nary factory conditions.

220. Butter yield from milk of different richness.
a. Use of butter chart. The approximate yield of but-
ter from milk of different richness is shown in Table XI
in the Appendix. This table is founded on ordinary
creamery experience and will be found to come near to
actual every-day conditions of creameries where modern
methods are followed in the handling of the milk and
its products. The table has been prepared in the fol-
lowing manner:

It is assumed that the average) loss of fat in the skim milk is
.20 per cent., and that 85 Ibs. of skim milk is obtained from each
100 Ibs. of whole milk; to this loss of fat is added that from
the butter milk; about 10 Ibs. of butter milk is obtained per 100
Ibs. of whole milk, testing on the average .30 per cent.

If f designate the fat in 100 Ibs. of milk, then the fat recov-
ered in the butter from 100 Ibs. of milk will be

Calculation of Butter- and Cheese Yield 197

There is, on the other hand, an increase in weight in the but--
ter made, owing to the admixture of non-fatty components
therein, principally water and salt. Butter packed and ready
for the market will contain in the neighborhood of 84 per cent.
of fat (214), so that the fat recovered in the butter must be in-
creased by i^0— 1.19. If B therefore designate the yield of but-
ter from 100 Ibs. of milk, the following formula will express the
relation between yield and fat content, provided there are no
other factors entering into the problem, viz.:
B=(f— .20) 1.19

From this value for B, should be deducted the loss due to
wastes in thet manufacturing processes, amounting to 3 per cent.
of the total fat in the milk handled, and we therefore have:
B=(f— .20) 1.16

Since this table is based on a fat content of .2 per
cent, in the skim milk, the figures for the overrun are
slightly lower than may be obtained in creameries pro-
vided with up-to-date cream separators.

221. Table XI in the Appendix, founded on this
formula, may be used to determine the number of
pounds of butter which milk containing 3 to 5.3 per
cent, fat will be likely to make. It presupposes good
and careful work at the separator, churn and butter
worker, and under such conditions will generally show
yields of butter varying but little from those actually
obtained. It may be conveniently used by the butter
maker or the manager to check up the work in the
creamery; the average test of the milk received during
a certain period is found by dividing the total butter
fat received, by the total milk, and multiplying the
quotient by 100 ; the amount of butter which the total
milk of this average fat content will make, according to
the table, is then compared with the actual churn yield.

198 Testing Milk and Its Products.

Example: A creamery receives 200,000 Ibs. of milk during
a month ; the milk of each patron is tested and the fat contained
therein calculated. The sum of these amounts of fat may be
7583 Ibs; the average test of the milk is then 3.79 per cent. Ac-
cording to Table XI, 10,000 Ibs. of milk, testing 3.8, will make
418 Ibs. of butter, and 200,000 Ibs., therefore, 8360 Ibs. of but-
ter. The total quantity of butter made during the month will
not vary appreciably from this figure if the work in the cream-
ery has beien properly done.

222. b. Use of overrun table. The table referred to
above gives a definite calculated butter yield for each
grade of milk, according to average creamery condi-
tions. As it may be found that this table will give uni-
formly either too low or too high results, Table XII in
the Appendix is included, by means of which the butter
yield corresponding to overruns from 10-20 per cent,
may be ascertained in a similar way as above described.

The total yield of butter is divided by the total num-
ber of pounds of fat delivered; the quotient will give
the amount of butter made from one pound of fat, and
this figure multiplied by the fat delivered by each pat-
ron shows the pounds of butter to be credited to each
patron. To use the table, find in the upper horizontal
line the number corresponding nearest to the number of
pounds of butter from one pound of fat. The vertical
column in which this falls gives the pounds of butter
from 100 Ibs. of milk containing the per cents, of fat
given in the outside columns (Babcock).

B.— CALCULATION OP YIELD OP CHEESE.

223. a. From fat. The approximate yield of green
Cheddar cheese from 100 Ibs. of milk may be found by
multiplying the per cent, of fat in the milk by 2.7 ; if /

Calculation of Butter- and Cheese Yield. 199

designate the per cent, of fat in the milk, the formula
will, therefore, be:

Yield of cheese=2.7 f (I)

The factor 2.7 will only hold good as the average of a
large number of cases. In extensive investigations dur-
ing three consecutive years, Van Slyke* found that the
number of pounds of green cheese obtained for each
pound of fat in the milk varied from 2.51 to 3.06, the
average figures for the three years 1892- '94, inclusive,
being 2.73, 2.71, and 2.72 Ibs., respectively. The richer
kinds of milk will produce cheese richer in fat, and
will yield a relatively larger quantity of cheese, pound
for pound, than poor milk, for the reason that an in-
crease in the fat content of milk is accompanied by an
increase in the other cheese-producing solids of the
milk.2 The preceding formula would not, therefore, be
correct for small lots of either rich or poor milk, but
only for milk of average composition, and for large
quantities of normal factory milk. For cured cheese
the factor will be somewhat lower, viz., about 2.6, on
the average.

224. b. From solids not fat and fat. If the percent-
ages of solids not fat and of fat in the milk are known,
the following formula by Babcock will give close results :

Yield of green cheo?=1.58 (f +.91 f) . . (II)

1 N. Y. experiment station (Geneva), bulletins 65 and 82.

2 Investigations as to the relation between the quality of the milk
and the yield of cheese have been conducted by a number of experi-
ment stations; the following references give the main contributions
published on this point; N. Y. (Geneva) exp. station, reports 10-18, inch;
Wis. exp. sta., reports 11 and 12; Ont. Agr. College, reports 1894-'96, incl.;
Minn. exp. sta., b. 19, reports 1892-'94, incl.; Iowa exp. sta., bull. 21;
Hoard's Dairyman, 1892, p. 2400.

200 Testing Milk and Its Products.

s being the per cent, of solids not fat in the milk, and /
the per cent, of fat.1

The solids not fat can be readily ascertained from the
lactometer reading and the per cent, of fat, as shown on
p. 106, by means of Table VI in the Appendix.

Table XIII in the Appendix gives the yield of cheese
from 100 Ibs. of milk containing from 2.5 to 6.0 per
cent, fat, the lactometer readings of which range be-
tween 26 and 36. By means of this table cheese makers
can calculate very closely the yields of cheese which
certain quantities of milk will make; as it takes into
consideration the non-fatty solids as well as the fat of
the milk, the results obtained by the use of this formula
will be more correct than those found by means of
formula (I). The uncertain element in the formula lies
in the factor 1.58, which is based on an average water
content of 37 per cent, in the green cheese. This may,
however, be changed to suit any particular case, e..g.,
35 per cent. (^^1.54), 40 per cent. yV°=l-67, etc.
The average percentages of water in green cheese found
by Van Slyke in his investigations referred to above,
were for the years 1892- '94, respectively, 36.41, 37.05
and 36.70 per cent.

225. c. From casein and fat. If the percentages of
casein and fat in the milk are known, the yield of cheese
may be calculated by the following formula, also pre-
pared by Dr. Babcock:

Yield of cheese=l.l f+2.5 casein .... (III).

This formula will give fairly correct results, but no
more so than formula (II) ; it is wholly empirical.

l For derivation of this formula, see Wisconsin experiment station.
twelfth report, p. 105.

Calculation of Butter- and Cheese Yield. 201

Questions.

1. What is the average composition of American creamery
butter, and between what extremes does the composition of butter
vary ?

2. What is the difference between the churn yield and the re-
sults obtained by the Babcock test?

3. What does the overrun represent?

4. Mention several factors that cause a large overrun.

5. Give an illustration of how the per cent, of increase of
churn over test is found, and how the overrun is calculated.

6. Show by an example that butter containing 20% fat can-
not give an overrun of more than 25%.

7. How many pounds of butter containing 80% fat can be
made from 100* Ibs. fat?

8. Why is the overrun from cream greater than from milk?

9. What is the overrun when 70.5 Ibs. of butter are made
from 140 Ibs. of milk, testing 3.15 per cent?

10. What is the overrun in each of the following cases?

220 Ibs. butter from 8000 Ibs. milk, testing 2.3% fat.
250 Ibs. butter from 4000 Ibs. milk, testing 5.8% fat.
600 Ibs. butteir from 2000 Ibs. cream, testing 25.0% fat.
480 Ibs. butter from 1000 Ibs. cream, testing 40.0% fat.

11. How much butter containing (a) 80% fat and (b) 82.5%
fat can be made from 3250 Ibs. milk, testing 4.3% fat, assum-
ing that the skim milk is 80% of the whole milk and contains
0.1% fat, and the butter milk, which is the cream minus the fat,
contains 0.25% fat? What is the overrun in each case?

12. How much butter is obtained from 5800 Ibs. milk, testing
3.7% fat, when the overrun is (a) 125% and (b) 16%?

13. Two cows in full milk produce, one 17.5 Ibs. of milk a day,
containing 4.35% fat; the other. 27.3 Ibs. of milk, testing 3.4%.
If the milk of both is made into butter or cheese, what may be
expected from each one in a week?

14. What is a fair percentage of loss of fat by waste other
than in skim milk and butter milk under average creamery con-
ditions?

15. How much butter may be made from (a) 15,640 Ibs. milk,
testing 3.8% fat, and (b) 35 842 Ibs. milk, testing 4.1% fat?
(Use Table XT, Appendix.}

16. How can the per cent, of fat in butter be determined
without making a test of it?

17. How may the yield of cheese from milk of any known test
be approximately calculated?

18. How many pounds of cheese can be made from 3570 Ibs.
milk, testing 3.5% fat and having a lactometer reading of 32 5
at 67° F.? (Use Table XIII, Appendix.)

CHAPTEE XIII.
CALCULATING DIVIDENDS.

226. The simplest method of calculating dividends at
creameries is to base the calculations on the amount of
butter fat delivered by the various patrons. Each lot
of milk is weighed when delivered at the creamery, and
a small quantity thereof is. saved for the composite sam-
ple, as previously explained under Composite Tests
(180). Some creameries test these samples at the end
of each week, and others after collecting them for ten
days or two weeks. If the four weekly composite sam-
ples of a patron's milk tested 3.8, 4.0, 3.9, 4.1 per cent ,
these four tests are added together, and the sum divided
by 4; the result, 3.95 per cent., is used as the average
test of this milk. Py multiplying the total number of
pounds of milk delivered by this patron, by his average
test, the total weight in pounds of butter fat delivered
to the factory during the month is obtained. This
weight of fat is then multiplied by the price to be paid
by the creamery per pound of butter fat; the product
shows the amount of money due this patron for the milk
delivered during the time samples were taken.

227. Price per pound of butter fat. The method of
obtaining the price to be paid for one pound of butter
fat varies somewhat in different creameries, on account
of the different ways of paying for the cost of manu-
facturing the hnttor. The method to be followed is

Calculating Dividends. 203

generally determined by agreement between the manu-
facturer and the milk producers, in case of proprietary
creameries, or among the shareholders, in co-operative
creameries. The following methods of paying for the
cost of manufacture are at the present time met with
in American creameries.

228. I. Proprietary creameries. First. — When the
creamery is owned by some one person or company, the
owner or owners agree to make the butter for about 3
cents a pound; the difference between the total receipts
of the factory and the amount due the owner is then
divided between the different patrons, according to the
amount of butter fat contained in the milk which they
delivered.

In the majority of cases, the price charged for making
butter is now 3 cents a pound; 2% and 2y2 cents are
sometimes charged. The larger the amount of milk re-
ceived at a factory, the lower will naturally be the cost
of manufacturing the butter.1

Second.— The proprietor of the creamery sometimes
agrees to pay a certain price for 100 Ibs. of milk deliv-
ered, according to its fat content, the price of milk con-
taining 4 per cent, of butter fat being the standard.
This price may change during the different seasons of
the year by mutual agreement.

Third.— A creamery owner may offer to pay 1 to 2
cents, usually li/o cents, below the average market price
of butter, for each pound of butter fat received in the
milk.

1 Bull. 56, p. 26, Wisconsin exp. station; see Report 18, Iowa State
Dairy Commissioner, p, 33,

204 Testing Milk and Its Products.

229. II. Co-operative creameries. In this case, where
the creamery is owned by the patrons, one of the stock-
holders who is elected secretary attends to the details of
running the factory and selling the product. His ac-
counts show the amount of money received each month
for the butter and other products sold, and the expenses
of running the factory during this time. The expenses
are subtracted from the receipts, and the balance is
divided among the patrons, each one receiving his pro-
portionate share according to the amounts of butter fat
delivered in each case, as shown by the total- weight and
the average test of milk delivered during this time.

In nearly all cases, the farmers receive about eighty
pounds of skim milk for each one hundred pounds of
whole milk they deliver to the factory, in addition to
the amount received for the milk, calculated according
to one or the other of the preceding methods.

230. Illustrations of calculations of dividends. Tn order
to illustrate the details of calculating dividends, or the amount
to be paid each patron for the milk supplied each month, when
payments are made by each of the four systems given, it will be
assumed that a creamery receives 5000 pounds of milk daily for
thirty days, and makes 6650 Ibs. of butter from the 150,000 Ibs.
of milk received during this time. Thet average test of this milk
may be found by multiplying the total weight of milk delivered
by each patron by his average test, and dividing the sum of
those products by the total weight of milk received at the cream-
ery (in the example given, by 150.000), the quotient being mul-
tiplied by 100. Such calculations may show that, e. g., 5700 Ibs.
of butter fat have been received in all the milk delivered by the
different patrons; this multiplied by 100 and divided by 150,000
gives 3.8 as the average test, or the average amount of butter
fat in each 100 Ibs. of milk received during the month.

So far the method of calculation is common for all different
systems of payment given above; the manner of procedure now

Calculating Dividends.

205

differs according to the agreement made between owner and
patrons, or among the shareholders, in case of co-operative
creameries.

231. I. First. — If the net returns for the 6650 Ibs. of butter
sold during the month were $1197, and the creamery is to re-
ceive 4 cents per pound of butter as the cost of manufacture,
etc., the amount due the creamery is 6650X.04=$266, and the
patrons would receive $1197— $266=$931. This sum, $931, is to
be paid to the patrons for the 5700 Ibs. of butter fat, which, as
shown above, was the weight of fat contained in the 150,00.0 Ibs.
of milk delivered during the month. The price of one pound of
butter fat is then easily found: $931-f-5700=16% cents. This
price is paid to all patrons for each pound of butter fat deliv-
ered in their milk during the month. The monthly milk record
of three patrons may, e. g., be as given in the following table:

First

Second

Third

Fourth

"M .

week

Tot'l

a o

Milk
Ibs.

Test
per
cent.

Milk
Ibs.

Test
per ct.

Milk
Ibs.

Test
per
cent.

Milk
Ibs.

Test
per ct.

Milk

Ibs.

No. 1

3500

3.6

3000

3.5

3600

3,65

3450

3.45

13,550

3.55

No. 2....

700

3.8

665

3.8

720

3.6

750

3.7

2,825

3.73

No. 3....

2480

4.2

2000

3.8

1850

4.0

1500

3.6

7,830

3.90

Multiplying each patron >s total milk by his average test gives
the number of pounds of butter fat in his milk, and this figure
multiplied by .16% shows the money due for his milk, "as given
below:

Patron

Total
milk
Ibs.

Average
test,
per cent.

Butter fat
tt>s.

Price of fat
per lb., cents

Amount
due

No. 1...
No. 2
No. 3

13,550
2,825
7 830

3.55
3.7
3 9

481.0
104.5
305 4

16%
16%
16 H

$78.56
17.06

48 87

232. Second. — When the proprietor of a creamery agrees to
pay a certain price for 100 Ibs. of 4 per cent, milk, the receipts
for butter sold and the price per pound of butter do not enter
into the calculation of the amount due each patron for his milk;

206

Testing Milk and Its Products.

but the weight and the test of each patron's milk are as im-
portant as before. If it is agreed to pay 66 cents per 100 Ibs.
of 4 per cent, milk (i. e., milk containing 4 per cent, of butter
fat), the price of one pound of butter fat will be 66-^-4=16%
cents, and the amount due each patron is found by multiplying
the total weight of butter fat *fn his milk by this price. To
facilitate this calculation, so-called Relative-Value Tables have
been constructed, the use of which is explained below (238).

233. Third. — If a creamery- agrees to pay for butter fat, say
iy2 cents per pound below tl*e average market price of butter
each month, the price of one" pound of butter fat is found by
averaging the market quotations and subtracting 1% cents there-
from. If the four weekly market prices were 17%, 17, 16% and
19 cents, the average of these would be 17% cents, and this less
1% gives 16 cents as the price per pound of fat to be paid to
the patrons; this price is then used in calculating the dividend
as in case of first method (231).

Patron

Total
milk
tt>s.

Average
te*st,
percent.

Butter fat
tt>s.

Price of fat,
pr. lb., cents

Amount
due

No. 1...

13,550

3.55

481.0

$76.96

No. 2...
No. 3

2,825
7,830

3.7

3.9

104.5
305.4

16
16

16.72

48.86

234. II. If the creamery is owned by the farmers, the run-
ning expenses for a month are subtracted from the gross returns
received for the butter, and the price to be paid per pound of
butter fat is found by dividing the amount left by the total
number of pounds of butter fat delivered during the month.
This price is used for paying e.ach patron for his milk according
to the amount of fat contained therein, as already explained un-
der Proprietary Creameries (231).

The monthly running expenses of a co-operative creamery gen-
erally include such items as the wages of the butter maker (and
manager or secretary, if these officers are salaried), labor (haul-
ing, helper, etc.), cost of butter packages, coal or wood, salt
and other supplies, freight and commission on the butter sold,
repairs and insurance on buildings, etc. A certain amount is
also paid into a sinking fund (say, 5 cents per 100 Ibs. of milk),

Calculating Dividends. 207

which represents the depreciation of the property, wear and tear
of building and machinery, bad debts, etc. These items are
added together, and their sum subtracted from the gross receipts
for the butter sold during the month.

235. Assuming the receipts for the butter during the month
to be $1197, and the running expenses of the factory $285, the
amount to be divided among the patrons is $912; the quantity
of butter fat received was 5700 Ibs., and the price per pound of
butter fat will therefore be 16 cents. The account will then
stand as given in (233).

236. Other systems of payment. Besides these four
systems of payment, there are various other agreements
made between manufacturer and producer, but with
them all the one important computation is the price to
be paid per pound of butter fat ; this forms the b^sis of
calculating the factory dividends, when milk is p. .d for
by the Babcock test.

237. Paying for butter delivered. In some instances
patrons desire to receive pay for the quantity of butter
which the milk delivered by them will make. This can
be ascertained quite accurately from the total receipts
and the total weights of both butter fat and butter. The
total money to be paid for butter (the net receipts) are
divided by the number of pounds of butter sold, to get
the price to be paid per pound of butter; the total yield
of butter divided by the total amount of butter fat de-
livered in the milk, gives the amount of butter corre-
sponding to one pound of butter fat, and the number of
pounds of fat delivered by each patron is then multi-
plied by this figure. This method requires more figur-
ing than those given in the preceding, and the dividends
are no more accurate, in fact less so, than when calcula-
tions are based on the price per pound of fat.

208 Testing Milk and Its Products.

238. Relative-value tables. These tables give many
of the multiplications used in computing the amount
due for various weights of milk testing from 3 to 6 per
cent, of fat. They can easily be constructed by any one
as soon as the price of one pound of fat is determined
in each case. If the price to be paid per pound of fat
is, say 15 cents, the value of each 100 Ibs. of milk of
different quality is found by multiplying its test by 15.
If the average tests of the different patrons' milk vary
from 3 to 5 per cent., the relative-value table would be
as follows.

3.0X15=45c. per 100 Ibs.

3.lXl5=46.5c.

3.2Xl5=48c.

3.3X15r=49.5c.

3.4X15=51c.

3.5X15=52.5c.

3.6Xl5=54c. per 100 Ibs.
3.7Xl5=55.5c. "
3.8Xl5=57c. "

3.9Xl5=58.5c. "
4.0Xl5=60c. "

etc.

By continuing this* multiplication, or adding the mul-
tiplier each time for each tenth of a per cent, up to 5
per cent, of fat, a table is made that can be used for
calculating the amount due per 100 Ibs. of milk, at this
price per pound, and the weight of milk delivered by
each patron is multiplied by the price per 100 Ibs. of
milk shown in the table opposite the figure representing
his test.

Example: A patron supplies 2470 Ibs. of milk, testing 3.2
per cent, of fat; price per pound of fat, 15 cents; he should
then receive 24.70X.48=$11.85 (see above table). Another pat-
ron delivering 3850 Ibs. of milk testing 3.8 per cent, will re-
ceive, at the same price per pound of fat, 38.50X.57=$21.94.

The relative-value tables in the Appendix give the
price per 100 Ibs. of milk testing between 3 and 6 per
cent, fat, when the price of three per cent, milk varies
from 30 to 90c. per 100 Ibs. In using the tables, first

Calculating Dividends.

209

find the figure showing the price which it has been de-
termined to pay for 100 Ibs. of milk of a certain qual-
ity, say 3 or 4 per cent.-milk; the figures in the same
vertical column then give the price to be paid per 100
Ibs. of milk testing between 3 and 6 per cent.

Example 1: It has been decided to pay 90 cents per 100 Ibs.
of 4 per cent.-milk. The figure 90 is then sought in the table in
the same line as 4.0 per cent., and the vertical column in which
it is found gives the price per 100 Ibs. of 3 to 6 per cent.-milk,
3.8 per cent.-milk is thus worth 85 cents per 100 Ibs. and 4.5 per
cent.-milk, $1.01, under the conditions given. The prices of milk
of other qualities are found in the same way.

Example 2: In the example referred to under Illustrations of
calculating creamery dividends (I b, 231), the figures for the
patrons Nos. 1, 2 and 3, would be as follows:

Patron

Milk delivered,
Ibs.

Average
test,
per cent.

Price per 100 Ibs.
of milk, cents

Amount
due

No. 1

13,550

3 55

58 5

$79.26

No. 2
No. 3

2,825
7,830

3.7
3 9

61.0
64 0

17.23
50 XI

239. Milk- and cream dividends^ When cream from
farm hand separators or ether sources is brought to a
factory receiving and skimming whole milk, the cream
patron's dividend should be calculated a little differ-
ently than that of the milk patron.

In one case the dividend is based on the weight and
the test of cream and in the other on the weight and
the test of milk; the difference between the two being
represented by the fat left in the factory skim milk.
This skim milk fat is included in the milk patron's
dividend and consequently ought also to be allowed for
in calculating the amount due the cream patron. Such

210 Testing Milk and Its Products.

an allowance can be fairly made by multiplying the
cream fat by 1.03. This is assuming that the one-tenth
or more of fat returned to the milk patron in his skim
milk is about three per cent, of the total fat in his whole
milk.

Both milk and cream patron suffer the same manu-
facturing losses in the butter milk so that an equaliza-
tion of the skimming losses is all that is necessary in
order to put both on a uniform basis for calculating
dividends.

240. The following illustration will help to make these cal-
culations clearer. Milk patron No. 1 delivers to the creamery
during the month 5320 Ibs. of milk testing 3.8 per cent, fat,
which therefore contains (^*f>8) =202 Ibs. butter fat. If the
price paid the patrons is 20c., then the 202 lbs.X20c. amounts to
$40.40, the money due this patron for his milk. If another pat-
ron sent 485 Ibs. of cream testing 22.0 per cent, fat to the same
factory during the month, the weight of fat in the cream is first
found in the same way as in the milk. ^85X2A =106.7 Ibs. but-
ter fat. Now, instead of multiplying this butter fat by 20c., as
was done for the whole milk patron, it must first be multiplied
by 1.03, which makes the necessary allowance for the skim milk
fat that the milk patron was paid for. 106.7X1.03=109.9 Ibs.
butter fat which is now multiplied by 20c. per pound, giving
$21.98. This is the amount due the cream patron when both
milk and cream are received at the same factory and the cream
from both patrons is churned together.1

B.— CALCULATING DIVIDENDS AT CHEESE FACTORIES.

241. The amount of cheese made from a certain quan-
tity of milk depends, as before shown, in a large meas-
ure on the richness of the milk in butter fat (223).
Rich milk will give more cheese per hundred weight

1 17th report Wis. exp. station, p. 90; 20th report, pp. l;JO-l:U.

Calculating Dividends. 211

than poor milk, and within the ordinary limits of nor-
mal factory milk the increased yields will be nearly, but
not entirely, proportional to the fat contents of the dif-
ferent kinds of milk. Since the quality of the cheese
produced from rich milk is better than that of cheese
made from thin milk and will demand a higher price,
it follows that no injustice is done by rating the value
of milk for cheese production by its fat content. This
subject was discussed frequently during the nineties in
experiment station publications and in the dairy press
(223). Among others, Babcock has shown that the price
of cheese stands in a direct relation to its fat content.1
Prof. Eobertson, ex-Commissioner of Agriculture of Can-
ada, is authority for the statement that the quality of
the cheese made from milk containing 3.0 to 4.0 per
cent, of fat was increased in value by one-eighth of a
cent per pound for every two-tenths of a per cent, of
fat in the milk,2 a figure which is fully corroborated by
Dr. Babcock 's results. The injustice of the "pooling
system/7 by which all kinds of milk receive the same
price, is evident from the preceding; if the milk of a
certain patron is richer than that of others, it will make
a higher grade of cheese, and more of it per hundred-
weight; hence a higher price should be paid for it.

Payment on the basis of the fat content of milk is,
therefore, the most equitable method of valuing milk
for cheese making, and in case of patrons of cheese fac-
tories as with creamery patrons, dividends should be
calculated on the basis of the results obtained by test-

1 Wisconsin exp. station, llth report, p. 134.

2 Hoard's Dairyman, March 29, 1895.

212 Testing Milk and Its Products.

ing the milk delivered.1 The testing may be conven-
iently arranged by the method of composite sampling,
in the way already described for creameries (180).

242. Calculation of dividends. As with creameries,
the price to be paid per pound of butter fat must first
be ascertained. The factory records should show the
number of pounds of cheese made from the total milk
delivered to the factory during a certain time, generally
one month, and the money received for this cheese. The
cost of making the cheese and all other expenses that
should be paid for out of the money received for the
cheese, are deducted from the total receipts, and the
difference is divided among the patrons in proportion
to the amounts of butter fat delivered in the milk.

The weights of the milk delivered and the tests of the
composite samples furnish data for calculating the
quantities of butter fat to be credited to each patron.
The money to be paid to the patrons is then divided by
the total weight of butter fat delivered to the factory
and the price of one pound of fat thus obtained. The
money due each patron is now found by multiplying
the total number of pounds of butter fat in his milk by
this price per pound.

The illustrations already given for calculating patrons'
dividends at creameries according to the various meth-
ods will serve equally well to show the manner in which

1 Prof. Dean of Quelph (Ont.) agricultural college advocates adding
2 to the per cent fat in the milk in calculating the money due patrons
for milk delivered- at cheese factories. This method has IMM-II adopted
at many Canadian cheese factories and also at some factories in this
country. (Bull. 114, Ont. agr, college; Dean, Canadian Dairyman, p, 1N'>.)

Calculating Dividends.

213

dividends are calculated at a cheese factory. For the
sake of clearness an example is given that applies di-
rectly to cheese factories.

243. Illustration of calculation of dividends. It may be

assumed that 15,000 libs, of green cheese is made from 150,000
Ibs. of milk delivered to a factory in a Inonth. According to the
weighings and the tests made, the milk contained 5,700 Ibs. of
butter fat. If thei cheese sold at an average price of 7^ cents
a pound, the gross receipts would be $1,125.00. The amount to
be deducted from the gross receipts will depend on the agree-
ment made between the factory operator and the patrons, in
case of proprietary cheese factories, or between the shareholders
and the maker, when the factory is run on the co operative plan.
As before we shall consider these systems separately.

244. I. Proprietary cheese factories. The owner of the
factory generally agrees to make the cheese for a certain price
per pound and to pay the patrons what is left after deducting
this amount. If the price agreed on is 1^ cents per pound of
green cheese, this would amount to $225 in the example given.
Subtracting this sum from the gross receipts, $1,125, leaves $900,
which is to be paid the patrons. The total amount of butter fat
delivered by the patrons was 5,700 Ibs.; hence the price of one
pound of butter fat will be 900-^5.700=.1577, or 15.8 cents.
Taking the figures for the three patrons already mentioned un-
der Creamery Dividends, we then have:

Patron

Total milk,
Ibs.

Average
test,
per cent.

Butter fat,
Ibs.

Price per
lb. of fat,
cents

Amount
due

No. 1...
No. 2
No. 8

13,550
2,825
7,830

3.55
3.7
3.9

481.0
104.5
305.4

15.8
15.8
15.8

$76.00
16.51

48.25

245. II. Co-operative cheese factories. The method of pay-
ment at co-operative cheese factories is nearly the same as that
already given, except that a certain sum representing the ex-
penses is subtracted from the gross receipts for the cheese, and
the balance is divided among the patrons according to the amount

214 Testing Milk and Its Products.

of butter fat furnished by each, in the same manner as in the
above case, after the price of a pound of fat has been obtained.
The price per 100 Ibs. of milk can be calculated in the same
way as at creameries, by multiplying the test of each lot by the
price per pound of fat.1

Questions.

1. How much money is due each of three patrons of a cream-
ery when the following weights of milk are delivered by each:

A — 5750 Ib. milk, composite tests, 4.0 — 4.8 — 4.2 per cent.
B — 955 Ib. milk, composite tests, 4.6 — 5.0 — 4.8 per cent.
C — 10,538 Ib. milk, composite tests, 3.2—3.5—3.0 per cent.

(a) When 700 Ibs. of butter are sold for $200, and the cost of
making is 3%c. per Ib;

(b) When the factory agrees to pay $1.00 per 100 Ibs. milk,
testing 4% fat;

(d) When the factory agrees to pay 23c. per pound for butter
and to give a 14% overrun?

2. How much is due a milk patron and a cream patron at the
same factory when the milk patron has delivered 875 Ibs. of
milk, testing 3.9% fat and the cream patron 380 Ibs. cream, test-
ing 26% fat; the factory selling 160 Ibs. of butter at 28c. per
Ib., and charging 3c. per Ib. for making?

3. How much is due patrons A, B, C, in question 1, if 1800
Ibs. of cheese were made and sold for $200.00 and the cost of
making the cheese is l^c. per Ib.?

4. When cheese seflls for 10 cents per Ib., what must the price
of butter be to pay the same price for milk, the cost of making
being l1/^ cents per Ib. of cheese, and 4 cents per Ib. for butter?

1 Suggestions regarding the organization of co-operative cr< ;nu-
eries and cheese factories will be found in the Appendix, following
Table XV. Draft of constitution and by-laws for co-operative fnrtory
associations are also given in the Appendix. It is hoped that these will
prove helpful to farmers who contemplate forming such associations.

CHAPTER XIV.

CHEMICAL ANALYSIS OF MILK AND ITS
PRODUCTS.

246. An outline of the methods followed in determin-
ing quantitatively the main components of milk and its
products is given in the following for the guidance of
more advanced dairy students. This work cannot be
done outside of a fairly well-equipped chemical labora-
tory, or by persons who have not been accustomed to
handling delicate chemical apparatus and glassware,
analytical balances, etc., and who have not a knowledge
of, at least, the elements of chemistry and chemical
reactions.

A.— MILK.

247. In a complete milk analysis, the specific gravity
of the milk is determined, and the following milk com-
ponents: water, fat, casein and albumon, milk sugar,
and ash. The methods of analysis described in the fol-
lowing are those adopted by the Association of Official
Agricultural Chemists, which, with but slight modifica-
tions, are in general use in the chemical laboratories of
all American experiment stations and agricultural col-
leges.1

1 The complete methods of analysis adopted by the Association of
Official Agricultural Chemists are published by the Bur. of Chemistry
of the U. 8. Department of Agriculture; see Bull. No. 107, pp. 117-128.

216 Testing Milk and Its Products.

248. a. Specific gravity is determined by means of
a picnometer cr specific-gravity bottle, since more ac-
curate results will thus be reached than by using an or-
dinary Quevenne lactometer. A thermometer is ground
into the neck of the specific-gravity bottle so as to form
a stopper, and the bottle is provided with a glass-stop-
pered side-tube, to furnish an exit for the liquid on ex-
panding. A specific-gravity bottle holding 100 grams
of water is preferably used. The empty and scrupu-
lously cleaned bottle is first weighed on a chemical bal-
ance. The bottle is then filled with recently-boiled dis-
tilled water of a temperature below 60° F. (15.5° C.) ;
the thermometer is inserted, and the bottle is warmed
slightly by immersing it for a moment in tepid water
and left standing until the thermometer shows 60° F. ;
the opening of the side tube is then wiped off and closed
with the stopper, and the water on the outside of the
bottle and in the groove between its neck and the ther-
mometer is wiped off with filter paper or a clean hand-
kerchief, when the bottle is again weighed. The weight
being recorded, the bottle is emptied and dried in a
water oven, or if sufficient milk is at hand, the bottle is
repeatedly rinsed with the milk, the specific gravity of
which is to be determined. It is then filled with milk
in a vsimilar manner as in case of water ; the tempera-
ture of the milk should be slightly below 60° F. and is
slowly brought up to this degree after the bottle has
been filled, proceeding in the same way as before with
water ; the weight of the bottle and milk is then taken.

The weights of water and of milk contained in the
specific-gravity bottle are found by subtracting the

Chemical Analysis of Milk and Its Products. 217

weight of the empty bottle from the second and the
third weights, respectively, and the specific gravity of
the milk then found by dividing the weight of the milk
by that of the water.

Example: Weight of sp. gr. bottle-f-water . . .146.9113 grams.
Weight of sp. gr. bottle empty. . . 46.9423 grams.

Weight of water 99.9690 grams.

Weight of sp. gr. bottle+milk 149.8708 grams.

Weight of sp. gr. bottle empty. . . 46.9423 grams.

Weight of milk 102.9285 grams.

Sp. gr. of milk=:1-|^r=1.0296

249. If a plain picnometer without a thermometer attached,
is available, the method of procedure is similar to that described,
with the difference that the temperature of the water and of the
milk must be brought to 60° F. before the picnometer is filled,
or the picnometer filled with either liquid is placed in water in a
small beaker, which is very slowly warmed to 60° F. and kept at
this temperature for some time so as to allow the liquid in the
picnometer to reach the temperature desired; the temperature of
the water in the beaker is ascertained by means of an accurate
chemical thermometer. The perforated stopper is then wiped off,
the picnometer is taken out of the water, wiped and weighed. It
is necessary to weigh very quickly if the room temperature is
much above 60° F.. as in such cases the expanding liquid will
flow on to the balance pan, with a resultant loss in weight from
evaporation.

The weights of specific-gravity bottle or picnometer, empty
and filled with water, need only be determined a couple of times,
and the averages of these weighings are used in subsequent de-
terminations.

250. Westphal balance. Where only a small^ amount
of milk is available, or in rapid work, the specific grav-
ity may be taken with considerable accuracy by means
of a Westphal balance. The arrangement and use of
this convenient little apparatus is readily explained
verbally.

218 Testing Milk and Its Products.

For the determination of the specific gravity of lop-
pered milk, see 263.

251. b. Water. The milk is weighed into a perfor-
ated copper tube filled with prepared dry asbestos. The
tubes are made from perforated sheet copper, with holes
about .7 mm. in diameter and about .7 mm. apart ; they
are 60 mm. long, 20 mm. in diameter and closed at the
bottom. The asbestos is prepared from clean fibrous
asbestos, which is ignited at low heat in a muffle oven,
treated with a little dilute HC1 (1:3) and then with
distilled water till all acid is washed out; it is then
torn in loose layers and dried at a low temperature in
an air bath ; when dry it can be easily shredded in fine
strings and is placed in a wide-mouth, glass-stoppered
bottle.

About two grams of asbestos are placed in each tube,
packing it rather loosely; the tube is then weighed, a
small narrow beaker being inverted over it on the scale
pan. 5 cc. of milk are now dropped on to the asbestos
from a 5 cc. fixed pipette, the beaker again placed over
the tube, and the weight of the 5 cc. of milk delivered
+copper tube taken. The weight of the milk is ob-
tained by difference. The tubes are then placed in a
steam oven and heated at 100° C. until they no longer
decrease in weight, which ordinarily will take about
three hours. Place in a desiccator until cold, and weigh ;
the difference between the weight of the tube-fmilk and
this last weight gives the water contained in the milk,
which is then calculated in per cent, of the quantity of
milk weighed out.

Chemical Analysis of Milk and Its Products. 219

Example: Weight of tube-fbeaker+milk ---- 29.3004 grams.
Weight of tube-fbeaker .......... 24.1772 grams.

Milk weighed out .......... 5.1232 grams.

Weight of tube+beaker+milk ____ 29.3004 grams.

Weight of tube+beaker+milk,dry 24.9257 grams.

Weight of water ........... 4.3747 grams.

Per cent, of water in milk— — 85.39 per cent.

O. 12t)jS

Note. The per cent, of total solids in milk is often
given, instead of that of water; this may be readily ob-
tained by subtracting the weight of the empty tube
from that of the tube filled with milk solids, and finding
the per cent, of the milk weighed out which this differ-
ence makes. In the above example, the weight of milk
solids thus is 24.9257— 24:1772=7485 gram, and the
per cent, of total solids in the milk=14.61 per cent.

252. Alternate Method. Five cc. of milk are measured out
on a weighed flat porcelain dish (50-60 mm. in diameter; porce-
lain crucible covers will answer the purpose better than any
other vessel on the market, if the handles be broken off or ground
off level on an emery wheel) ; this is weighed rapidly; two or
three drops of 30 per cent.-acetic acid are added, and the dish
is dried in a steam oven at 100° C. until no further loss in
weight is obtained. After cooling in a desiccator, the weight of
the milk solids is obtained, and by calculation as before, the per
cent, of water or total solids in the milk.

253. c. Fat. The dried tubes from the water deter-
mination are placed in Caldwell extractors and con-
nected with weighed, numbered glass flasks (capacity,
2-3 oz.) ; the extractors are attached to upright Liebig
condensers and the tubes extracted with pure ether,
free from water, alcohol or acid, until all fat is dis-
solved; 4-5 hours' extraction is sufficient for whole
milk ; in case of samples of skim milk it is well to con-
tinue the extraction for 8 hours. The ether is then dis-

220 Testing Milk and Its Products.

tilled off -and recovered, and the flasks dried in a cop-
per oven until constant weight; after cooling they are
weighed and the amount of fat contained in the quan-
tity of milk originally weighed into the tubes is thus
ascertained, and the per cent, present in the milk cal-
culated.

Example: Weight of flask + f at ............. 15.8039 grams.

Weight of flask ................. 15.5171 grams.

Weight of fat ............... 2868 gram.

Milk weighed out ............................. 5.1232 grams.

Per cent, of fat in milk==5.60 per cent.

5. 12oz

254. The Gottlieb method for the determination
of fat.1 10 cc. of milk are measured into a glass cyl-
inder, % inch in diameter and about 14 inches long (a
100 cc. burette or a Eudiometer tube will do) ; 1 cc.
cone, ammonia is added and mixed thoroughly with the
milk; the following chemicals are next added in the
order given: 10 cc. of 92 per cent, afcohol, 25 cc. of
washed ether, and 25 cc. petroleum ether (boiling pt.,
below 80° C.), the cylinder being closed with a moist-
ened cork stopper and the contents shaken several times
after the addition of each. The cylinder is then left
standing for six hours or more. The clear fat solution
is next pipetted off into a small weighed flask, by means
of a siphon drawn to a fine point (see fig. 6, loc. cit.),
which is lowered into the fat solution to within 1/2 cm-
of the turbid bottom layer. After evaporating the ether
solution in a hood, the flasks are dried in a steam oven
for two to three hours, and weighed. This method is
applicable to new milk, skim milk, butter milk, whey,

1 Landw. Vers. Sta., 40 (1892), pp. 1-27. The method is also spoken of
as the Rose-Gottlieb method.

Chemical Analysis of Milk and Its Products. 221

cream, cheese, condensed milk and milk powder, but has
been found of special value for determining fat in skim
milk, butter milk, cheese, and condensed milk. In the
case of products high in fat, a second treatment with
10 cc. each of ether and petroleum is advisable in order
to recover the last traces of fat.

255. d. Casein and albumen. The sum of these com-
ponents is generally determined by the Kjeldahl
method.1 5 cc. of milk are measured carefully into a
flat-bottom 800 cc. Jena flask, 20 cc. of concentrated sul-
furic acid (C. P. ; sp. gr., 1.84) are added, and .7 gram
of mercuric oxid (or its equivalent in metallic mer-
cury) ; the mixture is then heated over direct flame
until it is straw-colored or perfectly white; a few crys-
tals of potassium permanganate are now added till the
color of the liquid remains green. All the nitrogen in
the milk has then been converted into the form of am-
monium sulfate. After cooling, 200 cc. of ammonia-
free distilled water are added, 20 cc. of a solution of
potassium sulfid (containing 40 grams sulfid per liter),
and a fraction of a gram of powdered zinc. A quan-
tity of semi-normal HCl-solution, more than sufficient
to neutralize the ammonia obtained in the oxidation of
the milk, is now carefully measured out from a delicate
burette (divided into -fa cc.) into an Erlenmeyer flask,
and the flask connected with a distillation apparatus.
At the other end, the Jena flask containing the watery
solution of the ammonium sulfate is connected, after
adding 50 cc. of a concentrated soda solution (1 pound
"pure potash" dissolved in 500 cc. of distilled water

1 Fresenius' Zeitschrift, 22, p. 366; U. S. Dept. Agr., Bur. of Ohem.,
Bull. 107, p. 5.

222 Testing Milk and Its Products.

and allowed to settle) ; the contents of the Jena flasks
are now heated to boiling, and the distillation is contin-
ued for forty minutes to an hour, until all ammonia
has been distilled over.

The excess of acid in the Erlenmeyer receiving-flask
is then accurately titrated back by means of a tenth-
normal standard ammonia-solution, using a cochineal-
solution1 as an indicator. From the amount of acid
used, the per cent, of nitrogen is obtained; and from it,
the per cent, of casein and albumen in the milk by mul-
tiplying by 6.25.2 The amount of nitrogen contained in
the chemicals used is determined by blank experiments
and deducted from the nitrogen obtained as described.

Example: The weight of 5 cc. of milk (as obtained in deter-
mining the water in the milk) was 5.1465 grams. 5 cc. of stand
ard HC1 are added to the receiver, and 1.55 cc. of - - alkali-
solution are used in titrating back the excess of acid. 1.55 cc.

of -^- alkali=^^=.31 cc. — acid-solution; the ammonia dis-

10 5

tilled over therefore neutralized 5.00 — .31=4.69 cc. acid. By

blank trials it was found that the reagents used furnished an
equivalent of .02 cc. acid in the distillate; this quantity sub-
tracted from the acid-equivalent of the nitrogen of the milk
leaves 4.67 cc. 1 cc. semi-normal HCl-solution corresponds to
7 milligrams or .007 gram of nitrogen; 4.67 cc. -^-HCl therefore
represents .03269 gram of nitrogen. The quantity of nitrogen
was obtained from the 5.1465 grams of milk measured out; the
milk therefore contains i^^^-=.635 per cent, of nitrogen, and
.635X6.25=3.97 per cent, of casein and albumeto.

256. Casein and albumen may be determined sepa-
rately by Van Slyke's method;3 10 grams of milk are

1 Sutton, Volumetric Analysis, 4th edition, p. ttl.

2 The factor 6.30 or 6.37 is more correct for the albuminoids of milk,
but has not yet been generally adopted (p. 15, foot note>.

8 Bulletin 107, p. 117, Bur. of Ohem., U. S. Dept. of Agriculture.

Chemical Analysis of Milk and Its Products. 223

weighed out and diluted with about 90 cc. of water at
40°-42° C. 1.5 cc. of a 10 per cent, acetic-acid solution
are then added ; the mixture is well stirred with a glass
rod and the precipitate allowed to settle for 3-5 min-
utes. The whey is decanted through a filter and the
precipitate washed two or three times with cold water.
The nitrogen is determined in the filter paper and its
contents by the Kjeldahl method; blank determinations
with the regular quantities of chemicals and the filter
paper used are made, and the nitrogen found therein
deducted. The per cent, of nitrogen obtained multi-
plied by 6.25 gives the per cent, of casein in the milk.

257. Albumen is determined in the filtrate from the
casein-precipitate ; the filtrate is placed on a water bath
and heated to boiling temperature of water for ten to
fifteen minutes. The washed precipitate is then treated
by the Kjeldahl method for the determination of nitro-
gen; the amount of nitrogen multiplied by 6.25 gives
the amount of albumen in the milk. The difference be-
tween the total nitrogenous components found by the
Kjeldahl method, arid the sum of the casein and the
albumen, as given above, is due to the presence in milk
of a third class of nitrogen compounds (18).

258. Hart's test for casein in milk. The folllowing
test for casein in milk has been published by the Wis-
consin experiment station r1

Two cc. of chloroform, 20 cc. of a .25 per cent, solu-
tion of acetic acid, and 5 cc. of milk (both these latter
of a temperature of about 70° F.) are measured into
small tubes of special construction holding about 35 cc.,

1 Report 24, p. 117: "A simple method for the estimation of casein
in cow's milk," by E. B. Hart.

224 Testing Milk and Its Products.

the lower end of which is narrow and graduated to
.1 cc. The mixture is shaken for 10 to 20 minutes and
the tubes then whirled 7y2 or 8 minutes in a centri-
fuge of 15 inches diameter, making 2000 revolutions per
minute. (The use of a metronome is recommended to
facilitate the control of the speed.) After whirling,
the tubes are taken out of the centrifuge and allowed
to stand for 10 minutes, and the percentage of casein
read off directly from the scale on the lower end of the
casein when 5 cc. of milk are measured out. The test
tubes, each division of which represents .2 per cent, of
casein when 5 cc. of milk are measured out. The test
calls for considerable nicety of manipulation, but ap-
pears to give reliable results when properly conducted.

259. e. Milk sugar is generally determined by differ-
ence, the sum of fat, casein and albumen (totalNX6.25),
and ash, being subtracted from the total solids. It may
be determined directly by means of a polariscope, or
gravimetrically by Fehling's solution; only the former
method, as worked out by Wiley,1 will be given here.

The specific gravity of the milk is accurately deter-
mined, and the following quantities of milk are meas-
ured out -by means of a 100 cc. pipette graduated to .2
cc. (or a 64 cc. pipette made especially fcr this purpose,
with marks on the stem between 63.7 and 64.3 cc.), ac-
cording to the specific gravities given : 1.026, 64 3 ce. :
1.028, 64.15 cc.; 1.030, 64.0 cc.; 1.032, 63.9 cc.; 1.034,
63.8 cc.; 1.036, 63.7 cc. These quantities refer to the
Schmidt-Haensch half-shadow polariscopes, standard-
ized for a normal weight of 26.048 grams of sugar. The
milk is measured into a small flask graduated at 100 cc.

i Agricultural Analysis, ill, p. 275; Am. Ohem. Jour., 6, p. 289 et seq.

Chemical Analysis of Milk and Its Products. 225

and 102.6 cc. ; 30 cc. of mercuric-icdid solution (pre-
pared from 33.2 grams potassium iodid, 13.5 grams mer-
curic chlorid, 20 cc. glacial acetic acid and 640 cc.
water) are added; the flask is filled to 102.6 cc. mark
with distilled water, the contents mixed, filtered through
a dry filter, and when the filtrate is perfectly clear, the
solution is polarized in a 200 millimeter tube. The
reading of the scale divided by 2, shows the per cent,
of lactose (milk sugar) in the milk. Take five readings
of two different portions of the filtrate, and average
the results.

260. f. Ash. About 20 cc. of milk are measured into
a flat-bottom porcelain dish and weighed ; about one-half
of a cc. of 30 per cent.-acetic acid is added, and the
milk first dried on water bath and then ignited in a
muffle oven at a low red heat. Direct heat should not
be applied in • determining the ash in milk, since alkali
chlorids are likely to be lost at the temperature to which
milk sclids have to be heated to ignite all organic carbon.

Example: Weight of porcelain dish -f milk 49.0907 grams.

Weight of porcelain dish 28.3538 grams.

Weight of milk 20.7369 grams.

Weight of dish + milk, after ignition 28.5037 grams
Weight of dish 28.3538 grams.

Weight of milk ash 1499 gram.

Per cent, of ash^r^^^ — 72 per cent.
The residue from the determination of solids (252)
may also be used for the ash determination.

261. Acidity of milk. The acidity of milk is conven-
iently determined by means of Farrington's alkaline
tablets (see p. 122), or by a tenth-normal soda solu-
tion. In the latter case 20 cc. of milk are measured into

226 Testing Milk and Its Products.

a porcelain casserole ; a few drops of an alcoholic phe-
nolphtalein solution are added, and soda solution is
dropped in slowly from a burette until the color of the
milk remains uniformly pinkish on agitation. 1 cc, of
Y^ alkali corresponds to .009 gram lactic acid, or to
.045 per cent, when 20 cc. of milk are taken (see p. 121).

B.— CREAM, SKIM MILK, BUTTER MILK, WHEY, CON-
DENSED MILK.

262. The analysis of these products is conducted in
the same manner as in case of whole milk, and the same
constituents are determined, when a complete analysis
is wanted. Skim milk, butter milk, and whey con-
tain relatively small quantities of solids, and espe-
cially of fat, and it is, therefore, well to weigh out a
larger quantity than in case of whole milk; if possible,
toward 10 grams. The acidity of sour milk and butter
milk must be neutralized with sodium carbonate pre-
vious to the drying and extraction, as lactic acid is solu-
ble in ether and would thus tend to increase the ether-
extract (fat), if not combined with an alkali previous
to the extraction.

263. Specific gravity of butter milk. The specific gravity
of butter milk (as well as of sour or loppered milk) is deter-
mined by Weibull 's method ; a known volume of the milk is
mixed with a certain amount (say 10 per cent.) of ammonia of
a definite specific gravity, and the specific gravity of the liquid
determined after thorough mixing and subsequent standing for
an hour. If A designate the volume of butter milk taken, B that
of ammonia, and C that of the mixture; and if furthermore S
designate the specific gravity of the butter milk, s^ that of the
ammonia, and s2 that of the mixture, we have

Cs2— Bs,

Chemical Analysis of Milk and Its Products. 227

Klein1 has modified this method by weighing the liquids, thus
securing greater accuracy ; 22 to 24 per cent.-ammonia is used,
one-tenth as much being taken as the amount of milk weighed
out. The results come uniformly .0005 too high, and this correc-
tion should always be made. The following formula will give
the specific gravity of the milk, which in case of careful work
will be accurate to one-half lactometer degree; if the letters
given above designate weights (instead of volumes as before)
and specific gravities of the liquids, respectively, we have

~ ~~

264. Condensed milk. The same methods are, in gen-
eral, followed in the analysis of condensed milk as with
whole milk. Condensed milk is preferably diluted with
five times its weight of water prior to the analysis, both
because such a solution can be more easily handled
than the undiluted thick condensed milk, and the errors
of analysis are thereby reduced, and because the fat is
not readily extracted except when the milk has been
diluted.2 The same constituents are determined as in
case of whole milk, viz., solids, fat, casein and albumen,
ash, milk sugar, and cane sugar (if any has been added
to the milk) . The cane sugar is determined by the dif-
ference between the solids not fat and the sum of the
casein, albumen, milk sugar and ash ; if the student has
a knowledge of the manipulation of the polariscope and
has had experience in gravimetric sugar analysis, the
milk sugar is determined gravimetrically, and the cane
sugar by the difference between the polariscope reading
after inversion and the milk sugar present.

1 Milch z^itunpr, 1896, p. 656: see also De Koningh, Analyst, 1899, p. 142.

2 A second extractiorf following leaching: and subsequent drying of
the tubes is necessary to extract all the fat in condensed milk: see
Bull. 104, Bur. of Ohem., IT. S. Dept. of Agr., p. 102 and 154.

228 Testing Milk and Its Products.

The specific gravity of condensed milk may be deter-
mined by a method similar to that of McGill.1 50 gr.
of the thoroughly mixed sample are weighed into a
tared beaker and washed with warm water into a 250 cc.
flask, cooled to 60°, filled to the mark and carefully
mixed. The specific gravity of this solution (a) is then
taken and the original density is calculated by means
of the following formula:

Sp. gr. of condensed milk=-l—

b — 5ft

Concentration. The extent of concentration of con-
densed milk may be determined approximately by the
formula devised by McGill (loc. cit.) :
Concentration (c)™-5^

fttSi

where a and £ designate the solids not fat and specific
gravity, respectively, of the condensed milk, and a± and
s^ the corresponding data for the milk used. If $,=
1.030 and a±=9 per cent., then c— -^- gives the con-
centration.

C.— BtTTTER.

265. Sampling. A four- to eight-ounce sample of
butter is melted in a tightly-closed pint fruit jar,
shaken vigorously and cooled until the butter is hard-
ened, the jar being shaken vigorously at short intorva\s
during the cooling so as to keep the water of the butter
evenly distributed in the mass.

266. a. Determination of water. Small pieces of
butter (about 2 grams in all) are taken from the sam-
ple by means of a steel spatula and placed in glass tubes.
seven-eighths of an inch in diameter and two and a half

1 Bulletin 54, Laboratory Inland Rev. Dept., Ottawa, (1anndn.

Chemical Analysis of Milk and Its Products. 229

inches long, closed at the bottom by a layer of stringy
asbestos, and filled two-thirds full of asbestos prepared
as for milk analysis (252). The tubes are dried at
100° C. in a water oven, until no further loss in weight
takes place, and are then cooled and weighed. The loss
in weight shows the per cent, of water present.

267. b. Fat. The tubes are placed in Caldwell ex-
tractors and extracted for four hours with anhydrous
ether ; the ether is then distilled off, and the flasks dried
in the steam bath and weighed,, the increase in weight
giving the fat in the samples of butter weighed out.

268. c. Casein. 10 grams of butter are weighed into
a small beaker provided with a lip, and treated twice
with about 50 cc. of gasoline each time; the solution is
filtered off, and the residue transferred to a filter and
dried; its nitrogen content is then determined by the
Kjeldahl method (255). The nitrogen in the filter and
the chemicals used is determined by blank trials and
deducted. The nitrogen multiplied by 6.25 gives the
casein in the butter.

269. d. Ash. (1) 10 grams of butter are weighed
into a porcelain dish and treated twice with gasoline, as
in the preceding determination; the solution is filtered
through an ash-free (quantitative) filter, and the filter
when dry is transferred to the dish. The dish is heated
in an air-bath for half an hour and then placed in a
muffle oven, where the contents are burnt to a light
grayish ash; the dish is now cooled in a desiccator and
weighed. The difference between this weight and that
of the empty dish gives the amount of ash in the butter
weighed out.

230 Testing Milk and Its Products.

270. (2) About two grams of "butter are weighed into
a small porcelain dish, half filled with stringy asbestos ;
the dish is dried for half an hour in the water oven,
and the fat then ignited with a match, the asbestos
fibre serving as a wick. When the flame has gone out,
the dish is placed in a muffle oven, and the residue
burnt to a grayish ash. After cooling, the dish is
weighed, and the per cent, of ash in the butter calcu-
later as under method 1.

271. Complete analysis of butter in the same sam-
ple. About 2 grams of the butter are weighed into a-
platinum gooch half filled with stringy asbestos, and
dried in a water oven at 100° C. to constant weight,
cooled and weighed. The difference gives water in the
sample. The gooch is then treated repeatedly with
small portions of gasoline, suction being applied, and
again dried in the water oven, cooled, and weighed ; the
fat in the sample is obtained from the difference be-
tween this and the preceding weight. The gooch is
then carefully heated over direct flame until a light
grayish ash is obtained; this operation is preferably
done in a muffle oven to avoid a loss of alkali chlorids.
The loss in weight gives the casein in the sample
weighed out, and the increase in the weight of the gooch
over that of the empty gooch with asbestos, gives the
ash (mainly salt) of the butter. The salt in the ash
may be dissolved out by hot water, and the chlorin
content of the solution determined by means of a stand-
ard silver-nitrate solution, using potassium chromate as
an indicator.

Chemical Analysis of Milk and Its Products. 231

272. Rapid estimation of water in butter. A num-
ber of different methods have recently been proposed
for the rapid estimation of water in butter, the object
sought being to enable the buttermaker himself to ascer-
tain the^ water content of his butter without much
trouble or delay, and by using such simple apparatus
as he is likely to have in the creamery or can easily
procure at a low price. The subject of controlling the
per cent, of water in butter has become more important
than was earlier the case, through the passage of the
pure-food law and the promulgation of government food
standards in 1906 (305) ; these measures rendered the
question of guarding against an excessive water content
in the butter one of great importance to all butter-
makers.

All the methods suggested but three (Wagner, Car-
roll, and Gray's, see below) are essentially the common
methods of chemical analysis, modified to meet the de-
mands of every-day factory conditions. It is difficult
to predict which one of these methods will be generally
adopted in creameries in the future, but references to
where descriptions of the different methods will be
found, are given below, and a few that are most likely
to be used in factories and outside of chemical labora-
tories, are described in detail, so that students may
readily understand and employ any one of these meth-
ods that may be deemed preferable.

In all these rapid methods of determining the water
content in butter, the sample of butter must be pre-
pared so as to accurately represent the lot of butter
sampled and must be carefully weighed on a delicate

232 Testing Milk and Its Products.

scale, as previously described (93). The directions,
in so far as they are given in detail in the following,
therefore, presuppose that a carefully prepared, fair
sample has been obtained in all cases.

273. Among the methods recently proposed for the
rapid determination of the per cent, of water
in butter that are adapted for use in creamer-
ies may be mentioned :

Richmond's method,1 Carroll's tester,2 Geld-
ard's butter tester,3 the Irish "common sense
butter and cheesy moisture test," Dean's,4
Gray's,5 Patrick's,6 and the Wisconsin high-

pressure oven methods.7

The followiAg four of these methods will be
— "H
'— ^ briefly described:

274. a. Gray's method. This ingenious
method was invented by Prof. C. E. Gray, of
the Dairy Division of the U. S. Dept. of Agri-
culture, and was published in 1906; the method
consists of heating ten grams of butter in a
special flask of about 70 cc. capacity (see fig.
^) with 6 cc. of "amyl reagent" (five parts
°f amyl acetate and one part amyl valerianate).
me?hod.s The water is boiled out of the butter by heating
over direct flame, and together with some of the reagent,
is condensed, cooled, and measured in a graduated tube

1 Dairy Chemistry, p. 252.

2 Dept. of Agr., Ottawa, Dairy Tom' r Branch, hull. 6, pp. 10-11.

3 Dept. of Agr., Ottawa, Dai- y Oom'r Branch, bull. 14, pp. 6-8.
« •* Ontario Agr. College, rept. 1906, p. 120.

« Oirc. 100, Bur. An. Ind., U. S. Dept. of Agr.

6 Journal Am. Ohem. Soc., 28, 1906, p. 1611.

7 Bull. 154, Wis. cxprnim-nt station.

Chemical Analysis of Milk and Its Products. 233

attached to the flask. The accompanying illustration
shows the arrangement of the distilling flask and the
graduated tube in which the water is measured. For
details of manipulation, reference is made to the orig-
inal publication, or to the files of our dairy press pub-
lished during 1906-7.1

275. Patrick's method. Ten grams of butter are
accurately weighed into a 300 cc. aluminum beaker
(about 3 inches tall and 2 inches in diameter) ; this is
held by means of a hand
clamp over the flame of
the alcohol lamp or a gas
burner (see fig. 60) and
very carefuHy heated until
all the water is expelled.
The beaker is then cooled
by sinking it to the rim in
water of 50° to 60°, wiped
dry, and the loss in weight
calculated as water. If ten
grams of butter weighed
8.45 grams after heating,
the loss in weight of 1.55 grams represents 15.5 per
cent, of the weight of the sample, and the butter there-
fore contained 15.5 per cent, of water. The results ob-
tained by this method seldom vary more than .2 per
cent, from those of chemical analysis, and* often less
than .1 per cent, when proper care in sampling and
weighing has been taken.

1 E. g., New York Produce Review, Jan. 16, 1907; American Cheese
Maker, Jan., 1907.

Fm. ^ Alumlnum beaker and
ho1 lam> used in the Patrick

234 Testing Milk and Its Products.

A few points .need special attention in using this
method: First, care must be taken not to heat the
beaker too fast so that spattering occurs ; there is not so
much danger from this source when an alcohol lamp is
used as with a gas burner, which easily raises the tem-
perature too high, causing a fine spray of material to
be thrown about, and thus giving too high results for
water content. Second, it is important to discontinue
the heating at the exact point when all the water has
been driven oft' and before burning of the non-fatty
solids (casein, milk sugar, and organic acids) occurs,
as indicated by a slight darkening in color. It is not
necessary to cool the beakers in water, but they can be
left to cool in the air. The determination of water in
butter by this method can be finished in ten minutes
or less by an experienced operator. The Irish test is
similar to the method described in the preceding, dif-
fering from the same mainly in the shape of the alumi-
num dishes used.

276. Dean's method. Three cc. of a melted sample
of butter are placed in an ordinary "patty-pan" tin
dish (about 2y2 inches in diameter and y2 inch deep)
and accurately weighed; the dish is then placed in a
steam oven provided with a pop safety valve, a steam
pressure gauge, and a thermometer. The oven used
by Professor Dean, of Guelph (Ont.) Dairy School, the
originator of this method, was 6x8 inches. It was made
of galvanized iron by a local tin-smith at a cost of
about $5.00, exclusive of safety valve and steam gauge,
and was made to withstand a pressure of about 10
pounds. After five or six hours' drying in the oven,

Chemical Analysis of Milk and Its Products. 235

the samples of butter are ready to be weighed, and the
loss gives the amount of water present therein. The
average results obtained by this method with nine sam-
ples of butter came within .13 per cent, of those found
by chemical analyses.

The same method is recommended by the author for
determining the per cent, of water in curd or cheese.

277. The Wisconsin high-pressure oven method
(see fig. 61). Either 10 or 50 grams of butter are
weighed in a flat-bottomed tin or aluminum dish. This
is placed in an oven heated
by high-pressure steam to a
temperature of 240° to 280°
F. The length of time re-
quired to expel all the water
from the butter will depend on
the temperature of the oven
and the diameter of the dish
in wThich the butter is heated.
If the dish is large enough to
permit the butter to spread
out into a verv thin layer and

FIG. 61. The Wisconsin high- -

the temperature of the oven pressure oven,

reaches 260° F., the water will be completely expelled
in half an hour. Ovens of this construction have now
been placed on the market by one of the manufacturers
of dairy supplies. A steam pressure of 60 Ibs. and a
temperature of 280° F. may be obtained in such an
oven; by employing the boiler pressure ordinarily used
in a creamery, temperatures of 240° to 260° may be
easily obtained. The temperature thus reached is suf-

236 Testing Milk and Its Products.

ficiently high to dry the cutter completely within an
hour, provided pans large enough to spread the butter
in a thin layer are used.

If 10 grams of butter are used in making tests, a
more delicate scale is necessary than when 50 grams
are taken. There are other advantages in using as large
a quantity as 50 grams of butter for making tests of
water. First, a sample can be taken directly from a
package into a weighing pan. Second, ordinary tin
basins at least 5 inches in diameter can be used for dry-
ing the butter. Third, scales with a graduated side
beam and sensitive to .1 gram instead of those with
smaller locse weights can be used for weighing the but-
ter. (See fig. 35.)

278. A practical method of estimating the salt content
of butter. A method of estimating the salt content of butter,
which is applicable also outside of chemical laboratories, has
been worked out jointly by Messrs. Alfred Vivian and C. L.
Fitch.1 The salt of the butter is dissolved in hot water, and a
certain portion of the solution when cool is pipetted off and
titrated with a silver-nitrate solution prepared by dissolving one
silver-nitrate tablet in 50 cc. water,* potassium chromate being
used as an indicator. The silver nitrate tablets are sold for 60
cents per 100, which number is sufficient to make 100 to 150 tests.
The method has been advertised in the dairy press under the
name of " Fitch's Salt Analysis." Directions for making tests
by this method are furnished with the apparatus when this is
bought. The price of a complete outfit is $4.50.

DETECTION OF ARTIFICIAL BUTTER?

279. Determination of the specific gravity of the fil-
tered butter fat serves as a good preliminary test. A
number of practical methods for the detection of artifi-
cial butter have been proposed, but they are either

1 Wls. experiment station, report 17, pp. 98-101; Hoard's Dairyman,
February 15, 1901, "Uniform Baiting of Butter."

Chemical Analysis of Milk and Its Products. 237

worthless, in case of samples containing a considerable
proportion of natural butter, or give satisfactory results
only in the hands of experts. The Reichert-Wollny
method given in detail below is the standard method the
world over, and the results obtained by it are accepted
in the courts.

280. Filtering the butter fat. The butter to be ex-
amined is placed in a small narrow beaker and kept at
60° C. for about two hours. The clear supernatant fat
is then filtered through absorbent cotton into a 200 cc.
Erlenmeyer flask, taking care that none of the milky
lower portion of the contents of the beaker be poured
on the filter. In sampling the butter fat, it is poured
back and forth repeatedly from a small warm beaker
into the flask, and the quantity wanted is then drawn
off with a warm pipette.

281. Specific gravity. This is generally determined
at 100° C. The method of procedure is similar to that
described under milk (248). The picnometer (capacity
about 25 cc.) is filled with dry filtered butter fat, free
from air bubbles ; the fat is heated for 30 minutes in a
beaker, the water in which is kept boiling. On cooling,
the weight of picnometer and fat is obtained, and by
calculation as usual, the specific gravity of the fat.

The specific gravity of pure natural butter fat at
100° C. ranges between .8650 and .8685, while artificial
butter fat (i. e., fat from other sources than cow's milk)
has a specific gravity at 100° C. of below .8610, and gen-
erally about .85.

282. Reichert-Wollny method (Volatile Acids.} 5.75
cc. of fat are measured into a strong 250 cc. weighed
saponification flask, by means of a pipette marked to

238 Testing Milk and Its Products.

deliver this amount, and the flask when cool is weighed
again. 20 cc. of a glycerol-soda solution (20 cc. of
soda solution (1:1) fo 180 cc. of pure glycerol), are then
added to the flask and the flask is heated over a naked
flame or hot asbestos plate until complete saponification
has taken place, as shown by the mixture becoming per-
fectly clear. If foaming occur, the flask is shaken
gently.

135 cc. of recently-boiled distilled water are now
added, drop by drop, at first, to prevent foaming, and
when the solution is clear, cooled to about 70° C. ; 5 cc.
of dilute sulfuric acid (200 cc. cone. H2SO4 per liter) are
added to the soap solution to decompose the soap into
free fatty acids and glycerol. A few pieces of pumice
stone (prepared by throwing the pieces at white heat
into distilled water and keeping them under water until
used) are added, the flask connected with a glass con-
denser, heated slowly till boiling begins, and the con-
tents then distilled at such a rate as will bring 110 cc.
of the distillate over in as nearly thirty minutes as pos-
sible.

The distillate is mixed thoroughly and filtered
through a dry filter; 100 cc. of the filtrate are poured
into a 250 cc. beaker and titrated with a deci-normal
barium-hydrate solution, half a cubic centimeter of phe-
nolphtalein solution being used as an indicator. A blank
test is made in the same manner as described, and the
amount of alkali solution used deducted from the re-
sults obtained with the samples analyzed. The number
of cubic centimeters of barium-hydrate solution used is
increased by one-tenth, and the so-called Reichert or
Reichert-Meissl number thus obtained.

Chemical Analysis

The Reichert number forv^^4&^^^^^s:ordi-
narily come above 24 cc. ; butter faTTrom^stripper cows
will have a low Reichert number. Pure oleomargarine
will have a Reichert number of 1 to 2 cc. ; and mixtures
of artificial and natural butter will give intermediate
numbers.

TESTS FOB THE DETECTION OF OLEOMARGARINE OR RENO-
VATED BUTTER.

283. The boiling test.1 A piece of butter of the size
of a small chestnut is melted in an ordinary tablespoon
(or a small tin dish) at a low heat, stirring with a splin-
ter of wood. The heat is increased until as brisk a boil
as possible, and after boiling has begun, the melted mass
is stirred thoroughly two or three times, always shortly
before boiling ceases. Oleomargarine and renovated
butter will boil noisily, sputtering like a mixture of
grease and water when boiled, and will produce but
little or no foam. Renovated butter produces usually a
very small amount of foam, while genuine butter boils
with less noise and produces an abundance of foam.

284. The Waterhouse test for distinguishing oleo-
margarine and renovated butter.2 Half fill a 100 cc.
beaker with sweet skim milk (or distilled water), heat
nearly to boiling and add 5 to 10 grams of butter or
oleomargarine. Stir with a small wooden stick of about
the size of a match until the fat is melted; the beaker is

1 Patrick, Household tests for the detection of oleomargarine and
renovated butter, Farmers' Bulletin, No. 131. For detection and exam-
ination of renovated or "process" butter, see also Oochran, Journ.
Frankl. Insf., 1899, p. 04; Analyst, 1899, p. 88.

2 Farmers' Bulletin, No. 131, p. 7.

240 Testing Milk and Its Products.

then placed in ice water, and the milk (or water) stirred
until the temperature falls sufficiently for the fat to
congeal. If oleomargarine, the fat can now be easily
collected into one lump by means of the stick, while if
genuine or renovated butter, the fat will granulate and
can not be so collected.1

D.— CHEESE.

For method of sampling, see p. 104.

285. a. Water. Five grams of cheese cut into very
thin slices are weighed into a smdll porcelain dish filled
about one-third full with freshly-ignited stringy asbes-
tos ; the dish is placed in a water oven and heated for ten
hours. The loss in weight is taken to represent water.
(See also Dean's method for determining water in but-
ter, curd and cheese, p. 234).

286. b. Fat. About 5 grams of cheese are ground
finely in a small porcelain mortar with about twice its
weight of anhydrous copper sulf ate, until the mixture is
of a uniform light blue color and the cheese evenly dis-
tributed throughout the mass. The mixture is trans-
ferred to a glass tube of the kind used in butter analysis
(263), only a larger size; a little copper sulf ate is placed
at the bottom of the tube, then the mixture containing
the cheese, and on top of it a little extracted absorbent
cotton or ignited stringy asbestos; the tube is placed in
an extraction apparatus and extracted with anhydrous
ether for fifteen hours. The ether is then distilled off,
the flasks dried in a water oven at 100° C. to constant
weight, cooled and weighed. The method is apt to

i For tests for artificial coloring mattepin oleomargarine, see Olrc.
629, Oom. of Internal Rev., Treasury Dept.

Chemical Analysis of Milk and Its Products. 241

too low results and, therefore, not to be preferred to
the Babcock test for cheese (105).

287. c. Casein (total nitrogenX6.25). About 2 grams
of cheese are weighed out on a watch glass and trans-
ferred to a Jena nitrogen flask, and the nitrogen in the
sample determined according to the Kjeldahl method
(253) ; the percentage of nitrogen multiplied by 6.25
gives the total nitrogenous components of the cheese.

288. d. Ash. The residue from the water determina-
tion is taken for the ash ; it is preferably set fire to, in
the same manner as explained under determination of
ash in butter (270), before it is placed in the muffle
oven and incinerated. The increase in the weight above
that of the empty dish-f-asbestcs, gives the amount of
ash in the sample weighed out.

289. e. Other constituents. The sum of the percent-
ages of water, fat, casein and ash, subtracted from 100,
will give the per cent, of other constituents, organic
acids,- milk sugar, etc., in the cheese.

DETECTION OF OLEOMARGARINE CHEESE ("FILLED"
CHEESE. )

290. About 25 grams of finely-divided cheese are ex-
tracted with ether in a Caldwell extractor or a paper
extraction cartridge; the ether is distilled off, and the
fat dried in the water oven until there is no further
loss in weight. 5.75 cc. of the clear fat are then meas-
ured into a 250 cc. saponification flask and treated ac-
cording to the Reichert-Wollny method, as already ex-
plained under Detection of Artificial Butter (282). 1

i:See:Arb. Kals. Ges.-Amt., 14, 506-598
6

242 Testing MUk and Its Products.

TESTS FOR ADULTERATION OF MILK AND CREAM.

291. The nitric acid test may prove useful as cor-
roborating evidence that a sample of milk has been
watered (126). Normal fresh milk does not contain
nitrates, while common well-water, particularly on
farms where precautions to guard against contamina-
tion of the water supply have not been taken, in gen-
eral contains appreciable amounts of nitrates, nitrites
and ammonia compounds, and watered milk will, there-
fore, in such cases also contain nitrates.1 The method
for detection of small amounts of nitrates in milk, as
given by Richmond2 is as follows : Place a small quan-
tity of diphenylamin at the bottom of a porcelain dish,
and add to it about 1 cc. of pure H2S04 (cone.) ; allow
a few drops of the milk serum (obtained by adding a
little acetic acid to the milk and warming) to flow down
the sides of the dish and over the surface of the acid.
If a blue color develops in the course of ten minutes,
though it may be faint, it shows the presence of nitrates ;
after ten minutes a reddish-brown color is always de-
veloped from the action of the acid on the serum.
There should be no difficulty in detecting an addition of
10 per cent, of water to the milk by this test, if the
water added contained 5 parts of nitric acid, or more,
per 100,000.

The following test for nitric acid is proposed by Mc-
Kay and Bouska: About 5 cc. of milk is placed in a
test tube. Some Kaniss' reagent (about 1 part formal-

1 Uffelmann, Deutsche Vierteljahresschr. f. off. Ges.-pfl. 15, p. »>rc',.

2 The Analyst, 1893, p. 272.

Chemical Analysis of Milk and Its Products. 243

dehyd in 500 cc. G. P. H2S04) is poured down the side
of the tube so it will form a layer under the milk. If
nitrates or nitrites are present, a violet ring will form
at the place of contact. This is Hehner's test for for-
maldehyd reversed, see (304).

292. Besides by the methods given in the preceding
(pp. 109-115), watering or skimming of milk may be de-
tected by determining the specific gravity of a, the skim
milk, b, the milk serum, and c, the whey.

a.' Specific gravity of skim milk. The milk is set in a flat
porcelain or glass dish for 12-24 hours in a cold room; the layer
of cream formed is then skimmed off, and the sp. gr. of the skim
milk determined at 60° F. Skim milk has a sp. gr. of .002 to
.0035 (2 to 3.5 lactometer degrees) above that of the correspond-
ing whole milk; a smaller difference than this indicates that the
milk was skimmed. If both skimming and watering had been
practiced, the difference given above might be obtained, but the
analysis of the milk would in such case easily disclose the adul-
teration.

b. Specific gravity of the milk serum. To 100 cc. milk 2
cc. of 20 per cent.-acetic acid are added, and the mixture heated
in a covered beaker or closed flask for 5-10 min. on a water -bath
at 55-65° C. After cooling, the milk serum is filtered off and its
sp. gr. determined at 60° F. In case of pure milks, the sp. gr.
of the milk serum (at 60°) will come above 1.0270. Serum from
normal milk contains 6.3 to 7.5 per cent, solids and .22 to .28
per cent, fat; by the addition of 10 per cent, of water, the
solids in the serum are lowered .3 to .5 per cent., and the sp. gr.,
.0005.1

c. Specific gravity of whey. 500 cc. of milk are warmed in
water of 40-50° C. until its temperature is 35° C.; one-half cc.
of rennet extract (12-15 drops) is added, and the milk stirred
thoroughly. After allowing the curd to solidify for 10 minutes,
it is cut and the whey filtered off through several layers of cheese
cloth. The whey must be clear; it is cooled to 60° F. and its

1 Konig, Menschl, Nahrungsmittel, II, p. 276.

244 Testing Milk and Its Products.

sp. gr. determined. The sp. gr. of whey from normal milk ob-
tained in the manner given will range between 1.027 and 1.031.
A sp. gr. of 1.026 or below indicates watering. An addition of
4 per cent, of water lowers the sp. gr. of the whey about 1 lac-
tometer degree.1

293. Detection of coloring matter. Milk which has
been watered cr skimmed, or both, is sometimes further
adulterated by unscrupulous milk dealers by an addi-
tion of a small quantity of cheese color; this will mix
thoroughly with the milk, and, if added judiciously, will
impart a rich cream color to it. The presence of for-
eign coloring matter in milk is easily shown by shaking
10 cc. of the milk with an equal quantity of ether; on
standing, a clear ether solution will rise to the surface;
if artificial coloring matter has been added to the milk,
the solution will be yellow colored, the intensity of the
color indicating the quantity addded; natural fresh
milk will give a colorless ether solution.

A method given by Wallace2 is claimed to detect one
part of coloring matter in 100,000 of milk.

Inorganic coloring matter like chromates and bi-chro-
mates have, although fortunately rarely, been used to
impart a rich color to adulterated milk or poor cream.
Chromates may be detected by the reddish yellow color
produced when a little 2 per cent. -silver nitrate solution
is added to a few cubic centimeters of the milk.

294. Detection of pasteurized milk or cream. Prof.
Storch, of Copenhagen, Denmark,3 in 1898, published a
simple method for ascertaining whether milk, cream,

1 Slats, Unters. landw. wicht. Stoffe, p. 88.

2 N. J. Dairy Commissioner, report. 1896, p. 36.
8 40th report, Copenhagen experiment station.

Chemical Analysis of Milk and Its Products. 245

or other dairy products have been heated to at least
176° F. (80° C.). The test is made as follows: A
teaspoonful of the milk is poured into a test tube, and
1 drop of a weak solution of peroxid of hydrogen (2
per cent.) and 2 drops of a paraphenylenediamin-solu-
tion (2 per cent.) are added. The mixture is then
shaken; if a dark violet color appears at once, the milk
has not been heated, or at any rate not beyond 176° P.
If a sample of butter is to be examined, 25 grams are
placed in a small beaker and melted by being placed in
water of 60° C. The clear butter fat is poured off, and
the remaining liquid is diluted with an equal volume of
wrater. The mixture thus obtained is examined as in
case of milk.

Guaiacum tincture has also been recommended for the
detection of pasteurized cream or milk; this solution is
easily obtained, keeps well, and is convenient to use
(McKay).

295. Boiled milk. The preceding tests will serve to
distinguish between raw and boiled milk, and also to
ascertain if milk has been adulterated with diluted con-
densed milk. To what extent such an adulteration can
be practiced without being detected by this or similar
tests, has not been determined, but if a control test be
made at the same time with a sample of milk of known
purity, a small admixture of boiled (or diluted con-
densed) milk can doubtless be detected.1

296. Gelatine in cream. This method of adultera-
tion is sometimes practiced in the city cream trade, to

1 See also Slats, Unters. landw. wicht. Stoffe, p. 60, and Molkerei-Ztg.
(Hildesheirn), 1899, p. 677.

246 Testing Milk and Its Products.

impart stiffness and an appearance of richness to the
cream. To detect the gelatine, a quantity of the sus-
pected cream is mixed with warm water, and acetic acid
is added to precipitate the casein and fat (1.5 cc. of 10
per cent.-acetic acid per 10 cc. of cream is sufficient).
The precipitate is filtered off, and a few drops of a
strong tannin solution are added to the clear filtrate.
Pure cream will give a slight precipitate, while in the
presence of gelatine a copious precipitate will come
down.

The picric-acid method has also been proposed for
the detection of small quantities of gelatine in cream.1

297. Starch in cream. Starch is mentioned in the
dairy literature as an adulterant of milk and cream. It
is doubtful, however, if it is ever used for this purpose
at the present time. In the case of ice-cream, on the
other hand, a small quantity of corn starch is often
added to thicken the milk used. It may in such a case
be readily detected by means of the iodin reaction. A
solution of iodin will produce a deep blue color in the
presence of starch ; a small amount of iodin is taken up
by the cream before the blue coloration appears.

298. Macroscopic impurities (particles of hay, litter,
woolen or cotton fibres, dung, etc.). These impurities
may be separated by repeated dilution of the milk with
pure distilled water, leaving the mixture undisturbed
for a couple of hours each time before the liquid is
syphoned off. When the milk has been entirely re-
moved in this manner, the residue is filtered off, dried

1 The Analyst, 1897, p. 820.

Chemical Analysis of Milk and Its Products. 247

and weighed. A quart of milk or cream should not
give any visible sediment on standing for several hours.
A very simple and striking method of showing dirt
in milk has been suggested by Gerber. About a pint of
milk is poured into an inverted bottomless long-necked
bottle, over the mouth of which a piece of linen is tied.
The milk will filter through this cloth, leaving the dirt
en it. When the milk has run through, the cloth is
taken off and can be shown to the producer of the milk.1

DETECTION OF PRESERVATIVES IN DAIRY PRODUCTS.

299. a. Boracic acid (borax, borates, preservaline,
etc.). 100 cc. of milk are made alkaline with a soda
or potash solution, and then evaporated to dryness and
incinerated. The ash is dissolved in water to which a
little hydrochloric acid has been added, and the solu-
tion filtered. A strip of turmeric paper moistened with
the filtrate will be colored reddish brown when dried at
100° C. on a watch glass, if boracic acid is present.

If a little alcohol is poured over the ash to which con-
centrated sulfuric acid has been added, and fire is set
to the alcohol; after a little while this will burn with a
yellowish green tint, especially noticeable if the ash is
stirred with a glass rod and when the flame is about to
go out.

300. The following modification of the first test given is said
to show the presence of only a thousandth of a grain of borax
in a drop of milk (about .15 per cent.) :*

Place in a porcelain dish one drop of milk with two drops of
strong hydrochloric acid and two drops of saturated turmeric

1 Hoard's Dairyman, Nov. 29, 1907.

2 N. J. Dairy Commissioner, report 1896, p. 37.

248 Testing Milk and Its Products.

tincture; dry this on the water bath, cool and add a drop of
ammonia by means of a glass rod. A slaty blue color changing
to green is produced if borax is present.1

301. b. Bi-carbonate of soda. 100 cc. of milk to
which a few drops of alcohol are added, are evaporated
and carefully incinerated; the proportion of carbonic
acid in the ash as compared with that of milk of known
purity is determined. If an apparatus for the deter-
mination of carbonic acid is available, like the Scheibler
apparatus, etc., the per cent, of carbonic acid per gram
of ash (and quart of milk) can be easily ascertained.
Normal milk ash contains only a small amount of car-
bonic acid (less than 2 per cent.), presumably formed
from the citric acid of the milk in the process of incin-
eration.

The following qualitative test is easily made: To 10
cc. of milk add 10 cc. of alcohol and a little of a one
per cent, rosolic-acid solution. Pure milk will give a
brownish yellow color; milk to which soda has been
added, a rose red color. A control experiment with
milk of known purity should be made.

302. c. Fluorids. 100 cc. of milk are evaporated in
a platinum or lead crucible, and incinerated; the ash is
made strongly acid with concentrated sulfuric acid. If
fluorids are present hydrofluoric acid will be generated
on gentle heating and will be apparent from its etching
a watch glass placed over the crucible.2

303. d. Salicylic acid (salicylates, etc.}. 20 cc. of
milk are acidulated with sulfuric acid and shaken with

1 See also 151.

8 Chromates in dairy products may be readily determined by the use
of a silver-nitrate solution, see Molkerei-Ztg. (Berlin) 1899, p. 608.

Chemical Analysis of Milk and Its Products. 249

ether; the ether solution is evaporated, and the residue
treated with alcohol and a little iron-chlorid solution;
a deep violet color will be obtained in the presence of
salicylic acid.

304. e. Formaldehyde (a forty-per cent, solution in
water) .

* The following method by Hehner is stated to show
the presence of one part of formaldehyde in 200,000
parts of milk : the milk is diluted with an equal volume
of water, and strong H2S04 (sp. gr. 1.82-1.84) is added.
A, violet ring is formed at the junction of the two
liquids if formaldehyde is present ; if not, a slight green-
ish tinge will be seen. The violet color is not obtained
with milk containing over .05 per cent, formaldehyde.1

The same color reaction is obtained in the Babcock
test and is easily recognized by persons familiar with
milk testing when their attention has once been called
to the characteristic color.

An adulteration of milk with formaldehyde may be
readily detected by the following method, which will
show the presence of only a trace of formaldehyde in
the milk. 5 cc. of milk is measured into a white porce-
lain dish, and a similar quantity of water added. 10
cc. of HC1 containing a trace of Fe2Cl6 is added, and
the mixture is heated very slowly. If formaldehyde is
present, a violet color will be formed.

1 Ohem. News, 1896, No. 71; Milchzeitung, 1896, 491; 1897, 40, 667; The
Analyst, 1895. 152, 154, 157; 1896, 285.

GOVERNMENT STANDARDS OF PURITY FOR
MILK AND ITS PRODUCTS.1

a. MILKS.

1. Milk is thei fresh, clean, lacteal secretion obtained by the
complete milking of one or more healthy cows, properly fed
and kept, excluding that obtained within fifteen days before and
ten days aftetr calving, and contains not less than eight and one-
half (8.5) per cent, of solids not fat, and not less than three
and one-quarter (3.25) per cent, of milk fat.

2. Blended milk is milk modified in its composition so as to
have a definite and stated, percentage of one or more of its con-
stituents.

3. Skim milk is milk from which a part or all of the cream
has been removed and contains not less than nine and one-quarter
(9.25) per cent, of milk solids.

4. Pasteurized milk is milk that has been heated below boil-
ing but sufficiently to kill most of the active organisms present
and immediately cooled to 50° Fahr. or lower.

5. Sterilized milk is milk that has been heated at the tem-
perature of boiling water or higher for a length of time suffi-
cient to kill all organisms present.

6. Condensed milk, evaporated milk, is milk from which a
considerable portion of water has been evaporated and contains
not less than twenty-eight (28) per cent, of milk solids, of which
not less than twenty-seven and five-telnths (27.5) per cent, is
milk fat.

7. Sweetened condensed milk is milk from which a consid-
erable portion of water has been evaporated and to which sugar
(sucrose) has been added, and contains not less than twenty-
eight (28) per cent, of milk solids, of which not less than
twenty-seven and five-tenths (27.5) per cent, is milk fat.

1 Circular No. 19, Office of the Secretary, U. 8. Dept. of Agriculture,
June 26, 1906.

Government Standards of Purity. 251

8. Condensed skim milk is skim milk from which a consid-
erable portion of water has been evaporated.

9. Buttermilk is the product that remains when butter is re-
moved from milk or cream in the process of churning.

10. Goat's milk, ewe's milk, etc., are the fresh, clean, lac-
teal setcretions, free from colostrom, obtained by the complete
milking of healthy animals other than cows, properly fed and
kept, and conform in name to the species of animal from which
they are obtained.

b. CREAM.

1. Cream is that portion of milk, rich in milk fat, which
rises to thei surface of milk on standing, or is separated from it
by centrifugal force, is fresh and clean and contains not less
than eighteen (18) per cent, of milk fat.

2. Evaporated cream, clotted cream, is cream from which
a considerable portion of watetr has been evaporated.

C. MILK FAT OB BUTTER FAT.

1. Milk fat, butter fat, is the fat of milk and has a Eeich-
ert-Meissl number not less than twenty-four (24) and a specific
gravity of not less than 0.905 ( ^^\

V 40 O. /

d. BUTTER.

1. Butter is the clean, non-rancid product made by gather-
ing in any manner the fat of fresh or ripened milk or cream
into a mass, which also contains a small portion of the other
milk constituents, with or without salt, and contains not less
than eighty-two and fivehtenths (82.5) per cent, of milk fat. By
acts of Congress approved August 2, 1886, and May 9, 1902,
butter may also contain added coloring matter.

2. Renovated butter, process butter, is the product made
by melting butter and reworking, without the addition or use of
chemicals or any substances except milk, cream, or salt, and
contains not more than sixteen (16) per cent, of water and at
least eighty-two and five-tenths (82.5) per cent, of milk fat.

252 Testing Milk and Its Products.

e. CHEESE.

1. Cheese is the! sound, solid, and ripened product made from
milk or cream by coagulating the casein thereof with rennet or
lactic acid, with or without the addition of ripening ferments
and seasoning, and contains, in the water-free substance, not less
than fifty (50) per cent, of milk fat. By act of Congress, ap-
proved June 6, 1896, cheese may also contain added coloring
matter.

2. Skim milk cheese is the sound, solid, and ripened product,
made - from skim milk by coagulating the casein thereof with
rennet or lactic acid, with or without the addition of ripening
ferments and seasoning.

3. Goat's milk cheese, ewe's milk cheese, etc., are the
sound, ripened products made from the milks of the, animals
specified, by coagulating the casein thereof with rennet or lactic
acid, with or without the addition of ripening ferments and
seasoning.

f. ICE CREAMS.

1. Ice cream is a frozen product madei from cream and sugar,
with or without a natural flavoring, and contains not less than
fourteen (14) per cent, of milk fat.

2. Fruit ice cream is a frozen product made from cream,
sugar, and sound, clean, mature fruits, and contains not less than
twelve (12) per cent, of milk fat.

3. Nut ice cream is a frozen product made from cream,
sugar, and sound, non-rancid nuts, and contains not less than
twelve (12) per cent, of milk fat.

g. MISCELLANEOUS MILK PRODUCTS.

1. Whey is the product remaining after the removal of fat
and casein from milk in the process of cheese-making.

2. Kumiss is the product made by the alcoholic fermentation
of mare's or cow's milk.

STANDARDS FOR BABCOCK GLASSWARE.
(Holland; adopted by Eastern Experiment Stations.)

SEC. 1. The unit of graduation for all Babcock glassware
shall be the true cubic centimeter (.998877 gram of water at
40° C.).

(a) With bottles, the capacity of each per cent, on the scale
shall be two-tenths (0.20) cubic ceoitimeter.

(b) With pipettes and acid measures the delivery shall be the
intent of the graduation and the graduation shall be read with
the bottom of the meniscus in line with the mark.

SEC. 2. The official method for testing bottles shall be cali-
bration with mercury (13.5471 grams of clean, dry mercury at
20° C., carefully weighed on analytical balances, to be equal to
5 per cent, on the Babcock scale), the bottles being previously
filled to zero with mercury.

SEC. 3. Optional methods. — The mercury and cork, alcohol and
burette, and alcohol and brass plunger methods may be employed
for the rapid testing of Babcock bottles, but the accuracy of all
questionable bottles shall be determined by the official method.

SEC. 4. The official method for testing pipettes and acid
measures shall be calibration by measuring in a burette the
quantity of water (at 20° C.) delivered.

SEC. 5. The limits of error. — (a) For Babcock bottles shall
be the smallest graduation on the scale, but in no case shall it
exceed five-tenths (-0.50) per cent., or for skim milk bottles one-
hundredth (0.01) per cent.

(b) For full-quantity pipettes, it shall not exceed one- tenth
(0.10) cubic centimeter, and for fractional pipettes, five-hun-
dredths (0.05) cubic centimeter.

APPENDIX.

Table I. Composition of milk- and its products.

No. of
analyses

Water

Fat

Casein
and
albumen

Milk
sugar

Ash

Authority

Cow's milk

793

pr. ct.

87.17
87.75
87.10
86.48
87.10
74.57
68.82
73.90
90.43
90.52
90.30
90.12
91.67
93.38
93.12

58.99

25.61
11.95
12.93
13.08
13.07
11.57
36.33
38.00
36.84
34.38

32.06
39.79
46.00
50.5

pr. ct.

3.69
3.40
3.90
4.20
3.90
3.59
22.66
17.60
.87
.32
.10
1.09
.27
.32
.27

12.42

10.35

84.27
84.53
84.26
85.24
84.70
40.71
30.25
33.83
32.71

34.43
23.92
11.65
1.2

pr. ct.

3.55
3.50
3.201
3.512
3.40
17. 644
3.76

pr. ct.

4.88
4.60
5.10

pr. ct.

.71
.75
.70
3.71
.75
1.56
.53
.62
.70

Kdnig5
Fleischmann
Van Slyke
Holland6
Richmond

Konig5

Holland6
Konig5
Holland6
Van Slyke
Konig5
Holland6
Konig5
Van Slyke

Konig5

1 1

Well

Konig5

1 1

Won

Farrington

Konig5

Van Slyke
Drew

Shutt

Konig5

Storch

it a

a n

5,552
2,173
200,000
42
43
203
56
354

a it

1 1 a

4.85
2.67
4.23

Colostrum milk

Cream

Cream Cooley

Skim milk (gravity) . .

a a a

Skim milk (centrifugal)
Butter milk

3.26

4.74

3.55
4.03

5.25
4.04

.80

.72

57
31

tt it

Whey

.86
.81

11.92

11.. 79
1.5

.61
.81
l.(

18.84
25.35
23.72
26.38

28.00
29.67
34.06
43.1

4.79
5.

14.49

50.06
56

.68
.66
)7
)5
1.02
1.43
5.
2.9$

5.
1.79
3.42

.65

2.18

2.19
2.58
1.25
1.19
.12
2.78
3.10
4.97
61
3.58

4.73
4.87
5.2

Condensed milk,
(no sugar added). . .
Condensed milk,
(sugar added) . .

64
1,676
10
11
242
350
127
143

Butter, salted

sweet cream . .
sour cream . . .
" unsalted
" World's Fair, 1893
Cheese, cream . .

full cream
cheddar, green
" cheddar, cured
World's Fair
Mam'th, 1893
tl half-skim . . . .
" skim

1
21
41

centrifugal skim..

1 .70 per cent, albumen.

2 Forty-two analyses.

3 Eight analyses.

4 13.60 per cent, albumen.
•*> Mostly European samples.
6 Massachusetts' samples.

256

Testing Milk and Its Products.

•J

^^' *

+* t

;

2^ ^

•

to
&

^a j

5 £ I

I 3 t

o«S

CHEES

ream, 30

Kim, 15 p
from sk]

i i:

\ \\

S S "oj
3«

M £ '

* ° ?

j"S i-

25 ,f
3c0 ^

a- ft C

r §*

gJ^

t» w ^, 2

. .&!

SoS ?*o

«1

5§°*£**

CREAM.

Per c£.

O iO O
(M rH Cq

3-5'

CO CO Jj,?

Oi O5 -g

H°

CO CO CO CO CO CO CO CO

coco

€

Solids
not fat.

Per ct.

»O i — ii — iCO i — i r— I

•

i — i i — no iO ,-25

•j M

3 "3

o—

ci gsssas^a

»— 1 i— I i-^ rH i— I

H£

i — i i — i X — <'

>H • : 4-s

5 : : 3 :

0 §

2 ">

cc T3

• QJ <f^

^ ^jev> M

^ * J£ 1 52

^ 0) Jaj 03

« .s jpi Ii

«**.. 1

V c § •§ * o - /

^ ^ ^.2

•-— 1> ^ ."j ^3

_ ^ — _^

C O ^ -^ •< ^5 ^ <^

J^^^O

Appendix.

257

^ a" p-

0 O QD

Not over |
14 per ct.
water.

CD" c<r

3*QQr4

»a-

o icco

c o t^ UD

eo*§

<MCO 0

3 <*

) CO CO O3

CO -^ (M CO

1 1
L__J

i — i 1C C

i — i i — ir— i

O 1C CM

•CO O

r^coos

. O CO O5

* -a

r^O

OC <S>0000

i — lO ^ »C

CM trd

(M • (M* 01 ^

Cq CO <M (M (M (M <M

• CO* ^g ^'

i — i

insylvania

(CitieiSdandSdclaai.)

ode Island
ith Carolina
Tiiont
May and June...

.aVi i n orf ,nn

|
£ C
f «

! 1

y of Baltimore....
1 Boston
Chicago
Denver
* Omaha
* Philadelphi<
i St. Louis

^•land (Soc. Pub
Analysts)
nee (Paris)
•many(Hambu'g
Ltzerland (Berne

Sll ^

e I ^ g o ^
e? fe O QD

'17

258

Testing Milk and Its Products.

Table III. Quevenne lactometer degrees corresponding to
N. Y. Board of Health degrees. (See p. 104)

Bd. & Health
decrees.

Quevenne
scale.

Bd. of Health
degrees.

Quevenne
scale.

Bd. of Health
degrees.

Quevenne
scale.

17.4

23.5

101

29.3

17.7

23.8

102

29.6

18.0

24.1

103

29.9

18.3

24.4

104

30.2

18.6

24.6

105

30.5

18.8

24.9

106

30.7

19.1

25.2

107

31.0

19.4

25.5

108

31.3

19.7

25.8

109

31.6

20.0

26.1

110

31.9

20.3

26.4

111

32.2

20.6

26.7

112

32.5

20.9

93.

27.0

113

32.8

21.2

27.3

114

33.1

21.5

27.6

115

33.4

21.7

27.8

116

33.6

22.0

28.1

117

33.9

22.3

28.4

118

34.2

22.6

- 99

28.7

119

34.5

22.9

100

29.0

120

34.8

23.2

Table IV. Value of m*-m for sp. gr. from 1.019 to 1.0369.

Sp.gr. (g) =

0.0000

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

1.019

1.864

1.874

1.884

1.894

1.903

1.913

1.922

1.932

1.941

1.951

1.020

1.961

1.970

1.980

1.990

1.999

2.009

2.018

2.028

2.038

2.047

1.021

2.057

2.066

2.076

2.086

2.095

2.105

2.114

2.124

2.133

2.143

L022

2.153

2.162

2.172

2.181

2.191

2.200

2.210

2.220

2.229

2.239

1.023

2.249

2.258

2.267

2.277

2.286

2.296

2.306

2.315

2.325

2.334

1.024

2.344

2.353

2.363

2.372

2.382

2.391

2.401

2.410

2.420

2.430

1.025

2.439

2.449

2.458

2.468

2.477

2.487

2.496

2.506

2.515

2.525

1.026

2.534

2.544

2.553

2.563

2.573

2.582

2.591

2.601

2.610

2.620

1.027

2.629

2.638

2.648

2.657

2.667

2.676

2.686

2.695

2.705

2.714

1.028

2.724

2.733

2.743

2.752

2.762

2.771

2.781

2.790

2.799

2>09

1.029

2.818

2.828

2.837

2.847

2.356

2.865

2.875

2.884

2.893

2.903

1.030

2.913

2.922

2.931

2.941

2.951

2.960

2.969

2.979

2.988

2.997

1.031

3.007

3.016

3.026

3.035

3.044

3.054

3.063

3.072

3.082

3.091

1.032

3.101

3.110

3.120

3.129

3.138

3.148

3.157

3.166

3.176

3.185

1.033

3.195

3.204

3.213

3.223

3.232

3.241

3.251

3.260

3.269

3.279

1.034

3.288

3.298

3.307

3.316

3.326

3.335

3.344

3.354

3.363

3.372

1.035

3.382

3.391

3.400

3.410

3.419

3.428

3.438

3.447

3.456

3.466

1.036

3.475

3.484

3.494

3.503

3.512

3.521

3.531

3.540

3.549

3.559

(See directions for use, p. 112)

Appendix. 259

Table V. Correction-table for specific gravity of milk.

2 •

fSf

Temperature of milk (in degrees Fahrenheit).

§2

19.3

19.4

19.5

19.6

19.7

19.8

19.9

20.0

20.3

20.4

20.5

20.6

20.7

20.8

20.9

21.0

21.3

21.4

21.5

21.6

21.7

21.8

21.9

22.0

22.3

22.4

22.5

22.6

22.7

22.8

22.9

23.0

23.3

23.4

23.5

2X6

23.6

23.7

23.8

23.9

24.0

24.2

24.3

24.4

24.5

24.6

24.7

24.8

24.9

25.0

25.2

25.3

25.4

25.5

25.6

25.7

25.8

25.9

26.0

26.2

26.3

26.4

26,5

26\6

26.7

26.8

26.9

27.0

27.1

27.2

27.3

27.4

27.5

27.6

27.7

27.8

27.9

28.0

. 28.1

28.2

28.3

28.4

28.5

28.6

28.7

28.8

28.9

29.0

29.1

29.2

29.3

29.4

-M.6

29.7

29.8

29.9

30.0

30.1

30.2

30,3

30.4

;;j.5

30.6

20.8

30.9

31.0

31.1

31.2

31.3

31.4

31.5

31.6

31.7

31.9

32.0

31.9

32.0

32.1

32.3

32.5

32.6

32.7

32.9

33.0

32.9

33.0

33.1

33.2

33.3

33.5

33.6

33.7

33.9

34.0

33.8

33.9

34.0

34.2

34.3

34.5

.•

34.6

34.7

34.9

35.0

20.1

20.2

20.3

20.4

20.5

20.6

20.7

20.9

21.0

21.1

21.2

21.3

21.4

21.5

21.6

21.7

21.8

22.0

22.1

22.2

22.3

22.4

22.5

22.6

22.7

22.8

23.0

23.1

23.2

23.3

23.4

23.5

23.6

23.7

23.8

24.0

24.1

24.2

24.3

24.4

24.5

24.6

24.7

24.9

25.0

25.1

25.2

25.3

25.4

25.5

25.6

25.7

25.9

26.0

26.1

26.2

26.3

26.5

26.6

26.7

26.8

27.0

27.1

27.2

27.1

27.3

27.4

27.5

27.6

27.7

27.8

28.0

28.1

28.2

28.1

28.3

28.4

28.5

28.6

28.7

28.8

29.0

29.1

29.2

29.1

29.3

29.4

29.5

29.6

29.7

29.9

30.1

30.2

30.3

30.1

30.3

30.4

30.5

30.7

30.8

30.9

31.1

31.2

31.3

31.2

31.3

31.4

31.5

31.7

31.8

31.9

32.1

32.2

32.4

32.2

32.3

32.5

32.6

32.7

32.9

33.0

33.1:

33. 3«

33.4

33.2

33.3

33.5

33.6

33.8

33.9

34.0

34.2

34.3

34.5

34.2

34.3

34.5

34.6

34.8

34.9

35.0

35.2

35.3

35.5

35.2

35.3

35.5

35.6

35.8

35.9

36.1

36.2

36.4

36.5

DIRECTIONS.— Bring the temperature of the milk to within 10° of
60° F. Take the reading of the lactometer and f hat of the temperature of
the milk; find the iormer in the first vertical column of the table and the
latter in the first horizontal row of figures; the figure where the horizontal
and vertical columns meet is the corrected lactometer reading; e.g., ob-
served, 31.0 at 67° F. ; corrected reading, 31.9.

260

Testing Milk and Its Products.

Table VI. Per cent, of solids not fat, corresponding to 0 to
6 per cent, of fat, and lactometer readings of 26 to

36. (See directions for use, p. 108.)

LACTOMETER READINGS AT 60° F.

6.50

6.75

7.00

7.25

7.50

7.75

8.00

8.25

8.50

8.75

9.00

0.1

6.52

6.77

7.02

7.27

7.52

/.77

8.02

8.27

8.52

8.77

9.02

0.1

0 2

6 54

6 79

7 04

7 29

7 54

7 79

8 04

8 29

8 54

8 79

9 04

0.2

0.3

6.56

6.81

7.06

7.31

7.56

7.81

8.06

8.31

8.56

8.81

9.06

0.3

0.4

6.58

6.83

7.08

7.33

7.58

7.83

8.08

8.33

8.58

8.83

9.08

0.4

0 5

6 60

6 85

7 10

7 35

7 60

7 a5

8 10

8 35

8 60

8 85

9 10

0.5

0.6

6.62

6.87

7.12

7.37

7.62

7.87

8.12

8.37

8.62

8.87

942

0.6

0.7

6.64

6.89

7.14

7.39

7.64

7.89

8.14

8.39

8.64

8.89

9.14

0.7

0 8

6 91

7 16

7 41

7 68

7 91

8 16

8 41

8 66

8 91

9 16

0 8

0.9

6.68

6.93

7.18

7.43

7.68

7.93

8.18

8.43

8.68

8.93

9.18

0.9

1.0

6.70

6.95

7.20

7.45

7.70

7.95

8.20

8.45

8.70

8.95

9.20

1.0

1.1

6.72

6.97

7.22

7.47

7.72

7.97

8.22

8.47

8.72

8.97

9.22

1.1

1.2

H.74

6.99

7.24

7.49

7.74

7.99

8^24

8.49

8.74

8.99

9.24

1.2

1.3

6.76

7.01

7.26

7.51

7.76

8.01

8.26

8.51

8.76

9.01

9.26

1.3

1 4

6 78

7 03

7 28

7 53

7 78

8 OS

8 28

8 53

8 78

9 03

9 28

1.4

1.5

6.80

7.05

7.30

7.55

7.80

8.05

8.30

8.55

8.80

9.05

9.30

1.5

1.6

6.82

7.07

7.32

7.57

7.82

8.07

8.32

8.57

8.82

9.07

9.32

l.C

1.7

6.84

7.09

7.34

7.59

7.84

8.09

8.34

8.59

8.84

9.09

9.34

1.7

1.8

6.86

7.11

7.36

7.61

7.86

8.11

8.36

8.61

8.86

9.11

9.37

1.8

1.9

6.88

7.13

7.38

7.63

7.88

8.13

8.38

8.63

8.88

9.13

9.39

1.9

2.0

6.90

7.15

7.40

7.65

7.90

8.15

8.40

8.66

8.91

9.16

9.41

2.0

2.1

6.92

7.17

7.42

7.67

7.92

8.17

8.42

8.68

8.93

9.18

9.43

2.1

2.2

6.94

7.19

7.44

7.69

7.94

8.19

8.44

8.70

8.95

9.20

9.45

2.2

2.3

6.96

7.21

7.46

7.71

7.96

8.21

8.46

8.72

8.97

9.22

9.47

2.3

2.4

6.98

7.23

7.48

7.73

7.98

8.23

8.48

8.74

8.99

9.24

9.49

2.4

2.5

7.00

7.25

7.50

7.75

8.00

8.25

8.50

8.76

9.01

9.26

9.51

2.5

2.6

7.02

7.27

7.52

7.77

8.02

8.27

8.52

8.78

9.03

9.28

9.53

2.6

2.7

7.04

7.29

7.54

7.79

8.04

8.29

8.54

8.80

9.05

9.30

9.55

2.7

2 8

7 06

7 SI

7 5f>

7 81

8 Or>

8 S1

8 57

8 8?

) 07

9 32

9 57

2 8

2.9

7.08

7.33

7.58

7.83

8.08

8.33

8.59

8.84

9.09

9.34

O.r,o

2.9

Appendix.

261

Table VI. Per cent, of solids not fat (Continued).

LACTOMETER READINGS AT 60° F.

fl+j

§~*

f«<M

3.0

7 10

7 35

7 60

7 85

8 10

8 36

8 61

8 86

9 11

9 3r

9.61

3,0

3.1

7.12

7.37

7.62

7.87

8.13

8.38

8.6b

8.88

9.13

9.38

9.64

3.1

3.2

7.14

7.31

7.64

7.89

8.15

8.40

8.65

8.90

9.15

9.41

9.66

3.2

3 3

7 16

7 41

7 66

7 99

8 17

8 49

8 67

8 99

9 18

9 43

9 68

3 3

3.4

7 18

7 43

7 69

7 94

8 If

8 44

8 69

8 94

9 ?,o

9 45

9.70

3.4

3.5

7.20

7.45

7.71

7.96

8.21

8.46

8.71

8.96

9.22

9.47

9.72

3.5

3.6

7.22

7.48

7.73

7.9S

8.23

8.48

8.73

8.98

9.24

9.49

9.74

3.6

3.7

7.24

7.50

/ .75

•s.OO

3.25

8.50

8.75

9.00

9.26

9.51

9.7(

3.7

3.8

7 W

7 59

7. 77

8 02

8 ?,7

8 59

8 77

9 09

9 9,S

9 53

9.78

3.8

3.9

7.28

7.54

7'. 7^

8.04

8.29

8.C4

8.79

9.04

9.30

9.55

9.80

3.9

4.0

7 30

7 5fi

7 SI

8 06

8 31

8 56

8 81

9 06

9 39

9 57

9 83

4 0

4.1
4.2

7.32
7.34

7.58
7.60

r7.83
7.85

8.08
8.10

8.33
S.35

8.58
8.60

8.83
3.85

SSf

(9.34
9.36

9.59
9.62

9.85
9.87

4.1
4.2

4.3

7.36

7.62

7.87

8.12

8.37

8.62

8.88

9.13

9.38

9.64

9.89

4.3

4 4

7 38

7 64

7 89

8 14

S 39

8 64

8 90

9 15

9 40

9 f>(>

9 91

4 4

4.5

7 40

7 66

7 91

8 16

8 41

S 60

8 9°

9 17

9 49,

9 (,8

9 93

4 5

4.6

7 43

7 6S

7 93

8 18

8 43

8 6S

S 94

9 19

9 44

9 70

9 95

4 6

4.7*

7.45

7.70

7.95

8.20

S.45

8.70

8.96

J.21

9.46

9.72

9.97

4.7

4.8

7 47

7 79

7 97

8 29

S 47

8 79

S 98

9 93

9 48

9 74

9 99

4 8

4.9

7.49

7.74

7.99

8.24

3.49

8.74

9.00

9.25

9.50

9.76

10.01

4.9

5.0

7.51

7.76

8.01

8.26

S.51

8.76

9 02

9.27

9.52

9.78

10.03

5.0

5.1

7.53

7.78

8.03

8.28

8.53

8.79

9.04

J.29

J.54

9.80

10.05

5.1

5.2

7.55

7.80

8.05

8.^0

8.55

8.81

9.06

9.31

J.56

9.82

10.07

5.2

5.3

7.57

7.82

8.07

8.32

S.57

8.83

9.08

9.33

J.58

9.84

10.09

5.3

5.4

7.59

7.84

8.09

8.34

8.60

8.85

9.10

J.36

9.61

9.86

10.11

5.4

5.5

7 61

7 86

8 11

8 36

S 69

8 87

9 19

9 SS

9 68

0 PS

10 13

5 5

5.6

7.63

7.88

3.13

8.39

8.64

8.89

J.15

9.40

9.65

9.90

10.15

5.6

5.7

7.65

7.90

8.15

8.41

8.66

8.91

.17

9.42

9.67

9.92

0.17

5 . 7

5.8

7.67

7.92

8.17

8.43

8.68

8.94

9.19

9.44

9.61)

9.94

0.19

5.9

7.69

7.94

3.20

8.45

3.70

8.96

J.21

J.46

9.71

9.96

10.22

5.9

6.0

7.71

7.96

8.22

8.47

B.72

8.98

9 2-°>

9.48

9.73

D.98

10.2*

6.0

262 Testing Milk and Its Products.

Directions for Use of Tables VII, VIII, IX, and XI.

TABLES VII, and VIII. Find the test of the milk in table VII or
of cream in table VIII; the first or last horizontal row of fig-
ures, the amounts of fat in ten thousand, thousands, hundreds,
tens, and units of pounds of milk are then given in this verti-
cal column. By adding the corresponding figures for any given
quantity of milk or of cream, the total quantity of butter fat
contained therein is obtained.

Example: How many pounds of fat is contained in 8925 Ibs. of milk
testing 3.«5 per cent.? On p. 264, second column the test 3.65 is round, and
by going downward in this coiumn we Lave:

80CO Ibs 292. Ibs.

900 Ib.s 32.9 Ibs.

20 Ibs 7 Ibs.

5 Ibs 2 ibs.

8925 Ibs. of milk. 32 3. 8 Ibs. of fat.

8925 Ibs. of milk testing 3.65 per cent., therefore, contains 325.8 Ibs. of
butter fat.

TABLC IX. The price per pound is given in the outside vertical
columns, and the weight of butter fat in the upper and lower
horizontal row of figures. The corresponding tens of pounds
are found by moving the decimal point one place to the left,
the units, by moving it two, and the tenths of a pound, by
moving it three places to the left. The use of tho table is,
otherwise, as explained above.

Example: How much money is due for 325.8 Ibs. of butter fnt at 1
p. 247>*

cents per pound? In the horizontal row of figures beginning with lo% ou
~^ find:

800 Ibs $40.50

20 Ibs 3.10

6 Ibs 77

.8 Ibs 12

325.8 Ibs. $50.49

826.8 Ibs. of butter fat at 15% cents per pound, therefore, Is worth $50.49.

TABLE XI. Find the test of milk in the upper or lower hori-
zontal row of figures. The amounts of butter likely to be made
from ten thousand, thousands, hundreds, tens, and units of
pounds of milk are then given in this vertical column. The use
of the table is, otherwise, as explained above in case of table VII.

Example: How much butter will 5845 Ibs. of milk testing 3.8 per cent,
be apt to make under good creamery conditions? In the column headed
3.8, we find :

6000 Ibs 209.0 Ibs.

800 Ibs 33.4 Ibs.

40 Ibs 1.7 Ibs.

6 Ibs 2 Ibs.

6845 Ibs. 244.3 Ibs.

5815 Ibs. of milk test ng 3.8 per cent, of fat will make about 244.3 lb§. of
butter, ui»il(M- conditions similar to those explained on pp. J%-7.

Appendix.

263

Table VII. Pounds of fat in I to 10,000 Ibs. of miik, testing 3.0
to 5.35 per cent. (See directions for use, p. 262.)

3.00

3.05

3.10

3.15

3.20

3.25

3.30

3.35

3.40

3.45

3.50

3.55

Milk

Ibs.

10,000

300

305

310

315

320

325

330

335

340

345

350

355

10,000

9,000

270

275

279

284

289

293

297

302

306

311

315

320

9,000

8,000

240

244

248

252

256

260

264

268

272

276

280

284

8,000

7,000

210

214

217

221

224

228

231

235

238

242

245

249

7,000

6,000

ISO

183

186

189

-192

195

198

201

204

207

210

213

6,000

5,000

150

153

155

158

160

163

165

168

170

173

175

178

5,000

4,000

120

122

124

126

128

130

132

134

136

138

140

142

4,000

3,000

90.0

91.5

93.0

94.5

96.0

97.5

99.0

101

102

104

105

107

3,000

2,000

60.0

61.0

62.0

63.0

64.0

65.0

66.0

67.0

68.0

69.0

70.0

71.0

2,000

1,000

30.0

30.5

31.0

31.5

32.0

32.5

33.0

33.5

34.0

34.5

35.0

35.5

1,000

900

27.0

27.5

27.9

28.4

28.8

29.3

29.7

30.2

30.6

31.1

31.5

32.0

900

800

24.0

24.4

24.8

25.2

25.7

26.0

26.4

26.8

27.2

27.6

28.0

28.4

800

700

21 0

9-| /|

91 7

•>9 1

99 4

9-? 8

<>3 1

93 5

93 8

94 9

94 5

94 9

700

600

18.0

18.3

18.6

18.9

19.2

19.5

19.8

20.1

20.4

20.7

21.0

21.3

600

500

15.0

15.3

15.5

15.8

10.0

16.3

16.5

16.8

17.0

17.3

17.5

17.8

500

400

12.0

12.2

12.4

12.6

12.8

13.0

13.2

13.4

13.6

13.8

14.0

14.2

400

300

9.0

9.2

9.3

9.5

9.6

9.8

9.9

10.1

10.2

10.4

10.5

10.7

300

200

6.0

6.1

6.2

6.3

6.4

6.5

6.6

6.7

6.8

6.9

7.0

7.1

200

100

3 0

3 1

3 9

3 3

3 4

3 5

100

2.7

2.8

2.9

3.0

3.1

3.2

2.4

2.5

2.6

2.7

2.8

2.1

2.2

2.3

2.4

2.5

1.8

1,8

1.9

2.0

2.1

1 5

1 6

1 7

1 8

1.2

1.3

1.4

1.0

1.1

.31 -3

• 2

3.45

3.00

3.05

3.10

3.15

3.20

3.25

3.30

3.35

3.40

3.50

3.55

i
*

264 Testing Milk and Its Products.

Table VH. Pounds of fat in I to 10,000 Ibs. of milk ( Continued).

3.60

3.65

3.70

3.75

3.80

3.85

3.90

3.95

4.00

4.05

4.10

4.15

Milk

Ibs.

10,000

360

365

370

375

380

385

390

395

400

405

410

415

10,000

9,000

324

329

333

338

342

347

351

356

360

365

369

374

9,000

8,000

288

292

296

300

304

308

312

316

320

324

328

332

8,000

7.000

252

256

259

263

266

270

273

277

280

284

287

291

7,000

6,000

216

219

222

225

228

231

234

237

240

243

246

249

6,000

5,000

180

183

185

188

190

193

195

198

200

203

205

208

5,000

4,000

! 144

146

148

150

152

154

156

158

160

162

164

166

4,000

3,000

108

110

111

113

114

116

117

119

120

122

123

125

3,000

2,000

72.0

73.0

74.0

75.0

76.0

77.0

78.0

79.0

80.0

81.0

82.0

83.0

2,000

1,000

36.0

36.5

37.0

37.5

38.0

38.5

39.0

39.5

40.0

40.5

41.0

41.5

1,000

900

32.4

32.9

33.3

33.8

34.2

34.7

35.1

35.6

36.0

36.5

36.9

37.4

900

800

28.8

29.2

29.6

30.0

30.4

30.8

31.2

31.6

32.0

32.4

32.8

33.2

800

700

25.2

25.6

25.9

26.3

26.6

27.0

27.3

27.7

28.0

28.4

28.7

29.1

700

600

21.6

21.9

22.2

22.5

22. S

23.1

23.4

23.7

24.0

24.3

24.6

24.9

600

500

18.0

18.3

18.5

18.8

19.0

19.3

19.5

19.8

20.0

20.3

20.5

20.8

500

400

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

16.0

16.2

16.4

16.6

400

300

10.8

11.0

11.1

11.3

11.4

11.6

11.7

11.9

12.0

12.2

12. ij

12.5

300

200

7.2

7.3

7.4

7.5

7.6

7.7

7.8

7.9

8.0

8.1

8.2

8.3

200

100

3.6

3.7

3.8

3.9

4.0

4.1

4.2

100

3 9

3 3

3 4

3 5

3 6

3 7

2.9

3.0

3.1

3.2

3.3

2.5

2.6

2.7

2.8

2.9

2 9

9 9

9 3

9 4

? 4

9 5

1.8

1.9

2.0

2.1

Ofi

1.4

1.5

1.6

1 9

1.6

1.7

. Z

1 Z

3.60

3.65

3.70

3.75

3.80

3.85

3.90

5.95

4.00

4.05

4.10

4.15

Appendix.

265

Table VII. Pounds of fat in I to 10,000 Ibs. of milk (Continued).

i
§

4.20

4.25

4.30

4.35

4.40

440
396
352
308
264
220
176
132
88.0
44.0

39 6

4.45

4.50

4.55

4.60

4.65

4.70

4.75

Milk
Ibs.

10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000

900
800
700
600
500
400
300
200
100

90
80
70
60
50
40
30
20
10

9
8
7
6
5
4
3
2
1

420
378
336
294
252
210
168
126
84.0
42.0

37.8
33.6
29.4
25.2
21.0
16.8
12.6
8 4

425

383
340
298
255
213
170
128
85.0
42.5

3S 3

430
387
344
301
258
215
172
129
86.0
43.0

38 7

435
392
348
305
261
218
174
131
87.0
43.5

39 9

445
401
356
312
267
223
178
134
89.0
44.5

40 1

450
405
360
315
270
225
180
135
90.0
45.0

40 5

455
410
364
319
273
228
182
137
91.0
45.5

41 0

460
414
368
322
276
230
184
138
92.0
46.0

41 4

465
419
372
326
279
233
186
140
93.0
46.5

41 9

470
423
376
329
282
235
188
141
94.0
47.0

4ft 8

475
428
380
333
285
238
190
143
95.0
47.5

4ft 8

Milk
Ibs.

10,000
9,000
8,000
7,000
6,000
5,OCO
4,000
3,000
2,000
1,000

900
800
700
600
500
400
300
200
100

90
80
70
60
50
40
30
20
10

9
8
7
6
5
4
3
2
1

31.0
29.8
25.5
21.3
17.0
12.8
8 5

34.4
30.1
"5.8
21.5
17.2
12.9
8 fi

34.8
30.5
26.1
21.8
17.4
13.1
8 7

35.2

30.8
26.4
22.0
17.6
13.2
8 8

35.6
31.2
26.7
22.3
17.8
13.4
8 9

36.0
31.5
27.0
22.5
18.0
13.5
9 0

36.4
31.9
27.3

22.8
18.2
13.7
9 1

36.8
32.2
27.6
23.0
18.4
13.8
9 ft

37.2
32.6
27.9
23.3
18.6
14.0
9 3

37.6
32.9
28.2
23.5
18.8
14.1
9 4

38.0
33.3
28.5
23.8
19.0
14.3
9 5

4.2
3 8

4.3

3 8

4.3
8 9

4.4

3 9

4.4
4 0

4.5
4 0

4.5
4 1

4.6
4 1

4.7
4 ft

4.8
4 3

3 4

8 4

8 5

3 6

3 f>

3 7

8 8

ft 9

3 0

8 0

8 1

3 ft

3 8

8 8

3 3

ft 5

ft fi

9, 6

ft B

ft 6

ft 7

ft 8

ft 9

9, 1

ft 1

ft ft

ft 3

ft 8

ft 3

ft 4

1.7
1 3

1.8
1 3

1.8
1 8

1.8
1 4

1.9
1 4

1 0

.3
3

.3
8

.3
3

.3
8

.4
3

.4
8

.4
3

.4
8

.2
2

.2
ft

.2
2

.2
ft

.1
1

4 90

4 9,5

4 30

4 35

4 40

4 45

4 50

4 55

4 60

4 65

4 70

4 75

266 Testing Milk and Its Products.

Table VII. Pounds of fat in I to 10,000 Ibs. of milk ( Continued).

4.80

4.85

4.90

4.95

5.00

5.05

5. 10

5.15

5.20

5.25

5.30

5.35

Milk

Ibs.

10,000

480

485

490

495

500

505

510

515

520

525

530

535

10,000

9,000

432

437

441

446

450

455

459

464

468

473

477

482

9^000

8,000

384

388

392

396

400

404

408

412

416

420

424

428

8,000

7,000

336

340

343

347

350

354

357

361

364

368

371

375

7,000

6,000

288

291

294

297

300

303

306

309

312

315

318

321

6,000

5,000

240

243

245

248

250

253

255

258

260

263

265

268

5,000

4,000

192

194

196

198

200

202

204

206

208

210

212

214

4,000

3,000

144

146

147

149

150

152

153

155

156

158

159

161

3,000

'2,000

96.0

97.0

98.0

99.0

100

101

102

103

104

105

106

107

2,000

1,000

48.0

48.5

49.0

49.5

50.0

50.5

51.0

51.5

52.0

52.5

53.0

53.5

1,000

900

43.2

43.7

44.1

44.6

45.0

45.5

45.7

46.4

46.8

47.3

47.7

48.2

900

800

38.4

38.8

39.2

39.6

40.0

40.4

40.8

41.2

41.6

42.0

42.4

42.8

800

700

33.6

34.0

34.3

34.7

35.0

35.4

35.7

36.1

36.4

36.8

37.1

37.5

700

600

28.8

29.1

29.4

29.7

30.0

30.3

30.6

30.9

31.2

31.5

31.8

32.1

600

500

24.0

24.3

24.5

24.8

25.0

25.3

25.5

25.8

26.0

26.3

26.5

26.8

500

400

19.2

19.4

19.6

19.8

20.0

20.2

20.4

20.6

20.8

21.0

21.2

21.4

400

300

14.4

14.6

14.7

14.9

15.0

15.2

15.3

15.5

15.6

15.8

15.9

16.1

300

200

9.6

9.7

9.8

9.9

10.0

10.1

10.2

10.3

10.4

10.5

10.6

10.7

200

100

4.8

4.9

5.0

5.1

5.2

5.3

5.4

100

4.3

4.4

4.5

4.6

4.7

4.8

3.8

3.9

4.0

4.1

4.2

4.3

3.4

3.5

3.6

3.7

2.9

3.0

3.1

3.2

2.4

2.5

2.6

2.7

1.9

2.0

2.1

1.4

1.5

1.6

1.0

1.1

'.1

4.95

5.00

5.20

5.25

4.80

4.85

4.90

5.05

5.10

5.15

5.30

5.35

Appendix.

267

Table VIII. Pounds of fat in I to 1000 Ibs. of cream testing
12.0 to 50.0 per cent. fat.

(See directions for use, p. 262)

1000

120

180

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

900

108

117

126

135

144

153

162

171

180

18-'

198

207

216

225

284

243

252

261

270

800

104

112

120

128

136

144

152

160

168

176

184

192

200

208

216

224

232

24J

700

105

112

119

126

133

147

151

161

163

175

182

189

196

k03

210

600

102

108

114

120

126

132

138

144

150

156

162

168

174

180

500

100

105

110

115

120

125

130

135

140

145

150

400

100

104

108

112

116

120

800

200

5<>

100

10.8

11.7

12.6

13.5

14.4

15.3

16.2

17.1

18.0

18.9

19.8

20.7

21.6

22.5

23.4

24.3

25.2

26.1

27.0

9.6

10.4

11.2

12.0

12.8

13.6

14.4

15.2

16.0

16.8

17.6

18.4

19.2

0.0

20.8

21.6

22.4

23.2

24.0

8.4

9.1

9.8

10.5

11.2

11.9

12.6

13.8

14.0

14.7

15.4

16.1

16.8

17.5

18.2

18.9

19.6

20..3

21.0

7.2

7.8

8.4

9.0

9.6

10.2

10.8

11.4

12.0

12.6

13.2

13.8

14.4

15.0

15.6

16.2

16.8

17.4

18.0

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

4.5

15.0

4.8

5.2

5.6

6.0

6.4

6.8

7.2

7.6

8.0

8.4

8.8

9.2

9.6

10.0

10.4

10.8

11.2

11.6

12.0

3.6

3.9

4.2

4.5

4.8

5.1

5.4

5.7

6.0

6.3

6.6

6.9

7.2

7.5

7.8

8.1

8.4

8.7

9.0

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

5.2

5.4

5.6

5.8

6.0

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.8

2.4

2.5

2.6

2.7

2.8

2.9

3.0

1.08

1.17

1.26

1.85

1.44

I. S3

1.62

1.71

1.80

1.89

1.98

2.07

2.16

2.25

2.34

1.43

2.52

2.61

2.70

.96

1.04

1.12

1.20

1.28

1.36

1.44

1.52

1.60

1.68

1.76

1.84

1.92

2.00

2.08

2.16

2.24

2.32

2.40

.84

.91

.9>S

1.05

1.12

1.19

1.26

1.33

1.40

1.47

1.54

1.61

l.«8

1.75

1.82

1.89

1.96

2.03

2.10

.72

.78

.84

.90

1.02

1.08

1.14

1.20

1.26

1.32

1.38

1.44

1.50

1.56

1.62

1.68

1.74

1.80

.60

.65

.70

.75

.80

.85

.90

.95

1.00

l.Oo

1.10

1.15

1.20

1.25

1.30

1.85

1.40

1.45

1.50

.48

.52

.56

.60

.64

.68

.72

.76

.80

.84

.88

.92

.91.

1.00

1.04

1.08

1.12

1.16

1.20

.36

.39

.42

.45

.48

.51

.54

.57

.60

.63

.66

.69

.72

.75

.78

.81

.84

.87

.90

.24

.26

.28

.30

.32

.34

.36

.38

.40

.42

.44

.46

.48

.50

.52

.54

.51)

.58

.60

.12

.13

.14

.15

.16

.17

.18

.19

.20

.21

.22

.23

.24

.25

.26

.27

.28

.29

.30

268

Testing Milk and Its Products.

Table Mil. Pounds of fat in I to 1000 Ibs. of cream (continued).

1000

310

320

380

340

350

360

370

380

390

400

410

420

430

440

450

460

470

480

490

500

900

279

288

297

306

315

324

833

342

351

360

369

378

387

896

405

414

423

482

441

450

800

248

256

264

272

280

288

296

304

312

820

328

336

844

352

360

368

376

384

892

400

700

217

224

231

238

245

252

259

266

273

280

287

294

301

308

815

322

829

386

843

850

600

186

192

198

204

210

216

222

228

234

240

246

252

258

264

270

276

282

288

294

800

500

155

160

165

170

175

180

18)

190

195

200

205

210

215

2-20

225

280

235

240

245

250

400

124

128

132

136

140

144

148

152

156

160

164

168

172

176

180

184

188

192

196

200

800

102

105

108

111

114

117

120

123

126

129

132

135

188

141

144

147

150

200

100

27.9

28.8

29.7

30.6

31.5

82.4

33.3

84.2

35.1

86.0

36.9

37.8

38.7

39.6

40.5

41.4

42.3

43.2

44.1

45.0

24.8

25.6

26.4

27.2

28.0

28.8

29.6

30.4

21.2

32.0

32.8

33.6

34.4

35.2

36.036.8

37. 6188.4

39.2

40.0

21.7

22.4

23.1

23.8

24.5

25.2

25.9

26.6

27.8

28.0

28.7

29.4

30.1

30.8

31.5:32.2

32.988.6

34.8

35.0

18.6

19.2

19.8

20.4

21.0

21.6

22.2

22.8

28.4

24.0

24.6

25.2

25.8

26.4

27.027.6

28.2:28.8

29.4(80.0

15.5

16.0

16.5

17.0

17.5

18.0

18.5

19.0

19.5

20.0

20.5

21.0

21.5

22.0

22.523.0

28.524.0

24.5

25.0

12.4

12.8

13.2

13.6

14.0

14.4

14.8

15.2

15.6

16.0

16.4

16.8

17.2

17.6

18.0 18.4

18.8

19.2

19.6

20.0

9.8

9.6

9.9

10.2

10.5

10.8

11.1

11.4

11.7

12.0

12.3

12.6

12.9

18.2

18.518.8

14.1

14.4

14.7

15.0

8.2

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

10.0

8.1

8.2

8.8

3.4

8.5

8.6

8.7

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

2.79

2.88

2.97

8.06

8.15

3.24

3.38

3.42

3.51

3.60

3.69

8.78

3.87

8.964.9514.14

4.28

4.82

4.41

4.50

2.48

2.56

2.64

2.72

2.80

2.88

2.96

3.04

3.12

3.20

8.28

8.363.44

3.52

3.603.68

3.763.84

3.924.00

2.17

2.24

2.81

2.38

2.45

2.52

2.59

2.66

2.73

2.80

2.87

2.943.01

3.08

8.15:8.22

3.29

3.86

3.43

3.50

1.8ft

1.92

1.98

2.04

2.10

2.16

2.22

2.28

2.34

2.40

2.46

2.522.58

2,64

2.702.76

2.82

2.88

2.94

3.00

1.56

1.60

1.65

1.70

1.75

1.80

1.85

1.90

1.95

2.00

2.0-5

2.102.15

2.20

2.252.30

2.85

2.40

2.45

2.60

1.24

1.28

1.82

1.36

1.40

1.44

1.48

1.52

1.56

1.60

1.64

1.681.72

1.76

1.80

1.84

1.88

1.92

1.06

2.00

.93

.96

.99

1.02

l.Oo

1.08

1.11

1.14

1.17

1.20

1.23

1.26,1.29

1.82

1.35

1.38

1.41

1.44

l.*7

1.60

.62

.64

.66

.68

.70

.72

.74

.76

.78

.80

.82

.81

.86

.88

.90 .92

.94

.96

.98

1.00

.81

.82

.38

.34

.35

.£6

.87

.38

.39

.40

.41

.42

.43

.44

.45 .46

.47

.48

.49

.60

Appendix.

269

Table IX. Amount due for butter fat, in dollars and cents, at
12 to 25 cents per pound.

(See directions for use, page 262.)

12}

Pounds of butter fat.

p-o

12
12}
12}
12}

1,000

900

800

700

600

500

400

300

200

100

120.00
122.50
125.00
127.50

108.00
110.25
112.50
114.75

96.00
98.00
100.00
102.00

84.00
85.75
87.50
89.25

72.00
73.50
75.00
76.50

60.00
61.25
62.50
63.75

48.00
49.00
50.00
51.00

36.00
36.75
37.50
38.25

24.00
24.50
25.00
25.50

12.00
12.25
12.50
12.75

13}

130.00
132.50
135.00
137.50

117.00
119.25
121.50
123.75

104.00
106.00
108.00
110.00

91.00
92.75
94.50
96.25

78.00
79.50
81.00
82.50

65.00
66.25
67.50
68.75

52.00
53.00
54.00
55.00

39.00
39.75
40.50
41.25

26.00
26.50
27.00
27.50

13.00
13.25
13.50
13.75

13
13}
13}
13}

14
14}

140.00
142.50
145.00
147.50

126.00
128.25
130.50
132.75

112.00
114.00
116.00
118.00

98.00
99.75
101.50
103.25

84.00
85.50
87.00
88.50

70.00
71.25
72.50
73.75

56.00
57.00
58.00
59.00

42.00
42.75
43.50
44.25

28.00
28.50
29.00
29.50

14.00
14.25
14.50
14.75

14
14}
14}
14}

15
15}

150.00
152.50
155.00
157.50

135.00
137.25
139.50
141.75

120.00
122.00
124.00
126.00

105.00
106.75
108.50
110.25

90.00
91.50
93.00
94.50

75.00
76.25
77.50
78.75

60.00
61.00
62.00
63.00

45.00
45.75
46.50
47.25

30.00
30.50
31.00
31.50

15.00
15.25
15.50
15.75

15}
15}

16
16}
16}
16}

160.00
162.50
165.00
167.50

144.00
146.25
148.50
150.75

128.00
130.00
132.00
134.00

112.00
113.75
115.50
117.25

96.00
97.50
99.00
100.50

80.00

81.25
82.50

83.75

64.00
65.00
66.00
67.00

48.00
48.75
49.50
50.25

32.00
32.50
33.00
33.50

16.00
16.25
16.50
16.75

16
16}
16}
16}

17}

170.00
172.50
175.00
177.50

153.00
155.25
157.50
159.75

136.00
138.00
140.00
142.00

119.00
120.75
122.50
124.25

102.00
103.50
105.00
106.50

85.00
86.25
87.50
87.75

68.00
69.00
70.00
71.00

51.00
51.75
52.50
53.25

34.00
34.50
35.00
35.50

17.00
17.25
17.50
17.75

17
17}
17}
17}

181
18}

180.00
182.50
185.00
187.50

162.00
164.25
166.50
168.75

144.00
146.00
148.00
150.00

126.00
127.75
129.50
131.25

108.00
109.50
111.00
112.50

90.00
91.25
92.50
93.75

72.00
73.00
74.00
75.00

54.00
54.75
55.50
56.25

36.00
36.50
37.00
37.50

18.00
18.25
18.50
18.75

18
18}
18}
18}

1,000

900

800

700

600

500

400

300

200

100

270 Testing Milk and Its Products.

lable IX. Amount due for butter fat (Continued).

1 Price per I
| pound, cents. |

Pounds of butter fct.

1,000

900

800

700

600

500

400

300

200

100

19
19]

19}

190.00
192.50
195.00
197.50

171.00
173.25
175.50
177.75

152.00
154.00
156.00
158.00

133.00
134.75
136.50
138.25

114.00
115.50
117.00
118.50

95.00
96.25
97.50
98.75

76.00
77.00
78.00
79.00

57.00
57.75
58.50
59.25

38.00
38.50
39.00
39.50

19.00
19.25
19.50
19.75

19*
191

20
20}

20}

200.00
202.50
205.00
207.50

180.00
182.25
184.50
186.75

160.00
162.00
164.00
166.00

140.00
141.75
143.50
145.25

120.00
121.50
123.00
124.50

100.00
101.25
102.50
103.75

80.00
81.00
82.00
83.00

60.00
60.75
61.50
62.25

40.00
40.50
41.00
41.50

20.00
20.25
20.50
20.75

20*
201
20}

21
21*
211
21}

210.00
212.50
215.00
217.50

189.00
191.25
193.50
195.75

168.00
170.00
172.00
174.00

147.00
148.75
150.50
152.25

126.00
127.50
129.00
130.50

105.00
106.25
107.50
108.75

84.00
85.00
86.00
87.00

63.00
63.75
64.50
65.25

42.00
42.50
43.00
43.50

21.00
21.25
21.50
21.75

21
211
211
21}

22
22*

221
22}

220.00
222.50
225.00
227.50

198.00
200.25
202.50
204.75

176.00
178.00
180.00
182.00

154.00
155.75
157.50
159.25

132.00
133.50
135.00
136.50

110.00
111.25
112.50
113.75

88.00
89.00
90.00
91.00

66.00
66.75
67.50
68.25

44.00
44.50
45.00
45.50

22.00
22.25
22.50
22.75

22*
22*
22}

23
23*
231
23}

230.00
232.50
235.00
237.50

207.00
209.25
211.50
213.75

184.00
186.00
188.00
190.00

161.00
162.75
164.50
166.25

138.00
139.50
141.00
142.50

115.00
116.25
117.50
118.75

92.00
93.00
94.00
95.00

69.00
69.75
70.50
71.25

46.00
46.50
47.00
47.50

23.00
23.25
23.50
23.75

23
23*
231
23|

24
24*

241
24|
25

240.00
242.50
245.00
247.50
250.00

216.00
218.25
220.50
222.75
225.00

192.00
194.00
196.00
108.00
200.00

168.00
169.75
171.50
173.25
175.00

144.00
145.50
147.00
148.50
150.00

120.00
121.25
122.50
123.75
125.00

96.00
97.00
98.00
99.00
100.00

72.00
72.75
73.50
74.25
75.00

48.00
48.50
49.00
49.50
50.00

24.00
24.25
24.50
24.75
25.00

24*
24^
24:1
25

1,000

900

800

700

600

500

400

300

200

100

Appendix.

271

Table X. Relative-value tables.

(See directions for use, pp. 208-209.

Price of milk per 100 pounds, in dollars and cents.

3 0

.30

.31

.34

.36

.39

.43

3.1

.31

.33

.34

.36

.37

.39

.40

.42

.43

.45

3.2

.32

.34

.35

.37

.38

.40

.42

.43

.45

.46

.'48

3 8

.33

.36

.38

.40

.41

.43

.46

.48

3.4

.34

.36

.37

.39

.41

.42

.44

.46

.48

.49

.51

3.5

.35

.37

.38

.40

.42

.44

.45

.47

.49

.51

.52

3.6

.36 j

.38

.40

.41

.43

.45

.47

.49

.50

.52

.54

3.7

.37

.39

.41

.43

.44

.46

.48

.50

.52

.54

.55

3.8

.38

.40

.42

.44

.46

.47

.49

.51

.53

.55

.57

3.9

.39

.41

.43

.45

.47

.49

.51

.53

.55

.57

.58

4 0

.40

.42

.46

.48

.52

.56

.58

4.1

.41

.43

.45

.47

.49

.51

.53

.55

.57

.59

.61

4 a

.42

.44

.48

.50

.5-2

.55

.57

.59

.61

6«c

4.3

.43

.45

.47

.49

.52

.54

.56

.58

.60

.62

.64

4 4

.44

.46

.51

.53

.55

.57

.64

6C5

4.5

.45

.47

.49

.52

.54

.56

.58

.61

.63

.65

.67

4.6

.46

.48

.51

.53

.55

.57

.60

.62

.64

.67

.6f

4.7

.47

.49

.52

.54

.56

.59

.61

.63

.66

.68

.7C

4.8

.48

.50

.53

.55

.60

.62

.65

.67

.70

.72

4.9

.49

.51

.54

.66

.59

.61

.64

.66

.69

.71

.73

5.0

.50

.52

.55

.57

.60

.62

.65

.67

.70

.72

.76

5.1

.51

.54

.56

.59

.61

.64

.66

.69

.71

.74

.76

5.2

.52

.55

.57

.60

.62

.65

.68

.70

.73

.75

.78

5.3

.53

.56

.58

.61

.64

.66

.69

.72

.74

.77

.79

5.4

.54

.57

.59

.62

.65

.67

.70

.73

.76

.78

.81

5.5

.55

.58

.60

.63

.66

.69

.71

.74

.77

.80

.82

5.6

.56

.59

.62

.64

.67

.70

.73

.76

.78

.81

.84

5.7

.57

.60

.63

.66

.68

.71

.74

.77

.80

.83

.85

5.8

.58

.61

.64

.67

.70

.72

.75

-.78

.81

.84

.87

5.9

.59

.62

.65

.68

.71

.74

.77

.80

.83

.86

.88

6.0

.60

.63

.66

.60

.72

.75 .78

.81

.84

.87

.90

272

Testing Milk and Its Products.

Table X. Relative-value tables ( Continued).

S"Je

Price of milk per 100 pounds, in dollars and cents.

3.0

.46

.48

.49

.51

.52

.54

.55

.57

.58

.60

3.1

.48

.50

.51

.53

.54

.56

.57

.69

.60

.62

3.2

.50

.51

.53

.54

.56

.58

.59

.61

.62

.64

3.3

.51

.53

.54

.56

.58

.59

.61

.63

.64

.66

3 4

.53

.54

.56

.59

.63

.66

3.5

.54

.56

.58

.59

.61

.63

.65

.66

.68

.70

3.6

.56

.58

.59

.63

.65

.67

.68

.70

.72

8.7

.57

.69

.61

.63

.65

.67

.68

.70

.72

.74

8 8

.59

.61

.63

.66

.70

.74

3.9

.60

.62

.64

.66

.68

.70

.72

.74

.76

.78

4 0

.62

.64

.66

.70

7?,

.74

.78

4.1

.64

.66

.68

.70

.72

.74

.76

.78

.80

.82

4.2

.65

.67

.69

.71

.73

.76

.78

.80

.82

.84

4.3

.67

.69

.71

.73

.75

.77

.80

.82

.84

.86

4.4

.68

.70

.73

.75

.77

.79

.81

.84

.86

.88

4.5

.70

.72

.74

.76

.79

.81

.83

.85

.88

.90

4 6

.71

.74

.76

.80

.85

.90

4.7

.73

.75

.78

.80

.82

.85

.87

.89

.92

.94

4.8

.74

.77

.79

.82

.84

.86

.89

.91

.94

.96

4.9

.76

.78

.81

.83

.86

.88

.91

.93

.96

.98

5.0

.77

.80

.82

.85

.87

.90

.92

.95

.97

1.00

5.1

.79

.82

.84

.87

.89

.92

.94

.97

.99

1.02

5.2

.81

.83

.86

.88

.91

.94

.96

.99

1.01

1.04

5.3

.83

.85

.87

.90

.93

.95

.98

1.01

1.03

1.06

5.4

.84

.86

.89

.92

.94

.97

1.00

1.03

1.05

1.08

5.5

.85

.88

.91

.93

.96

.99

1.02

1.04

1.07

1.10

5.6

.87

.90

.92

.95

.98

1.01

1.04

1.06

1.09

1.12

5.7

.88

.91

.94

.97

1.00

1.03

1.05

1.08

1.11

1.14

5.8

.90

.93

.96

.99

1.01

1.04

1.07

1.10

1.13

1.16

5.9

.91

.94

.97

1.00

1.03

1.06

1.09

1.12

1.15

1.18

6.0

.93

.96

.99

1.02

1.05

1.08

1.11

1.14

1.17

1.20

Appendix.

273

Table X. Relative-value tables (Continued).

Per cent. II
fat.

Price of milk per 100 pounds, in dollars and cents.

3.0

.61

.63

.64

.66

.67

.69

.70

.72

.73

.75

3.1

.64

.65

.67

.68

.70

.71

.73

.74

.76

.78

3.2

.66

.67

.69

.70

.72

.74

.75

.77

.78

.80

3.3

.68

.69

.71

.73

.74

.76

.78

.79

.81

.83

3.4

.70

.71

.73

.75

.76

.78

.80

.82

.83

.85

3.5

.72

.73

.75

.77

.79

.80

.82

.84

.86

.88

3.6

.74

.76

.77

.79

.81

.83

.85

.86

.88

.90

3.7

.76

.78

.80

.81

.83

.85

.87

.89

.91

.93

3.8

.78

.80

.82

.84

.85

.87

.89

.91

.93

.95

3.9

.80

.82

.84

.86

.88

.90

.92

.94

.96

.98

4.0

.82

.84

.86

.88

.90

,92

.94

.96

.98

1.00

4.1

.84

.86

.88

.90

.92

,94

.96

.98

1.00

1.03

4.2

.86

.88

.90

.92

.94

.97

.99

1.01

1.03

1.05

4.3

.88

.90

.92

.95

.97

.99

1.01

1.03

1.05

1.08

4.4

.90

.92

.95

.97

.99

1.01

1.03

1.06

1.08

1.10

4.5

.92

.94

.97

.99

1.01

1.03

1.06

1.08

1.10

1.13

4.6

.94

.97

.99

1.01

1.03

1.06

1.08

1.10

1.13

1.15

4.7

.96

.99

1.01

1.03

1.06

1.08

1.10

1.13

1.15

1.18

4.8

.98

1.01

1.03

1.06

1.08

1.10

1.13

1.15

1.18

1.20

4.9

1.00

1.03

1.05

1.08

1.10

1.13

1.15

1.18

1.20

1.23

5.0

1.02

1.05

1.07

1.10

1.12

1.15

1.18

1.20

1.23

1.25

5.1

1.05

1.07

1.10

1.12

1.15

1.17

1.20

1.22

1.25

1.27

5.2

1.07

1.09

1.12

1.14

1.17

1.20

1.22

1.25

1.27

1.30

5.3

1.09

1.11

1.14

1.17

1.19

1.22

1.25

1.27

1.30

1.32

5.4

1.11

1.13

1.16

1.19

1.21

1.24

1.27

1.30

1.32

1.35

5.5

1.13

1.15

1.18

1.21

1.24

1.26

1.29

1.32

1.35

1.38

5.G

1.15

1.18

1.20

1.23

1.26

1.29

1.32

1.34

1.37

1.40

5.7

1.17

1.20

1.23

1.25

1.28

1.31

1.34

1.37

1.39

1.43

5.8

1.19

1.22

1.25

1.28

1.30

1.33

1.36

1.39

1.42

1.45

5.9

1.21

1.24

1.27

1.30

1.33

1.36

1.39

1.42

1.45

1.48

6.0

1.23

1.26

1.29

1.32

1.35

1.38

1.41

1.44

1.47

1.50

274

Testing Milk and Its Products.

Table X. Relative-value tables (Continued).

Percent. 1
fat.

1
Price of milk jwr 100 pounds, in dollars and cents.

3.0

.76

.78

.79

.81

.82

.84

.85

.87

.88

.90

3.1

.79

.81

.82

.84

.85

.87

.88

.90 .91

.93

3.2

.82

.83

.85

.86

.88

.90

.91

.93 .94

.96

3.3

.84

.86

.87

.89

.91

.92

.94

.96

.97

.99

3.4

.87

.88

.90

.92

.93

.95

.97

.99

1.00

1.02

3.5

.89

.91

.93

.94

.96

.98

1.00

1.01

1.03

1.05

3.6

.92

.94

.95

.97

.99

1.00

1.03

1.04

1.06

1.08

3.7

.94

.96

.98

1.00

1.02

1.03

1.05

1.07

1.09

1.11

3.8

.07

.99

1.01

1.03

1.04

1.06

1.08

1.10

1.12

1.14

3.9

.99

1.01

1.03

1.05

1.07

1.09

1.11

1.13

1.15

1.17

4.0

1.02

1.01

1.06

1.08

1.10

1.12

1.14

1.16

1.18

1.20

4.1

1.05

1.07

1.09

1.11

1.13

1.15

1.17

1.19

1.21

1.23

4.2

1.07

1.09

1.11

1.13

1.15

1.18

1.20

1.22

1.24

1.26

4.3

1.10

1.12

1.14

1.16

1.18

1.20

1.23

1.25

1.27

1.29

4.4

1.12

1.14

1.17

1.19

1.21

•1.23

1.25

1.28

1.30

1.32

4.5

1.15

1.17

1.19

1.21

1.24

1.26

1.28

1.30

1.33

1.35

4.6

1.17

1.20

1.22

1.24

1.26

1.29

1.31

1.33

1.36

1.38

4.7

1.20

1.22

1.25

1.27

1.29

1.32

1.34

1.36

1.39

1.41

4.8

1.22

1.25

1.27

1.30

1.32

1.34

1.37

1.39

1.42

1.44

4.9

1.25

1.27

1.30

1.32

1.35

1.37

1.40

1.42

1.45

1.47

5.0

1.27

1.30

1.32

1.35

1.37

1.40

1.42

1.45

1.47

1.50

5.1

1.30

1.33

1.35

1.38

1.40

1.43

1.45

1.48

1.50

1.53

5.2

1.33

1.35

1.37

1.40

1.43

1.46

1.48

1.51

1.53

1.56

5.3

1.35

1.38

1.40

1.43

1.46

1.48

1.51

1.54

1.56

1.59

5.4

1.38

1.40

1.43

1.46

1.48

1.51

1.54

1.57

1.59

1.62

5.5

1.40

1.43

1.46

1.48

1.51

.54

1.57

1.60

1.62

1.65

5.6

1.43

1.46

1.48

1.51

1.54

.57

1.60

1.62

1.65

1.68

5.7

1.45

1.48

1.51

1.54

1.57

.60

,.<J2

1.65

1.68

1.71

5.8

1.48

1.51

1.54

1.57

1.59

.62

1.65

1.68

1.71

1.74

5.9

•1.50

1.53

1.56

1.59

1.62

.65

1.68

1.71

1.74

1.77

6.0

1.53

1.56

1.59

1.62

1.65

.68

1.71

1.74

1.77

1.80

Appendix. 275

Table XI. Butter chart, showing calculated yield of butter (in
Ibs.) from I to 10,000 Ibs. of milk, testing 3.0 to 5.3 per
cent. (See directions for use, p. 262. )

3.00

3.10

3.20

3.30

3.40

3.50

3.60

3.70

3.80

3.90

4.00

4.10

**•

Milk,

Ibs.

Ibs.'

10,000

325

336

348

360

371

383

394

406

418

429

441

452

10,000

9,000

293

302

313

324

334

345

355

365

376

386

397

407

9,000

8,000

260

269

278

288

297

306

315

325

334

343

353

362

8,000

7,000

228

235

244

252

260

268

276

284

293

300

309

316

7,000

6,000

195

202

209

216

223

230

236

244

251

257

265

271

6,000

5,000

163

168

174

180

186

192

197

203

209

215

221

226

5,000

4,000

130

134

139

144

148

153

158

162

167

172

176

181

4,000

3,000

97.5

101

104

108

111

115

118

122

125

129

132

136

3,000

2,000

65.0

67.2

69.6

72.0

74.2

76.6

78.8

81.2

83.6

85.8

88.2

90.4

2,000

1,000

32.5

33.6

34.8

36.0

37.1

38.3

39.4

40.6

41.8

43.9

44.1

45.2

1,000

900

29.3

30.2

31.3

32.4

33.4

34.5

35.5

36.5

37.6

38.6

39.7

40.7

900

800

26 0

ft6 9

ft7 8

98 8

ft9 7

30 6

31 5

8ft 5

88 4

84 3

85 3

86 2

800

700

22.8

23.5

24.4

25.2

26.0

26.8

27.6

28.4

29.3

30.0

30.9

31.6

700

600

19 5

ftO ft

ftO 9

21 6

ftft 3

ft3 0

ft3 6

ft4 4

ft5 1

ft5 7

•?f> 5

ft7 1

600

500

16.3

16.8

17.4

18.0

18.6

19.2

19.7

20.3

20.9

21.5

22.1

22.6

500

400

13.0

13.4

13.9

14.4

14.8

15.3

15.8

16.2

16.7

17.2

17.6

18.1

400

300

9 7

10 1

10 4

10 8

11 1

11 5

11 8

1ft ft

1ft 5

1ft 9

13 ft

13 6

300

200

6.5

6.7

6.9

7.2

7.4

7.6

7.9

8.1

8.3

8.6

8.8

9.0

200

100

3.2

3.4

3.5

3.6

3.7

3.8

3.9

4.1

4.2

4.3

4.4

4.5

100

2.9

3.0

3.1

3.2

3.3

3.4

3.5

8.6

3.7

3.8

3.9

4.1

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.5

3.6

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

1 6

1 7

1 8

1 9

ft 0

ft 1

ft ft

ft 3

1.3

1.4

1.5

1.6

1.7

1.8

1.0

1.1

1.2

1.3

1.4

o
,4

3.00

3.10

3.20

3.30

3.40

3.50

3.60

3.70

3.80

3.90

4.00

4.10

276

Testing Milk and Its Products.

Table XI. Butter chart ( Continued).

-M

4.20

4.30

4.40

4.50

4.60

4.70

4.80

4.90

5.00

5.10

5.20

:>.30

Milk

Ibs.

Ibs,

10,000

464

476

487

499

510

522

534

545

557

568

580

592

10,000

9,000

418

428

438

449

459

470

481

491

501

511

522

533

9,000

8,000

371

381

390

399

408

418

427

436

446

454

464

474

8,000

7,000

325

333

341

349

357

365

374

382

390

398

406

414

7,000

6,000

278

286

292

299

306

313

320

327

334

341

348

355

6,000

5,000

232

238

244

250

255

261

267

273

279

284

290

296

5,000

4,000

186

190

195

200

204

209

214

218

223

227

232

.237

4,000

3,000

139

143

146

150

153

157

160

164

167

170

174

17b

3,000

2,000

92.8

95.2

97.4

99.8

102

104

107

109

111

114

116

118

2,000

1,000

46.4

47.6

48.7

49.9

51.0

52.2

53.4

54.5

55.7

56.8

58.0

59.2

1,000

900

41.8

42.8

43.8

44.9

45.9

47.0

48.1

49.1

50.1

51.1

52.2

>3.3

900

800

37.1

38.1

39.0

39.9

40.8

41.8

42.7

43.6

44.6

45.4

46.4

47.4

800

700

32 5

33 3

84 1

34 9

35 7

36 5

37 4

38 ?,

39 0

39 8

40 6

41 4

700

600

27.8

28.6

29.2

29.9

30.6

31.3

32.0

32.7

33.4

34.1

34.8

35.5

600

500

23.2

23.8

24.4

25.0

25.5

26 .-1

26.7

27.3

27.9

28.4

21). 0

29.6

500

400

18 6

19 0

19 5

?0 0

?0 4

?0 9

91 4

*>1 8

99 3

99 7

93 2

23 7

400

300

13.9

14.3

14.6

15.0

15.3

15.7

16.0

16.4

16.7

17.0

17.4

17.8

300

200

9.3

9.5

9.7

10.0

10.2

10.4

10.7

10.9

11.1

11.4

11.6

11.8

200

100

4.6

4.8

4.9

5.0

5.1

5.2

5.3

5.5

5.6

5.7

5.8

5.9

100

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5.0

5.1

5.2

5.3

3.7

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

4.6

4.7

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

4.1

2.*

2.9

3.0

3.1

3.2

3.3

3.4

3.5

3.0

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

1.9

2.0

2.1

2.2

2.3

2.4

30
9fi

1.4

1.4
i n

1.5
1(\

1.5
i n

1.6
i A

1.6

1.7

1.8

9ft

zo
10

j. . \j
.5

.u
.5

JL .U

JL.U

-L . U

. L

fni

»6

4.20

4.30

4.40

4.50

4.60

4.70

4.80

4.90

5. CO

5.10

5.20

5.30

F+

Appendix.

277

Table XII. Overrun table, showing pounds of butter from
one hundred Ibs. of milk. (See directions for use,
p. 198.)

Per

cent,
fat.

1.10

1.11

1.12

1.13

1.14

1.15

1.16

1.17

1.18

1.19

1.20

Per

cent,
fat.

3.0
3.1

3.2
3.3
3.4

3.5
3.6
3.7

3 8

3.30
3.41
3.52
8 63

3.33
3.44
3.55
3 66

3.36
3.47
3.58
8 70

3.39
3.50
3.62
3 73

3.42

8.53
8.65
8 76

3.45
3.57

3.68
-">» 80

3.48
3.60
3.71

8 83

3.51
3.63
3.74
3 86

3.54

3.66

3.78
3 89

3.57

3.68
3.81
3 98

3.60
3.72

3.84
8 96

3.0
3.1
3.2
3.3
3.4

3.5
3.6
3.7

1 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
5.2
5.3
5.4

5.5
5.6
5.7

5.8
5.9
6.0

3.74

3.85'
3.96
4.07
4 18

3.77

3.89
4.00
4.11

4 99

3.81

8.92
4.03
4.14
4 9fl

3.84

3.96
4.07
4.18
4 99

3.88

3.99
4.10
4.22
4 33

3.91

4.03
4.14
4.26
-1 87

3.94

4.06
4.18

4.29
4 41

3.98

4.10
4.21
4.33
4 45

4.01

4.13
4.25
4.37
4 48

4.05

4.17

4.28
4.40
1 5k>

4.08

4.20
4.32
4.44
4.56

3.9

4 99

4 88

4 37

4 41

4 45

4 49

4 59

4 56

4 60

4 64

4 68

4.0
4.1
4.2

4.40
4.51
4 6?

4.44
4.55
4 66

4.48
4.59
4 70

4.5!>
4.03
4 7r>

4.56
4.67
4 79

1.60
4.72
4 83

4.64
4.76
4 87

4.68
4.80
4 91

4.72
4.84
4 96

4.76

4.88
"i 00

4.80
4.92
5 04

4.3
4.4

4.73
4 84

4.77

4 88

4.82
4 98

4.86
4 97

4.90
5 09

4.95
i 06

4.99
=> 10

5.03
5 15

5.07
5 19

5.12
5 94

5.16
5 98

4.5
4.6
4.7
4.8
4.9

4.95
5.0G
5.17

5.28
5 39

5.00
5.11
5.22
5.33
5 44

5.04
5.15
5.26

5.38
5 49

5.09
5.20
5.31
5.42
5 54

5.13
5.24
5.36
5.47
5 59

5.18
5.29
5.41
5.5'->

5 64

5.22
5.34
5.45
5.57
5 68

5.27

5.38
5.49
5.62
5 73

5.31
5.43
5.55
5.66
5 78

5.36
5.47
5.59
5.71

5 83

5.40
5.52
5.64
5.7«
5 88

5.0
5.1
5.2
5.3

5.50
5.61
5.72
5 83

5.55
5.66
5.77
5 88

5.60
5.71
5.82
5 94

5.65
5.76

5.88
5 99

5.70
5.81
5.93
6 04

5.75

5.87
5.98
6 10

5.80
5.92
6.03
6 15

5.85
5.97
6.08
6 90

5.90
6.02
6.14
6 95

5.95
6.07
6,19
6 31

6.00
6.12
6.24
6 36

5.4
5.5

5.94
6 05

5.99
6 11

8.05
6 16

6.10

6 99

6.16

6 97

6.21
6 33

6.26
6 38

6.32
6 44

6.37
6 49

6.43
6 55

6.48
6 60

5.6

6 16

6 9?l

6 97

6 33

6 38

6 44

6 50

6 55

6 61

6 66

6 79

5.7
5.8

6.27
6 38

6.33
6 44

6.38
6 50

6.44

6 55

6.50
6 61

6.56
6 67

6.61
6 73

6.67
6 79

6.73

6 84

6.78
6 90

6,84
6 96

5.9
6.0

6.49
6 60

6.55
6 66

6.61
6,7?,

6.67
6 78

6.73

fi 84

6.79
6 90

6.84
6 96

6.90
7 09,

6.96

7 08

7.02
7 14

7.08
7 90

278

Testing Milk and Its Products.

Table XIII. Yield of Cheese from 100 Ibs. milkwith2 5 to 6'per cent
of fat, and lactometer readings from 26 to 30. (See p. 200)

«J

LACTOM KTKK UKUUKKS.

C-M

r ••-»

f°

5 o

2 ft

7.28

7.41

7.54

7 67

7.81

7.94

8.07

8.20

8.33

8.47

8 6' '

2.5

2.6

7.44

7.57

7.70

7.83

7.96

8.09

8.22

8.35

8.49

8.62

8.76

2.7

7.59

7.72

7.85

7.99

8.1*

8.25

8.38

8.51

8.64

8.77

8.91

L.I

2 8

7.74

7.87

8.00

8 14

8.27

8.40

8.53

8.67

8.80

8.94

9.07

? ft

O Q

7.90

8.03

8.16

8 30

8.44

8.56

8.69

8.82

8.95

9.i'9

9.22

2.9

3.0

8.05

8.18

8.31

8.4ft

8.58

8.71

8.84

8.97

9.11

9.24

vi. 37

3.0

3.1

8.21

8.34

8.47

8.60

8/74

8.87

9.00

9.13

9.26

9.39

9.53

3.1

3.2

8.36

8.4u

8.62

8.75

8.89

9.02

9.15

9.28

9.42

9.55

9.68

3.2

3.3

8.52

8i65

8.78

8.91

9.05

9.18

9.31

9.44

9.57

9.70

9.84

3.3

3 4

8.67

8.80

8.93

9 OH

9.20

9.33

9.46

9.59

9.73

9.86

9.9U

3 4

3. ft

8.82

8.96

9.09

9.22

9.35

9. '8

9.62

9.75

9.88

10.01

10. 1-

3.5

3.6

8.98

9.11

9.24

9.37

9.50

9.63

9.7:

9.90

10.03

10.17

10.30

3.6

3 7

9.13

9.26

9.39

9 ft?

9.65

9.7s

9.92

10.05

10.19

10.32

10.46

3 7

9.29

0.42

9.55

9.68

9.81

9.94

1« .21

10.34

10.48

10.61

3.8

3*.9

9.44

9.57

9.70

9.84

9.97

10.10

10/23

10.36

10.50

10.04

10.77

3.9

4.0

9.60

9.73

9.86

10.00

10.13

10.26

10.39

10.53

10.66

10.79

10.93

4.0

4.1

9.75

9.88

10.02

,0.15

10.28

10.39

10.54

10.68

10.81

10.94

11.08

4.1

4 *>

9 90

10.03

10.17

10.30

10.43

10.57

10.70

10.84

10.97

11.10

11.24

4 2

4.3

10.06

10.19

10.32

10.45

10.58

10.72

10.85

10.99

11.12

11.25

11.39

4.3

4.4

10.21

10.34

10.48

10.61

10.74

10.87

11.00

11.14

11.27

11.41

11.55

4.4

4.5

10.36

10.49

10.63

10.76

10.89

11.03

11.16

11.29

11.42

11.56

11.70

4.5

4.6

10.52

10.65

10.78

10.92

11.05

11.18

11.31

11.45

11.58

H.71

11.85

4.6

4.7

10.67

10.81

10.94

11. Of

11.20

11.34

11.47

11.60

11.73

11.87

12.0

1.7

4.8

10.KS

10.96

11.09

11.22

11.36

11.49

11.62

11.76

11.89

i2.02

12.16

4.8

4.9

10.98

11.11

11.25

11.38

11.51

11.65

11.78

11.91

12.04

12.18

12.32

4.9

5.0

11.14

11.27

11.40

11.54

11.67

11.80

11.93

12.07

12.20

12.34

12.48

0.0

5.1

11.29

11.42

11.55

11.69

11.82

11.96

12.09

12.23

12.36

12.49

12.63

o.l

5.2

11.45

11.58

11.71

11.85

11.98

12.11

12.24

12.38

12.52

12.66

12.80

o.2

5.3

11.60

11.73

11.86

11.99

12.13

12.27

12.40

12.53

12.67

12.71

12.8

5.3

5.4

11.76

11.89

12.02

12.16

12.29

12.42

12.55

12.69

12.83

12.97

3.01

o.4

5.5

11.91

12.04

12.17

12.31

12.44

12.58

12.71

12.85

12.99

13.12

13.25

5.5

•5. (3

12.07

12.20

12.33

12.47

12.60

12.73

12.87

13.00

13.14

13. 28

13.41

0.6

5.7

12.22

12.35

12.48

12.62

12.75

12.89

13.02

13.16

I3.3i

13.44

13. .-7

5.8

12.38

12.51

12.64

12.77

12.91

13.05

13.18

13.31

13.45

13. M)

13.72

>.8

5.9

12.53

12.66

12.79

12.93

13.06

13.19

13.33

13.47

13.6i

13.74

13.87

o.9

6.0

12. 6y

12.82

12.95

13.09

13.22

13.35

13.49

13.6.

13.7;")

13.8U

14.02

(5.0

Appendix.

279

fable XIV. Comparisons of Fahrenheit and Centigrade
(Celsius) thermometer scales.

Fahren-
heit.

Centi-
grade.

Fahren-
heit.

Centi-
grade.

Fahren-
heit.

Centi-
grade.

+212

+100

+176

+80

+140

+60

211

99.44

175

79.44

139

59.44

210

98.89

174

78.89

138

58.89

209

98.33

173

78.33

137

58.33

208

97.78

172

77.78

136

57.78

207

97.22

171

77.22

135

57.22

206

96.67

170

76.67

134

56.67

205

96.11

169

76.11

133

56.11

204

95.55

168

75.55

132

55.55

203

167

131

202

94.44

166

74.44

130

54.44

201

93.89

165

73.89

129

53.89

200

93.33

164

72.33

128

53.33

199

92.78

163

72.78

127

52.78

198

92.22

162

71.22

126

52.22

197

91.67

161

71.67

125

51.67

196

91.11

160

71.11

124

51.11

195

90.55

159

70.55

123

50.55

194

158

122

193

89.44

157

69.44

121

49.44

192

88.89

156

68.89

120

48.89

191

88.33

155

68.33

119

48.33

190

87.78

154

67.78

118

47.78

189

87.22

153

67.22

117

47.22

188

86.67

152

66.67

116

46.67

187

86.11

151

66.11

115

46.11

186

85.55

150

65.55

114

45.55

185

149

113

184

84.44

148

64.44

112

44.44

183

83.89

147

63.89

111

43.89

182

83.33

146

63.33

110

43.33

181

82.78

145

62.78

109

42.78

180

82.22

144

62.22

108

42.22

179

81.67

143

61.67

107

41.67

178

81.11

142

61.11

106

41.11

177

80.55

141

60.55

105

40.55

280

Testing Milk and Its Products.

Table XIV. Comparisons of thermometer scales ( Continued. )

Fahren-
heit.

Centi-
grade.

Fahren-
heit.

Centi-
grade.

Fahren-
heit.

Centi-
grade.

+104

+40

+68

+20

+32

103

39.44

19.44

—0.55

102

38.89

' 18.89

1.11

101

38.33

18.33

1.67

100

37.78

17.78

2.22

37.22

17.22

2.78

36.67

16.67

3.33

36.11

16.11

3.89

35.55

15.55

4.44

34.44

14.44

5.55

33.89

13.89

6.11

33.33

13.33

6.67

32.78

12.78

7.22

32 22

12.22

7.78

31.67

11.67

8.33

31. 11

11.11

8.89

30.55

10.55

9.44

29.44

9.44

10.55

28.89

8.89-

11.11

28.33

8.33

11.67

27.78

7.78

12.22

27.22

7.22

12.78

26.67

6.67

13.33

26.11

6.11

13.89

25.55

5.55

14.44

15.00

24.44

4.44

15.55

23.89

3.89

16.11

23.33

3.33

16.67

22.78

2.78

17.22

22.22

2.22

17.78

21.67

1.67

—1

18.33

21.11

1.11

18.89

20.55

0.55

19.44

To convert deg. Fahrenheit to corresponding deg. Centigrade:
Subtract 32, multiply difference by 5, and divide by 9.
Example: Which degree Centigrade corresponds to 110° F.? 110 - 82 =

78; 78 X 5 = 390; 390 -»- 9 = 43.33.

To convert deg. Centigrade to corresponding deg. Fahrenheit:
Multiply by «9, divide product by 5, and add 32 to quotient.
Example: Which degree Fahrenheit corresponds to 95.5° C.? 95.5 X 9 =

859.5; 859.5 -•- 5 = 171.9; 171.9 -f 32 = 203.6.

Appendix.

281

Table XV. Comparison of metric and customary weights and

measures.

Customary
weights and
measures.

Equivalents in
metric system.

Metric weights
and
measures.

Equivalents in
customary system.

1 inch

2.54 centimeters.
.3048 meter.
1.6094 kilometers.
6.452 sq. centimeters.
9.29 sq. decimeters.
.836 sq. meter.
.4047 hectare.
16.387cc.
.0283 cub. meter.
.765 cub. meter.
.3552 hectoliter.
29.57 cc.
.9464 liter.
3.7854 liters.
64.8 milligrams.
28.35 grams.
.4536 kilogram.

1 meter

39.37 inches.
1.0936 yards.
.6214 mile.
.155 sq. inch.
10. 764 sq. feet.
1.196 sq. yards.
2.471 acres.
.061 cubic inch.
61.023 cubic inches.
35.314 cub. feet.
2.8377 bushels.
.0338 fluid ounce.
1.0567 quarts.
2.6417 quarts.
15.43 grains.
.035274 ounce.
2. 2046 pounds (av.)

1 foot

1 meter

1 mile .. ..

1 kilometer..

1 square inch..
1 square foot ..
1 square yard.
1 acre

1 sq. centimeter
1 square meter..
1 square meter..
1 hectare

1 cubic inch...
1 cubic foot....
1 cubic yard...
1 bushel

1 cc

1 cub. decimeter
1 cub. meter
1 hectoliter
1 cc

1 fluid ounce..
1 quart

1 liter.

1 gallon

1 decaliter

1 grain

1 gram

1 ounce (av.)..
1 pound (av. )

1 gram

1 kilogram

282 Testing Milk and Its Products.

SUGGESTIONS regarding the organization of co-operative
creameries and cheese factories.

When the farmers of a neighborhood are considering the
establishment of a creamery or cheese factory, they should first
of all make an accurate canvas of the locality to ascertain the
number of cows that can be depended on to supply the factory
with milk. The area which may be drawn from will vary
according to the kind of factory which it is de-sired to operate.
A successful separator creamery will need at least 400 cows
within a radius of four to five miles from the proposed factory.1
Small cheese factories can be operated with less milk, and
g ithered-cream and butter factories generally cover a much
larger territory than that mentioned. In all cases, however,
the question of the number of cows contributing to the enter-
prise must be fully settled before further steps are taken, since
this is a point upon which success will largely depend.

Methods of organization. The farmers should form their own
organization, and not accept articles of agreement proposed by
traveling agents. An agreement to supply milk from a stated
number of cows should be signed by all expecting to join the
association. When a sufficient number of cows has been
pledged to insure the successful operation of a factory, the farm-
ers agreeing to supply milk should meet and form an organi-
zation. This may be done according to either of the following
plans which have been known to give good satisfaction.

Raising money for building and equipment.

First. — Each member will sign an agreement to pay on or
. before a given date for a certain number of shares in the com-
pany at dollars per share; or,

Second. — An elected board of directors may be authorized to

borrow a sum of money not exceeding thousand dollars

on their individual responsibility, and the sum of cents,

(usually five cents) per hundred pounds of milk received at
the factory shall be reserved for the payment of this borrowed
money.

iBull. 56, Wisconsin experiment station.

Appendix. 283

Constitution and by-laws of a co-operative association are drawn
up and signed by the prospective members of the association
when it has been determined to form such an association. It
is impossible to include in an illustration all the articles and
rules that may be found useful in each particular instance; the
following suggestions in regard to some of the points to be in-
cluded in the documents are given as a guide only. It may be
found advisable to modify them in various ways to meet the
needs of the organization to be formed.

After the constitution and by-laws have been drawn up and
made plain to all the members of the association, they should
be printed and copies distributed to all parties interested.

CONSTITUTION

ARTICLES OF AGREEMENT OF THE ASSOCIATION.1

1. The undersigned, residents within the Counties of ,

State of , hereby agree to become members of the

Co-operative Association, which is formed for the purpose of
manufacturing butter or cheese from whole milk.

2. The regular meetings of the association shall be held an-
nually on the day of the month of. Special

meetings may be called by the president, or on written request
of one-third of the members of the association, provided three
day's notice of such meeting is sent to all members.

Meetings of the board of directors may be called in the same
way, either by the president or by any two members of the
board of directors.

3. Ten members of the association, or three of the board of
directors, shall constitute a quorum for the transaction of busi-
ness.

4. The officers of the association shall include president, sec-
retary, treasurer, one of whom is also elected manager, and
these officers together with three other members of the associa-

iThe following publications have been freely used in preparing this
constitution and by-laws: Woll, Handbook f. Farmers and Dairymen;
Minn, experiment station, bull. No. 35; Ontario Agriculture College, spec-
ial bulletin, May 1897.

284 Testing Milk and Its Products. •

tion shall constitute the board of directors. Each of these six
officers shall be elected at the annual meeting and hold office
for one year, or until their successors have been elected and
qualified. Any vacancies in the board of directors may be filled
by the directors until the next annual meeting of the association.

5. The duties of the president shall be to preside at all meet-
ings of the association, and perform the usual duties of such
presiding officers. He shall sign all drafts and documents of
any kind relating to the business of the association, and pay
all money which comes into his possession by virtue of his
office, to the treasurer, taking his receipt therefor. He shall
call special meetings of the association when deemed necessary.

In the absence of the president, one of the board of directors
shall temporarily fill the position.

6. The secretary shall attend all business meetings of the
association and of the board of directors and shall keep a care-
ful record of the minutes of the meetings. He shall also give
notices of all meetings and all appointments on committees,
etc. He shall sign all papers issued, conduct the correspond-
ence and general business of the association, and keep a correct
financial account between the association and its members. He
shall have charge of all property of the association not other-
wise disposed of, give bonds for the faithful performance of his
duties, and receive such compensation for his services as the
board of directors may determine.

7. The treasurer shall receive and give receipt for all money
belonging to the association, and pay out the same upon orders
signed by the president and the secretary. He shall give such
bonds as the board of directors may require.

8. The board of directors shall audit the accounts of the
association, invest its funds, appoint agents, and determine all
compensations. They shall prescribe and enforce the rules and
regulations of the factory. They shall cause to be kept a rec-
ord of the weights and tests of the milk or cream received from
each patron, «,~ae products sold, the running expenses, etc., and
si all divide among the patrons the money due them each
month. They shall also make some provision for the with-

Appendix. 285

drawal of any member from the association, and make a report
in detail to the association at the annual meeting. Such report
shall include the gross amount of milk handled during the
year, the receipts from products sold, and all other receipts, the
amounts paid for milk and for running expenses, and a com-
plete statement of all other matters pertaining to the business
of the association.

9. Among the rules and regulations to be enforced by the
board of directors may be included some or all of the following:

a. Patrons shall furnish all the milk from all the cows prom-
ised at organization of the association.

b. Only sweet and pure milk will be accepted at the factory,
and any tainted or sour milk shall be refused.

c. The milk of each patron shall be tested at least three times
a mouth.

d. Any patron proved to be guilty of watering, skimming or
otherwise adulterating the milk sent to the factory, or by tak-
ing more than 80 pounds of skim milk or whey for every 100
pounds of whole milk delivered to the factory, shall be fined as
agreed by the association.

e. A partron's premises may be inspected at any time by the
board of directors, or their authorized agent, for the purpose of
suggesting improvements in the methods of caring for the milk
or the cows, in drainage and general cleanliness; or to secure
samples of the milk of his cows for examination when it is
deemed necessary.

10. Any changes or amendments to the by-laws or constitu-
tion of the association must be made in writing by the parties
proposing the same, and posted prominently in a conspicuous
place at the creamery, at least two weeks previous to their being
acted upon. Such changes to be in force must be adopted by a
two-thirds vote of the stockholders.

11. In voting at any annual or special meeting of the asso-
ciation, the members shall be entitled to one vote for each cow
supplying milk to the factory, or for each share of the stock
owned by them, as agreed upon.

INDEX

The figures rkfcr to pages in the book.

Acid bottle, Swedish, 47.

Acid measures, 31, 46, 54.

Acid tester, Swedish, 67.

Acidimeter, Devarda's, 122.

Acidity of cream, 123, 127; es-
timation of, 133.

Acidity of milk, cause of, 117;
determination of, 130, 225;
methods of testing, 118.

Acidity pellets, 123.

Adulteration of milk, 109, 113,
224; calculation of, 113.

Adulterated butter, 236, 239;
cheese, 241.

Albumen, 14; determination of,
in milk, 223.

Albuminoids, 13.

Albumose, 14.

Alkaline tablet test, 122; stand-
ard solution of, 124; accu-
racy, 126.

Alkaline tabs, 134.

American Cheddar cheese, 21.

Amphoteric reaction of milk,
117.

Analysis, chemical, of butter,
228; butter milk, 226; cheese,
240; condensed milk, 227;
cream, 226; milk, 215; skim
milk, 226; whey, 226.

Appendix, 255.

Artificial butter, detection of,
236.

Ash, determination of, In but-
ter, 229, 230; in cheese, 241;
in milk, 225.

Babcock test, the, 4, 28; Bart-
lett's modification, 72; direc-
tions for, 29; discussion of

details, 37; for butter, 94; for
butter milk, 92; for cheese,
95; for condensed milk, 96;
for cream, 75, 179; for ice-
cream, 98; for skim milk, 88;
for whey, 92; glassware used
in, 37; modifications of, 71;
scales for weighing cream,
cheese, etc., 80; water to be
used in, 68.

Babcock testers, 54; electrical,
63; hand testers, 60; power
testers, 61; steam turbine, 61.

Bartlett's modification of Bab-
cock test, 48; 72.

Bausch and Lomb centrifuge,
72.

Beimling test, 5.

Bi-carbonate of soda, detection
.of, 248.

Bi-chromate of potash, 106, 166;
solution of, 106.

Blended milk, 250.

Board of health degrees, 104.

Boiled milk, detection of, 245.

Boiling test, the, 239.

Boracic acid, in dairy products,
133, 247.

Borax in dairy products, 247.

B. & W. bottle, 90.

Butter, artificial, 12; detection
of, 236.

Butter chart, 275; use of, 196.

Butter, 20; artificial, detection
of, 236; Babcock test for, 94;
chemical analysis of, 228;
complete analysis in same
sample, 230; composition of,
21, 255; definition, 251; deter-
mination of ash, 229; casein,

Index.

287

229; fat, 229; salt, 236; water,
228; rapid estimation of water,
231: Dean's method, 234;
Gray's method, 232; Irish test,
233; Patrick's method, 233;
Wisconsin high-pressure oven
method, 235; process, 251;
renovated, 236, 251; sampling
for analysis, 93, 228; scales
for weighing, 93; standard,
251; variations in composi-
tion, 187; yield, calculation
of, 186.

Butter fat, amount due, at
12-25 cents per lb., 269;
conversion factor for, 195;
definition, 251; determina-
tion of specific gravity, 237;
volatile fatty acids, 237; ex-
pansion coefficient, 36; price
per pound, 202; specific grav-
ity, 38; determination, 237;
standard, 251; table showing
amounts due for, at 12 to 25
cents per pound, 269; test and
yield of butter, 186.

Butter making, quantities of
products obtained in, 21.

Butter milk, 21; Babcock test
for, 92; chemical analysis of,
226; composition, 255; defini-
tion, 251; specific gravity, 226.

Calculation of adulteration of
milk, 113; of concentration of
condensed milk, 228; of milk
solids, 107; of overrun, 194;
of sp. gr. of milk solids, 111;
of yield of butter, 186, 192,
196; of cheese, 198; of divi-
dends at creameries, 202, 204;
at cheese factories, 212; of
percentages, 170.

Calibration of glassware, 48;
Trowbridge method, 51.

Carbohydrates, 15.

Casein, 13; determination of, in
butter, 229; in cheese, 241; in
milk, 221; Hart's method, 223.

Centrifugal machines, 54.

Chamberland filters, 14.

Cheddar cheese, American, 21;
compositimi, 255. /\^~^

Cheese, 21;^^a#?Jtote=*test ~for,
95; calcujs^f»*^eld of, from
casejjfjind^fat, 200; from fat,
l^^rtroinsolids not fat and

(m#f 199; composition, 21, 255;
chemical analysis of, 240;
definitions, 251; determination
of ash; 241; casein, 241; fat,
240; water, 240; "filled," de-
tection of, 241; quality of,
from milk of different rich-
ness, 210; sampling, 95;
standard, 251; yield, calcula-
tion of, 198; yield of, from
milk with 2.5 to 6 per cent,
fat and lactometer readings
from 26 to 36, 278; yield of,
and quality of milk, relation
between, 199.

Cheese factories, calculating
dividends at, 210; co-opera-
tive, 213, 282; proprietary,
213.

Cholesterin in milk, 18.

Citric acid in milk, 18.

Cleaning solutions for test bot-
tles, 43.

Cleaning test bottles, 40; ap-
paratus for, 41, 44.

Cochran's test, 5.

Coloring matter in milk, de-
tection of, 244.

Colostrum milk, 18; composi-
tion of, 255.

Composite samples, 149; care
of, 169; case for holding, 165;
methods of taking, 158; pre-
servatives for, 166.

Composite sampling, accuracy
of, 165; use of drip sample,
160; McKay sampler, 163;
Michels' cream sampling
tube, 163; one-third sample
pipette, 164; Scovell sampling
tube, 161; tin dipper, 158.

288

Index.

Composition of butter, 255; but-
ter milk, 255; cheese, 255;
colostrum milk, 255; con-
densed milk, 255; cream, 255;
milk, 18, 255; milk ash, 17;
skim milk, 255; whey, 255.

Condensed milk, 22; analysis
of, 227; composition of, 254;
determination of concentra-
tion, 228; of sp. gr. of, 228;
testing of, 96.

Control samples of milk, 109.

Conversion factor for butter
fat, 195.

Conversion tables for thermo-
meter scales, 279; for weights
and measures, 281.

Cows, number of tests required
in testing, 145; single, sam-
pling milk of, 148; when to
test, 147.

Cream, 19, 226; acidity of,
123, 127; Babcock test for,
75, 179; bottles, the bulb-
necked, 79; the Winton, 79;
care in sampling, necessity
of, 180; clotted, 251; defini-
tion, 251; determination of
acidity of, 123, 133; errors of
measuring in testing, 76; evap-
orated, 251; fat in 1 to 1000
Ibs., testing 12 to 50 per
cent., 267; gelatin in, detec-
tion of, 245; overrun, 193; pas-
teurized, detection of, 244;
scales, 80; separator, 19; gath-
ering and sampling, 184; sep-
aration of, influence of tem-
perature, 184; sour, determina-
tion of acidity, 123; spaces,
175; specific gravity, 77; stand-
ard, 251; starch in, 246; test-
ing, 75; testing outfit, 179;
testing at creameries, 175;
tests, correct readings of,
85; use of 5 cc. pipette in
sampling, 84; use of milk test
bottles, 83 -test bottles, 79;
calibration, 53; weight of, de-

livered by a 17.6 cc. pipette,
77.

Creameries, calculating divi-
dends at, 202; co-operative,
204, 282; cream testing at,
175; proprietary, 203.

Creamery inch, 1, 176.

Curd test, the Wisconsin im-
proved, 135.

Dean's method for determining
water in butter, 234.

Definitions of milk and its
products, 250.

DeLaval's butyrometer, 8.

Devarda's acidimeter, 122.

Diameter of tester and speed
required, relation between, 57.

Dividends, calculating at cheese
factories, 212; at creameries,
202; of both milk and cream
at the same factory, 209.

Dividers, use of, 37.

Double-necked test bottles, 90;
value of divisions of, 91.

Draining-rack for test bot-
tles, 42.

Eichler's Sikirepillen, 123.
Expansion coefficient of butter
fat, 36.

Failyer and Willard's test, 4.

Farrington's alkaline tablet
test, 122.

Fat, 11; color of, an index to
strength of acid used, 67;
content, causes of variation
in, 144; determination of, In
butter, 229; in cheese, 240;
in milk, 219; globules, 11;
Gottlieb's method for deter-
mining, 220; influence of tem-
perature on separation of,
69; measuring of, in cream
testing, 85; in milk testing,
35; pounds in 1-10,000 Ibs. of
milk, testing, 3 to 5.35 per
cent., 263; speed required for
complete separation of, 59.

Index.

289

Fermentation test, the, 137.
Filled cheese, detection of, 241.
"Fitch's Salt Analysis," 236.
Fjord's centrifugal cream test,

Fluorids, detection of, 248.
Food, influence of on quality of

milk, 143, 145.
Food standards, Government,

250.

Fool pipettes, 46.
Formaldehyd, detection of, 249.
Frozen milk, sampling of, 27.

Gauges of cream, 165.
Gelatine in cream, detection of,

245.
Gerber's acid-butyrometer, 7;

fermentation test, 128.
Glassware used in the Babcock

test, 37; calibration of, 48.
Globulin, 15.

Glycerids of fatty acids, 13.
Goat cheese, 14.
Gottlieb method, the, 220.
Government food standards,

250.
Gray's test for water in butter,

232.
Grain-feeding, heavy, influence

of, on quality of milk, 153.

Hand separator cream, gather-
ing and sampling, 184.

Hand testers, 60.

Hart's test for casein in milk,
223.

Hemi-albumose, 14.

Herd milk, variations in, 151;
ranges in variations of, 152.

Hypoxanthin, 18.

Ice-cream, test of, 98; defini-
tions, 252.

Introduction, 1.

Iowa station test, 5.

Irish test for water in butter,
234.

Kumiss, 252.

Lactic acid in milk, 16.

Lactocrite, 5, 7.

Lactose, 15.

Lactochrome, 18.

Lactometer, the, and its appli-
cation, 100; bi-chromate, in-
fluence on, 106; cleaning of,
106; degrees, 101; N. Y. board
of health, 104, 258; Quevenne,
101; reading the, 104; testing
accuracy of, 106; time of tak-
ing readings, 105.

Lecithin in milk, 18.

Leffmann and Beam test, 5.

Legal standards for milk, 110,
256.

Liebermann's method, 5.

Macroscopic impurities in milk,
246.

Manns' test, 119; testing out-
fit, 122.

Marschall acid test, 120; ren-
net test, 138.

McKay sampling tube, 163.

Measuring fat column in test-
ing cream, 85; in testing milk,
35.

Mercury, calibration with, 51;
cleaning, 52.

Metric and customary systems
of weights and measures,
comparison of, 281.

Michels' cream sampling tube,
163.

Milk, acidity of, 117, 130; albu-
men in, 12; adulteration of,
109; amphoteric reaction of,
117; ash, composition of, 17;
boiled, detection of, 245;
casein in, 13; chemical analy-
sis of, 215; cholesterin in, 18;
churned, sampling of, 24; cit-
ric acid in, 18; colostrum, 18;
composition of, 10, 18; table
showing composition of, 255;
composite sampling of, 158;
condensed, 22, 96, 254; correc-
tion table for specific grav-

290

Index.

ity, 259; definitions, 250; de-
tection of coloring matter,
244, of preservatives, 133,
247; determination of acidity,
130, 225; of ash, 225; of casein
and albumen, 221; of fat, 219;
of milk sugar, 224; of solids,
219; of specific gravity, 216;
of water, 218; fat in, 11; fat
available for butter in differ-
ent grades of, 192; from cows
in heat, 110; from sick cows,
110; from single cows, sam-
pling of, 148; variations in,
140; frozen, sampling of, 27;
gases, 18; hypoxanthin, 18;
lactochrome, 18; lactose, 15;
lecithin, 18; legal stand-
ards, 110, 256; macroscopic
impurities, 246; mineral
components, 17; partially
churned, sampling of, 24;
pasteurized, detection, 244;
preservatives, detection, 247;
quality of, influence of food,
155; of heavy grain feeding,
153; of pasture, 154; method
of improving, 156; sampling.
23, 29; scale, Richmond's, 108;
scales, 139; serum, 10; skim-
ming, 113; solids, 10; calcu-
lation of, 107; specific grav-
ity of, 111; souring of, 15;
sour, sampling of, 26; stand-
ards, 102, 250; sugar, 15;
tests for adulteration: nitric
acid test, 242; sp. gr. of
skim milk, milk serum, or
whey, 242; testing on the
farm, 140; testing purity of,
135; urea, 18; water, 11;
watering of, 114; watering
and skimming, 114.

Milk test, a practical, need of,
1; requirements of, 6; bottle,
use of, In testing cream, 83;
Russian, 71.

Milk tests, Babcock, 4, 6; Beim-
linp: (L,effmann and Beam), 5;

Cochran, 5; DeLaval butyro-
meter, 8; Failyer and Wil-
ward, 4; Fjord, 8; foreign, 7;
Gerber acid-butyrometer, 7;
introduction of, 4; lactocrite,
5, 7; Liebermann, 5; Lind-
strom, 9; Nahm, 5; Parson,
5; Patrick (Iowa station test),
5; Rose -Gottlieb, 5, 220; sal-
method, 5; Schmied, 5; Short,
4; sin-acid, 5; Thorner, 5;
Wollny refractometer, 9.

Milk products, composition of,
19, 255.

Monrad rtennet test, the, 138.

Milk testing, 28; on the farm,
140.

Nahm's test, 5.

N. Y. board of health lacto-
meter, 104; degrees corre-
sponding to Quevenne lacto-
meter degrees, 258.

Nitric acid test for adulteration
of milk, 242.

Non-fatty milk solids, 10.

Normal solutions, 119.

Nuclein, 14.

Oil-test churn, 2, 176.

Ohlsson test bottle, 90.

Oleomargarine, detection of,
239; cheese, detection of, 241;
tests for artificial coloring
matter in, 240.

One-third sampling pipette, use
of, 164.

Organization of co-operative
creameries and cheese fac-
tories, suggestions concern-
ing, 282.

Overrun, 189; calculation of,
194; factors influencing, 189;
table, 198, 277; from cream,
193; from milk, 189.

Parsons' test, 5.
Pasteurized milk or cream, de-
tection of, 244,

Index.

291

Pasture, influence on quality of
milk, 154.

Patrick's test, 5; method for
determining water in butter,
233.

Patron's dilemma, a, 172.

Percentages, average, methods
of calculation, 171; fallacy of
averaging, 170.

Phenolphtalein, 120.

Physician's centrifuge, use of,
in milk testing, 72.

Pipettes, 30, 45; proper con-
struction of points, 45; proper
method of emptying, 31; cali-
bration, 54.

Pooling system, 3.

Potassium bi-chromate, 166.

Power testers, 61.

Preservaline, 133, 247; detec-
tion of in milk, 133.

Preservatives, for composite
samples, 166; in milk, detec-
tion of, 133, 247.

Primost, 14.

Process butter, detection of,
239.

Proteose, 14.

Quevenne lactometer, the, 101;
degrees corresponding to
scale of N. Y. board of health
lactometer, 104, 258.

Readings of cream tests, 85;
of milk tests, 35.

Recknagel's phenomenon, 105.

Refractometer, 9.

Reichert number, 239.

Reichert-Wollny method, 237.

Relative-value tables, 208, 271.

Rennet tests, 138.

Renovated butter, detection of,
239; boiling test, 239; Water-
house test, 239.

Reservoir for water in Babcock
test, 70.

Richmond's milk scale, 108.

R5se -Gottlieb method, 5, 220.

Russian milk test, the, 71.

Salicylic acid, detection of, 248.

Salt, estimation in butter, 236.

Sampling cheese, 95; milk, 23,
29; milk from single cows,
148.

Sampling tube, for cream, 179;
McKay, 163; Michels, 163;
Scovell, 161.

Scales for weighing cream, 80;
milk, 148.

Schmied method, the, 5.

Scovell sampling tube, 161.

Serum solids, 10.

Short's test, 4.

Siegfeld's modification of Bab-
cock test, 72.

Sinking fund, 206. •

Separator cream, 19.

Skimming of milk, detection of,
113.

Skim milk, 19; Babcock test
for, 88; chemical aanalysis of,
226; composition of, 255; con-
densed, 250; definition, 250;
sp. gr., 100; test bottles, 90,
92.

Solids not fat, 10; formulas for
calculating, 108; tables show-
ing, corresponding to 0-6 per
cent, fat and 26-36 lactometer
degrees, 260.

Sour milk, sampling, 26; analy-
sis, 226.

Space system, the, 175.

Specific gravity, 100; cylinders,
101, 105; influence of tem-
perature, 102; of butter fat,
determination of, 237; of but-
ter, milk, 226; of condensed
milk, 228; of milk, 216; of
milk solids, 111; of sour milk,
226; temperature correction
table, 259.

Speed required for complete
separation of fat, 57; ascer-
taining necessary speed, 59.

Spillman's cylinder, 129.

Standard measure for calibrat-
ing test bottles, 50.

292

Index.

Standards of purity, Govern-
ment, for milk and its prod-
ucts, 250.

Starch in cream, 246.

Steam turbine testers, 61.

Stokes' acidity pellets, 123.

Storch's test, 245.

Sulfuric acid, 64; table show-
ing strength of, 67; testing
strength of, 65.

Sweetened condensed milk, 96.

Swedish acid bottle, 47.

Swedish acid tester, 67.

Tank for cleaning test bottles,
43.

Temperature of turbine test-
ers, 36; of fat when tests are
read, 36.

Test bottles, 30, 37; apparatus
for cleaning, 41, 44; bulb-
necked cream, 78; calibra-
tion, 48; cleaning, 40; cream,
79; double -necked, 79; drain-
ing-rack for, 42; marking, 39;
for cream testing, 79; for
skim milk testing, 90, 92;
rack for use in creameries
and cheese factories, 165;
tank for cleaning, 43; Winton
cream, 79.

Testers, 54; ascertaining speed
of, 58; electrical, 63; hand,
60; power, 61.

Testing cows, number of tests
required during a period of
lactation, 145.

Testing milk and its products,
1; on the farm, 140.

Test sample, size of, 151.

Tests of cows, official, 148.

Thermometer scales, compari-
son of, 279.

Thorner's method. 5.

Total solids in milk, 10; deter-
mination, 219.

Trowbridge method of calibra-
tion, 49.

Turbine testers, 61; hot, er-
rors In, 36.

Variation in composition of
butter, 187; in quality of milk,
140, 151; causes of, 144; lati-
tude of, 110; ranges in, for
herd milk, 152.

Volatile acids in butter fat,
determination, 237.

Wagner skim milk bottle, 92.

Waste acid jar, 40.

Water, calibration with, 48; de-
termination of, in butter, 228;
in cheese, 240; in milk, 218,
219; reservoir for, 70; to be
used in the Babcock test,
69.

Waterhouse test, 239.

Watering of milk, detection
of, 114; watering and skim-
ming, detection of, 114.

Weights and measures, com-
parison of metric and cus-
tomary, 281.

Westphal balance, 217. i^

Whey, 22; Babcock test for, 92;
chemical analysis, 226; composi-
tion, 255; defl nation, 252.

Winton cream bottle, the, 79.

Wisconsin creamery butter,
summary of analyses, 188.

Wisconsin curd test, the im-
proved, 135.

Wisconsin high-pressure oven
test, for water in butter, 235.

Wollny refractometer, 9.

World's Fair breed tests, com-
position of butter from, 187;
variation in quality of milk,
152.

Yield of butter, calculation of,
186. and butter fat test, 186;
from different grades of milk,
192, 196; table showing, from
1 to 10.000 Ibs. of milk, test-
ing 3 to 5.3 per cent., 275.

Yield of cheese, calculation of,
198; relation between, and
quality of milk, 199; table
showing, corresponding to 2.5
to 6 per cent, of fat, with
lactometer readings of 26 to
36, 278.

NEW 19O8

DE LAVAL

CREAM

SEPARATORS

January 1, 1908 marks another great move forward in the
development of the Cream Separator — the introduction of a
complete new line of DE LAVAL Farm and Dairy Sizes of
machines, ranging in separating capacity from 135 Ibs. to 1350
Ibs. of milk per hour.

As nearly perfect as the DE LAVAL machines have been
before, they are now still further improved in practically every
detail of construction and efficiency, and every feature reflects
the past two years of experiment and test by the De Laval
engineers and experts throughout the world.

The principal changes are in greater simplicity of con-
struction, ease of cleaning and replacement of parts; less cost
of repairs when necessary; easier hand operation; more com-
plete separation under hard conditions; greater capacity, and a
material reduction of prices in proportion to capacity.

The DE LAVAL was the original Cream Separator and for
thirty years it has led in making every new separator invention
and improvement. Every good feature is now bettered and
retained and many new and novel ones added, rendering
DE LAVAL superiority over imitating machines even greater
in every way than ever before.

A new 1908 DE LAVAL catalogue and any desired par-
ticulars are to be had for the asking.

THE DE LAVAL SEPARATOR Co.

RANDOLPH & CANAL STS.

CHICAGO
1213 & 1215 FILBERT ST.

PHILADELPHIA

DRUMM & SACRAMENTO STS.

SAN FRANCISCO

General Offices :

74 CORTLANDT STREET,

NEW YORK.

173-177 WILLIAM STREET

MONTREAL
14 & 16 PRINCESS STREET

WINNIPEG

IO7 FIRST STREET

PORTLAND, OREG.

WIZARD TURBINE
BABCOCK TESTERS

Complies with the strictest requirements of
milk testing authorities; turbine on top in separ-
ate case; spring brake for
stopping;t wo bearings in-
sure freedom from vibra-
tion, heating controlled
by damper in exhaust out-
let.The same high-grade
construction may be had
in theTwentieth Century
Hand Tester. The ^Of-
ficial" is a 2 and 4 bottle
hand tester for farm use.
Write for full descrip-
tion and prices.

Creamery Package Mfd- Co.,

TKe Farrington Moisture Test

(Wisconsin High-Pressure Oven Principle)

Consists of an insulated high-pressure oven fitted fon»connecting
direct to a steam line in your creamery; four sample dishes, lifter
and a special moisture per cent. scale. The oven is handsomely
finished in oxidized copper and is an ornament to any creamery. The
steam compartments are tested to 100 Ibs. pressure before assem-
bling and the outfit has "quality' ' as well as "looks".

The scale is a Torsion Balance with moisture per cent beams,
which does away with calculations and errors. It is sensitive to
1-300 of a gram.

Take it all in all it's a moisture test worth while. We particu-
larly want to sell them to people who would appreciate a moisture
test that is something better than a guessing machine. If you're
interested in it, let us quote you prices.

Oven and scales will be sold separate if you want them that way
but if you want the best moisture test, get the complete outfit.

CREAMERY PACKAGE MFG. CO., Chicago, 111.

THE "FACILE"

Iron Frame Babcock Milk Testers

FACILE JR. TESTER
Two Bottle

FACILE STEAM TURBINE TESTER
24 Bottle

FACILE HAND TESTER
Sizes 6, 8, 10 and 12 Bottle

D. H. Burrell & Co., Little Falls, N. Y.

Creamery, Cheese Factory and Dairy Apparatus and Supplies
SEND FOR CATALOGUE

The Tubular Cream Separator

Different from All Others

Low Supply Tank
Suspended Bowl
Perfect Self Oiling
Bottom Feed
Fewest Bowl Parts
Quickest Gleaned

No Exposed Gear
No Oil Cups or Holes
Plain Smooth Bowl
Waist-lowCranfcshaft
No Bowl Vibration
Least Weight Bowl

Above are some reasons why the Tubular is different from and
better than other cream separators, why it is in a class alone, why
it belongs to the XXth Century, while others are of the XlXth.

They are plain reasons, which your own eyes may prove, if you
carefully look at and compare separators.

The Sharpies Separator Co.

West Chester, Pennsylvania

Toronto, Canada Chicago, Illinois

The "World's Record" Test

Of Skimmilk was made at the Pan-American Exposition
"Model Dairy"in Buffalo. N.Y., 1901, when the improved

U. S. CREAM SEPARATOR

established and has since held the present
World's Record for Cleanest Skimming

by averaging in 50 consecutive runs to leave 25 per cent
LESS butter fat in the sklmmilk than its nearest com-
petitor. This record was never equaled until at the
Lewis & Clarke Exposition, the U. 8. lowered its own
World's Record in a three days' composite test of the
separated milk from all the cows of all the dairy herds
at the Exposition. This was even
a harder tost than the famous
Pan- American run.

As the test at the Pan- Amer-
ican Exposition is the last ac-
tual, protracted, public, na-
tional and international test
— the U. S. continues to main-
tain indisputable right to the
title of the Best and Most
Efficient Machine of its kind.

The U. S. has been on the
market sixteen years. Its re-
liability is a proved fact. It is
built by the same Company that
manufactures the popular
"Agos" Babcock testers shown
on pages 60 and 63.

The U. S. is also the simplest, strongest, safest sep-
arator. Only two parts in the bowl— easy to wash-
saves time and work. Gears run in oil and turn easy,
fiood for a lifetime of service with ordinary care. Let
us tell you all about it.

Just write, "Send me new Illustrated Catalog."
The thirty pictures tell ihe story. Free to you. Write
today, mentioning this book and address

VERMONT FARM MACHINE COMPANY
BELLOWS FALLS, VERMONT, U. S. A.

Eighteen Distributing Warehouses

Chr. Hansen's
Laboratory

Headquarters for
Dairy Preparations Unequaled in Purity and Strength

Chr. Hansen's Danish Rennet Extract
Ghr. Hansen's Danish Cheese Color

VEGETABLE BUTTER COLOR and LACTIC
FERMENT CULTURE

Rennet Tablets and Cheese Color Tablets for Cheese-
Making on the Farm

Special Junket Cream Tablets for Ice Cream Mfrs.
Junket Tablets, Pure Food Colors and Flavoring Extracts

CHR. HANSEN'S LABORATORY

Box 1031 LITTLE FALLS, NEW YORK

Electric Babcock Testers

See Page 63 of This Book

Dry, Glean
Convenient

Bui. 706

Board of Health
Centrifuge for
Bacteria Test

Bui. 705

International
Instrument Co.

CAMBRIDGE, MASS.

PDCAMU/CIPUIWP Q P A I C For Use in Connection
UnLHlVI-ff LlUniHU OUALC with the Babcock Test

"THIS SOALE is especially designed
1 for very accurate weighing of
cream, butter and cheese. All bear-
ings are agate; plates are porcelain;
base and under connections are gal-
vanized, making a rust proof scale. It
has a side bar in front to balance the
test bottle, and is provided with the
necessary weights. Base of scale 10>2
in. long; porcelain plates 3 in. square.
Manufactured by

Price $10 710 Market St., Philadelphia, Pa. HENRY TROEMMER

Woll's Book on Silage

Is the best book yet published on
Silos and Silage— Hoard's Dairy man

Will be sent postage paid on re-
ceipt of One Dollar. :: ::

MENDOTA BOOK CO., Madison,Wis.

ALL TEXT AND REFERENCE BOOKS

.... USED IN ....

American Dairy Schools

MAY BE OBTAINED FROM

MENDOTA BOOK CO., Madison.Wis.

SEE LIST ON FOLLOWING PAGE

THIS BOOK IS DUE ON THE LAST DATE
STAMPED BELOW

AN INITIAL PINE OP 25 CENTS

•== WILL BE ASSESSED FOR FAILURE TO RETURN —
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
Th< DAY AND TO $1.OO ON THE SEVENTH DAY
OVERDUE.

-I RUG 1 9 1940

Le;

Sn;

Mi.

Scl

Joi

y-.:-

Jei

1 LIBRARY, BRANCH OP THE COLLEGE OF AGRICULTURE

"W\ UNIVERSITY OP CALIFORNIA 5m-8,'37(s)

CrLi&, wu^ani^ .,,%. VM.M.X. otrucmxi «-<i C7ea \IUIIH-V

la.,' 1901, 193 pp . , ° 00

King, The Physics of Agriculture, Second ed , Madi-

Son, Wis., 1901, 604 pp 175

MENDOTA BOOR CO., Madison, Wisconsin

Call Number:

UNIVERSITY OF CALIFORNIA LIBRARY

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