I

t I

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

TESTING MILK

AND ITS PRODUCTS

A MANUAL FOR DAIRY STUDENTS, CREAMERY AND

CHEESE FACTORY OPERATORS, FOOD CHEMISTS,

AND DAIRY FARMERS

BY

E. H. ^FARRINGTON and F. W. WOLL

Professor in Charge of Dairy School Professor of Animal Nutrition

UNIVERSITY OF WISCONSIN UNIVERSITY OF CALIFORNIA

With Illustrations

TWENTY-THIRD REVISED AND ENLARGED EDITION

MADISON, WIS.

MENDOTA BOOK COMPANY,

1916

ALL RIGHTS RESERVED

COPYRIGHT, 1897, 1899, 1901, 1904, 1909, 1911 AND 19>3.
BY E. H. FARRINGTON AND F. W. WOLL

CANTWELL PRINTING COMPANY

MADISON, wis.

PREFACE TO FIRST EDITION.

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 givetn; 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 detee-
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.

355208

PREFACE TO TWENTY-SECOND EDITION.

Each year that passes brings some valuable contributions to our
knowledge of the subjects treated in this book and a frequent re-
vision 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 information pub-
lished since the last revision of the book has been carefully sifted,
and what was deemed of sufficient importance has been incorpo-
rated in such detail as the scope of the book permitted; many
changes and additions suggested by the experience of the authors
have also been introduced. The book has, in brief, been subjected
to a. renewed critical examination and careful revision.

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. : Cream-
ery Pkg. Mfg. Co., Chicago, 111.; Vermont Farm Machine Co.,
Bellows Falls, Vt.; D. H. Burrell & Co., Little Falls, N. Y.; Henry
Tromner, Philadelphia, Pa.; Torsion Balance Co., New York City,
and Marschall Dairy Laboratory, Madison, Wis.

Madison, Wis., Oct. 1, 1913.

TABLE OF CONTENTS.

PAGE

Introduction 1

Chap. I. COMPOSITION OF MILK AND ITS PRODUCTS 10

Chap. II. SAMPLING MILK 23

Chap. III. THE BABCOCK TEST — MILK 28

A. Directions for making the test 29

B. Discussion of the details of the test 37

Chap. IV. THE BABCOCK TEST — CREAM 75

Chap. V. THE BABCOCK TEST — OTHER MILK PRODUCTS 90

Chap. VI. THE LACTOMETER AND ITS APPLICATION 102

Chap. VII. TESTING THE ACIDITY OP MILK AND CREAM 119

Chap. VIII. TESTING THE PURITY OP MILK 137

Chap. IX. TESTING MILK ON THE FARM 142

Chap. X. COMPOSITE SAMPLES OP MILK 160

Chap. XI. CREAM TESTING AT CREAMERIES 176

Chap. XII. CALCULATION OP BUTTER AND CHEESE YIELDS 187

Chap. ~XIII. CALCULATING DIVIDENDS 203

Chap. XIV. CHEMICAL ANALYSIS OP MILK AND ITS PROD-
UCTS 217

Appendix 259

Table I. Composition of milk and its products.

Table II. State ana city standards for dairy products.

Table III. Quevenne lactometer degrees corresponding to
the scale of the M. Y. Board of Health lactometers.

Table IV. Value of 10° S~10-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 1,000 pounds of milk
testing 3 to 5.35 per cent.

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

vi Testing Milk and Its Products.

Table IX. Amount due for butter fat, in dollars and cents,
at 12 to 2u cents per pound.

Table X. Relative-value tables.

Table XI. Butter chart, showing calculated yield of but-
ter, in pounds, from 1 to 1,000 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.

Table XVI. Specific gravity and weight of one gallon of
cream, arranged according to the per cent, of fat.

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

Constitution and by-laws for co-operative factory associa-
tions.
Index-- - 291

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

^Testing .I/:/./,- and Its Products.

sources,; gr 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.

1 Wis. Expt. Station, bulletin 12 (see also under 203).

Introduction. 3

full justice cannot be done to different patrons of cream-
eries 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. Formerly private dairymen and breeders of dairy
cattle who desired to ascertain the butter-producing ca-
pacities of the individual cows in their herds were
obliged to do this by the cumbersome method of trial
churnings : by saving the milk of each 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 tested, and can not therefore
be dene except with cows of great excellence or by farm-
ers having plenty of hired help. Here again the need of
a practical milk test was strongly felt.

4 Testing Milk and Its Products.

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 milk, especially adapted to creameries and
cheese factories. This test, which is now known in all
parts of the world where dairying is an important in-
dustry, was not, however, the first method proposed for
this purpose which could be successfully operated out-
side of chemical laboratories. It was preceded by a num-
ber of different methods, the first one published in this
country being Short's method, invented by the late 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
method,2 Parsons' method,3 Cochran's test,4 the Patrick or Iowa

1 See 48, footnote.

2 Kansas experiment station report, 1888, p. 149.
«N. H. experiment station report, 1888, p. 69.

« Journal of Anal. Chem., Ill (1889), p. 381.

Introduction. 5

station test,1 and the Beimling (Leffmann and Beam) test.2 Of
foreign methods published at about the same time, or previously,
the Lactocrite,8 Liebermann's method,4 the Schmid,8 Thorner,*
Nahm,7 Rose-Gottlieb,8 sin-acid method,9 and the Gerber sal-
method10 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 twenty years
it has now been in almost exclusive use in creamer-
ies and 'cheese factories in this country, where payments
are made on the basis of the quality of the milk deliv-

1 la. exp. sta., bull. No. 8, Feb. 1890 ; Iowa Homestead, June 1.4, 1889.

2 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.

3 Analyst, 1887, p. G.
4Fresenius' Zeitschr., 22, 383.
5 Ibid., 27, 464.

«Chem. CentralbL, 1892, 429.

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

8 Landw. Vers. Stat., 40, 1.

9 Milch-Zeitung, 1904, No. 27.

10 Milch-Zeitung, 1906, No. 8.

6 Testing Milk and Its Products.

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.

10. Foreign methods. In European countries five
practical milk and cream tests, besides the Babcock test,

JFor a summary of comparative analyses made by the Babcock test
and gravimetric analysis up to 1892, see Hoard's Dairyman, Oct. 7, 1892,
p. 2560 ; also Schrott-Fiechtl, Milchzeitung, 1896, p. 183 et seq.

8 The Babcock test, like the ether-extraction method gives, however,
somewhat too low results in the case of skim milk (97).

Introduction.

are in use at the present time, viz.: Gerber 's acid-
butyrometer, the sin-acid (or no-acid) test, the lactocrite,
De Laval's lutyrometer, and Fjord's centrifugal cream
test.1

Of these tests the last
one has never, to our
knowledge, been intro-
duced into this country,
and the first four only to
a limited extent.

11. The Gerber method

(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

FIG. 1. The Gerber acid-
small quantity of amyl alco- butyrometer.

hoi 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.

lla. The sin-acid test was invented by the German chemist
A. Sichler and published in 1904.3 In place of the sulfuric acid
used in the Babcock and Gerber tests, Sichler employs a solution of

JThe 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 affixed their name; the same applies to the
Ahnorn-Babcock and the Krugmann-BdbcocTc methods.

2 Gerber, Die praktische Milch priifung, 7th edition, 1900.

3 Milchztg., 1904, p. 417. The word sin (sine) is Latin and means
without; hence, when introduced into this country in 1909 the method
was called the no-acid test.

8

Testing Milk and Its Products.

Rochelle salts, sodium sulfate and sodium hydroxid.1 150 cc. of this
mixture of salts are dissolved in 1 liter of water. In testing milk,
11 cc. of this solution and 0.6 cc. of "sinol" (isobutylalcohol) are
added to 10 cc. of milk. After thorough mixing of the milk and
solution the test bottles are placed in water of 113° F. for 3-5
minutes, when they are shaken till all the curd dissolves. They
are then revolved in a centrifuge for 3 minutes and the results read
off. By heating the bottles for 1 hour in boiling hot water correct
results may be obtained without the use of a centrifuge. The
main advantages of the method appear to lie in this fact and in
that the use of a corrosive acid is avoided.

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

13.

FIG. 2. De Laval's butyrometer.
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-
ingly small quantity of acid used. Where a large number of

1 Barthel-Goodwin, Methods used In Examination of Milk and Dairy
Products, p. 77.

Introduction. 9

milk samples are tested every day, as, for instance, in milk control
stations, the butyrometer may be preferable to the Babcock test;
but it requires more skill of the operator and does not work satis-
factorily in case of sour, loppered, 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
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°C (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; FIG. 3. Fjord's centrifugal cream
outside of these limits the test

is, however, unreliable, especially in case of very rich milk and
strippers' 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
are used in some creameries.2

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

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

CHAPTER I.
COMPOSITION OF MILK AND ITS PRODUCTS.

Before taking up the discussion of the Bab cock 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 sufficient prac-
tical importance to 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
uf 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, - -^= — = 9.28 per cent, of

y i

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
twenty-two 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 not 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 of 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
.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 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 met
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 milk 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 (primost, 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 Chamberland 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 from 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
purpose 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 its cleanliness and
the temperature of the surrounding medium, it will
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 ordi-
nary milk in immense numbers, and under favorable
conditions of temperature multiply rapidly, feeding on

1 The factor 6.25 is generally used for obtaining the casein and albu-
men from the total nitrogen in the milk, on the theory that protein
compounds contain 16% N. ; the factor 6.37 would, however, be more
correct, since casein and albumen, according to our best authorities,
contain on the average 15.7 per cent of nitrogen

16 Testing Milk and Its Products.

the milk sugar 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.
This is shown by the following chemical formula :

CiaH^OnHaO (lactose) =4 C3H603 (lactic acid)*

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 loss 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 milk sugar is composed of 12 atoms of carbon (C),
22 atoms of hydrogen (H), 11 atoms of oxygen (O), and one molecule
of water (H2O). In the same way, the lactic acid molecule consists of 3
atoms of carbon, 6 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) _________ .19perct. 25.64 per ct.

Sodium oxid ^N^O) _________ .09

Lime (CaO) _________________ .18

Magnesia ^MgG; _____________ .02

Iron oxid (Fe2O3) _____________ .002

Phosphoric anhydrid (P2O5) ___ .16

Chlorin (Cl) _________________ .12

.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 Wisconsin experiment station report 12, p. 93.

2

18 Testing Milk and Its Products.

The ash content of normal cow's milk varies but lit-
tle, as the rule only between .6 and .8 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
cows ' 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
contents of albumen and ash are characteristic, and also
its low content of milk sugar. Owing to the large quan-
tity of albumen which colostrum contains, it will coagu-

Composition of Milk and Its Products. 19

late on being heated toward the boiling point. In the
course of three or four 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, 01 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. **

In modern creameries the milk is now always 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 25 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 A 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
most people. Nearly all butter made in this coun
try 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
unavoidable 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 about 13 per cent water, 1 per cent curd and lactic
acid, and 3 per cent salt.

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 loss 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 7.7% 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.

0

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 one
vessel to another. In sampling milk for testing it
should always be mixed just before the milk is
measured into the bottle ; if several tests are made of a
sample, the milk should be mixed 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 of 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 of butter floating in the milk
or sticking to the glass. This churning of the milk can

Sampling Milk. 25

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 rjj-(j.X4.2=.21 per cent., and the original milk there-
fore contained 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 a 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 is 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, souring does not there-
fpre 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-

1 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.
43, p. 112). As to length of time Babcock tests will keep, see Vt.
exp. sta., bull. 106.

Testing MM and Its Products. 27

bonates in the alkali) that the mixture will be thrown
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 I 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

Fio. 4. The first Babcock tester made. , . ,. ., , ..

whirling, the length

of the column of fat is read off, showing the per cent,
of fat contained in the sample tested.

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 Babcock test. Breed, period of lactation, qual-
ity or age of the milk are 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 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

30

Testing Milk 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 is 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-
pette 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 fairly dry
in measuring out the milk so
that the delivery of milk may
be readily checked by gentle
pressure on the upper end of
the pipette.

The point of the pipette is
now placed in the neck of a

FIG. 5. Babcock milk

test bottle. Babcock test bottle (fig. 5),

17

FIG. 6.

See p. 45, foot note.

The Babcock Test.

31

this way, there is

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

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
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 ol

FIG. 7. The right way of emptying
pipette into test bottle.

32

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 FlG 8 The Wrong way of emptying pipette

a dark layer is of-
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

The Babcock Test.

33

with the water of the milk will bring about too strong
an action of the acid en 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

FIG. 9. 17.5 cc.

taken that the liquid is not shaken into acid cylinder,
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.

3

34 Testing Milk and Its Products.

Colostrum milk or milk from fresh <jows 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-
sium 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. This difficulty is
still more pronounced with milk preserved with form-
aldehyd.

39. Whirling bottles. After the milk and the acid
have been thoroughly 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
fifteen minutes before whirling.

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

The Babcock Test.

35

40. Adding water. Hot water is now added by means
of a pipette or some special device (10 in fig. 58),1 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
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.

The fat is measured from the
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 b, and not to c or to d. Comparative

—-6

FIG. 10. Measuring the
column of fat in a
Bnbcock test bottle.

1 See under 204.

36 Testing milk and its Products.

gravimetric analyses have shown that the readings ob-
tained in this manner give 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.

Results with 8% boltles (44a) agree well with those
obtained with the 10% bottles, when care is taken to
read the fat column to the extreme top of the menis-
cus. This appears especially thin in the former bottles
and cannot be seen quite as readily as in the 10%
bottles.

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

1 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. (22.3° C.) would make a difference in the vol-
ume of the fat column obtained in the case of 10 per cent, milk of
.00064 x2x22.3=.028544 cc., or .14 per cent., .00064 being the expansion
coefficient of pure butter fat per degree Centigrade between 50 and 100°

The Babcock Test. 3?

42. Headings 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,
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 & 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.

C. (Zune, Analyse dcs Beurrcs, 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
extreme difference would therefore be about .07, or nearly .1 of 1%.
1 See Wis. Expt. Sta. rep., XVII, p. 76.

38 Testing Milk and Us Products.

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
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.

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° F.), is 0.9, then 1.8 grams of fat will oc-
cupy a volume of ^-=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-

The Babcock Test. 39

tenth, or even five-hundredths, of one per cent, of fat
in the samples tested.

In the best kinds of Babcock bottles the per cent,
marks are complete circles and the half per cent,
marks are semi-circles. This greatly aids in making
correct readings.

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.

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, 99).

443. Eight-per-cent. bottles. Milk test bottles with
scale graduated from 0 to 8 per cent, have come into
general use of late years, having been adopted in 1911
by the National Dairy Instructors' Association as
" standard." The specifications for this bottle and
other Babcock 'glassware are given in par. 307.

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.

40 Testing Milk and Its Products.

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 as a collar
around the necks of the bottles. They are, however,
easily lest, especially when the top of the bottle is
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

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

are to be marked 1 to 24, or as many as are bought,
and the dealer may 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 often happen when the operator

The Babcock Test.

41

trusts to his memory for locating the different bottles
in which tests are made at the same time.

46. Cleaning test bottles. The fat in the neck of
the test bottles must be liquid when these are cleaned.

FIG. 13. Apparatus for cleaning test bottles. A, apparatus in posi-
tion ; the water flows from the reservoir through the iron pipe 6 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.

In emptying the acid the bottle should be shaken in
order to remove the white residue of sulfate of lime,
etc., from the bottom; if the acid is allowed to drain
out of the bottle without shaking it, this residue will

42 Testing Milk and Its Products.

be found to stick very tenaciously to the bottom of the
bottle in the subsequent cleaning with water.

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.
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
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

occasionally be wiped
clean and dry.

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

PM.14. Draining rack for test bo.t.es.

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

The Babcock Test.

43

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 cccasional 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
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, Leivis'
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.

44

Testing Milk and Its Products.

test bottles must be rinsed twice with hot water aftei
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

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

A convenient device for cleaning test bottles.

the frame in which the bottles are placed, one in each
socket; the metal plate E is put over the necks of tL°
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 thus firmly held in the crate. When secured in
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

1 Michels, Am. Cheesemaker, Jan. 1903.

2 Wisconsin experiment station, bull. 129.

The Babcock Test. 45

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 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 from 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., \iz., 18 divided by 1.03, which is
very 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.

For convenience in measuring the milk,

' FIG. 17. Pipette

the shape of the pipette is of importance. . points—

A, proper con-

The mark on the stem should be two inches

or more from the upper end of the pip- construction.

1<Cubic centimeterr (abbreviated : cc.) are the standard used for
measuring volume in the metric system, similar to the quart or pint

46 Testing Milk and Its Products.

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
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 about % 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 cc. 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 to conditions beyond his control; it can-
not therefore be used as a standard in the same manner as the
fat content of 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 popularly termed "fool"
pipettes. It is not known that such pipettes have been sold of
late years.

A 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

measure in 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
4° Centigrade weighs 1 gram ; 1,000 grams (=1 kilogram) are equal to
2.2 Ibs. Avoirdup. (Sec Appendix for Comparisons of metric an<1
customary weights and measures.)
1 Laws of 1903, chapter 43.

The Babcock Test. 47

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
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 apparatus, so that it is a
very difficult matter to design a form which will re-
main in good working order for a long time. Auto-
matic pipettes attached to acid bottles or reservoirs, to
prove satisfactory, must be made entirely of glass, and
strong, of simple construction, tightly closed and
quickly operated.

51. The Swedish acid bottle1 answers these require-
ments better than any other device known to the writ-
ers at the present time. Its use is easily understood
(see fig. 18) ; it gives good satisfaction if the hole in
the glass stop-cock through which the acid passes has

1 Now generally sold and kno\rn as the Combined Acid Bottle.

48 Testing Milk and Its Products.

a diameter of at least one-eighth of an inch, as is gener-
ally the case. We have used or inspected some half a
dozen other devices placed on
the market by various deal-
ers for delivering 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 add-
ing 20 cc. directly to the milk in
the test bottles, till the mixture
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 add (83). This method
of adding the acid is in the line of
simplicity, but has not become gen-
erally adopted. If the method is

FIG. 18. Swedish acid-bottle;
used, the marks should be put on the side tube is made to

by the manufacturers, as the oper- hold 17-5 cc- of acid-

ator in attempting to do so will be apt to weaken or break the

bottles.

CALIBRATION OP 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
for test bottles and other Babcock glassware adopted by
the Association of Official Agricultural Chemists of
America 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

1 Maine experiment station, bull. 31.

The Babcock Test. 49

cent. The correctness of the graduations 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.

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 one-twentieth of a 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 extremely simple and accurate method of calibrating
test bottles has been proposed by Mr. 0. A. Trowbridge
of Columbus, Wis. The capacity of the graduated por-

1 Hoard's Dairyman, March 8, 1901, by DeWitt Goodrich.

4

50 Testing Milk and Its Products.

tion of the neck of a milk test bottle is measured with a
piece of metal which is carefully 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 to it a short piece of fine wire.
Manufacturers have improved on this rather crude de-
vice and standard measures for calibrating
test bottles can now be bought of dairy
supply houses (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 upper point of the
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 calibrators
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 be ascer-
tained.

56. The standard measure. In the place
of an iron nail, as originally proposed, a
piece of metal or glass rod may be advan- Trowbridge caf-
tageously used as a standard measure. The
standardization of this measure is most conveniently

The Babcock Test. 51

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
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 20° 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 meniscus 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.

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
under (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 the Association of Official Agricultural
Chemists (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 mer-
cury are to be made.

Mercury forms the most satisfactory and accurate material
for calibration of test bottles, on account of its heavy weight

The Babcock Test. 53

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 1.355 grams.

62. Calibration of 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 81.30 grams of mercury.

The Trowbridge method of calibrating milk test bot-

54 Testing Milk and Its Products.

ties will 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, 20 to 30, 30 to 40 per cent., etc., 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 de-
liver, viz., 17.5 grams. The necessity of previous thor-
ough 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 out 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 gram, when
weighed in a vacuum at the temperature of the maximum density of
water (4° C.) ; 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 BabcocU 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 be run smoothly at full speed. A machine
that trembles when in motion is neither satisfactory 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 there-
fore be subjected to a severe test before they are ac-
cepted.

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 clean and
be 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 MUk 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 the higher figure as a standard, the cen-
trifugal 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

F= W-Y'2 (1)

32.2r *

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 2irrX 8£Q° = 2x3.1415 X192-X|88= 62.83
feet per second. The weight of a bottle, with milk and acid, is
about 3 ounces, or ^ 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

T== /32.2 FXr _

I/ w

Substituting the values for F and w, we have

/32.2 X 30.65 r_
~ V ~K~ "1/5264 r

In this equation the values r = 5, 6, 7, 8, 9, 10, 11, 12 inches
are substituted in each case (j^, r62, -/f, . . }f), 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 = — r, v being as before

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, e. g., 24 inches in diameter,
will require less than 700 revolutions per minuate 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

xys=9X8002, or

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 the wheel revolves, 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 \5-f=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 know 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 care-
lessness, worn-out or dry bearings, 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 separation of fat and

1 Private communication.

The Babcock Test. 59

good duplicates 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
C53 et seq.).

60 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 tester answers
every purpose. These may be had in
sizes from two to twelve bottles. In
selecting a particular make of tester
*iu -20 Type of the Dairyman nas the choice of a large
Babcock hand testers, 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, FlG- 21- T^e of Babcock hand testers.

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

The Babcock Test.

61

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. 22-24) are most satisfactory when
well made and well cared for. They should be pro-
vided 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 FIG. 22.
wrought or malleable iron, or
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 most machines should
be so made that the bottles will not strike the
center of the revolving frame when in a horizontal posi-
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 or be much reduced in size
from that of the opening in the tester. A free escape
of the exhaust steam is necessary to prevent the steam
from collecting in the test bottle chamber and overheat-
ing the test bottles when whirled (41).

Type of Babcock steam
turbine testers.

62

Testing Milk and Its Products.

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 chamber dur-
ing the whirling, and force the steam
into the exhaust pipe. If skim milk is
being tested, the opening in the cover!
should be closed. This
shuts off the draft of
air, and the exhaust
steam heats the test
bottles during whirl-
ing to 200° F. in some
cases. This high tem-
perature aids in sepa-
rating the fat in skim
milk and gives fairly FIG. 23.

steam turbine

24. Type ui liabcock turbine testers
(for testing cream in 0-in. cream bottles).

testers.

correct tests of
samples containing
less than one-tenth
per cent, fat (98).
Some turbine test-
ers are provided
with holes in the
•overs and damp-
ers and a thermo-
meter is placed in
the cover.

The Babcock Test.

63

Babcock testers run by electricity have lately been
put on the market by a couple of manufacturers (fig.
25). Where no
steam, but elec-
trical current is
available, these
machines may
be installed to
great advantage,
as they are con-
venient to use
and may be de-
pended on to
run at the re-
quired speed.
Some provision
for getting hot
water must be at hand in using electrical Babcock testers. 1

3.— SULFURIC ACID.

72. The sulfuric acid to be used in the Babcock test
should have a specific gravity of 1.82-1.83.2 Commer-
cial sulfuric acid (sometimes called oil of vitriol] is
always 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 glass bottles or jugs, prefer-
ably glass or rubber stoppered ones, since a cork stop-

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

2 A specific gravity of 1.82 means that a given volume of the acid
weighs 1.82 times as much as the same volume of water at the same
temperature (see also under Lactometer, 109).

FIG. 25. Type of Babcock electrical testers.

64 Testing Milk and Its Products.

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
should be used after the acid has been washed off with
water. The red color caused by the action of the acid
on clothing can be removed by wetting the spot with
weak ammonia water; the ammonia must, however, be
applied while the stain is fresh, and is in its turn
washed off with water.

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 other particular line of the scale. It is then
again weighed accurately; the difference between the
two weights will give the weight of the acid in the bot-
tle. The bottle is then emptied and thoroughly rinsed
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

The Babcock Test. 65

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 acid is of
correct strength. The outside of the test bottle should
always be wiped dry before the liquids are weighed.
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
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-

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

66 Testing Milk and Its Products.

ceriii 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 mi Ik turns
black.

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

(15°C., water k"C.). (H.280J

1.841 97 per cent.

1.840 96

1.839 i>5

1.837 94

1.834 93

1,830 92

1.825 91

1.820 90

1.815 89

1.808— 88

The Babcock Test. 67

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 duch 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
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

68 Testing Milk and Its Products.

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 millc)
and D (weak add) is much lighter colored than that in C (warm
milk) and F (strong acid), and that the color of the fat in B
(normal temperature) and E (normal acid) is somewhere be-
tween that of these two series.

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-

The Babcock Test. 69

ference of forty degrees will often have considerable
influence on the 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. Both 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. Rain 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
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 held more or less 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-

70 Testing Milk and Its Products.

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. (See also 96 on the use of glymol in cream
testing.)

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 may be
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 \)y means of a pinch cock. The water must
be hot when added to the test bottles so as to keep the
fat 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. 22-24).

The use of zinc or steel oilers, or perfection oil cans
has been suggested as a convenient 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 rub-
ber tubing connected with a reservoir, as shown in the
illustrations just referred to.

1 Ordinary tinware will soon rust with water standing in it, and cop-
per reservoirs are therefore more economical.

The Babcock Test. 71

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 running1, thus saving time and the trouble inci-
dent to the stopping of the tester and filling the bottles by
means of a pipette. The milk-measuring pipette (fig. 28) and

FIG. 26. The Russian test.

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 provided with a speed
indicator which shows at any time the number of revolutions at
which the bottles are being turned. The accompanying illustra-
tions show the apparatus used in this test. When the directions
for operating the test are followed closely, the results obtained
are accurate and very satisfactory.

1 A similar arrangement for the regular Babcock test has been
suggested by Mitchell and Walker of Kingston (Ont.) Dairy School
(see Ont. Dept. of Agriculture, bull. 170).

72

Testing Milk and Its Products.

i

(

83. Bartlett'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 minutes at the regular rate (52).

83a. Siegfeld's modification. The
German v dairy chemist Siegfeld in
1899 proposed a modification of the
Babcock test,2 using 2 cc. of amyl .alco-
hol 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 what-
ever in obtaining a clear fat column
in the BabcocK test as described in
this book, and the modification has not
therefore been generally introduced in
American factories. It has, however,
been adopted in many German creamer-
ies where the Babcock test is used.

84. Bausch and Lomb centrifuge.
Fig. 29 shows a form of hand centri-
fuge which may be used to advantage
by physicians or in pathological labora- sian test,
tories for the determination of fat in

Test bottle m^- The centrifuge is especially designed for ex-
amination of urine, sputum, blood, etc., but has
been adapted to milk analysis by the Leffmann &
Beam test, a special form of bottle (fig. 30) having been con
stn.icted for this purpose. The machine gives satisfactory re-
sults by the Babcock test as well, provided the acid used is
1.83-1.84, or if the bottles containing the acid-milk mixture be
placed in hot water for five or ten minutes prior to the whirling.

1 Maine experiment station, bull. 31 (s. s.)

2 Molkerei Ztg., 1899, p. 51.

i

j

(S

0

u

X

u

z

Flu. 28.

used in t In-
Russian test

The Babcock Test.

73

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 manipulation not called
for in case of regular Babcock testers constructed for the use
of factory operators and dairymen.

FIG. 30.

Test bottle and
pipette for phy-
sician's centri
fuge.

FIG. 29. Physician's centri-
fuge that may be used for milk
testing.

840. Whitman milk bottle. Dr. Koss C. Whitman has de
vised a milk testing bottle for the special use of physicians in
testing human milk and small amounts of cow's milk by the Bab-
cock test.1 The bottle, which can be placed in an ordinary urine
centrifuge, consists of two parts, a small tube for holding the
milk, acid and water, and a detachable graduated fine tube, into
which the fat column is brought after the final filling and whirl
ing. 5cc. of milk are used in this test.

iJour. Amer. Med. Asso., 47 (1906), p. 204. See also Doran, Jr.
Ind. and Eng. Chemistry, 1912, p. 841.

74 Testing Milk and Its Products.

Questions.

1. Give a brief description of the Babcock test.

2. State precautions to be observed ir 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 are evidently too low,
what is the probable cause, and how can the correct test be estab-
lished ?

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?

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 ^f
8, 15, and 20 inches?

11. Write an order for one gallon of sulfurie 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 does the color of the fat indicate in regard to the
strength of the acid or the 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 Bussian 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 temp'erature 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 are 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)
JL5=5 QQ 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 cream, 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.

1 For specific gravity of cream of different richness, see table on r>. 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 BaJ>-
cock 17.6 cc. pipette, the following weighings of sepa-
rator cream are given (column &.) Ths 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 cream have been
grouped according to their average fat contents.1

Per cent
of fat.
in cream.

Weight of cream deliv-
Speciflc gravity (17.5° C.) ered, grams,
(a) (I))

10

1.023

17.9

15

1.012

17.7

20

1.008

17.3

25

1.002

17.2

30

.996

17.0

35

.980

16.4

40

.966

16.3

45

.950

16.2

50

.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.

Babcock has calculated the specific gravity of cream
containing different percentages of butter fat, and the
weight of one gallon of each; see table XVI in the
Appendix. (Hoard's Dairyman, Jan. 10, 1910.)

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
samples on a small cream-weighing scale (see p. 81) into
one of the special forms of cream-test bottles.

1 This is recognized by a law passed by the Wisconsin legislature in
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
prescribe the standard measures for the use of the Babcock test in de-
termining the per cent, of butter fat in milk or cream.)

Cream Testing.

79

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.

89. The Winton cream bottle. The cream-test bottle
devised by "Winton,1 (fig. 32), has a neck of the usual
length, and of sufficient width to measure
30 or 50 per cent, of fat. The scale of
the neck is divided into parts represent-
ing one-half of one per cent,
each, but readings of a quarter
of a per cent, can easily be esti-
mated. Such readings of
cream tests are sufficiently ex-
act for most commercial pur-
poses. This form of cream bot-
tle will be found very conven-
ient in making tests of com-
posite samples of cream.

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

Other forms of cream-test bottles which
allow the testing of 50 or 55 per cent, cream
have been placed on the market during late
FIG 32a ^ears ^v some manufacturers. These bot-
Tne 50% ties (so-called 9-inch bottles) have long necks

9-inch cream .

test bottle, and require especially constructed, large and

PIG. 32.
The 30%
cream test
bottle.

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

80

Testing Milk and Its Products.

deep testers (see fig. 25). These machines and accom-
panying bottles have of late been adopted for cream
testing in many localities where farm separator cream
is delivered to the creameries.

90. The bulb-necked cream test bottles 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
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. Be-
ginners are especially apt to lose tests when this
bottle is first used, for the reason given. It is
recommended to fill these bottles with the first por-
tion 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 bottle is no longer used to any
extent, as it has been largely replaced
by the different forms of the Winton
cream-bottle.

91. Scales for weighing the
cream. When a small, delicate
balance is used, cream can be weighed rap-
idly into the bottles. Either of the scales
shown in the accompanying illustrations,
(figs. 34-35), will be found sufficiently ac-
curate for this purpose; a small scale of
this kind is also convenient and helpful
in testing cheese, butter and condensed milk, in deter-

FIG. 33.

The 50%
cream test
bottle.

Cream Testing.

81

FIG. 34. Scales used for weighing
cream in the Babcock test.

mining the strength of sulfuric acid, and in testing the

accuracy of test bottles and pipettes.

Cream scales similar to that shown in fig. 35 permit

the weighing of two or four samples of cream at a time

with only one taring of

the bottles, which great-
ly facilitates the work of

testing the cream.

In testing cream by

weight, the test bottle is

first weighed empty, and

again when 9 or 18

grams of cream have been placed in it; the difference

between the two figures gives the weight of cream taken

for the test. If the cream
contains less than 30 per
cent, of fat, the regular
milk test bottle can also
be used for testing the

II j 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.

The operator should be

FIG. 35. Torsion balance used for careful in weighing the
weighing cream in the Babcock test.

cream not to spill it on

the outside of the test bottle. If less than 18 grams
of cream has been weighed into the bottle sufficient

6

82

Testing Milk and Its Products.

water is added to the balance to make the total vol-
ume about 18 cc. The usual quantity of acid (17.5 cc.)
is then added, and the test completed in the ordi-
nary 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, of fat in the cream tested is obtained by multi-
plying the reading by 18, and dividing the product by
the weight of cream taken.

EXAMPLE: Weight of cream tested, 5.2 grams; reading of col-
umn of f at1) 9.8, 2) 9.7, average 9.75; per cent, of fat in the cream
9.75*18=33.75.

5.2

It is very convenient to weigh out 18 grams of cream

(or 9 grams) so that the
readings may be taken di-
rectly from the neck of the
bottle. The smaller the quan-
tity of cream taken for a
sample, the greater is the
error introduced by inaccu-
rate weighings or readings.
The result is rendered more
accurate if two or three tests
of a sample are made, and
the readings averaged.

913. The hydrostatic bal-
ance is a convenient device
for weighing cream and
•other dairy products to be
tested by the Babcock test
(see fi«r. 35R).1 This balance

FIG. 35a. The Wisconsin by
drostatic cream balance.

1 Wisconsin exp. station, bull. 195.

Cream Testing. S3

is built on the same principle as a lactometer : it is pro-
vided with a pan on the top of the stem, on which the
test bottles and the weights are placed. When put into
water the instrument is balanced to a certain point
with empty test bottles and weights on the pan; the
weights are then removed and sufficient cream added
to the test bottle by means of a pipette to sink it to
the same point as before.

The special advantages of the balance are that there
are no bearings to rust and become dull; it is durable,
inexpensive and sensitive, and with careful handling
will remain sensitive indefinitely. The balance can be
made large enough to weigh a number of bottles at a
time, as is the case with some of the cream scales on
the market.

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 of the cream test bottles or a common milk
test bottle may be used for this purpose. The table
en p. 77 shows 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 be -8X25=1.1 per cent, too

18

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.

84 Testing Milk and Its Products.

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

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 in the case of sweet cream of average richness,
and will then give only approximately correct results

93. Use of milk test bottles. Cream may be tested
by emptying a 17.6 cc. pipetteful into two or more milk
test bottles, dividing the sample about equally between
4he bottles and filling the pipette with water once or
twice, which is then in turn divided about equally be-
tween 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.

1 Press bull, dated August, 1901. Some creameries heat the samples
of cream in a water bath to about 140° F. before the test samples are
measured out by means of a 17.6 cc. pipette. This increases the fluidity
of the cream and causes less to adhere to the pipette. The Vermont ex-
periment station (report 16. pp. 191-6) found in examining: this method
that it did not yield satisfactory results in the case of cream of dif-
ferent richness and recommends that crcnm be weighed when accurate
tests are desired.

Professor Spillman (Bull. 32 of Washington experiment station) rec-
ommends the use of a 17.6 cc. pipette for testing cream, the results
obtained being corrected by a certain per cent., as shown 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.

Cream Testing. 85

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 dilution of the cream with water in the test bot-
tles 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
about 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 necessary 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.

Testing Milk and Its Products.

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 «jc. pipette, provided great care is taken in mix-
ing the cream before sampling; 5 cc. of cream are measured into
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 -^~~ r=3.53; if '95, -^y =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° F.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
FIG 36. Measur- acid, owing to the smaller proportion of
ingthee naeckCOloUfmS solids not fat contained in the cream.

meaadde The liquid beneath the fat in a com-

from a to c, not to i . -i , <» • • • «n

6 or to d. pleted test of cream is sometimes milky

1 The size of the meniscus Is magnified in this cut. A study of the
mensicus formed in bottles with narrow or wide necks, and its bearing

Cream Testing. 87

and the fat appears white and cloudy, making an exact
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° P. for some minutes before the
results are read off.

The subject of different methods of reading cream
tests have been studied by "Webster and Gray,1 who
conclude that correct results are obtained by taking
readings at 120° F., from the bottom to the extreme
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.

96. Eliminating the meniscus in cream tests. The
uncertainty concerning the exact point at which the
meniscus of the fat column should be read in cream
tests has been removed by the use of certain liquids
which do not mix with fat but when dropped on top of

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).

1 Bujl. 58, Bur. An. Ind., U. S. Dept. of Agriculture. See also Mass,
rept., 1909, p. 142.

88

Testing Milk and Its Products.

-o

the fat column change the curved surface of the menis-
cus into a straight line. Amyl alcohol, fat-saturated
alcohol and glymol have been suggested for this pur-
pose.

Amyl alcohol colored red by fuchsin was suggested
by Eckles.1 This may dissolve some of the fat and thus
cause a slightly low reading. Fat-saturated alcohol"
largely overcomes this objection. It is made by adding
about a teaspoonful of butter to six ounces of dena-
tured or wood alcohol in a stoppered bottle. This is
warmed slightly and shaken until the alcohol does not
dissolve any more of the fat. A small amount of
coloring matter may be added to
this solution to further facilitate
the reading. The use of glymol3 or
white mineral typewriter and sew-
ing machine oil was suggested by
Hunziker for reading cream tests,
after an exhaustive study of the
subject. Glymol may be colored
with alkanet root which can be ob-
tained from a druggist. One ounce
of alkanet root will color one quart
of glymol; this is done by placing
a small cheese cloth bag filled with
the alkanet root in the bottle of
glymol for one or two days.
A convenient way of adding alcohol, glymol, etc., to
the fat column after completing a test is to insert a

1 N. Y. Produce Review, Aug. 8, 1908.

»Wis. Expt. Sta. Bui. 195, p. 6.

•Purdue, Ind., Expt. Sta. Bui. 145, vol. XV, p. 593.

FIG. 26a. Showing the
use of fat-saturated
alcohol, glymol, etc.,
for eliminating the
meniscus in cream
tests.

Cream Testing. 89

glass tube through a cork or stopper of a bottle con-
taining the liquid and by placing a finger on the top
of the tube a small portion may be transferred from
the bottle to the top of the fat column. By the use of
either of the liquids mentioned the meniscus in cream
tests disappears, giving a straight line at the top as
well as the bottom of the fat column and thus making
it possible to obtain exact readings of the per cent, of
fat in any sample of cream.

Questions.

1. Give three reasons for weighing cream for testing.

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

3. What is 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° F., 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
fro mthe 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. Samples
of skim milk containing much less than one-tenth of a
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, will ever show 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 satisfactory separation.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. 91

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 are not 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 at least five-
hundredths 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 by European chemists as a standard for
analysis of these products. (See 254).

92

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 before the sample is taken so as to allow the air
to escape.

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, since owing to the con-
traction of the liquid by cooling, the fat
will otherwise adhere 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> 37t The
cent., and the marks, are so far apart that ^khnleinnkC bot-

,, „ , , ., ..tie (sometimes

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

.«',,,, . son or B. & W.

mated to single hundredths of one pei -bottle).

1 See Wis. exp. station, report 17, p. 81.

* First constructed by Mr. J. J. Nussbnumer, of Illinois; now manu-
factured by various firm*.

Babcock Test for other Milk Products. 93

cent. In the first forms, now out of use, the neck was
graduated to hundredths of one per cent.

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 slnm milk, thin butter milk and
whey. The milk, acid and water are added to the bottle
through the filling- 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 fester 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.

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

94

Testing Milk and Its Products.

This test bottle is more fragile and expensive than
the ordinary Babcock bottles, and must be carefully
handled; it is now generally made of heavier glass
than formerly, and this form is to be highly recom-
mended.1

100. The double-size 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
double-necked skim milk bottles, for reasons
that are readily seen.

101. Buttermilk and whey. The
testing of buttermilk by the Babcock
test offers no special difficulties if the
special directions for testing skim milk
are followed ; what has been said in re-
gard to tests of separator skim milk is
equally true in case of this by-product.
Whey contains only a small quantity
of solids not fat, viz., less than 7 per
cent. (27), and the mixing with acid
and the solution of the whey solids
therein is therefore readily accom-
plished; the acid solution is of a light
reddish color, turning black but very
slowly.

102. Butter. Butter is not so easily tested as other
dairy products, both because of the difficulties in ob-
taining a fair sample, and on account of the high per-
centage of fat it contains. Butter is a mechanical mix-

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

FIG. 38.
The double-bore
skim milk bottle.

Babcock Test for other Milk Products. 95

ture 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 water in the
small portion to be tested as 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 (preferably about 200 grams in
all) 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 repeatedly until the butter
either solidifies or becomes of a thick creamy consist-
ency. 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 very
accurately. Scales sensitive to less than .05 gram 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 rusted bearings
are worthless for testing butter. The scales should

96 Testing Milk and Its Products.

always be balanced before being used and the weights
kept bright and clean.

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. Scales sensitive to .01 gram are now
on the market, which permit 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 marked influ-
ence on the results, because the butter fat is such a
large per cent, of the butter. Tests should always be
made in duplicate.2

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

2 Special bottles for testing butter for its fat content have been put

Babcock Test for other Milk Products. 97

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.1

"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 (say 9 grams) 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. About 15 cc. of hot water is added to the
cheese in the test bottle, and this is shaken occasionally
until the cheese softens and forms a creamy emulsion

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 Stato
Dairy Commissioner, 1904, p. 40.
1U. S. Dept. of Agriculture, Chemical Division, bull. 46, p. 37.

7

98 Testing Milk and Its Products.

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.1

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
very carefully, 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 9 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 this is readily dissolved in water.
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.

Hunziker2 recommends adding hot, dilute sulfuric
acid solution after the first whirling, in the analysis of
unsweetened condensed milk (sulfuric acid and water,

1 See also Sammis, Journ. Ind. and Eng. Chem., I, p. 604.

2 Ind. expt. sta., bull. 134.

Babcock Test for other Milk Products. 99

1:1). He finds that this aids in giving a clear separa-
tion of the fat and obtaining satisfactory results.1

107. Sweetened condensed milk. The testing of
sweetened condensed milk presents peculiar difficulties,
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.2 A brief description of the method of analysis
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 pipette full of
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 tester.

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-

1 For analysis of unsweetened condensed milk, see also Jr. Ind. and
Eng. Chem., 1913, pp. 131 and 168. Good results may be secured by
adding 3 cc. of a mixture of equal parts of amyl alcohol and C. P.
hydrochloric acid to the milk, then 10 cc. of C. P. sulfuric acid, and
proceeding as given above (Amott).

2Wis. exp. station, report XVII, pp. 86-89.

100 Testing Milk and Its Products.

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 bottles are taken from the tester
and by being careful not to break the lamp 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
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. • The whey is again decanted and this second
washing removes so much of the sugar that what re-
mains will not interfere with testing in the usual way.
The curd remaining in the bottle after the second wash-
ing is shaken up with ten cc. of water; the water-emul-
sion 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 been worked out by
Holm,2 Howard3 and others. Holm recommends the
use of a mixture of equal parts of hydrochloric and
glacial acetic acid, in the place of sulfuric acid, as the

1 The Gottlieb method gives very satisfactory results with both cheese
and condensed milk (see 254). See also Jr. Ind. and Eng. Chem.,
1912, p. 672. For method of analysis of desiccated milk, milk powder,
etc., see ibid., 1912, p. 544.

2 Report Dept. of Health, City of Chicago, 1900, p. 50.

3 Journ. Am. Chem. Soc., 1907, p. 16. Methods of analysis of ice
cream have also been proposed by White, (Penna. exp. sta., rept. 1910,
p. 243), Baird, (N. Y. Prod. Rev., Feby. 26, 1913), and Halvorsen,
(Jr. Ind. and Eng. Chem., 5 (1913), p. 403).

The Lactometer and Its Applwatipn\ ItU

latter is likely to char the sugar in the ice cream, thus
giving difficulty in reading the results. Nine grams of
either the frozen or melted sample are weighed into a
Babcock milk bottle, which is then filled almost to the
neck with the mixture of the two acids given. This is
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

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) unsweetened and
sweetened 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?

JAn apparatus for determining the amount of overrun (214) in the
manufacture of ice cream has been devised by G. H. Benkendorf of
Wis. exp. station (see bull. 239 of the station).

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 l™-* =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. 77). *

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 a gallon of water weighs 8.34 Ibs., 1 gal. of milk will weigh
S.34Xl-ft32 or 8.6 Ibs.; 1 gal. of skim milk, 8.7 Ibs., and 1 gal. of
cream frpm 8.1 to 8.5 Ibs., according to its richness. (See Table XVI,
Appendix.)

The Lactometer and Its Application.

103

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 the 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.

FIG. 39.
Quevenne lacto-
meter floating in
milk in a tin cylin-
der (115).

104 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 are
generally standardized at 60° F., and to show the cor-
rect specific gravity the milk to be tested should first be
warmed (or cooled, as the case may be) to exactly
60° F.

112. Correction tables. Tables have been constructed
for correcting errors in lactometer readings due to
differences in temperature. 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 differing greatly from that of the
milk serum, the table cannot give absolutely accurate

The Lactometer and Its Application. 105

corrections for all kinds of milk, whether rich or poor.
But the error introduced by the use of one table for all
kinds of whole milk within a comparatively small
range of temperature, like ten degrees above or below
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 taking the spe-
cific gravity of a sample of milk by means of a lacto-
meter, 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 corrections 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 32.5
it will be about 32.5+.4=32.9 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-

106 Testing Milk and Its Products.

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

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.

The temperature correction for Board of Health lactometers
is as follows: for each degree of temperature above 60° F. .3 is
added to the reading, and for each degree below, .3 is subtracted.i

115. Reading the lactometer. For determining the
specific gravity of milk in factories or private dairies, tin
or copper cylinders are recommended, 1% inches in
diameter and 10 inches high, with a base about four
inches in diameter (see fig. 39) ; another form of speci-
fic-gravity cylinders, 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

1 A special form of lactometer that will allow of very accurate read-
ings has been constructed by Poetschke (see Jr. Ind. and Eng. Chom.,
1911, 'p. 405).

The Lactometer and Its Application. 107

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-
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 the 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 then be floating in par-
tially skimmed milk (24). In reading the lac-
tometer 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

FIG. 40. Spe-

contact with the lactometer stem will rise cific-gravity
above the level of the surface in the cylinder,
and this must be taken into consideration in making the
readings. It is not necessary to read closer than one-
half of a lactometer degree in factory or dairy work.

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-,
nag el'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

1 Milchztg. 1883, 419 ; bull. 43. Chem. Div., TJ. S. Dept. of Agriculture,
p. 191 ; Analyst, 1894, p. 76. See also Fleischmann and Wiegner, Jr.
f. Ldw., 1913, pp. 283-323.

108 Testing Milk and Its Products.

the mechanical condition of the nitrogenous compo-
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-ehromate, 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
(% gram 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-
loiP 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 the 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 ob-

lTechnik der Milchfriifung, p. 98.

The Lactometer and Its Application. 109

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

CALCULATION OP MILK SOLIDS.

119. 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 composition of samples of milk with con-
siderable accuracy, both cutside of and in chemical lab-
oratories. As the complete formulas given by various
chemists (Behrend and Morgen, Clausnitzer and Mayer,
Fleischmann, Hehner and Richmond, Richmond, Bab-
eock)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 Richmond, 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 the 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.

Solids not fat=(roo1^S0-|fsf-l)(100-f)2.5

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

2 Wisconsin .experiment station, twelfth report, page 120.

110 Testing Milk and Its Products.

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 + .2 f
Total solids=}4 L + 1.2 f,

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

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

The Lactometer and Its Application. Ill

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

ADULTERATION OF MILK.

J2i. 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 food chemists. Managers of creameries
and cheese factories are also sometimes interested in
ascertaining possible adulterations in the case of some
patron's milk, although 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, wateied or skimmed milk is occasion-
ally met with, in spite of the vigilance of their milk in-
spectors 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 Chemistry, p. 61.

112 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 composi-
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.1

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 shows a
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, Poods, their Composition and Analysis, London, 1903, p.
250 et seq.

The Lactometer and Its Application. 113

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 been skimmed or watered by the dealer or by the
cow ; in 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
be legally sold in most states in the Union, and the
farmer offering such milk for sale, even if he does not
know the composition of the milk produced by his cows
is liable to prosecution just 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-

114 Testing Milk and Its Products.

ids of low specific gravities. The specific gravity of the milk
solids is calculated by means of Fleischmann 's formula

t

S=-

100s -100
t

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 100X|-^"100 =3.101;
13.0-3.101=9.899; -^f^ =1.31, the specific gravity of the milk
solids.

The specific gravity of the solids does not change if the milk
is watered, while it is increased when the milk is skimmed. If a
sample of milk of the composition given in the preceding ex-
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, 8=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 100s~10Q 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

The Lactometer and Its Application. 115

horizontal line beginning with 1.034 under the column headed

0.0003, the figure 3.316, which is the value for 100s~100 when
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 both, 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 the milk is

sp. gr. of milk i \

fat and solids not fat j watered

sp. gr. of solids normal )

sp. gr. of milk and of solids "i , . , ]

solids not fat |nign I skimmed

fat and solids .__« low )

sp. gr. of milk normal ^j watered

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

fat and solids not fat low J skimmed

The extent of the adulteration is determined as given
below.

127. Calculation of extent of adulteration.1 In the

following formulas, percentages found in the control-
samples, if such are at hand, are always substituted for
the legal standards.

a. Skimming.— 1. If a sample of milk has been
skimmed, the following formula will give the number
of pounds of fat abstracted from 100 Ibs. of milk :

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

267-8.

116 Testing Milk and Its Products.

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

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=10°— iegai standard for fat ' (I1)

b. Watering.— If a sample is watered, the calcula-
tion is most 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-

terated milk =100-,- --- -i (HI)

legal standard for solids not fat

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

Example: A sample 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-sxi °° =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 original milk
100 X leg. stand, for sol. not fat

S

In the example given above,—*- — 100=20 per cent
of water was added to the original milk.

c. Watering and skimming.— If. a sample has been
both watered and skimmed, the extent of watering is

Babcock Test for other Milk Products. 117

ascertained by means of formula (III) or (IV), ana
the fat abstracted found according to the following
formula :
Per cent, fat abstracted=

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

B

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^lOO-^^i^^lO per cent.
Fat abstracted=3 — *l*±-=33 per cent.

8-1

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 determined?

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?

118 Testing Milk and Its Products.

9. How many pounds of fat have been removed from 100
pounds of a sample of milk testing 2.6%, and what per cent, of
the fat was removed?

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:

Lactometer Beading. per Cent Fat.

(a) 32.0 at 58° F. 4.0

(b) 33.5 at 56° F. 2.5

(c) 30.0 at 63° F. 3.5

(d) 28.0 at 54° F. 2.5

(e) 27.4 at 69° F. 2.4

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.

120 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 greatly
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 (147).
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

1 Jour. f. prakt. Chemie, 1872, p. 6, 19.

Testing the Acidity of Milk and Cream. 121

worked out by Soxhlet and Henkel has since been in
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,
j 131. Manns' test. The acid in milk or cream is
measured by using an alkali solution of a 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-

1 Fleischmann, Lehrb. d. Milch wirtschaft, 3rd ed., p. 57.

2 Illinois experiment station, bulletin 9.

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

23+16+1=40
NaOH

A normal soda solution then is made by dissolving 40 grams of soda
in water, making up the volume to 1000 c~. : a one-tenth normal solu-
tion will contain one-tenth of this amount of soda, or 4 grcitns dissolved
in one liter. One cubic centimeter of the latter solution will contain
.004 gram of soda, and will neutralize .009 gram of lactic acid. The
formula for lactic acid is C,HRO, (see p. 16), 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.

122 Testing Milk and Its Products.

termining the acidity of milk, and is the solution labeled
Neutralizer of the Manns' test.

The indicator used is a solution of plienolplitalein, 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 meas-
ure out with exactness the quantity of
liquid to be tested; Manns recom-
mended 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 so-
lution 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 re-

Fio. 41. Apparatus used

in Manns' test mains permanent for a time. No

Testing the Acidity of Milk and Cream. 123

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 standing, 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 di-
viding the product by the number of cc. of the sample
tested, the quotient being multiplied by 100.

c. c. alkali X. 009

Per cent. acidity= .X100

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 woulft be 32 *0°Q9 X10Q=.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)XlOO=.018; if a 25 cc.
pipette is used, the factor will be (.009-=-25) X 100=
.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.

124 Testing Milk and Its Products.

133. If a Babcock milk test pipette is used for meas-
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

134. Manns' testing outfit The apparatus (see fig. 41)
and chemicals necessary 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 measuring the sample.
This outfit will make about 100 tests and is sold for $5.00.a

135. The alkaline tablet test. Solid alkaline tab-
lets were proposed by Farrington in 1894, as a substi-
tute for the liquid used in Manns* test.3 It was found
possible to mix a solid alkali carbonate and coloring
matter, and compress 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

1 Van Norman recommends the use of a 50th -normal solution for
testing cream (see Purdue exp. sta., bull 104). 37 cc. 01 a normal soda
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 the
usual manner, using phenolphtalein as an indicator. See also Cornell
Univ. circ. No. 7.

*Devaida'8 acidimeter (Milchzeitung 1896, p. 785) is based oil the
same principle as Manns' test; one-tenth soda solution is added to 100
cc. of milk in a glass-stoppered granulated flask, j 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.

8 Illinois experiment station, bulletin 32, April, 1894.

Testing the Acidity of Milk and Cream. 125

will keep far better than a standard alkali solution,
and they can be safely sent by mail; they also require
less apparatus and are considerably cheaper than
standard alkali solutions; 1000 of these tablets, costing
$2.00, will make about 400 tests.1 Similar alkaline
tablets were placed on the market in Europe at about
the same time, viz., Stokes ' Acidity Pellets 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>^hnder»
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 cream, to examine

1 The tablets are sold by dealers in dairy supplies.

2 Milchzeitung, 1895, pp. 518-16.

126 Testing Milk and Its Products.

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 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.
Fitch,1 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. 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 dissolved 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,

1 Hoard's Dairyman, Sept. 3, 1897.

Testing the Acidity of Milk and Cream. 127

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-
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 p(r 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 soon as one is emptied, tablets and water are again
added, and the cylinder is corked and placed in a hori-

1 Illinois experiment station, bulletin 32 ; Wisconsin experiment sta-
tion, 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.

128 Testing Milk and Its Products.

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
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, " 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 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
strength of the standard tablet solution.

1413. Powdered sodium carbonate weighed out in
the exact quantity required for making a gallon of
tenth normal solution has of late been placed on the
market; these "test powders" are cheaper than alka-
line tablets and when put out by a reliable firm are
equally as accurate as these.

Testing the Acidity of Milk and Cream. 129

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
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 sam-
ple shows when the acid contained therein has beer
neutralized. This shade of color is easily recognized
with a little practice. The pink color is not permanent
unless 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

1 A helpful suggestion has been made by the Danish State Dairy In-
structor, Dr. G. Ellbrecht, for obtaining a uniform color in acidity tests.
Small strips of pink paper are moistened and 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.

9

130 Testing Milk and Its Products.

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.
tablet solution. As the cream ripens, its acidity in-
creases. The rate of ripening depends largely on the tem-
perature at which the cream is kept. Cream containing
.5 to .6 per cent, of acid will make such butter as the
general 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-

1 Washington experiment station, bulletin 32.

2 Chicago Dairy Produce. April 21, 1900, p. 80 ; Iowa expt. sta., bull.
52.

Testing the Acidity of Milk and Cream. 131

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.

145. 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
thoroughly mix the milk and the tablet solution. *
In shaking the graduate, give it a rotary motion pIG
to prevent spilling any of the liquid. Continue man's cylinder,
adding the tablet solution until a permanent pink fining °he acid-
color can be detected in the milk. The level of Ky of cream or
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 a tenth-normal alkaline

1 Washington experiment station, bulletin 24.
* See Wis. exp. sta.. bull. 129.

132

Testing Milk and Its Products.

solution ("Neutralize!*"), 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. The burette
is filled by tipping the bottle and the surplus of the
." neutralized' will flow back, leaving the solution at

the zero mark. With
the quantity of milk
given, the readings ob-
tained represent per
cent of acidity direct.
147. Rapid estima-
tion of the acidity
of apparently sweet
milk or cream. a,
Milk. The alkaline
tablet method offers a
ready means of esti-
mating 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 previously noted, milk which gives the
highest acid test contains, as a rule, a larger number of
bacteria and spores not destroyed by pasteurization
than does milk giving a low acid test (129) ; the acidity
test may therefore be used to advantage for the pur-
pose of selecting milk best adapted for pasteurization,

FIG. 44. The Marschall acid test.

Testing the Purity of Milk.

133

as well as such as is to be retailed or used in the manu-
facture 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

S Ounce Bottk. Measure

FIG. 45.

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

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
four-ounce bottle; six, in a six-ounce bottle, etc.j the
amount of tablet solution prepared depending on the

134 Testing Milk and Its Products.

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
milk and this is poured into the white cup. The same or
another No. 10 shell is now filled t\vice with 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.

Testing the Acidity of Milk and Cream. 135

By proceeding in the manner described, the man re-
ceiving and inspecting the milk at the 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.

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
pie 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-

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

136 Testing Milk and Its Products.

suits 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 the 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
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 to .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 heavy filter paper, each of about the size of an old-
style copper cejit; 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. If 20 cc. cream require 12 cc. ^ alkali for neutralization,
what per cent, acid in the sample T

2. If 1 cc. £jj 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!

3. 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!

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

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 long 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 ''Wisconsin 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

1 Herz, Unters. d. Kuhmilch, Berlin, 1889, p. 87 ; Siats, 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 StHtion for 181)8 (fifteenth report, pp. 47-53'), from which source
the accompanying illustration is taken (see fig. 46).

138

Testing Milk and Its Products.

quantity; they are then placed in a water tank, the
water of which is heated 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. Cross-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 out-
let ; DP, 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-

Testing the Purity of Milk. 139

ered, and the curds allowed to ferment in the sample
jars for six to twelve hours.

During this time the impurities in any particular
sample will cause gases to be developed in the curds 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 it 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,

140

Testing Milk and Its Products.

Fm. 47. The CJerher fermentation test,
kept at 104-106° R, for

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
patron whose milk was
placed therein. The
tubes in the rack are
put in the tank, which is
two-thirds full of water;
the temperature of the water is
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, and should not 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

1 Die praktische Milchpriifung, p. 85.

Testing Milk on the Farm.

141

then quickly added to the warm milk and the time

required 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
water. Fill the cup with

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 coagulatinp

the milk is shown di-

rectly by a scale on the

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

1 Decker, Cheese Making, Revised ed., 1909 p. 39.

FIG. 48. The Monrad rennet test.

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 the
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 quantity
of milk from day to day.

1 Illinois experiment station, bulletin 24.

Testing Milk on the Farm. 143

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. U< ; Woll's Hand-
hook for Farmers and Dairymen, Fifth ed., p. 250.

144 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 year2
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.
aSee 175.

Testing Milk on the Farm.

145

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

Daily milk Test of

Yield of fat

£

yield

one day's milk

per day

MONTH

Is

g

«>

«,

-

^ .

•

1

IS

OJ— '

||

W~

S1

|

I|

Is

1"

S

Ss
3

December

920

12.1

16.0

10.0

3.8

4.9

3.0

.46

.60

.34

January .

927

16.0

17.7

14.0

3.7

4.6

2.7

.59

.76

.44

February 1 1035

16.1

17.7

13.5

3-6

5.8

3.2

.58

.84

.51

March 1047

14.3

16-0

12.5

3.8

4.7

3.4

.54

.61

.50

April

1054

13.8

16 5

11.5

4 0

5 8

3 0

55

72

46

May .

1079

14.5

17 2

10.0

3.8

4.6

3.4

.55

.70

.44

June

1105

12.1

14 0

9 2

3 9

4 6

3 2

47

57

35

July- . . 1 1180

9.3

12.2

6.0

4-2

6.2

2.8

.39

.60

.27

August

1130

6.4

9.3

3-5

4.7

7.9

2.9

.30

.50

.16

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 -f- 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
10

146 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 decreased 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 of 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. 147

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 tel]
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
one day every two weeks gave 97.6 per cent, of the
total milk, and 98.5 per cent, of the total butter fat,
and tests made one day per 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.

1 66. 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-

148

Testing Milk and Its Products.

tained 254 Ibs. of butte? 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

Weigrht of milk

Test of Milk

Yield of butter fat

Nov 4

Lbs.
20 5

Per cent.
4 7

Lbs.
96

Dec. 4 .

18.7

4.6

86

Jan. 3

17.7

4.9

86

Feb. 2

20.0

45

90

Mar. 3

18 2

4 7

86

April 2

19 5

44

81

May 2

17.7

4.8

85

June 1 _

13.1

5.5

.72

July 1 ___

12.2

6.2

76

July 31

3.2

7.2

23

Total.

160.8 Ibs.

7 81 Ibs

Average per day_.

16.08 Ibs.

4.85

.78 Ib.

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 Ike Farm. 149

isfactory 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.

i66a. Official tests of dairy cows. The various ex-
periment stations conduct tests of dairy cows for breed-
ers and farmers, by which means records of production
of milk and butter fat are obtained for periods of 7 or
30 days, or for an entire year. This system of official
testing is described in bulletins issued by several sta-
tions.1

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.2 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.

FIRST SAMPLE

SECOND SAMPLE

For spring cows,
For summer ' '
For fall "

6 weeks after calving
g t ( ( ( t (

8-10" " "

6l/o-7y2 mos. after calving
5.7 « « «

5y2-7 " " ' "

If only one test is to be made, approximately correct
results may be obtained by testing the milk during the

1 See, e. g., Wis. exp. station bull. 191 and 242: also bull. 226, The
Wisconsin Dairy Cow Competition, and research bull. 26, Studies in
Dairy Production, published by this station.

'Sixth report, 1882, p. 106; Ninth report, 1895, p. 176.

150 Testing Milk and Its Products.

sixth month from calving, in case of spring cows ; dur-
ing the third to fifth month in case of summer-calving
cows, and during the. fifth to seventh month for fall-
calving cows.

In all cases composite samples of the milk for at least
two 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."
b. As to quantity of milk produced. The milk may
be weighed for two 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 a factor, ac-
cording to the number of days in the dif-
ferent months. The weighing is 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
Milk placed on the market, but so far as known

have not proved satisfactory.
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

Testing Milk on the Farm. 151

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
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
for milk production she should be milked dry the last
milking previous to the day when the test is to be made.
The entire quantity of milk obtained at each milking is
mixed and sampled separately. On account of the vari-
ations 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 preferable ; the method of composite sampling and test-
ing 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 cows' 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 half a gram (8 grains) of powdered
potassium bi-chromate. If a number of composite sam-
ples of the milk of single eows are taken', each jar should

1 Agricultural Science, 6, pp. 540-42.

152 Testing Milk and Its Products.

be labeled with the number or name of the particular
cow. Composite tests are generally taken for two or four
days cr 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 -^ 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. Testing warm milk. The opinion is some-
times expressed that a considerable error is intro-
duced by measuring out milk warm from the cow
for the Babcock test, since milk expands on being
warmed, and a too small quantity is obtained in
this manner. By calculation of the expansion of
milk between different temperatures it is found that

1 Decker, Wis. experiment station, report 16, p. 155.

Testing Milk on the Farm. 153

1 cc. of milk at 17.5° C. (room temperature) will
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 are 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, about 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-

154

Testing Milk and Its Products.

position in Chicago in 1893 illustrate the 'correctness of
this statement. The .tests included twenty-five Jersey
and Guernsey 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

47 "

44 "

38 "

July 19, 1893

4.6 "

4.6 "

3.7 ' '

July 20, 1893

5.0 "

4.5 "

3.8 "

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. There was no change in the feed of the cows or
in the method of handling them on these days.

173- Ranges in variations of herd milk. According
to Fleischmann,1 the composition of herd milk will vary
on single days 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-
ag6 by more than 30 per cent.

1 Book of the Dairy, p. 32.

Testing the Purity of Milk. 155

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

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 -f ^ X 4.0=5.2, or may go below 2.8 per cent, (viz.,
4.0_ ^j). X4.0) ; if the average specific gravity is 1.031 (lacto-
meter degrees, 31 )* the specific gravity of the milk on a single
day may vary between 1.0279 and 1.0341 (31+-^ X 31=34.1;
31— i10°oX31=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; this 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. 144, furnish illustrations as to the
effect of heavy feeding on the quality of milk. The

1 See page 103.

156 Testing Milk and Its Products.

feed, as well as the milk of the cows, was weighed each
day of the experiment. During the month of December
each cow was fed a daily ration consisting of 10 ibs. ol
timothy hay, 20 Ibs. of corn silage and 2 Ibs. of oil meal ;
the table on p. 145 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.

Testing Milk on the Farm. 157

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

1For 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., re-
port, 1888 ; Hoard's Dairyman, 1896, pp. 924-5 ; W. Va. exp. sta., b.
109.

2 On this point numerous discussions have taken place in the past in
the agricultural press of this and foreign countries, and the subject
has been under debate at nearly every gathering of farmers where feed-
ing problems have been considered. Many farmers are firm in their be-
lief 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 conclusively,
however, in the direction stated, and the evidence on this point is over-
whelmingly against the opinion that the fat content of the milk can be
materially and for any length of time increased by changes in the sys-
tem of feeding. The most conclusive evidence in this line is perhaps

158 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 #f 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 phase of the question ; the quantity is
another, and an equally important one. Much less dis-
satisfaction and complaint 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,

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, under whose direction the experiments
have been conducted, is : that the changes of feed made in the different
lots of cows included on the experiments had practically no influence
on the chemical composition (the fat content) of the milk produced. In
these experiments grain feeds were fed against roots, oil cake, wheat
bran or shorts ; grain and oil cake were furthermore fed against roots,
and roots were given as an additional feed to the standard rations
tried, — in all case" with practically negative results so far as changes
in the fat contents of the milk produced are concerned.

Testing Milk on the Farm. 159

as the average for all mature cows in the herd.
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.

Questions.

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 £ general rule, change during the
first couple of weeks 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
vvwfc>v 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. sampies 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

1 Bulletin 9, May 1890.

Composite Samples of Milk. 161

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
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 delivered dur-
ing the sampling period by the test of the composite
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

162 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. 163

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
and confining within the tube a column of milk scoveii
representing exactly the quality of the milk sampling
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.

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

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

164 Testing Milk and Its Products.

184. If the diameter of the sampling pail used is 8
inches, and that of the sampling tube V* incn> tne "quan-
tity of milk secured in the tube will always stand in the
ratio to that of the milk in the pail, of (V2)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 ^
part of the milk. For composite sampling of the milk
of single cows, this proportion will prove about ri^ht:
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 diameter of the tube or 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-

1 The contents of a cylinder are represented by the formula IT r2h, r
being the radius of the cylinder, and h its height. The relation be-
tween two cylinders of the same height, the radii of which are R and r,
Is therefore as 1TR2h to ITr'h, or as R2 to r2.

Composite Samples of Milk. 165

sition in 1893, in which tests this method was adopted
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. 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 will 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
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 :2

Babcock test

Gravimetric
analysis

Drip composite sample- _

4.0 per cent.

4.04 per cent.

Scovell tube composite sample

4.0 per cent.

4.06 per cent.

187. d. The McKay sampler (fig. 53), constructed by
Professor G. L. McKay, formerly 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 turning the handles at right angles the

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. 1S07.

2 See also 199 et sea.

166

Testing Milk and Its Products.

»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.
1873. e. Michels' cream-sam-
pling tube consists of a modified
Scovell sampler in a tin jacket. It-
was constructed by Professor John
Michels, late of North Carolina agri-
cultural college. This sampler ren-
ders possible an accurate and rapid
sampling of any cream, regardless
of its richness and acidity, without
stirring the cream.

188. f. Composite sampling with a
"one-third sample pipette." Milk is
FIQ' Sampler6 McKny sometimes sampled directly from the
weighing can into the Babcock test bottle
by means of a pipette hold-
ing 5.87 cc., which is one-
third the size of the regu-
lar pipette. This quantity
is measured into the test
bottle from three successive
lots of milk from the same
patron and the test then
made in the ordinary man-
ner. In this way one test
shows the average composi-
tion of the milk delivered
during three successive days
or deliveries. When this
method is adopted, as many
test bottles are provided as ^ 55 TeBt.bottle rack for use in
there are patrons; there is no creameries and cheese factories.

Composite Samples of MUk. 167

need of using any preservatives for milk in this case. Fig. 55
shows a convenient rack for holding the test bottles used in com-
posite 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 delivered daily and each lot is sampled with the one-third
pipette, twice or three times the number of tests are required 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 sampling 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 ascer-
taining the fat content of the milk delivered during the three
days is lost; if a similar accident should occur in testing com-
posite samples collected in jars, another test can readily be made.

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.

168 Testing Milk and Its Products.

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 1892,1
and has been generally adopted in dairy regions in this
country and abroad. 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 of bi-chromate necessary for pre-
serving half a pint to a pint of milk for a period of
one or two weeks is about one-half gram (nearly 8
grains), about one-half as much as can be placed on a
dime.

According to Winton and Ogden,2 a .22-inch pistol
cartridge shell y2 inch long, or a .32-inch caliber shell
14 inch long, when loosely filled, will hold enough pow-
dered bi-chromate to preserve % pint, and a .32-inch
caliber shell y2 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

1 Biedermann's Centralblatt, 1892, p. 549.

2 Connecticut experiment station, report for 1884, p. 222

Composite Samples of Milk. 169

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-chromate can be bought
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 containing the
correct quantity of preservative for a quart or pint sam-
ple have also been placed on the market and will be
found convenient.

193. Corrosive sublimate tablets for composite
samples. During late years corrosive sublimate tablets
have come into general use in factories. These contain
mercuric chlorid with anilin color (rosanilin).1 The
coloring matter is added to give a rose color to the sam-
ple preserved, thus showing that the milk is not fit for
consumption; the bi-chromate giving naturally a yellow
color to the milk, renders unnecessary the addition of
any special coloring matter.

Compounds containing corrosive sublimate are violent
poisons 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.

Among other substances recommended for use in but-
ter or cheese factories as milk preservatives for com-

1 Iowa experiment station, bulletins 9, 11, 32.

170 Testing Milk and Its Products.

posite samples may be mentioned formaldehyde, boracic-
acid compounds, chloroform, carbon bi-sulfid,1 copper
ammonium sulfate, sodium fluorid and ammonia glycerin
(sp.gr., 1.031).

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 it 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 carefully,
the cream will become lumpy and will dry on the sides
of the jars. In some cases it is nearly impossible to
evenly distribute this dried cream through the entire
sample at testing time so as to make the composite

1 Delaware experiment station, eighth report, 1896, which also see for
trials with a large number of different preservatives.

Composite Samples of Milk. 171

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
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-

172

Testing Milk and Its Products.

age of a number of single tests and the true average test
of the various lots.

Methods of calculating average percentages.

I. Milk varying1 in weights
and tests.

II. Milk of uniform weights
and tests.

Lot

Weight
of milk.

Test
of milk.

4-> .

f3
I*

Lot

Weight
of milk.

Test
of milk.

Weight
of fat.

I

Ibs.

120
570
360
55

82

per ct.

3.5
5.0
5.2
3.0

4.0

Ibs.

4.2
28.5
18.7
1.6
3.2

I

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

It...

II

Ill

III

IV..

IV

v

v

Total

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

1 OOf

*56. 2X100

=4.73

149.8X100

-=4.22

1187 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 by divid-
ing 56.2 (the total amount of fat in the mixed milk)
by 1187 (the total amount of milk), which is 4.73;
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

Composite Samples of Milk. 173

the total amount of fat by the total quantity of milk,
making 4.22 per cent., instead of 4.20 per cent., which is
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 satisfactory results 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 average tests
of different lots of milk.

The 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 them 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

xln the experiment given on p. 148. the arithmetical mean of the
tests is 5.15 per cent., while the true average fat content of milk
is 4.85 per cent.

174 Testing Milk and Its Products.

ought to be 5.1, instead of 4.0, and naturally asked for an ex-
planation.

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.
(-^±^), but 1-^~=3.87 per cent. If the fat in the mixed
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 milkings 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 5-1^00 =4.56 per cent.

llo.u

of fat, and the night milk, 4-^^°° r=3.80 per cent, of fat.

ioO»y

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 lOJgllW _4il per cent of fat Thig ig 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-

Composite Samples of Milk.

175

ered at the creamery, a sample of each was taken 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 dip-
per

4.4 per cent.

3.8 per cent.

Sample taken at creamery with Sco-
vell tube _

4.5 "

3.7 "

Calculated from weights and tests of
milk from each cow

4.5 "

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 I

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? Mention the more common preservatives used
and quantities to be adtf " fl.

CHAPTER XI.
CREAM TESTING AT CREAMERIES.

200. The cream delivered at gathered-cream factories
is now tested by the Babcock test in many localities, 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 were pre-
viously used for this purpose.

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

1Conn. experiment station (New Haven), bull. 108 and 119; report
1894. pp. 214-244.

2Maino experiment station, bull. 3 and 4 (S. S.)

8 Hatch experiment station, report 1894, pp. 92-103: 1895. pp. 67-70.

4 The space is the volume of a cylinder. Sl/2 inches in diameter and
£f 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 I lie side of the can (Conn. exp. sta., bull. 119).

Cream Testing at Creameries.

177

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-
rhent 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

*A layer of two inches in an 8-inch pail contains 100.531 cubic
inches, two inches in a 8% -inch pail 110.18 cubic Indies, and two
inches in a 8%-inch pail 113.49 cubic inches.
12

FIG. 56. The oil-test churn.

178

Testing Milk and Its Products.

his rule and records the depth of the cream in the can,
in inches and 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
DRIVERS CASEV 111 patron's name, together
with the number of
inches of cream fur-
nished by him.

On the arrival at the
creamery the tin cards
holding the tubes are placed in a vessel filled with
water of the churning temperature (say, 60° in summer
and 65° to 70° in winter). When ready for churning
they are placed in the oil-test churn (fig. 56), 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° Pahr., 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 cooled to churning temperature and churned
again, by which process the curd is broken into fine

FIG. 57. Cream-gatherer's
sample case.

Cream Testing at Creameries. 179

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°
P., allowing them to remain therein for at least twenty
minutes. Some samples must be churned three or four
times before a good 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 inch, op-
posite the number of the particular patron. The test
multiplied by the inches and tenths of an inch of cream
supplied will give the amount of butter 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 of cream delivered by different patrons lies in
the fact that it determines the churnaUe fat, and not
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-

180 Testing Milk and Its Products.

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,
on 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 takes 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), a 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,
the scales, and one small collecting bottle. He should

1 It follows from this that there can be no definite relation between
the results obtained • by the Babcock test and the oil-test readings ;
a reading of 100 in the oil-test is. however, on the average, equivalent
to about 28 per cent, of butter fat in the cream.

Testing Cream at Creameries.

181

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
near 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. D». uutnt ror cream testing

by the Babcock test at gathered- the dial will Stand at Zero
cream factories.

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 ^ of an
inch thick, and a few inches longer than the weighing pail which

1 The necessity of care in mixing the cream is shown by the follow-
ing illustration given by the authors referred to.

Per cent of fat in cream which stood for 24 hours.

Sample drawn
Surface. Bottom. with sampling tube.

Not mixed 28.00 5.00 10.25

Poured once .__ 23.75 22.00 22.50

Poured twice 22.25

182 Testing Milk and Its Products.

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 ^ to over ^4 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 i36- 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 diameter 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-
tior 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 be 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 outsiue 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."

Testing Cream at Creameries. 183

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 are 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
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 nor less than 48 pounds of cream testing 25 per
cent.; in either case 12 pounds of pure butter fat is

184 Testing Cream and Its Products.

delivered. This will make the same amount of butter
in either case, viz., about 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
creaming the milk, like the centrifugal process, is used
and all factors remain as nearly the same as possible 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

Testing Cream at Creameries. 185

standing for 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.

21 o. 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-

1Bull, 3 (S. S.), Maine experiment station.

1 Spillman (Dairy and Creamery, Chicago, April 1, 1899) recom-
mends the use of the factor 1.044.

1 This subject is discussed in detail in the 17th annual report of Wis.
experiment station, pp. 90-92 ; see also the 20th report of that Station,
pp. 130-31.

186 Testing Milk and Its Products.

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 operator 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 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 or 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

188

Testing Milk and Its Products.

same proportion of fat contained in the milk is re-
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.

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

Curd

Salt and
ash

water, curd,
salt and

ash

Average of 350

Per cent.

Per cent .

Per cent.

Per cent.

Per cent.

analyses

11.57

84.70

.95

2.78

15.30

Lower and up-

per limits

8 63-15 00

76 53-88 2Q

. 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 on the following page i1

1 Wisconsin experiment station, bull. 56.

Calculation of Butter- and Cheese Yield. 189

Summary of analyses of Wisconsin creamery butter.

Sum of

Water

Fat

Curd

Salt and
ash

water, curd,
salt and

ash

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

Highest

17.03

87-50

2.45

4.73

22.95

Lowest

9.18

77.07

.36

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 the samples 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 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.

butter than there was butter fat, since

83 : 100 : : 100 : x ; therefore

^100X100^3,5.

190 Testing Milk and Its Products.

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, from 110 to
116 Ibs. of butter ready for market will be obtained from
it. The overrun from cream will be somewhat larger,
18 to 22 per cent, but will never exceed 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,

Calculation of Butter- and Cheese Yield. 191

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.

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 of the different grades of milk:

4000 Ibs. of milk testing 2.5 per cent will contain 100 Ibs. of fat.
2857 " " " 35 " " " 100 " " "

2500 « (( tt 40 (( (i (( -J^QQ (i (( tt

1666 ":."" " 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-

192

Testing Milk and Its Products.

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
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 tfnder
good management (219).

Fat available for butter in different grades of milk.

Grade of milk

Whole
milk

Skim
milk

Butter
milk

03

1
£

Total
loss

Fat
available
for
butter

2.5 percent

4000 Ibs.
2.5 per ct.

3400 Ibs.
.1 per ct.

400 Ibs.
.3 per ct.

Lbs.

Lbs.

Per ct.

Fat.. ..

100 Ibs.

3.4 Ibs.

1.2 Ibs.

3 0

7 6

92.4

3.5 percent

2857 Ibs.
3.5 per ct.

2429 Ibs.
.Iper ct.

286 Ibs.
.3 per ct.

Fat
4.0 per cent

100 Ibs.

2500 Ibs.
4 per ct.

2.4 Ibs.

2125 Ibs.
.1 per ct.

.91b.

250 Ibs.
.3 per ct.

3.0

6.3

93.7

Fat
6.0 percent

100 Ibs.

1666% Ibs.
6 per ct.

2.1 Ibs.

1417 Ibs.
.1 per ct.

.71b.

167 Ibs.
.3 per ct.

3.0

5.8

94.2

Fat :

100 Ibs.

1.4 Ibs.

.51b.

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 30 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

Calculation of Butter- and Cheese Yield. 193

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.

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 case
will be as follows:

100 Ibs. of fat from

Available
fat

Butter cont.
83 per ct. fat

Overrun

Lbs.

Lbs.

Per ct.

4,000 Ibs. of 2.5 per cent, milk

92.4

113.3

11.3

2,857 Ibs. of 3.5 per cent, milk

93.7

113.0

13.0

2,500 Ibs. of 4.0 per cent, milk

94.2

113.9

13.5

1,666 Ibs. of 6.0 per cent, milk

95.1

114.6

14.6

The overrun figures given above may be increased by
saving some of the three pounds of butter fat lost by
waste. If it were possible to entirely eliminate this loss
there would be three pounds more available fat in each
case, viz., 95.4, 96.7, 97.2, 98.1 Ibs. These amounts of
fat will make 115, 116.5, 117.1, and 118.2 Ibs. butter,
corresponding to an overrun of 15, 16.5, 17.1, and 18.2%
from milk of the different fat contents mentioned.

All butter makers should obtain more butter from a
certain quantity of milk than the Babcnck 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. A

13

194

Testing Milk and its Products.

butter maker's skill is shown by his ability to reduce the
losses by waste in handling the milk, cream and butter,
as well as the losses of butter fat in skim milk and butter
milk, and his carefulness in weighing, sampling and
testing the milk, cream and butter made.

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 slightly larger over-
run than thin cream, for the same reasons as have been
shown in the calculations of overrun from milk of dif-
ferent fat contents. If similar calculations are made
for cream of different richness as those given above for
milk, 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 mechanical loss in the process
of butter-making amounting to 2 per cent, has been
assumed in these calculations :

100 Ibs. fat in
cream

Available fat

Butter of 83
per ct. fat

Overrun

Per cent

Lbs.

Lbs.

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 for 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.

If no losses from waste are considered in the account,
the figures for fat available for butter will be 98.8, 99.3,

Calculation of Butter- and Cheese Yield. 195

and 99.6 Ibs., and the overruns when the butter contains
83% fat will be 19, 19.3, and 20 per cent. These over-
runs are higher than will be obtained under ordinary
creamery conditions with butter containing 83.7% fat,
because it is impossible to reduce the manufacturing
losses in handling the cream and butter appreciably
below 2 per cent.

2173. Maximum overrun for butter of a legal
water content. If we assume that the butter contains
the maximum amount of water allowed by law, viz., 16
per cent, (and therefore about 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%

°1.0

3.5%

17.1

30% . .

._ _ _ _ _21.6

4.0%

17 8

6.0%.

18.9

40%

22 0

This table shows the highest overruns that are likely
to be obtained when the butter 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

196 Testing Milk and Its Products.

of butter made from it, and finding what per 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 the milk contained 8000 X
.038—304 Ibs. of butter fat. 350 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,

46 Ibs.; 46 is ^j^MrrlS.l per cent, of the quantity of the butter

fat in the milk; that is, the overrun for the day considered was
15.1 per cent.

The formula for the overrun is as follows :
V_(b-)fl00

~r~

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 : cso-aoOjaoo =15>1 per cent

o04

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 calculated by subtracting the butter
fat from the butter, 304 — 250=54 Ibs., then divide this by the

fat in the cream and multiply by TOO; or ?14^==21.8 per cent.,

250

which is the cream overrun.

219. Conversion factor for butter fat. In the ninety-
day dairy test at the World's Columbian Exposition,
96.67 per cent, of the fat in the whole milk was recovered
in the butter. This butter, en 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 exact conversion factor

xWhen 82.37 Ibs. of butter fat will make 100 Ibs. of butter, how
much butter will 96.67 )bs, of butter fat make? 83.37 :96 :17 : :100 :x,

Calculation of Butter- and Chce.se Yield 197

would be 1.173. As this is an awkward number to use,
and as 1% is so nearly the same, it was recommended
at the time 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 in milk.

*•

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 in 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

198 Testing Milk and Its Products.

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 ^rril.lQ. 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 the 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 in separating and churning 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 ICO; the amount
of butter which the total milk of this average fat con-
tent will make, according to the table, is then compared
with the actual churn yield.

Calculation of Butter- and Cheese Yield. 199

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
net vary appreciably from this figure if the work in the cream-
ery has been 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 to 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 OF YIELD OF 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 /

200 Testing Milk and Its Products.

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 Slyke1 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 cheese=1.58 (_|— |-.91f ) • _ _ (II)

XN. 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. sta., reports 10-13, incl. ;
Wis. exp. sta., reports 11 and 12, bull. 197 ; Ont. Agr. College, reports
1894-'96, incl. ; Minn. exp. sta., b. 19, reports 1892-'D4, incl. ; Iowa exp.
sta!, bull. 21 ; Hoard's Dairyman, 1892, p. 2400.

Calculation of Butter- and Cheese Yield. 201

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 in
par. 120, 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. ( -W-=l-54), 40 per cent. *££=1.G7, 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.

1 For derivation of this formula, see Wisconsin experiment station,
twelfth report, p. 105.

202 Testing Milk and Its Products.

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 80% 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 i
220 Ibs. butter from 8000 -Ibs. milk, testing 2.3% fat.
250 Ibs. butter from 4000 Ibs. milk, testing 5.8% fat.
600 Ibs. butter 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) 12.5% 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, how much
butter or cheese 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 in case of milk and cream?

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 XI, Appendix.}

CHAPTER XIII.
CALCULATING DIVIDENDS.

A. — CALCULATING DIVIDENDS AT CREAMERIES.

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. By multiplying the total number of
pounds of milk delivered by this patron, by his average
test, the total weight of butter fat in pounds 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-

204 Testing Milk and Its Products.

facturing the butter. The method to be followed is
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 in use 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.

The price charged for making butter varies from 2%
to 4 cents per pound; the larger the amount of milk
received 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 be changed during the different seasons
of the year by mutual agreement.

Third.— A creamery, owner may offer to pay 1 to 2
cents, usually 1% 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. 83.

Calculating Dividends. 205

229. II. Co-operative creameries. 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. Illustration of calculation of dividends. Tn order
to illustrate the details of calculating dividends, or the amount
to be paid each patron for the milk delivered, when
payments are made by each of the four systems given, it will be
assumed that a creamery receives 5000 pounds of milk daily during
a month, and makes 6650 Ibs. of butter from the 150,000 Ibs.
of milk received during this time. Thei 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
these 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 aveirage amount of butter
fat in each 100 Ibs. of milk received during the month.

So far the method of calculation is common for the different
systems of payment given above; the manner of procedure now

206

Testing Milk and Its Products.

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 150,000 Ibs.
of milk delivered during the month. The price of one pound of
butter fat is then easily found: $931-=-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:

Pat on

First
week

Second
week

Third

week

Fourth
week

Total
Milk

Average
test

Milk

Test

Milk

Test

Milk

Test

Milk

Test

No. 1 ..
No. 2_...
No. 3_—

Lbs.

3500
700
2480

%
3.6

3.8
4.2

Lbs.

3000
665

2000

%
3.5
3.8
3.8

Lbs.

3600
720
1850

%
3.65
3.6

4.0

Lbs.

3450
750
1500

%
3.45
3.7
3.6

Lbs.

v 13,550

2,825
7,830

%
3.55
3.73
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

Average
test

Butter

fat

Price of fat
per Ib.

Amount
due

No. 1__

Lbs.
13,550

Per cent
3.55

Lbs.
481.0

Cents

16%

$78.56

No. 2 _

2,835

3.7

104.5

16%

17.06

No. 3

7,830

3.9

305.4

16%

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;

Calculating Dividends.

207

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-J-4=16%
cents, and the amount due each patron is found' by multiplying
the total weight of butter fat in 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
1% cents per pound below the 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
iy2 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
miik ,

Average
test

Butter
fat

Price of fat
per Ib.

Amount
due

No. 1

Lbs.
13,550

Per cent
3 55

Lbs.
481 0

Cents
16

$76 96

No. 2

2,825

3 7

1045

16

16 72

No. 3

7,830

3 9

305 4

16

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 each 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),

208 Testing Milk and Its Products.

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 basis of
calculating the factory dividends, when milk is paid 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 or cream delivered by them would make
This can be ascertained quite satisfactorily from the total
receipts and the total weights of both butter fat and but-
ter. The total money to be paid for butter (the net re-
ceipts) 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 delivered in the milk, gives the amount of
butter corresponding to one pound of butter fat, and
the number of pounds of fat delivered by each patron
is then multiplied by this figure. This method requires
more figuring than those given in the preceding, and the
dividends are no more accurate, in fact less so, than
when calculations are based on the price per pound of
fat.

Calculating Dividends. 209

2373. Making butter "for the overrun." When
cream is bought on the basis of paying the market price
of butter for each pound of butter fat in the cream, the
margin received by the cream buyer, if he makes this
cream into butter, is influenced both by the price of
butter and the per cent, of overrun he obtains. If the
price of butter is 20c. and the overrun is 20%, each
pound of butter fat makes 1.2 Ibs. of butter, and the
buyer receives 24 cents for the butter, or 4 cents margin
on the 1.2 Ibs. of butter made, which is equal to 3%
cents per pound of butter. If the price of butter is
36 cents, and the overrun 20%, the cream buyer receives
1.2X36=43 cents for the butter, or 1 cents for 1.2 Ibs.
of butter, equivalent to 5.8 c. per pound of butter.

238. Relative-value tables. These tables give many
of the multiplications used in computing the amount
due for various weights of milk of different fat con-
tents. 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 25 cents, the value of each 100 Ibs. of milk of
different quality is found by multiplying its test by 25.
If the average tests of the different patrons' milk vary
from 3 to 5 per cent., the relative- value .table would be
as follows.

3.0X25=75c. per 100 Ibs.
3.lX25=77.5c. "
3.2X25=80e. "

3.3X25=82.5c.
3.4X25=85.0c.
3.5X25=87.5c.

3.6X25=90c. per 100 Ibs.
3.7 X 25=92 5e. "
3.8X25=95.0c.
3.9X25=97.5c.
40X25=100c.
etc.

By continuing this multiplication, or adding the mul-
tiplier each time for each tenth of a per cent, up to 5

14

210

Testing Milk and Its Products.

per cent, of fat, a table is made that can be used for
calculating the amount due per 100 Ibs. of milk at the
price per pound given, 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, 25 cents; he should
then receive 24.70 X.80=$19.76 (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, 38.50 X.95=$35.57.

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
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

Average
test

Price per 100 Ibs.
of milk

Amount
. due

No. 1_

Lbs.
13,550

Per cent
355

Cents

58 5

$79 26

No. 2

2,825

3 7

61 0

1723

No. 3. _

7 830

3 9

64 0

50 11

Calculating Dividends. 211

239. Milk- and cream dividends. When cream from
farm hand separators or other 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 (210).

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
an allowance can be fairly made by multiplying the
cream fat by 1.03. The amounts of fat thus obtained
represent very nearly the fat in the milk from which
the cream was skimmed and assumes that the fat re-
turned to the milk patron in his skim milk is about
three per cent, of the total fat in his whole milk.

Since both milk and cream patron suffer the same
manufacturing losses in the butter milk, 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 (523°1(^3'8) —202 Ibs. butter fat. If the
price paid the patrons is 20c., then 202 multiplied by 20 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, f485 x 22>)r= 106 .7 Ibs. but-

\ 100 /

212 Testing Milk and Its Products.

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. 106.7X1.03=109.9 Ibs. butter fat which is now multi-
plied 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 to-
gether.1

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
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.2
Prof. Robertson, 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,3 a figure which is fully corroborated by

1 17th report Wis. exp. station, p. 90; 20th report, pp. 130-131.
2 Wisconsin exp. station, llth report, p. 134.
8 Hoard's Dairyman, March 29, 1895.

Calculating Dividends. 213

Dr. Babcock's results. The injustice of the "pooling
system," 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-
ing the milk delivered. The testing may be conven-
iently arranged by the method of composite sampling,
in the way already described for creameries (180).

242. Cheese factory dividends, (a) Dividends
based on fat test alone. As in the case of 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.

214 Testing Milk and Its Products.

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.

(b) Dividends based on fat and solids-not-fat (lacto-
meter readings). A close estimate of the cheese value
of each patron's milk may be made, as explained in
par. 224, b., by the use of table XIII in the Appendix.
When the cheese yield of each patron's milk is found by
this method, the money to be distributed among the
patrons is divided by the sum of the figures found
by these two tests, instead of by the total butter fat. The
figure thus obtained is the price to be paid each patron
per pound cheese that may be made from his milk as
shown by both the fat test and the lactometer reading.

(c) Dividends based on "the fat plus two method. •'
The money due patrons for milk delivered at cheese
factories may be calculated by adding two to the per
cent, of fat in the milk, and otherwise proceeding as
explained above under par. 242a. This is the method
advocated by Prof. H. H. Dean of Guelph (Ont.) Ag-
ricultural college.1 It has been adopted at many Cana-
dian cheese factories and at some factories in this coun-
try.

(d) Dividends based on the fat and casein tests. The
results obtained by the fat test and the Hart casein

1 Bull. 114, Ont. Agr. College; see also Dean, Canadian Dairying, p.
146.

Calculating Dividends. 215

test (258) are added together; the pounds of milk de-
livered by each patron are multiplied by this figure
and the product multiplied by the price to be paid foi
the sum of the fat and the casein.1 This price per
pound is obtained in the same way as the price per
pound of fat. Each patron's milk is multiplied by the
sum of the fat and the casein tests and the money to
be distributed to the patrons is divided by the sum of
these figures obtained for all patrons for the period
covered.

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
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 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 month. According to the
weighings and the tests made, the milk contained 5,700 Ibs. of
butter fat. If the 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,

1 Wisconsin expt. station, bull. 197.

216

Testing Milk and Its Products

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-i-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

Average
test

Butter fat

Price per
Ib. of fat

Amount
due

Lbs.

Per cent

Lbs.

Cents

No. 1
No. 2
No. 3

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
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% fatj

1 Suggestions regarding the organization of co-operative creameries
and cheese factories will be found in the Appendix, following Table
XV. Draft of constitution and by-laws for co-operative factory as-
sociations 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
advanced dairy students. This work cannot be done
outside of a fairly well-equipped chemical laboratory,
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 albumen,- milk sugar,
and ash. The methods of analysis described in the fol-
lowing are those adopted by the Association of Official
Agricultural Chemists of North America, which, with
but slight modifications, are in general use in the chemi-
cal laboratories of all American experiment stations and
agricultural colleges.1

248. a. Specific gravity is determined by means of
a picnometer or specific-gravity bottle, since more ac-

1 The complete methods of analysis adopted by the Association of
Official Agricultural Chemists are published by the Bur. of Chemistry
of the U. S. Department of Agriculture ; see Bull. No. 107, pp. 117-128.

218 Testing Milk and Its Products.

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 milt
in a similar 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
weight of the empty bottle from the second and the
third weights, respectively, and the specific gravity of

Chemical Analysis of Milk and Its Products. 219

the milk then found by dividing the weight of the milk
by that of the water.

Example: Weight of sp. gr. bottle+ 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 milfcfjf =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; th 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.

220 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, 25 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 b» aker 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° 0. until they no longer
decrease in weight, which will ordinarily take about
three hours. Place in a desiccator until cold, and weigh ;
the difference between the weight of the tube+milk 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. 221

Example : Weight of tube-f beaker+milk 29.3004 grams.

Weight of tube+beaker 24.1772 grams.

Milk weighed out 5.1232 grams.

Weight of tube+beaker-fmilk 29.3004 grams.

Weight of tube+beaker+milk,dry 24.9257 grams.

Weight of water 4.3747 grams.

Per cent, of water in milk=4;3!47 * 10° =85.39 per cent.

5 . 12*32

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 covers will answer the purpose well if the handle be broken
off or ground off level on an emery wheel) ; this is weighed rap-
idly; 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 occurs. 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-

222 Testing Milk and Its Products.

tinue the extraction for 8 hours. The ether is then re-
covered by distillation, and the flasks dried in a steam
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+fat ............. 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.

D . 1 .,'. >'2

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, alcohol, 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 chemical. 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 % cm.
of the turbid bottom layer. After evaporating the ether
solution in a hood, the flasks are dried in a steam oven

1 Landw. Vers. Sta., 40 (1892), pp. 1-27. The method is also spoken of
as the R<5se-Gottlieb method.

Chemical Analysis of Milk and Its Products. 223

for two to three hours, and weighed. This method is
applicable to new milk, skim milk, butter milk, whey,
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
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 nitrogen in the milk, is now carefully measured out
from a delicate burette (divided into -fa cc.) into a re-
ceiving flask and the flask connected with a distillation
apparatus. At the other end, the Jena flask containing

lFresenius' Zeitschrift, 22, p. 366; U. S. Dept. Agr., Bur. of Chem.,
Bull. 107, p. 5.

224 Testing Milk and Its Products.

the watery solution of ammonia sulfate is connected,
after adding 50 cc. of a concentrated soda solution (1
pound "pure potash" dissolved in 500 cc. of distilled
water and allowed to settle) ; the contents of the Jena
flasks are now mixed and heated to boiling, and the
distillation is continued 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. -y- acid solution; the ammonia dis-
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. — HC1 therefore
represents .03269 gram of nitrogen. This quantity of nitrogen
was obtained from the 5.1465 grams of milk measured out; the
milk therefore contains -03269 * 1QO— .635 per cent, of nitrogen, and
.635X6.25=3.97 per cent, of casein and albumen.

1 Sutton, Volumetric Analysis, 4th edition, p. 31.
* The factor 6.30 or 6.37 is more correct for the albuminoids of milk,
hut has not yet been generally adopted (p. 15, foot note).

Chemical Analysis of Milk and Its Products. 225

256. Casein and albumen may be determined sepa-
rately by Van Slyke's method;1 10 grams of milk are
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 to 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 for a period of from 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, and 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). 2

25 7a. The protein of milk may also be obtained by
calculation from the total solids of the milk by the use
of the following formula worked out by Mr. Geo. A.

1 Bulletin 107, p. 117, Bur. of Chem., U. S. Dept. of Agriculture.

2 Volumetric determinations of casein in milk have been proposed
by Van Slyke and Bosworth (Geneva, N. Y.) expt. station, tech. bull.
10) and by Hart (Wis. expt. station, research bull. 11).

15

226 Testing Milk and Its Products.

Olson1: P=T— i The results obtained by this
formula are quite satisfactory. If we assume that .8
of the milk protein is casein, this component can also be
obtained from the solids of the milk by a simple calcula-
tion by the use of the preceding formula.

258. Hart's test for casein in milk. The following
test for casein in milk has been published by the Wis-
consin experiment station.2

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 ^0° F.) are measured into
small tubes of special construction holding about 35 cc.,
the lower ends of which are narrow and graduated to
.1 cc. The mixture is shaken for 10 to 20 seconds and
the tubes then whirled 7% 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
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 the directions given
are strictly followed.8

259. e. Milk sugar is generally determined by differ-
ence, the sum of fat, casein and albumen (total NX6.25) ,

1 Journ. Ind. and Eng. Chemistry, I, 1909, p. 253.

2 Report 24, p. 117 : "A simple method for the estimation of casein
in row's milk."

8 See also Clrc. 10, Wis. expt sta., Operating the casein test at cheese
factories.

Chemical Analysis of Milk and Its Products. 227

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 \Yiley,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 for 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 cc. ;
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.
and 102.6 cc. ; 30 cc. of mercuric-iodid 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

1 Agricultural Analysis, III, p. 275 ; Am. Chem. Jour., 6, p. 289 et scq.

228 Testing Milk and Its Products.

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 solids have to be heated to ignite all organic carbon.

Example: Weight of porcelain dish+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— •1^99^1Q00— 72 per cent.

The residue from the determination of solids by the
Alternate Method given (252) may also be used for the
ash determination.

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.

Chemical Analysis of Milk and Its Products. 229

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 (7 that of the mixture; and if furthermore S
designate the specific gravity of the butter milk, st that of the
ammonia, and s, that of the mixture, we have

"Cs2-Bsi

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

jC ._ JB

S2 " Si

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

1 Milchzeitung, 1896, p. 656 ; see also De Koningh, Analyst, 1899,
p. 142.

230 Testing Milk and Its Products.

diluted.1 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.

The specific gravity of condensed milk may be deter-
mined by a method similar to that of McGill.2 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= 1

6— 5a

Concentration. The extent of concentration of con-
densed milk may be determined approximately by the
formula devised by McGill (loc. cit.) :
Concentration (c)= as

ais,

where a and s designate the solids not fat and specific
gravity, respectively, of the condensed milk, and 0± and
s± the corresponding data for the milk used. If *,=

XA second extraction following leaching and subsequent drying of
the tubes is necessary to extract all the fat in condensed milk ; see
Bull. 104, Bur. of Chem., U. S. Dept. of Agr., p. 102 and 154.

2 Bulletin 54, Laboratory Inland Rev. Dept., Ottawa, Canada.

Chemical Analysis of Milk and Its Products. 231

1.030 and ai=9 per cent., then c==^ gives the con-
centration.

C.— BUTTER.

265. Sampling. A four- to eight-ounce sample of
butter is melted in a tightly-clcsed pint fruit jar,
shaken vigorously and cooled until the butter is hard-
ened, the jar being shaken vigorously at short intervals
during the cooling so as to keep the water of the butter
evenly distributed in the mass (102).

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
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 steam 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 sample 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

232 Testing Milk and Its Products.

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.

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
carefully burnt to a grayish ash. After cooling, the dish
is weighed, and the per cent, of ash in the butter calcu-
lated 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 steam 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

Chemical Analysis of Milk and Its Products. 233

fat in the sample is obtained from the difference be-
tween this and the preceding weight. The gooch is
then carefully heated at a low red heat 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 (278).

272. Creamery methods of estimating water in
butter. A number of different methods have been pro-
posed of late years
for the rapid esti-
mation of water in
butter, the object
sought being to en-
able a buttermaker
to ascertain the
water content of his

butter Without much Fm. 58a. Balance for weighing butter

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

234 Testing Milk and Its Products.

1906 (305) ; these measures have rendered the question
of guarding against an excessive water content in the
butter one of the greatest importance to all butter-
makers.

Most of the methods suggested for this purpose are
essentially the common method of chemical analysis/
modified to meet the demands of every-day factory con-
ditions. Keferences to
descriptions of the dif-
ferent methods pro-
posed are given below,
and a few that are now
used in factories and
outside of chemical lab-
4700 oratories, are described

FIG. 58b. Scale for weighing but-
ter for testing. in detail.

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 (see 102), and must be carefully weighed on a
delicate scale (see figures 58a and b). 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 proposed for the rapid de-
termination of the per cent, of water in butter that
are adapted for use in creameries may be mentioned :

Richmond's method,1 Carroll's tester,2 Geldard's but-

1 Dairy Chemistry, p. 252.

1 Dept. of Agr., Ottawa, Dairy Com'r Branch, bull. 6, pp. 10-11.

Chemical Analysis of Milk and Its Products. 235

ter tester,1 the Irish ''common sense butter and cheese
test," Dean's,2 Gray's,3 Pi trick's,4 the Wisconsin high
pressure oven method,5 the Ames method,6 and the
Cornell moisture test.7

g The following four of these methods will be
briefly described:

274. a. Gray 's method. This method, in-
vented by Prof. C. E. Gray, formerly of
the Dairy Division of the U. S. Dept. of Agri-
culture, was published in 1906; the method
consists of heating ten grams of butter in a
special flask of about 70 cc. capacity (see fig.
59) with 6 cc. of "amyl reagent" (five parts
of amyl acetate and one part amyl valerianate) .
The water is boiled out of the butter by heating
over direct flame, and together with some of
the reagent, is condensed, cooled, and meas-
ured in a graduated tube attached to the flask.
The accompanying illustration shows the ar-
rangement of the distilling flask and the gradu-
FlG. 59. ated tube in which the water is measured. For
uspused details of manipulation, reference is made to

in Gray's . . , IT,- .-, n-, <•

method, the original publication, or to the files 01 our
dairy press published during 1906-7.8

1 Dept. of Agr., Ottawa, Dairy Com'r Branch, bull. 14, pp. 6-8.

2 Ontario Agr. College, rept. 1906, p. 120.

8 Circ. 100, Bur. An. Ind., U. S. Dept. of Agr.
4 Journal Am. Chem. Soc., 28, 1906, p. 1611.
"Bull. 154, Wis. experiment station.

6 Bull. 97, Iowa experiment station.

7 Bull. 281, Cornell experiment station.

8 E. g., New York Produce Review, Jan. 16, 1907 ; American Cheese
Maker, Jan., 1907.

236

Testing Milk and Its Products.

A modification of the Gray method has been proposed
by Mitchell and Walker of the Kingston (Ont.) Dairy
School, and described as the Mitchell-Walker test.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 carefully 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
8.45 grams after heating, test
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.2 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.

A few points need special attention in using this

'Bull. 167, Dairy Branch, Ont. Dept. of Agriculture.

2 A convenient table showing per cents of moisture in butter direct
when 9 to 10.15 grams are weighed out, has been published by the
Copenhagen experiment station (62nd report ; see N. Y. Produce Rev..
1008, p. 5BO).

weighed FlG- 60. Aluminum beaker and
alcohal lamp used in the Patrick

Chemical Analysis of Milk and Its Products. 237

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 off 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, differing from the same mainly in the
shape of the aluminum dishes used. Modifications of
this test have also been worked out by the Iowa and
Cornell experiment stations, which are designed to pre-
vent losses by spattering when the dish is heated. In
the Ames method the aluminum dish containing the
sample is heated with a paraffme bath, while in the Cor-
nell test a thin sheet of asbestos is placed between the
flame and the dish holding the samples.

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)
ind accurately weighed; the dish is then placed in a
steam oven provided with a pop safety valve, a steam

238 Testing Milk and Its Products.

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,
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 de-
pend on the temperature of the oven and the diameter
of the dish in which the butter is heated. If the dish
is large enough to permit the butter to spread into
a very thin layer and the temperature of the 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 manufacturers of dairy
supplies. A steam pressure of 60 Ibs. and a tempera-
ture of 280° F. may be obtained in such an oven; by
employing the boiler pressure ordinarily used in a

Chemical Analysis of Milk and Its Products. 239

creamery, temperatures of 240° to 260° may be easily
obtained. The temperature thus reached is sufficient to
dry the butter 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
weighed out directly from a
package. 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 in-
stead of those with smaller
Loose weights can be used for
weighing the butter. (See figs.
58a and 58b.)

278. Creamery methods of estimating salt in butter. I.

The ordinary volumetric method used in chemical laboratories for
determining the salt content of butter has been adapted for
work in the creamery by Prof. Sammis.1 5.1 grams of chemically
pure nitrate crystals are dissolved in 250 cc. of water. Each cc.
of this solution will represent 1 per ct. of salt when 17.6 cc. of
the liquid are measured which is obtained by shaking 10 grams
of butter with 250 cc. of clean, warm water. The silver nitrate
solution is added from a 25 or 50 cc. burette divided into tenths
of a cubic centimeter. One or two drops of the usual indicator

FIG. 61. Tne Wisconsin high-
pressure oven.

1 (Mrc. 14, Wisconsin expt. station.

240 Testing Milk and Its Products.

employed (1 oz. potassium chromate dissolved in 100 cc. of water)
are added prior to the titration.

II. The use of silver nitrate tablets for making standard
solutions for volumetric determinations of salt in butter was
proposed by Prof. A. Vivian and C. L. Fitch in 1901.1 The tab-
lets have not been on the market during late years.

2783. Shaw's test for fat and salt in butter. R. H.

Shaw has devised a method for determining the per-
centages of fat and salt in the same sample of butter
which has considerable merit. For description of this
method see Circ. 202, Bur. of Animal Ind., U. S. Dept.
of Agriculture.

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
worthless for the examination of samples containing a
considerable proportion of natural butter, or give satis-
factory results only in the hands of experts. §The Reich-
ert-Meissl 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

1 Wis. experiment station, report 17, pp. 98-101 ; Hoard's Dairyman,
February 15, 1901, "Uniform Salting of Butter."

Chemical Analysis of Milk and Its Products. 241

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-MeissI 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
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) to 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. H2S04 per liter) are

16

242 Testing Milk and Its Products.

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-flleissl number thus obtained.

The Reichert number for pure butter fat will ordi-
narily come above 24 cc. and may go over 30 cc; butter
fat from stripper cows will have a low Reichert num-
ber. Pure oleomargarine will have a Reiehert number
of 1 to 2 cc. ; and mixtures of artificial and natural but-
ter will give intermediate numbers.

TESTS FOB THE DETECTION OP 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

1 Patrick, Household tests for the detection of oleomargarine and
renovated butter, Farmer's Bulletin, No. 131. For detection and

Chemical Analysis of Milk and Its Products. 243

(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.1 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
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.2

D.— CHEESE.
For method of sampling, see par. 104.

285. a. Water. Five grams of cheese cut into very
thin slices are weighed into a small porcelain dish filled
about one-third full with freshly-ignited stringy asbes-

exnmination of renovated or "process" butter, see also Cochrnn, Journ
Franl-1. 7n.s/.. 180!). p. 94 : Analyst, 1899, p. 88.

1 Farmers' Bulletin No. 131, p. 7.

2 For tests for artificial coloring matter in oleomargarine, see Circ.
629, Com. of Internal Rev., Treasury Dept.

244 Testing Milk and Its Products.

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, par. 276.)

286. b. Fat. About 5 grams of cheese are ground
finely in a small porcelain mortar with about twice its
weight of anhydrous copper sulfate, 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 sulfate 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 give
too low results and, therefore, not to be preferred to
the Babccck 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

Chemical Analysis of Milk and Its Products. 245

that of the empty dish-j- asbestos, 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 Eeichert-Meissl method, as already ex-
plained under Detection of Artificial Butter (282). 4

TESTS FOR ADULTERATION OF MILK AND CREAM.

291. Use of the ref ractometer. The immersion re-
fractometer furnishes a delicate apparatus for the de
tection of watered milk.2 100 cc. of milk and 2 cc. of
25% acetic acid are heated for twenty minutes at 70° C.
This is then placed on ice for ten minutes and filtered.
The refractometer reading of the clear filtrate is then
taken at 20° C. If this reading is above 40 the milk is
not watered, while figures below 40 show adulteration by
watering.

2913. The nitric acid test may prove useful as cor-
roborative evidence that a sample of milk has been

1 See Arb. Kais. Ges.-Amt., 14, 506-598.

2 Leach, Food Analysis, 2nd ed., p. 168. See also Jr. Ind. and Eng.
Chem., 1911, p. 44 and p. 573.

246 Testing Milk and Its Products.

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 ELjSOj (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 -
dehyd in 500 cc. C. 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).

1UfEelmann, Deutsche Vierteljahresschr. f. off. Ges.-pfl., 15, p. 663.
8 The Analyst, 1893, p. 272.

Chemical Analysis of Milk and Its Products. 247

292. Besides by the methods given in the preceding
(pp. 121-127), watering or skimming of milk may be de-
tected by determining the specific gravity of a, the skim
milk, &, 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 to 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.

&. 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
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.2

Menschl. Nahrungsmittel, II, p. 276.
a Slats, Unters. landw. wicht. Stoffe, p. 88.

248 Testing Milk and Its Products.

293. Detection of coloring matter. Milk which has
been watered or 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 added; natural fresh
milk will give a colorless ether solution.

A method gived by Wallace1 is claimed to detect one
part of coloring matter in 100,000 of milk.

Inorganic coloring matter like ehroniates and bi-chro-
mates have, although fortunately rarely, been used to
impart a rich color to adulterated milk or poor cream.
Chrcmates 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,2 in 1898, published a
simple method for ascertaining whether milk, cream,
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-

i N. J. Dairy Commissioner, report 1896, p. 36.
1 40th report, Copenhagen experiment station.

Chemical Analysis of Milk and Its Products. 249

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° F.
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
water. 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
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).

1 See also Siats, Unters. landw. wicht. Stoffe, p. 60, and Molkerei-
Ztg. (Hildesheim), 1899, p. 677.

250 Testing Milk and Its Products.

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
and weighed. A quart of milk or cream should not
give any visible sediment on standing for several hours.

A 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

» The Analyst, 1897, p. 320.

Chemical Analysis of Milk and Its Products. 251

bottle, over the mouth of which a piece of cotton is
placed. The milk will filter through, leaving the dirt
on the cotton, which is then removed and can be shown
to the producer of the milk.1

A modification of the apparatus used has been de-
scribed in publications of the Wisconsin experiment
station.2

DETECTION OP 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, 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.) :8

Place in a porcelain dish one drop of milk with two drops of
strong hydrochloric acid and two drops of saturated turmeric
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.4

1 Hoard's Dairyman, Nov. 29, 1907.

2 Bull. 195 and Circular 41.

8N. J. Dairy Commissioner, report, 1896 p. 36.
4 See also par. 151.

252 Testing Milk and Its Products.

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, solution of rosolic acid (corallin). 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.1

303. d. Salicylic acid (salicylates, etc.). 20 cc. of
milk are acidulated with sulfuric acid and shaken with
ether; the ether solution is evaporated, and the residue
treated with alcohol and a little iron-chlorid solution;

1 Chromates in dairy products may be readily determined by the use
of a silver-nitrate solution, see Molkerci-Ztg. (Berlin) 1899, p. 603.

Chemical Analysis of Milk and Its Products. 253

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 Chem. News, 1896. No. 71 ; Milchzeitung, 1896, 491 ; 1897, 40.
667 ; The Analyst, 1895, 152, 154, 157 ; 1896, 285.

305. GOVERNMENT STANDARDS OF PURITY
FOR MILK AND ITS PRODUCTS.1

a. MILKS.

1. Milk is the 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 after 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. Blendid milk is milk modified in its composition so as to
have a definite and stated percentage of one or more of its con
stitnents.

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-
-ng but sufficiently to kill most of the active organisms present
and immediately cooled to 50° Fehr. or lower.

5. Sterilized milk is milk that has been heated at the tern
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-tenths (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. S. Dept. of Agriculture
June 26, 1906.

Government Standards of Purity. 255

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 secretions, free from colostrum, 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 the 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 water has been evaporated.

C. MILK FAT OR BUTTER FAT.

1. Milk fat, butter fat, is the fat of milk and has the Eeich-
ert-Meissl number not less than twenty-four (24) and a specific

gravity of not less than 0.905 (|§5§^)

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 five^tenths (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.

256 Testing Milk and Its Products.

6. 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 made 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 loss 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.

306. STANDARDS FOR BABCOCK
GLASS WARE.

(Adopted by the Association of Official Agricultural Chemists of
North America.)

SEC. 1. The unit of graduation for all Babcock glassware
shall be *the true cubic centimeter (.998877 gram of water at
4° C.).

(a) With bottles, the capacity of each per cent, on the scale
shall be two-tenths (0.20) cubic centimeter.

(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.

(c) For acid measures it shall not exceed two-tenths (0.20)
cubic centimeter.

307. SPECIFICATIONS FOR STANDARD
BABCOCK GLASS WARE.

(Adopted by the Official Dairy Instructors' Association, 1911)

I. Milk Test Bottle. 8% 18 gram, so-called 6-inch.
Graduation: The total per cent graduation shall be 8. The

graduated portion of the neck shall have a length of not less than
63.5 mm. (2^ inches). The graduation shall represent whole per
cent, five-tenths per cent and tenths per cent. The tenths per cent
graduations shall not be less than 3 mm. in length; the five-tenths
per cent graduations shall be 1 mm. longer than the tenth per cent
graduations, projecting 1 mm. to the left; the whole per cent
graduations shall extend one-half way around the neck to the right
and projecting 2 mm. to the left of the tenths per cent gradua-
tions. Each per cent graduation shall be numbered, the number
being placed on the left of the 'scale. The error at any point of
the scale shall not exceed one-tenth per cent.

Neck: The neck shall be cylindrical for at least 9 mm. below
the lowest and above the highest graduation mark. The top of
the neck shall be flared to a diameter of not less than 10 mm.

Bulb: The capacity of the bulb up to the junction of the neck
shall not be less than 45 cc. The shape of the bulb may be either
cylindrical or conical, with the smallest diameter at the bottom.
If cylindrical, the outside diameter shall be between 34 and 36
mm.; if conical, the outside diameter of the base shall be between
31 and 33 mm., and the maximum diameter between 35 and 37 mm.

The Charge of the bottle shall be 18 £rams.

The Total Height of the bottle shall be between 150 and 165
mm. (5% and 6% inches).

Each bottle shall bear a permanent identification number.

II. Cream Test Bottles. 50% 9-gram, so-called 6-inch, and
50% 9-gram, so-called 9-inch.

A. 50% 9- gram, so-called 6-inch.

Graduation: The total per cent graduation shall be 50. The
graduated portion of the neck shall have a length of not less
than 63.5 mm. (2% inches). The graduation shall represent 5
per cent, 1 per cent and five-tenths per cent. The five-tenths per
cent graduations shall be at least 3 mm. in length; the 1 per cent

Specifications for Glassware. 258a

graduations shall be 2 mm. longer than the five-tenths per cent
graduations, projecting 2 mm. to the left; the 5 per cent gradua-
tions shall extend half way around the neck to the right and pro-
ject 4 mm. to the left of the five-tenths per cent graduations.
Each 5 per cent graduation shall be numbered, the number being
placed on the left of the scale. The error at any point of the
scale shall not exceed five-tenths per cent.

Neck: (Same as standard milk test bottle.) The neck shall
be cylindrical for at least 9 mm. below the lowest and above the
highest graduation mark. The top of the neck shall be flared to a
diameter of not less than 10 mm.

Bull> : (Same as standard milk test bottle.) The capacity of
the bulb up to the junction of the neck shall not be less than
45 cc. The shape of the bulb may be either cylindrical or conical,
with the smallest diameter at the bottom. If cylindrical the out-
side diameter shall be between 34 and 36 mm.; if conical, the
outside diameter of the base shall be between 31 and 33 mm. and
the maximum diameter between 35 and 37 mm.

The Charge of the bottle shall be 9 grams. All bottles shall
bear on top of the neck above the graduations in plainly legible
characters, a mark defining the weight of the charge to be used
(9 grams).

The Total Height of the bottle shall be between 150 and 165
mm. (5% and 6% inches). (Same as standard milk test bottles.)

Each bottle shall bear a permanent identification number.

B. 5C% 9-gram, so-called 9-inch.

The same specifications in every detail as specified for the 50%
9-gram 6-inch cream test bottle shall apply to the 9-inch bottle,
with the exception, however, that the total height of this bottle
shall be between 210 and 225 mm. (8*4 and 8% inches).

III. The Standard Babcock Pipette. Total length of
pipette not more than 330 mm. (13^4: inches). Outside diameter
of suction tube 6 to 8 mm. Length of suction tube 130 mm. Out-
side diameter of delivery tube, 4.5 to 5.D mm. Length of deliv-
ery tube, 100 to 120 mm. Distance of graduation mark above bulb,
30 to 60 mm. Nozzle straight. Delivery 17.6 cc. of water at 20
degrees C. in 5 to 8 seconds.

In view of the fact that the skimmilk bottle can give only ap-
proximate quantitative results, it should be given no consideration
as a standard bottle.

APPENDIX.

Table I. Composition of milk and its products.

No. of
analyses

Water

Fat

Casein
and

albumen

Milk
sugar

Ask

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
17.64*
3.76

pr. ct.

4.88
4.60
5.10

„.«.

.75
.70
«.71
.75
1.56
.53
.62
.70

K5nigB
Fleischmann
Van Slyke
Holland6
Richmond

Konig*
«

Holland*
Konig*
Holland8
Van Slyke
Konig5
Holland8
Konig6
Van Siyke

Konig*
ii

Woll

K6nig§
ii

Woll
Parrington
Konig8

Van Slyke
Drew

Shutt
Konig*

Storch

« «

ii ii

5,552
2,173
200,000
42
43
203
56
354

ii ii

ii ii

4.85
2.67
4.23

Colostrum milk

Cream, Cooley

Skim milk (gravity) . .
M ii ii

Skim milk (centrifugal)
Butter milk

3.26

4.74

3.55
4.03

5.25
4.04

.80
.72

57
31
46

ii «

Whey . .
™

.86
.81

11.92

11.79
I.S

.61
.81
1.1

.£

18.84
25.35
23.72
26.38

28.00
29.67
34.06
43.1

4.79
5.

14.49

50.06
!6
.68
.66
>7
15
1.02
1.43
5.
2.95

5.
1.79
3.42

.65
30

2.18

2.19
2.58
1.25
1.19
.12
2.78
3.10
4.97
61
3.58

51
14.73
4.87
5.2

Condensed milk,
(no sugar added). . .
Condensed milk,

36

64
1,676
10
11
242
350
127
143

Butter, salted

sweet cream..
" sour cream...
" unsalted
" World's Fair, 1893

full cream....
cheddar, green
" eheddar, cured
" World's Pair
Mam'th, 1893
•' half -skim ....
" gkim

27

1
21
41

centrifugal skim . .

i .70 per cent, albumen.

* Forty- two analyses.

* Eight analyses.

* 13.60 per cent, albumen.

• Mostly European samples.
6 Massachusetts' samples.

260

Testing Milk and Its Products.

III!

« ^s! o

QO o ft Si • oo

10 oo o

rH rH CM

CO

IS -^

10

co

CO

10 CM t-

co co co* co co co co

iq 10

GO OS

010
CM (M

CM CO CM <M tlJLCO

tH iH iH i— I - ?; i— I

do

cc •

10

CO CM CM CM T-i

0

Appendix.

261

262

Testing Milk and Its Products.

Table RL Quevenne lactometer degrees corresponding to
N. Y. Board of Health degrees. (See par. 114)

Bd. ot Health
degrees.

Quevenne
scale.

Bd. of Health
degrees.

Quavenne
scale.

Bd. of Health
degrees.

Quevenne
scale.

60

17.4

81

23.5

101

29.3

61

17.7

82

23.8

102

29.6

62

18.0

83

24.1

103

29.9

63

18.3

84

24.4

104

80.2

64

18.6

85

24.6

105

30.5

65

18.8

86

24.9

106

80.7

66

19.1

87

25.2

107

81.0

67

19.4

88

25.5

108

81.3

68

19.7

89

25.8

109

81.6

69

20.0

90

26.1

110

81.9

70

20.3

91

26.4

111

82.2

71

20.6

92

26.7

112

32.5

72

20.9

93

27.0

113

82.3

73

21.2

94

27.3

114

83.1

74

21.5

95

27.6

115

83.4

75

21.7

96

27.8

116

83.6

76

22.0

97

28.1

117

33.9

77

22.3

98

28.4

118

84.2

78

22.6

99

28.7

119

84.5

79

22.9

100

29.0

120

84.8

80

23.2

Table IV. Value of

for sp. gr. from 1.019 to 1.0369.

Sp.gr. (•)=

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

1.022

2.153

2.162

2.172

2.181

2.191

2.200

2.210

2.220

2.229

2.239

1.028

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. 809

1.029

2.818

2.828

2,837

2.847

2.856

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

L034

3.288

3.298

3.307

3.316

3.326

3.335

3.344

3.354

3.363

3.372

1.035

3.382

8.391

3.400

8.410

3.419

3.428

3.438

3.447

3.456

3.466

1.036

3.475

8.484

3.494

3.503

8.512

3.521

3.531

3.540

3.549

3.559

(See direction* for OM,

Appendix. 263

Table V. Correction-table for specific gravity of milk.

a! bi

Temperature of milk (in degrees Fahrenheit).

g C

51

52

53

54

55

56

67

58

59

60

20

19.3

19.4

19.4

19.5

19.6

19.7

19.8

19.9

19.9

20. u

21

20.3

20.3

20.4

20.5

20.6

20.7

20.8

20.9

20.9

21.0

22

21.3

21.3

21.4

21.5

21.6

21.7

21.8

21.9

21.9

22.0

23

22.3

22.3

22.4

22.5

22.6

22.7

22.8

22.8

22.9

23.0

24

23.3

23.3

23.4

23.5

23.6

23.6

23.7

23.8

23.9

24.0

25

24.2

24.3

24.4

24.5

24.6

24.6

24.7

24.8

24.9

25.0

26

25.2

25.2

25.3

25.4

25.5

25.6

25.7

25.8

25.9

26.0

27

26.2

26.2

26.3

26.4

26.5

26.6

26.7

26.8

26.9

27.0

28

27.1

27.2

27.3

27.4

27.5

27.6

27.7

27.8

27.9

28.0

29

28.1

28.2

28.3

28.4

28.5

28.6

28.7

28. 8

28.9

29.0

30

29.1

29.1

29.2

29.3

29.4

29.6

29.7

29.8

29.9

30.0

31

30.0

30.1

30.2

30.3

30.4

30.5

30.6

30.8

30.9

31.0

32

31.0

31.1

31.2

31.3

31.4

31.5

31.6

31.7

31.9

32.0

33

31.9

32.0

32.1

32.3

32.4

32.5

32.6

32.7

32.9

33.0

34

32.9

33.0

33.1

33.2

33.3

33.5

33.6

33.7

33.9

34.0

35

33.8

33.9

34.0

34.2

34.3

34.5

34.6

34.7

34.9

35.0

61

62

63

64

65

66

67

68

69

70

20

20.1

20.2

20.2

20.3

20.4

20.5

20.6

20.7

20.9

21.0

21

21.1

21.2

21.3

21.4

21.5

21.6

21.7

21.8

22.0

22.1

22

22.1

22.2

22.3

22.4

22.5

22.6

22.7

22.8

23.0

23.1

23

23.1

23.2

23.3

23.4

23.5

23.6

23.7

23.8

24.0

24.1

24

24.1

24.2

24.3

24.4

24.5

24.6

24.7

24.9

25.0

25.1

25

25.1

25.2

25.3

25.4

25.5

25.6

25.7

25.9

26.0

26.1

26

26.1

26.2

26T.3

26.5

26.6

26.7

26.8

27.0

27.1

27.2

27

27.1

27.3

27.4

27.5

27.6

27.7

27.8

28.0

28.1

28.2

28

28.1

28.3

28.4

28.5

28.6

28.7

28.8

29.0

29.1

29.2

29

29.1

29.3

29.4

29.5

29.6

29.7

29.9

30.1

30.2

30.3

30

30.1

30.3

30.4

30.5

30.7

30.8

30.9

31.1

31.2

31.3

31

31.2

31.3

31.4

31.5

31.7

31.8

31.9

32.1

32.2

32.4

32

32.2

32.3

32.5

32.6

32.7

32.9

33.0

33.11

33.3

33.4

33

33.2

33.3

33.5

33.6

33.8

33.9

34.0

34.2

34.3

34.5

34

34.2

34.3

34.5

34.6

34.8

34.9

35.0

35.2

35.3

35.5

35

35.2

35.3

35.5

35.6

35.8

S5.9

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 that of the temperature of
the milk; find the former 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 (57° F. : corrected reading, 81.9.

264

Testing Milk and Its Products.

fable 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, par. r_>0)

Per cent, of
fat.

LACTOMETER READINGS AT 60° F.

Percent, of
fat.

26

27

28

29

30

31

32

33

34

35

36

0

6.50

6.75

7.00

7.25

7.50

7.75

8.00

8.25

8.50

8.75

9.00

0

0.1

6.52

6.77

7.02

7.27

7.51:

/.77

8.02

8.27

8.52

8.77

9.02

0.1

0.2

6.54

6.79

7.04

7.29

7.5-4

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

7.85

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

9.12

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

6.66

6.91

7.16

7.41

7.66

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

A

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

6.74

6.99

7.24

7.49

7.74

7.99

8.24

8.49

8.74

8.99

9.24

.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

.8

1.4

6.78

7.03

7.28

7.53

7.78

8.03

8.28

8.53

8.78

9.03

9.28

.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

.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

.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

.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

.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

.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

7.31

7.56

7.81

8.06

8.31

8.57

8.82

9.07

9.32

9.57

2.8

2.9

7.08

7.33

7.68

7.83

8.08

8.33

8.59

8.84

9.09

9.34

9.50

2.9

Appendix. 265

Table VI. Per cent, of solids not fat (Continued).

J .

LACTOMETER READINGS AT 60° P.

w

p

26

27

28

29

30

31

32

33

34

35

36

p

3.0

7.10

7.35

7.60

7.85

8.10

8.36

8.61

8.86

9.11

9.36

9.61

3.0

3.1

7.12

7.37

7.62

7.87

8.13

8.38

8.63

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

7.92

8.17

8.42

8.67

8.92

9.18

9.43

9.68

3.3

3.4

7.18

7.43

7.69

7.94

8.19

8.44

8.69

8.94

9.20

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

7.98

8.23

8.48

8.73

8.98

9.24

9.49

9.74

3.6

3.7

7.24

7.50

7.75

8.00

8.25

8.50

8.75

9.00

9.26

9.51

9.76

3.7

3.8

7.26

7.52

7.77

8.02

8.27

8.52

8.77

9.02

9.28

9.53

9.78

3.8

3.9

7.28

7.54

7.7l>

8.04

8.29

8.54

8.79

9.04

9.30

9.55

9.80

3.9

4.0

7.30

7.56

7.81

8.06

8.31

8.56

8.81

9.06

9.32

9.57

9.83

4.0

4.1

7.32

7.58

7.83

8.08

8.33

8.58

8.83

9.08

9.34

9.59

9.85

4.1

4.2

7.34

7.60

7.85

8.10

8.35

8.60

8.85

9.11

9.36

9.62

9.87

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

8.39

8.64

8.90

9.15

9.40

9.66

9.91

4.4

* 5

7.40

7.66

7.91

8.16

8.41

8.66

8.92

9.17

9.42

9. 08

9.93

4.5

4^6

7.43

7.68

7.93

8.18

8.43

8.68

8.94

9.19

9.44

9.70

9.95

4.6

4.7

7.45

7.70

7.95

8.20

8.45

8.70

8.96

9.21

9.46

9.72

9.97

4.7

4.8

7.47

7.72

7.97

8.22

8.47

8.72

8.98

9.23

9.48

9.74

9.99

4.8

4.9

7.49

7.74

7.99

8.24

8.49

8.74

9.00

9.25

9.50

9.76

10.01

4.9

5.0

7.51

7.76

8.01

8.26

8.51

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

9 29

9 54

9 80

10 05

5 1

5 ?,

7 55

7 80

8 05

8 80

8 55

8 81

9 06

9 31

9 56

9 82

10 07

5 2

5.3

7.57

7.82

8.07

8.32

8.57

8.83

9.08

9.33

9.58

9.84

10.09

5.3

5.4

7.59

7.84

8.09

8.34

8.60

8.85

9.10

9.36

9.61

9.86

10.11

5.4

5.5

7.61

7.86

a.n

8.36

8.62

8.87

9.12

9.38

9.63

9.88

10.13

5.5

5.6

7.63

7.88

8.13

8.39

8.64

8.89

9.15

9.40

9.65

9.90

10.15

5.6

5.7

7.65

7.90

8.15

8.41

8.66

8.91

9.17

9.42

9.67

9.92

10.17

5.7

5.8

7.67

7.92

8.17

8.43

8.68

8.94

9.19

9.44

9.69

9.94

0.19

5.8

5.9

7.69

7.94

8.20

8.45

8.70

8.96

9.21

9.46

9.71

9.96

10.22

5.9

6.0

7.71

7.96

8.22

8.47

8.72

8.98

9.23

9.48

9.73

9.98

10.24

6.0

266 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 o>
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 pr>nnds of fat Is contained in 8925 Ibs. of milk
testing 3.05 per cent.? On p 264. -econd column the test 3.65 is found, and
by going downward in this cu.uum we have:

8000 Ibs 292. Ibs.

900 Ibs 32.9 Ibs.

20 Ibs 7 Ibs.

6 Ibs 2 Ibs.

8925 Ibs. of milk. 825.8 Ibs. of fat.

8025 Ibs. of milk testing 3.65 per cent., therefore, contains 825.8 Ibs. of
butter fat.

TABLE 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 thG table is,
otherwise, as explained above.

Example: How much money is due for 825.8 Ibs. of butter fat at 15%
cents per pound? In the horizontal row of figures beginning with 15% on
p. 247. we find t

800 Ibs $48.50

20 Ibs 8.10

6 Ibs 77

.8 Ibs 13

825.8 IbB. $50.49

825.8 Ibs. of butter fat at 15% cents per pound, therefore, Is worth 950.49.

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 nnd :

6000 Ibs 209.0 Ibs.

800 Ibs 33.4 Ibs.

40 Ibs 1.7 Ibs.

6 Ibs .2 Ibs.

6845 Ibs. 244.8 Ibs.

5845 Ibs. of milk testing 3.8 per cent, of fat will make about 244.8 Ibs. of
butter, under oondi Lions similar to those explained in par. 220.

Appendix.

267

Table VII. Pounds of fat in I to 10,000 Ibs. of milk, testing 3.0
to 5.35 per cent. (See directions for use, p. 266 )

1

3.00

3.05

3.10

3.15

3.20

3.25

3.30

3.35

3.40

3.45

3. 50

3.55

. 1

H

r

Milk

Milk

Ibs.

Ibs.

10,000

300

305

310

315

320

325

330

335

340

&5

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

180

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

07.0

68.0

09.0

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

21.4

21.7

22.1

22.4

22.8

23.1

23.5

23.8

24.2

24.5

24.9

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

16.0

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

3.1

3.2

3.2

3.3

3.3

3.4

3.4

3.5

3.5

3.6

100

90

2.7

2.8

2.8

2.8

2.9

2.9

3.0

3.0

3.1

3.1

3.2

3.2

90

80

2.4

2.4

2.5

2.5

2.6

2.6

2.6

2.7

2.7

2.8

2.8

2.8

80

70

2.1

2.1

2.2

2.2

2.2

2.3

2.3

2.3

2.4

2.4

2.5

2.5

70

60

1.8

1.8

1.9

1 9

1.9

2.0

2.0

2.0

2.0

2.1

2.1

2.1

60

50

1.5

1.5

1.6

1.6

1.6

1.6

1.7

1.7

1.7

1.7

1.8

1.8

50

40

1.2

1.2

1.2

1.3

1.3

1.3

1.3

1.3

1.4

1.4

1.4

1.4

40

80

.9
ft

.9
6

.9
6

.9

1.0
6

1.0

1.0

1.0

1.0

1.0

1.1

7

1.1

7

30
20

10

.3

.3

.3

.3

.8

.8

.3

.3

.3

.3

.4

.4

A\J

10

9

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

9

8

.2

.2

.2

.3

.3

.3

.3

.3

.3

.3

.3

.3

8

7

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

7

6

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

6

5

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

5

4

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

4

3

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

3

2

.1

.1

.1

.1

.1

1

.1

.1

.1

.1

.1

.1

2

1

1

•

J_

3.00

3.05

3.10

3.15

3.20

3.25

3.30

3.35

3.40

3.45

3.50

.55

I

268

Testing Milk and Its Products.

Table VII. Pounds of fat in I to 10,000 Ibs. of milk ( Continued).

,j

I

3.60

3.65

3.70

3.75

3.80

3.85

3.90

3.95

4.00

4.05

4.10

4.15

»

e-

£

Milk

Milk

Ibs.

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

33.8

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

22.8

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.o

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

3.7

3.8

3.8

3.9

3.9

4.0

4.0

4.1

4.1

4.2

100

90

3.2

3.3

3.3

3.4

3.4

3.5

3.5

3.6

3.6

3.7

3.7

3.7

90

80

2.9

2.9

3.0

3.0

3.0

3.1

3.1

3.2

3.2

3.2

3.3

3.3

80

70

2.5

2.6

2.6

2.6

2.7

2.7

2.7

2.8

2.8

2.8

2.9

2.9

70

60

2.2

2.2

2.2

2.3

2.3

2.3

2.3

2.4

2.4

2.4

2.5

2.5

60

50

1.8

1.8

1.9

1.9

1.9

1.9

2.0

2.0

2.0

2.0

2.1

2.1

50

40

1.4

1.5

1.5

1.5

1.5

1.5

1.6

1.6

1.6

1.6

1.6

1.7

40

30

1.1

1.1

1.1

1.1

1.1

1.2

1.2

1.2

1 2

1.2

1.2

1.2

30

20

.7

.7

.7

.8

.8

.8

.8

.8

.8

.8

.8

.8

20

10

4

4

4

4

4

4

4

4

4

4

4

4

10

9

.3

.3

.3

.3

.3

.3

.4

.4

.4

.4

.4

.4

9

8

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

8

7

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

7

3

.2

.2

.2

.2

.2

.>

.2

.2

.2

.2

.2

.2

6

5

.2

.2

.2

.2

.2

•

.2

.2

.2

.2

.2

.2

5

4

q

.1

.1

.1

.2

.2

'2
i

.2

.2

.2

.2

.2

.2

4

o

2

.1

.1

.1

.1

.1

. i
.1

.1

.1

.1

.1

.1

.1

2

1

1

4.10

1

3.60

3.65

3.70

3.75

3.80

3.85

3.90

3.95

4.00

4.05

4.15

I

Appendix.

269

Table VII. Pounds of fat in I to 10,000 Ibs. of milk (Continued).

1

4.20

4.25

4.30

4.35

4.40

4.45

4.50

4.55

4.60

4.65

4.70

4.75

i

Milk

Milk

Ibs.

Ibs.

10,000

420

425

430

435

440

445

450

455

460

465

470

475

10,000

9,000

378

383

387

392

396

401

405

410

414

419

423

428

9,000

8,000

336

340

344

348

352

356

360

364

368

372

376

380

8,000

7,000

294

298

301

305

308

312

315

319

322

326

329

333

7,000

6,000

252

255

258

261

264

267

270

273

276

279

282

285

6,000

5,000

210

213

215

218

220

223

225

228

230

233

235

238

5,OCO

4,000

168

170

172

174

176

178

180

182

184

186

188

190

4,000

3,000

126

128

129

131

132

134

135

137

138

140

141

143

3,000

2,000

84.0

85.0

86.0

87.0

88.0

89.0

90.0

91.0

92.0

93.0

94.0

95.0

2,000

1,000

42.0

42.5

43.0

43.5

44.0

44.5

45.0

45.5

46.0

46.5

47.0

47.5

1,000

900

37.8

38.3

38.7

39.2

39.6

40.1

40.5

41.0

41.4

41.9

42.3

42.8

900

800

33.6

34.0

34.4

34.8

35.2

35.6

36.0

36.4

36.8

37.2

37.6

38.0

800

700

29.4

29.8

30.1

30.5

30.8

31.2

31.5

31.9

32.2

32.6

32.9

33.3

700

600

25.2

25.5

'5.8

26.1

26.4

26.7

27.0

27.3

27.6

27.9

28.2

28.5

600

500

21.0

21.3

21.5

21.8

22.0

22.3

22.5

22.8

23.0

23.3

23.5

23.8

500

400

16.8

17.0

17.2

17.4

17.6

17.8

18.0

18.2

18.4

18.6

18.8

19.0

400

300

12.6

12.8

12.9

13.1

13.2

13.4

13.5

13.7

13.8

14.0

14.1

14.3

300

200

8.4

8.5

8.6

8.7

8.8

8.9

9.0

9.1

9.2

9.3

9.4

9.5

200

100

4.2

4.3

4.3

4.4

4.4

4.5

4.5

4.6

4.6

4.7

4.7

4.8

100

90

3.8

3.8

3.9

3.9

4.0

4.0

4.1

4.1

4.1

4.2

4.2

4.3

90

80

3.4

3.4

3.4

3.5

3.5

3.6

3.6

3.6

3.7

3.7

3.8

3.8

80

70

2.9

3.0

3.0

3.0

3.1

3.1

3.2

3.2

3.2

3.3

3.3

3.3

70

60

2 5

9 6

9 6

9 fi

9 6

9 7

9 7

9 7

9 8

9 8

9 8

9 9

60

50

2.1

2.1

2.2

2.2

2.2

2.2

2.3

2.3

2.3

2.g

2.4

2.4

50

40

1.7

1.7

1.7

1.7

1.8

1.8

1.8

1.8

1.8

1.9

1.9

1.9

40

30

1.3

1.3

1.3

1.3

1.3

1.3

1.4

1.4

1.4

1.4

1.4

1.4

30

20

.8

.9

.9

.9

.9

.9

:9

.9

.9

.9

.9

1.0

20

10

4

4

4

4

4

4

.5

5

5

5

5

5

10

9

4

4

4

4

4

4

4

4

4

4

4

4

9

8

3

3

3

3

4

4

4

4

4

4

4

4

8

7

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

7

6

.3

.3

.3

.3

.3

.3

.0

.3

.3

.3

.3

.3

6

5

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

5

4

.2

.2

.2

.2

.2

.2

0

.2

.2

.2

.2

.2

4

3

.1

.1

.1

.1

.1

.1

il

.1

.1

.1

.1

.1

3

2

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

2

1

1

4-. 30

4.35

4.50

4.55

4.60

|

4.20

4.25

4.40

4.45

4.65

4.70

4.75

H

EH

r*

"270

Testing Milk and Its Products.

Table VII. Pounds of fat in I to 10.000 Ibs. of milk (Continued).

1

4.80

4.85

4.90

4.95

5.00

5-. 05

5.10

5.15

5.20

5.25

5.30

5.35

I

Milk

Milk

Ibs.

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

3^6

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

4S.O

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

4.9

5.0

5.0

5.1

5.1

5.2

5.2

5.3

5.3

5.4

100

90

4.3

4.4

4.4

4.5

4.5

4.5

4.6

4.6

4.7

4.7

4.8

4.8

90

80

3.8

3.9

3.9

4.0

4.0

4.0

4.1

4.1

4.2

4.2

4.2

4.3

80

70

3.4

3.4

3.4

3.5

3.5

3.5

3.6

3.6

3.6

3.7

3.7

3.7

70

60

2.9

2.9

2.9

3.0

3.0

3.0

3.1

3.1

3.1

3.2

3.2

3.2

60

50

2.4

2.4

2.5

2.5

2.5

2.5

2.6

2.6

2.6

2.6

2.7

2.7

50

40

1.9

1.9

2.0

2.0

2?0

2.0

2.0

2.1

2.1

2.1

2.1

2.1

40

30

1.4

1.5

1.5

1.5

1.5

1.5

1.5

1.5

1.6

1.6

1.6

1.6

30

20

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.1

1.1

1.1

20

10

.5

.5

.6

.5

.5

.5

.6

.5

.5

.5

.5

.5

10

9

.4

.4

.4

.4

.5

.5

.5

.5

.5

.5

.5

.5

9

8

4

4

4

4

4

4

4

4

4

4

4

4

8

7

.3

.3

.3

.3

.4

.4

.4

.4

.4

.4

.4

.4

7

6

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

6

5

.2

.2

.2

.2

.3

.3

.8

.3

.3

.3

.3

.3

5

4

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

4

3

.1

.1

.1

.1

.2

.2

.2

.2

.2

.2

.2

.2

3

2

.1

.1

..1

.1

.1

.1

.1

.1

.1

.1

.1

.1

2

1

.1

.1

.1

.1

.1

.1

.1

.1

1

1

4.80

4.85

4.90

4.95

5.00

5.05

5.10

5.15

5.20

5.25

5.30

5.35

I

Appendix.

271

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. 266 )

1

12

18

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

£

1000

120

180

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

800

900

108

117

126

135

144

153

162

171

180

isy

198

207

216

225

234

243

252

261

270

800

96

104

112

120

128

136

144

152

160

168

176

184

192

200

208

216

224

28i>

240

700

84

91

98

105

112

119

126

133

HO

147

154

161

168

175

182

189

196

203

210

600

72

78

84

90

96

102

108

114

120

126

132

138

144

150

156

162

168

174

180

500

60

65

70

75

80

85

90

95

100

105

110

115

120

125

130

135

140

145

150

400

48

52

56

60

64

68

72

76

80

84

88

92

96

100

104

108

112

116

120

800

36

39

42

45

48

61

64

57

60

63

66

69

72

76

78

81

84

87

90

200

24

26

28

80

82

34

86

38

40

42

44

46

48

60

52

64

5(i

58

60

100

12

18

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

80

90

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

24.8

25.2

26.1

27.0

80

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

•20.0

20.8

21.6

22.4

23.2

24.0

70

8.4

9.1

9.8

10.5

11.2

11.9

12.6

18.S

14.0

14.7

15.4

16.1

16.8

17.5

18.2

18.9

19.6

20..3

21.0

60

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

60

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

40

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

80

8.6

8.9

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

20

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

10

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

9

1.08

1.17

1.26

1.35

1.44

1.53

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

8

.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

7

.84

.91

.98

1.05

1.12

1.19

1.26

1.33

1.40

1.47

1.54

1.61

1.R8

1.75

1.82

1.89

1.96

2.03

2.10

6

.72

.78

.84

.90

.9«

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

5

.60

.65

.70

.75

.80

.85

.90

.95

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

1.50

4

.48

.52

.56

.60

.64

.68

.72

.76

.80

.84

.88

.92

.96

1.00

1.04

1.08

1.12

1.16

1.20

8

.36

.39

.42

.45

.48

.51

.54

.67

.60

.63

.66

.69

.72

.75

.78

.81

.84

.87

.90

2

.24

.26

.28

.30

.32

.34

.36

.88

.40

.42

.44

.46

.48

.50

.52

.54

.56

.68

.60

1

.12

.13

.14

.15

.16

.17

.18

.19

.20

.2:

.22

.23

.24

.25

.26

.27

.28

.29

.80

is

272

Testing Milk and Its Products.

Table vm. Pounds of fat In I to (000 fbs. of cream (continued}.

I

81

82

88

84

85

86

87

88

39

40

41

42

43

44

45

46

47

48

49

50

U

1000

810

820

880

840

350

360

870

880

390

400

410

420

430

440

450

460

470

480

490

600

900

279

288

297

806

315

824

333

342

351

860

869

878

887

896

405

414

423

482

441

450

800

248

256

264

272

280

288

296

304

312

820

328

336

844

352

860

868

376

384

392

400

700

217

224

231

238

245

252

2f>9

266

273

280

287

294

801

808

315

322

829

836

343

350

000

188

192

198

204

210

216

222

228

234

240

246

252

258

264

270

276

282

288

294

800

600

165

160

16-5

170

175

180

18o

190

195

200

205

210

215

220

225

230

235

240

245

250

400

124

128

132

136

140

144

148

152

166

160

164

168

172

176

180

184

188

192

196

200

800

93

96

99

102

105

108

111

114

117

120

123

126

129

132

135

188

141

144

147

150

200

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

98

100

100

81

82

83

84

85

36

37

88

89

40

41

42

48

44

45

46

47

48

49

60

90

27.9

28.8

29.7

30.6

31.6

82.4

38.8

34.2

35.1

86.0

36.9

37.8

38.7

39.6

40.5

41.4

42.8

48.2

44.1

46.0

80

24.8

2o.6

26.4

27.2

28.0

28.8

29.6

30.4

21.2

32.0

32.8

33.6

34.4

&5.2

86.0

86.8

37.688.4

39.2

40.0

TO

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

31.582.2

32.983.6

84.8

85.0

00

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

27.0

27.6

28.228.8

29.4

80.0

60

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

22.6

23.0

28.624.0

24.5

25.0

40

12.4

12.8

13.2

13.8

14.0

14.4

14.8

15.2

15.6

16.0

16.4

16.8

17.2

17.6

18.0

18.4

18.819.2

19.6

20.0

80

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

13.2

18.5

18.8

14.1

14.4

14.7

15.0

20

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

10

8.1

8.2

8.8

8.4

8.5

3.6

8.7

3.8

8.9

4.0

4.1

4.2

4.8

4.4

4.5

4.6

4.7

4.8

4.9

5.0

9

2.79

2.88

2.97

8.06

8.15

3.24

8.88

3.42

8.51

3.60

8.69

8.78

3.87

3.064.95

4.14

4.28

4.32

4.41

4.60

8

2.48

2.56

2.64

2.72

2.80

2.88

2.96

3.04

3.12

3.20

3.28

8.36

3.44

3.523.60

8.68

8.76

8.84

3.924.00

7

2.17

2.24

2.81

2.38

2.45

2.52

2.59

2.66

2.73

2.80

2.87

2.94

8.01

3.088.168.22

3.29

8.86

8.48;8.50

6

1.86

1.92

1.98

2.04

2.10

2.16

2.22

2.28

2.34

2.40

2.46

2.62

2.58

2,64

2.702.76

2.82

2.88

2.94,8.00

6

1.65

1.60

1.65

1.70

1.75

1.80

1.85

1.90

1.95

2.00

2.05

2.10

2.15

2.20

2.25 2.80

2.35

2.40

2.45

2.50

4

1.24

1.28

1.82

1.3611.40

1.44

1.48

1.52

1.56

1.60

1.64

1.68

1.72

1.76

1.801.84

1.88

1.92

1.06

2.00

8

.93

.96

.99

1.021.0o

1.08

1.11

1.14

1.17

1.20

1.23

1.26

1.29

1.32

1.351.88

1.41

1.44

1.47

1.60

2

.62

.64

.66

.68 .70

.72

.74

.76

.78

.80

.82

.84

.86

.88

.90 .92

.94

.96

.98

1.00

.81

.82

.88

.34 .36

.86

.87

.88

.89

.40

.41

.42

.48

.44

.46 .46

.47

.48

.49

.60

Appendix.

273

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

(See directions for use, page JC6.)

nl

12

12*
12}
12f

Pounds of butter fat.

H Price per

pound, cents.

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. 7o
87.50
89.25

$

72.00
73.50
75.00
76.50

12
12*

1

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

13*
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}
13f

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}

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}
161

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

17

17*

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}

18

18*
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|

1,000

900

800

700

600

500

400

300

200

100

274 Testing Milk and Its Products.

I able IX. Amount due for butter fat (Continued),

ri

ll

^1

Pounds of butter fet.

Price per 1
pound, cents. |

1,000

900

800

700

600

500

400

300

200

100

$

$

$

$

$'

$

$

$

$

$

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
:M.50
39.00
39.50

19.00
19.25
19.50
19.75

19
191

20
201
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*
20|

21
21}

21f

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
21*

22
22}
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

221
22*
22!

23
23}
23*
23f

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

231
23*
231

24

24}
24*
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
198.00
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
07.00
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
2-h

2f>4

1,000

900

800

700

600

500

400

300

200

100

Appendix.

275

Table X. Relative-value tables.

(See directions for use, par. 238.)

\i

Price of milk per 100 pounds, In dollars and cents.

3.0

.30

.31

.33

.34

.36

.37

.39

.40

.42

.43

.45

3.1

.31

.33

.34

.36

.37

.39

.40

.42

.43

.45

.46

3.2

.32

.34

.35

.37

.38

.40

.42

.43

.45

.46

.48

3.3

.33

.35

.36

.38

.4J

.41

.43

.45

.46

.48

.49

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

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

.44

.46

.48

.50

.52

.54

.56

.58

.6C

4 1

41

43

.45

.47

49

.51

.53

.55

.57

.59

61

4 ?,

.42

.44

.46

.48

.50

.52

.55

.57

59

.61

4.3

.43

.45

.47

.49

.52

.54

.56

.58

.60

.62

.64

4.4

.44

.46

.48

.51

.53

.55

.57

.59

.62

.64

.66

.5

.45

.47

.49

.52

.54

.56

.58

.61

.63

.65

.67

.6

.46

.48

.61

.53

.55

.57

.60

.62

.64

.67

M

.7

.47

.49

.52

.54

.56

.59

.61

.63

.66

.68

.7C

.8

.48

.50

.53

.55

58

.60

.62

.65

.67

.70

.72

.9

.49

.51

.54

.56

.59

.61

.64

.66

.69

.71

.73

5.0

.50

.52

.55

.57

.60

.62

.65

.67

.70

.72

.75

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

.85

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

.05

.68

.71

.74

.77

.80

.83

.86

.88

6.0

.60

.63

.66

.09

.72

.75

.78

.81

.84

.87

.90

276

Testing Milk and Its Products.

Table X. Relative-value tables ( Continued).

h

Price <

»f mill

cperK

Wpoui

ids, in

dollar

landc

ents.

r

8.0

.46

.48

.49

.51

.52

.54

.55

.57

.58

.60

8.1

.48

.50

.51

.53

.54

.56

.57

.59

.60

.62

8.2

.50

.51

.53

.54

.56

.58

.59

.61

.62

.64

3.3

.61

.53

.54

.56

.58

.59

.61

.63

.64

.66

8.4

.63

.54

.56

.58

.59

.61

.63

.65

.66

.68

8.5

.64

.66

.68

.69

.61

.63

.65

.66

.68

.70

8.6

.66

.68

.69

.U

.63

.66

.67

.68

.70

.72

8.7

.57

.69

.61

.68

.65

.67

.68

.70

.72

.74

8.8

.69

.61

.63

.65

.66

.68

.70

.72

.74

.76

8 9

.60

6?

.64

.66

.68

.70

.72

.74

.76

78

4.0

.62

.64

.66

.68

.70

.72

.74

.76

.78

.80

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

.78

.80

.83

.85

.87

.90

.92

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

6.0

.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.

277

Table X. Relative-value tables (Continued).

li

Price of milk per 100 pounds, in dollars and cent*.

3.0

.61

.63

.64

.66

.67

.69

.70

.72

.73

.76

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

.05

4.3

.88

.90

.92

.95

.97

.99

1.01

1.03

1.05

.08

4.4

.90

.92

.95

.97

.99

1.01

1.03

1.06

1.08

.10

4.5

.92

.94

.97

.99

1.01

1.03

1.06

1.08

1.10

.13

4.6

.94

.97

.99

1.01

1.03

1.06

1.08

1.10

1.13

.15

4.7

.96

.99

1.01

1.03

1.06

1.08

1.10

1.13

1.15

.18

4.8

.98

1.01

.03

1.06

1.08

1.10

1.13

1.15

1.18

.20

4.9

1.00

1.03

.05

1.08

1.10

1.13

1.15

1.18

1.20

.23

5.0

1.02

1.05

.07

1.10

1.12

.15

1.18

1.20

1.23

.25

5.1

1.05

1.07

.10

1.12

1.15

.17

1.20

1.22

1.25

.27

5.2

1.07

1.09

.12

1.14

1.17

.20

1.22

1.25

1.27

.30

5.3

1.09

1.11

1.14

1.17

1.19

22

1.25

1.27

1.30

.32

5.4

1.11

1.13

1.16

1.19

1.21

!24

1.27

1.30

1.32

.35

5.5

1.13

1.15

1.18

1.21

1.24

1.26

1.29

1.32

1.35

.38

5.6

1.15

1.18

1.20

1.23

1.26

1.29

1.32

1.34

1.37

.40

5.7

1.17

1.20

1.23

1.25

1.28

1.31

1.34

1.37

1.39

.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

278

Testing Milk and Its Products.

Table X. Relative-value tables (Continued).

fl

Price of milk per 100 pounds, in dollars and cents.

3.0

.76

.78

.79

.8i

.82

.84

.85

.87 1 .88

.90

3.1

.79

.81

.82

.84

.85

.87

.88

.90

.91

.93

3.2

.82

.88

.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

.00

1.01

.03

1.05

3.6

.92

.94

.95

.97

.99

1.00

.03

1.04

.06

1.08

3.7

.94

.96

.98

1.00

1.02

1.03

.05

1.07

.09

1.11

3.8

.07

.99

1.01

1.03

1.04

1.06

.08

1.10

.12

1.14

3.9

.99

1.01

1.03

1.05

1.07

1.09

.11

1.13

.15

1.17

4.0

1.02

1.04

1.06

1.08

1.10

1.12

.14

1.16

1.18

1.20

4.1

1.05

.07

1.09

1.11

1.13

1.15

.17

1.19

1.21

1.23

4.2

1.07

.09

.11

1.13

1.15

1.18

.20

1.22

1.24

1.26

4.3

1.10

.12

.14

.16*

1.18

1.20

.23

.25

.27

1.29

4.4

1.12

.14

.17

.19

1.21

1.23

.25

.28

.30

1.32

4.5

1.15

.17

.19

.21

1.24

1.26

.28

.30

.33

1.35

4.6

1.17

.20

.22

.24

1.26

1.29

.31

.33

.36

1.38

4.7

1.20

.22

.25

.27

1.29

1.32

.34

.36

.39

1.41

4.8

1.22

1.25

1.27

.30

1.32

1.34

.37

.39

1.42

1.44

4.9

1.25

1.27

1.30

1.32

1.35

1.37

.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

.51

1.53

1.56

5.3

1.35

1.38

1.40

1.43

1.46

1.48

1.51

.54

1.56

1.59

6.4

1.38

1.40

1.43

1.46

1.48

1.51

1.54

.57

1.59

1.62

5.5

1.40

1.43

1.46

1.48

.51

1.54

.57

.60

1.62

1.65

5.6

1.43

1.46

1.48

1.51

.54

1.57

.60

.62

1.65

1.68

5.7

1.45

1.48

1.51

1.54

.57

1.60

.62

.65

1.68

1.71

5.8

1.48

1.51

1.54

1.57

.59

1.62

.65

.68

1.71

1.74

5.9

1.50

1.53

1.56

1.59

.(>2

1.65

.68

.71

1.74

1.77

6.0

1.53

1.56

1.59

1.62

1.65

1.68

.71

.74

1.77

1.80

Appendix. 279

Table XI. Butter chart, showing calculated yield of butter (in
5bs.) from I to 10,000 Ibs. of milk, testing 3.0 to 5.3 per
cent. (See directions for use, p. 266.)

1

3.00

3.10

3.20

3.80

3.40

3.50

3.60

3.70

3.80

3.90

4.00

4.10

i

Milk,

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 ?

31 3

3* 4

33 4

34 5

35 5

36 5

37 6

38 6

39 7

40 7

900

800

26.0

26.9

27.8

28.8

29.7

30.6

31.5

32.5

33.4

34.3

35.3

36.2

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

20.2

20.9

21.6

22.3

23.0

23.6

24.4

25.1

25.7

26.5

27.1

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

SOO

9 7

10 1

10 4

10 8

11 1

11 5

11 8

1? 9,

12 5

12 9

13 fl

13 6

300

200

6 5

6 7

6 9

7 fl

7 4

7 6

7 9

8 1

8 3

ft 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

90

2.9

3.0

3.1

3.2

8.3

3.4

3.5

3.6

3.7

3.8

3.9

4.1

90

80

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.4

3.5

3.6

80

70

2.3

2.3

2.4

2.5

2.6

2.7

2.8

2.8

2.9

3.0

3.1

3.2

70

60

1.9

2.0

2.1

2.2

2.2

2.3

2.4

2.4

2.5

2.6

2.7

2.7

60

50

1.6

1.7

1.7

1.8

1.9

1.9

2.0

2.0

2.1

2.2

2.2

2.3

50

40

1.3

1.3

1.4

1.4

1.5

1.5

1.6

1.6

1.7

1.7

1.8

1.8

40

30

1.0

1.0

1.0

1.1

1.1

1.2

1.2

1.2

1.3

1.3

1.3

1.4

80

20

.6

.7

.7

.7

.7

.8

.8

.8

.8

.9

.9

.9

20

10

8

3

4

4

4

4

4

4

4

4

4

6

10

9

ft

fl

8

3

R

3

.4

4

4

4

4

4

9

8

.8

.3

.8

.8

.8

.3

.3

.8

.8

.8

.4

.4

8

7

.2

.2

.2

.8

.8

.3

.3

.3

.3

.3

.3

.3

7

6

.2

.2

.2

.2

.2

.2

.2

.2

.3

.8

.3

.3

6

5

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

.2

6

4

.1

.1

.1

.2

.2

.2

.2

.2

.2

.2

.2

.2

4

8

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

3

2

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

2

1

1

i

8.00

3.10

3.20

3.30

3.40

3.50

3.60

3.70

3.80

3.90

4.00

4.10

I

280

Testing Milk and Its Products.

Table XI. Butter chart ( Continued),

«l

j

4.20

4.30

4.40

4.50

4.60

4.70

4.80

4.90

5.00

5.10

5.20

5.30

c?

H

r

Milk

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

178

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

53.3

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

34.1

34.9

35.7

36.5

37.4

38.2

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

29.0

29.6

500

400

18.6

19.0

19.5

20.0

20.4

20.9

21.4

21.8

22.3

22.7

23.2

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

90

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5.0

5.1

5.2

5.3

90

80

3.7

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

4.5

4.6

4.7

80

70

3.3

3.3

3.4

3.5

3.6

3.7

3.7

3.8

3.9

4.0

4.1

4.1

70

60

2.8

2.9

2.9

3.0

3.1

3.1

3.2

3.3

3.3

3.4

3.5

3.6

60

50

2.3

2.4

2.4

2.5

2.6

2.6

2.7

2.7

2.8

2.8

2.9

3.0

50

40

1.9

1.9

2.0

2.0

2.0

2.1

2.1

2.2

2.2

2.3

2.3

2.4

40

30

1.4

1.4

1.5

1.5

1.5

1.6

1.6

1.6

1.7

1.7

1.7

1.8

30

20

.9

1.0

1.0

1.0

1.0

1.0

1.1

1.1

1 1

1.1

1.2

1.2

20

10

.5

.5

.5

.5

.5

.5

.5

.6

.6

.6

.6

.6

10

9

.4

.4

.4

.5

.5

.5

.5

.5

.5

.5

.5

.5

9

8

4

4

4

4

4

4

4

4

5

5

5

5

8

7

3

4

4

4

4

4

4

4

7

6

.3

.3

.3

.3

.3

.3

.3

.3

.3

.3

.4

.4

6

5
4

.2
.2

.2
.2

.2

.3

.3

.3

.3

.3

.3

.3

.3

.3

5
4

3

c

.1
.1

.1
.1

.1

.1

.1

.1

.1

.1

J

.1

.1

.1

3
2

]

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

1

~T~

4.20

4.30

4.40

4.50

4.60

4.70

4.80

4.90

5. CO

5.10

5.20

5.30

8

H

r

Appendix.

281

Table XII. Overrun table, showing pounds of butter from
one hundred Ibs. of milk. (See directions for use,
par. 222.)

Per

cent.

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.

fat.

3 0

3 30

3 33

3 36

3 39

3 49,

3 45

3 48

3 51

3 54

3 57

3 60

3 0

3.1

3.41

3.44

3.47

3.50

3.53

3.57

3.60

3.63

3.66

3.68

3.72

3.1

3.2

3.52

3.55

3.58

3.62

3.65

3.68

3.71

3.74

3.78

3.81

3.84

3.2

3.3

3.63

3.66

3.70

3.73

3.76

3.80

3.83

3.86

3.89

;i.9S

3.96

3.3

3.4

3.74

3.77

3.81

3.84

3.88

3.91

3.94

3.98

4.01

4.05

4.08

3.4

3 5

3 85'

R 89

3 W

3 96

3 99

4 OS

4 06

4 10

4 13

4 17

4.20

3.5

3.6

3.96

4.00

4.03

4.07

4.10

4.14

4.18

4.21

4.25

4.28

4.32

3.6

3.7

4.07

4.11

4.14

4.18

4.22

4.26

4.29

4.33

4.37

4.40

4.44

3.7

3.8

4.18

4.22

4.26

4.29

4.33

4.C?

*.41

4.45

4.48

4.52

4.56

3.8

3.9

4.29

4.33

4.37

4.41

4.45

4.49

4.52

4.56

4.60

4.64

4.68

3.9

4.0

4.40

4.44

4.48

4.52

4.56

4.60

4.64

4.68

4.72

4.76

4.80

4.0

4.1

4.51

4.55

4.59

4.63

4.67

4.72

4.76

4.80

4.84

4.88

4.92

4.1

4.2

4.62

4.66

4.70

4.75

4.79

4.83

4.87

4.91

4.96

").00

5.04

4.2

4.3

4.73

4.77

4.82

4.86

4.90

4.95

4.99

5.03

5.07

5.12

5.16

4.3

4.4

4.84

4.88

4.93

4.97

5.02

5.06

5.10

5.15

5.19

5.24

5.28

4.4

4.5

4.95

5.00

5.04

5.09

5.13

6.18

5.22

5.27

5.31

5.36

5.40

4.5

4.6

5.06

5.11

5.15

5.20

5.24

5.29

5.34

5.38

5.43

5.47

5.52

4.6

4.7

5.17

5.22

5.26

5.31

5.36

5.41

5.45

5.49

5.55

5.59

5.64

4.7

4.8

5.28

5.33

5.38

5.42

5.47

5.52

5.57

5.62

5.66

5.71

5.7H

4.8

4.9

5.39

5.44

5.49

5.54

5.59

5.64

5.68

5.73

5. -78

5.83

5.88

4.9

5.0

5.50

5 55

5.60

5.65

5.70

5.75

5.80

5.85

5.90

5.95

6.00

5.0

5.1

5.61

5.66

5.71

5.76

5.81

5.87

5.92

5.97

6.02

6.07

6.12

5.1

5.2

5.72

5.77

5.82

5.88

5.93

5.98

6.03

6.08

6.14

6.19

6.24

5.i

5.3

5.83

5.88

5.94

5.99

6.04

6.10

6.15

6.20

6.25

6.31

6.36

5.3

5.4

5.94

5.99

6.05

6.10

6.16

6.21

6.26

6.32

0.37

6.43

6.48

5.4

5.5

6.05

6.11

6.16

6.22

6.27

6.33

6.38

6.44

6.49

6.55

e.eo

5.5

5.6

6.16

6.22

6.27

6.33

6.38

6.44

6.50

6.55

6.61

6.66

6.72

5.6

5.7

6.27

6.33

6.38

6.44

6.50

6.56

6.61

6.67

6.73

6.78

6.84

5.7

5 8

6 38

6 44

6 50

fi 55

6 61

6 67

6 73

6 79

6 84

6 90

6 96

5.8

5.9

6.49

6.55

6.61

6.67

6.73

6.79

6.84

6.90

6.96

7.02

7.08

5.9

6.0

6.60

6.66

6.72

6.78

fi.84

6.90

6.96

7.02

7.08

7.14

7.20

6.0

282

Testing Milk and Its Products.

Table XIII. Yield of Cheese from 100 Ibs. milk with 2.5 to
6 per cent, or rat, and lactometer readings from 26 to 30.

(See par. 224)

LACTOMETER DEGREES.

+$

gjj

26

27

28

29

30

31

32

33

34

35

36

1*

2.5

7.28

7.41

7.54

7.67

7.81

7.94

8.07

8.20

8.33

8.47

8.60

2.

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.

2.7

7.59

7.72

7.85

7.99

8.12

8.25

8.38

8.51

8.64

8.77

8.91

2.

2.8

7.74

7.87

8.00

8.14

8.27

8.40

8.53

8.67

8.80

8.94

9.07

2,

2.9

7.90

8.03

8.16

8.30

8.44

8.56

8.69

8.82

8.95

9.09

9.22

2.

3.0

8.05

8.18

8.31

8.45

8.58

8.71

8.84

8.97

9.11

9.24

9.37

3.

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

3.2

8.36

8.49

8.62

8.75

8.89

9.02

9.15

9.28

9.42

9.55

9.68

3.

3.3

8.52

8.65

8.78

8.91

9.05

9.18

9.31

9.44

9.57

9.70

9.84

3.

3.4

8.67

8.80

8.93

9.06

9.20

9.33

9.46

9.59

9.73

9.86

9.99

3.

3.5

8.82

8.96

9.09

9.22

9.35

9.48

9.62

9.75

9.88

10.01

10.15

3.

3.6

8.98

9.11

9.24

9.37

9.50

9.63

9.77

9.90

10.03

10.17

10.30

3.

3.7

9.13

9.26

9.39

9.52

9.65

9.78

9.92

10.05

10.19

10.32

10.46

3.

3.h

9.29

9.42

9.55

9.68

9.81

9.94

I'l.O.^

10.21

10.34

10.48

10.61

3.

3.9

9.44

9.57

9.70

9.84

9.97

10.10

10.23

10.36

10.50

10.64

10.77

3.

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.

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.

4.2

9.90

10.03

10.17

10.30

10.43

10.57

10.70

10.84

10.97

11.10

11.24

4.

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.

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.

4.5

10.36

10.49

10.63

10.76

10.89

11.03

11.16

11.29

11.42

11.56

11.70

4.

4.6

10.52

10.65

10.78

10.92

11.05

11.18

11.31

11.45

11.68

11.71

11.85

4.

4.7

10.67

10.81

10.94

11.07

11.20

11.34

11.47

11.60

11.73

11.87

12.0)

t.

4 8

10.83

10.96

11.09

11.22

11.36

11.49

11.62

11.76

11.89

12.02

12 16

4

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.

5.0

11.14

11.27

11.40

11.54

11.67

11.80

11.93

12.07

12.20

12.34

12.48

5.

5.1

11.29

11.42

11.55

11.69

11.82

11.96

12.09

12.23

12.36

12.49

12.63

5.

5.2

11.45

11,58

11.71

11.85

11.98

12.11

12.24

12.38

12.52

12.66

12.80

5.

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.

5.4

11.76

11.89

12.02

12.16

12.29

12.42

12.55

12.69

12.83

12.97

• 3.01

5.

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.cj

12.07

12.20

12.33

12.47

12.60

12.73

12.87

13.00

13.14

13.28

13.41

5.

5.7

12.22

12.35

12.48

12.62

12.75

12.89

13.02

13.16

13.30

13.44

13.57

*i4

5.8

12.38

12.51

12.64

12.77

12.91

13. (5

13.18

13.31

13.45

13.59

13.72

5.

5.9

12.53

12.66

12.79

12.93

13.06

13.19

13.33

13.47

13.60

13.74

13.87

5.

l>.(>

12.69

12.82

12.95

13.09

13.22

13.35

13.49

13.62

13.75

13.89

14.02

6.

Appendix.

283

Table 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

68.33

208

97.78

172

77.78

136

67.78

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

55.56

203

95

167

75

131

55

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

61.11

195

90.55

159

70.55

123

60.55

194

90

158

70

122

50

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

186

85

149

65

113

45

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

284 Testing Milk and Its Products.

Table XIV. Comparisons of thermometer scales ( Continued. )

Fahren-
heit.

Centi-
grade.

Fahren-
heit.

Centi-
grade.

Fahren-
heit.

Centi-
grade.

4-104

+40

+68

+20

+32

+0

103

39.44

67

19.44

31

—0.55

102

38.89

66

18.89

30

1.11

101

38.33

65

18.33

29

1.67

100

37.78

64

17.78

28

2.22

99

37.22

63

17.22

27

2.78

98

36.67

62

16.67

26

3.33

97

36.11

61

16.11

25

3.89

96

35.55

60

15.55

24

4.44

95

35

59

15

23

5

94

34.44

58

14.44

22

5.55

93

33.89

57

13.89

21

6.11

92

33.33

56

13.33

20

6.67

91

32.78

55

12.78

19

7.22

90

32 22

54

12.22

18

7.78

89

31.67

53

11.67

17

8.33

88

31.11

52

11.11

16

8.89

87

30.55

51

10.55

15

9.44

86

30

50

10

14

10

85

29.44

49

9.44

13

10.55

84

28.89

48

8.89

12

11.11

83

28.33

47

8.33

11

11.67

82

27.78

46

7.78

10

12.22

81

27.22

45

7.22

9

12.78

80

26.67

44

6.67

8

13.33

79

26.11

43

6.11

7

13.89

78

25.55

42

5.55

6

14.44

77

25

41

5

5

15.00

76

24.44

40

4.44

4

15.55

75

23.89

39

3.89

3

16. 11

74

23.33

38

3.33

2

16.67

73

22.78

37

2.78

1

17.22

72

22.22

36

2.22

0

17.78

71

21.67

35

1.67

—1

18.33

70

21.11

34

1.11

2

18.89

69

20.55

33

0.55

3

19.44

To convert deg. Fahrenheit to corresponding cleg. 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 -i- 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 =

869.6; 169.5 -•- 5 = 171.9: 171.9 + 82 =

Appendix. 285

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.
16.387 cc.
.0283 cub. meter.
.765 cub. meter
.3552 hectolitei
29.57 cc.
.9464 liter.
3.7854 liters.
64.8 milligrams.
28.35 grams.
.4536 kilogram.

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

meter .

1 mile

kilometer. .

1 square inch..
1 square foot..
1 square yard.
1 acre

sq. centimeter
square meter.,
square meter.,
hecta/re

1 cubic inch...
1 cubic foot....
1 cubic yard...
1 bushel
1 fluid ounce..
1 quart

cc

cub. decimeter
cub. meter
hectoliter
1 cc

1 liter

1 gallon

1 decaliter

1 grain

1 gram

1 ounce (av.)..
1 pound (av. )

1 gram

1 kilogram

Table XVI. Specific Gravity and Weight of one Gallon of
Cream, in Pounds, arranged according to the per cent, of fat.

Per cent
of fat
in cream

Specific
gravity
of cream

Weight of
one gallon
Z&s..

Per cent
of fat
in cream

Specific
gravity
of cream

Weight of
one gallon
Its.

0

1.036

8.6391

35

0.9963

8.3076

10

1.0243

8.5417

36

0.9952

8.2985

15

1.0186 8.4938 37 0.9941

8.2894

16

1.0174 8.4843 38 0.9930

8.2804

17

1.0163

8.4749

39

0.9919

8.2714

18

1.0152 8.4654

40

0.9908 1 8.2624

19

1.0140 8.4560

41

0.9897

8.2534

20

1.0129 8.4465

42

0.9886

8.2444

21

1.0118 8.4372

43

0.9875

8.2354

22

1.0107

8.4278

44

0.9864

8.2265

23

1.0096

8.4184

45

0.9854

8.2176

24

1.0085

8.4090

46

0.9843

8.2087

25

1.0073

8.3997

47

D.9832

8.1998

26

1.0062

8.3905

48

0.9821

8.1909

27

1.0051

8.3812

49

0.9811

8.1821

28

1.0040

8.3719

50

0.9801 8.1733

29

1.0029

8.3626

51

0.9790 8.1646

30

1.0017

8.3534

52

0.9780 8.1558 ~

31

1.0006 8.3443

53

0.9770 8.1470

32

0.9995 8.3352 54

0.9760

8.1382

33

0.9984 8.3260 55

0.9749

8.1294

34

0.9973 8.3168

286 . 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 desired 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
gathered-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.

1 Bull. 56, Wisconsin experiment station.

Appendix. 287

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

OB
ARTICLES OP AGREEMENT OF THE ............... ASSOCIATIONS

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-

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 Agricultural College,
special bulletin, May 1897. See also Iowa exp. station, bull. No. 139.

288 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, »iie products sold, the running expenses, etc., and
el all divide among the patrons the money due them each
mouth. They shall also make some provision for the with-

Appendix. 289

drawal of any member from the association, and make a re-
port 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 re-
ceipts, the amounts paid for milk and for running expenses,
and a complete 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 follow-
ing:

a. Patrons shall furnish all the milk from the cows prom-
ised at organization of the association.

b. Only sweet and pure milk will be accepted at the fac-
tory, and any tainted or sour milk shall be refused.

c. The milk of each patron shall be tested at least three
times a month.

d. Any patron proved to be guilty of watering, skimming
or otherwise adulterating the milk sent to the factory, or by
taking 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 patron's premises may be inspected at any time by
the board of directors, or their authorized agent, for the pur-
pose of suggesting improvements in the methods of caring
for the milk or the cows, in drainage and general cleanli-
ness; or to secure samples of the milk of his cows for ex-
amination when it is deemed necessary.

10. Any changes or amendments to the by-laws or consti-
tution of the association must be made in writing by the
parties proposing the same, and posted prominently in a con-
spicuous 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 the milk to the factory, or for each share of the
stock owned by them, as agreed upon.

INDEX

The figures refer to pages in the book.

Acid bottle, Swedish, 47.

Acid measures, 31, 47, 54.

Acid tester, Swedish, 67.

Acidimeter, Devarda's, 124.

Acidity of cream, 125, 129 ; esti-
mation of, 135.

Acidity of milk, cause of, 119 ; de-
termination of, 132 ; methods of
testing, 120.

Acidity pellets, 125.

Adulteration of milk, 111, 115,
244 ; calculation of, 115.

Adulterated butter, 240, 242;
cheese. 245.

Albumen, 14 ; determination of, in
milk, 225.

Albuminoids, 13.

Albumose, 14.

Alkaline tablet test, 124; stand-
ard solution of, 126 ; accuracy,
128.

Alkaline tabs, 136.

American cheddar cheese, 21.

Ames method for determining
water in butter, 237.

Amphoteric reaction of milk, 119.

Amyl alcohol, use in cream test-
ing, 88.

Analysis, chemical, of butter, 231 ;
butter milk, 228 ; cheese, 243 ;
condensed milk, 229 ; cream,
228 ; milk, 217 ; skim milk, 228 ;
whey, 228.

Appendix, 259.

Artificial butter, detection of, 240.

^.sh, determination of, in butter,
232; in cheese, 244; in milk,
227.

Babcock glassware, standard, spe-
cifications for, 258.

Rabcock test, the, 4, 28 ; Bart-
lett's modification, 72 ; direc-
tions for, 29 ; discussion of de-
tails, 37 ; for butter, 96 ; for
butter milk, 94 ; for cheese, 97 ;
for condensed milk, 98 ; for
cream, 75, 180 ; for ice-cream,
100 ; for skim milk, 90 ; for
whey, 94 ; glassware used in,
37 ; modifications of, 71 ; scales
for weighing cream, cheese, etc.,
80, 233 ; water to be used in, 68.

Babcock testers, 54 ; electrical, 63 ;
hand testers, 60 ; power testers,
61 ; steam turbine, 61.

Bartlett's modiflcallon of Babcocb
test, 48, 72.

Bausch and Lomb centrifuge, 72.

Beimling test, 5.

Bi-carbonate of soda, detection of,
251.

Bi-chromate of potash, 108, 168 ;
solution of, 108.

Blended milk, 254.

Board of health degrees, 106.

Boiled milk, detection of, 249.

Boiling test, the, 242.

Boracic acid in dairy products,
136, 251.

Borax in dairy products, 251.

Butter, artificial, 12 ; detection of,
240.

Butter chart, 278 ; use of, 197.

Butter, 20 ; Babcock test for, 196 ;
chemical analysis of, 231 ; com-
plete analysis in same sample.

292

Testing Milk and Its Products.

232; composition of, 21, 258;
creamery methods of estimating
water in, 233 ; definition, 255 ;
determination of ash, 232 ; case-
in, 231 ; fat, 231 ; salt, 233, 239 ;
water, 231 ; rapid estimation of
water, 233 ; Ames method, 237 ;
Cornell test, 237 ; Dean's meth-
od, 237 ; Gray's method, 235 ;
Irish test, 237 ; Mitchell- Walker
test, 236; Patrick's method,
236 ; Wisconsin high-pressure
oven method, 238 ; process, 255 :
renovated, 255 ; sampling for
analysis, 95, 231 ; scales for
weighing, 81, 233 ; standard,
255 ; variations in composition,
188 ; yield, calculation of, 187.

Butter fat, amount due, at 12-25
cents per lb., 272 ; conversion
factor for, 196 ; definition, 255 ;
determination of specific grav-
ity, 240; volatile fatty acids,
241 ; expansion coefficient, 36 ;
specific gravity, 38 ; determin-
ation, 241 ; standard, 255 ; test
and yield of butter, 187.

Butter making, quantities of prod-
ucts obtained in, 21.

Butter. milk, -21 ; Bubcock test for,
94 ; chemical analysis of, 228 ;
composition, 258 ; definition,
•255 ; specific gravity, 229.

Calculation of adulteration of
milk, 115; of concentration of
condensed milk, 230 ; of milk
solids, 109 ; of overrun, 195 ; of
sp. gr. of milk solids, -113; of
yield of butter, 187, 196, 197;
of cheese, 199 ; of dividends at
creameries, 203 ; at cheese fac-
tories, 213 ; of percentages, 172.

Calibration of glassware, 48;
Trovrbridge method, 51.

Carbohydrates, 15.

Casein, 13 ; determination of, in
butter, 231 ; in cheese, 243 ; in

milk, 3, 226; Hart's method,
226.

Centrifugal machines, 54.

Chaniberland filters, 14.

Cheddar cheese, American, 21 ;
composition, 258.

Cheese, 21 ; Babcock test for, 97 ;
calculating yield of, from casein
and fat, 201 ; from fat, 199 ;
from solids not fat and fat, 200 ;
composition, 21, 258 ; chemical
analysis of, 243 ; definitions,
256 ; determination of ash, 244 ;
casein, 243 ; fat, 243 ; water,
243 ; "filled," detection of, 244 ;
quality of, from milk of differ-
ent richness, 211 ; sampling, 97 ;
standard, 256 ; yield, calculation
of, 199; yield of, from milk'
with 2.5 to 6 per cent, fat and
lactometer readings from 26 to
36, 281 ; yield of, and quality of
milk, relation between, 200.

Cheese factories, calculating divi-
dends at, 213 ; co-operative, 216,
285 ; proprietary, 215.

Cholesterin in milk, 18.

Citric acid in milk, 18.

Cleaning solution for test bottles,
43.

Cleaning test bottles, 40 ; appa-
ratus for, 41, 44.

Cochran's test, 5.

Coloring matter in milk, detection
of, 247.

Colostrum milk, 18 ; composition
of, 258.

Combined acid bottle, 47.

Composite samples, 151 ; care of,
170 ; case for holding, 166 ;
methods of taking, 160 ; pre-
servatives for, 167.

Composite sampling, accuracy of,
167 ; use of drip sample, 162 ;
McKay sampler, 165 ; Michels'
cream sampling tube, 165 ; one-
third sample pipette, 166 ; Sco-
vell sampling tube, 163 ; tin dip-
per, 160.

Index.

293

Composition of butter, 258 ; but-
ter milk, 258 ; cheese, 258 ; col-
ostrum milk, 258 ; condensed
milk, 258 ; cream, 258 ; milk, 18,
258; milk ash, 17; skim milk,
258 ; whey, 258.

Condensed milk, 22 ; analysis of,
229 ; composition of, 258 ; de-
termination of concentration,
230 ; of sp. gr. of, 230 ; testing
of, 98.

Control samples of milk, 111.

Conversion factor for butter fat,
190.

Conversion tables for thermome-
ter scales, 282 ; for weights and
measures, 284.

Cornell test for determining water
in butter, 237.

Cows, number of tests required in
testing, 147 ; single, sampling
milk of, 150; when to test, 149.

Cream, 19, 228; acidity of, 125,
• 129; Babcock test for, 75, ISO;
bottles, 79 ; care in sampling,
necessity of, 182 ; clotted, 255 ;
definition, 255 ; determination of
acidity of, 125, 135 ; errors of
measuring in testing, 76 ; evap-
orated, 255; fat in 1 to 1000
IDS., testing 12 to 50 per cent.,
270 ; gelatin in, detection of,
249 ;x overrun, 194 ; pasteurized,
detection of, 248 ; scales, 80 ;
separator, 19 ; gathering and
sampling, 185 ; separation of,
influence of temperature, 185 ;
sour, determination of acidity,
125; spaces, 176; specific grav-
ity, 77, 102 ; standard, 255 ;
starch in, 250 ; testing, 75 ;
eliminating meniscus in, 87 ;
testing outfit, 181 ; testing at
creameries, 176 ; tests, correct
readings of, 85, 87 ; use of 5 cc.
pipette in sampling, 86 ; use of
milk test bottles, 84; test bot-
tles, 79 ; weight of, delivered by

17.6 cc. pipette, 77 ; weight of
1 gal., 285.

Creameries, calculating dividends
at, 203 ; co-operative. 205. 2S.*> :
cream testing at, 176; proprie-
tary, 204.

Creamery inch, 1, 177.

Curd test, the Wisconsin improved,
137.

Dean's method for determining
water in butter, 237.

Definitions of milk and its prod-
ucts. 254.

DcLaval's butyrometcr, 8.

Devarda's acidimeter, 124.

Diameter of tester and speed re-
quired, relation between, 57.

Dividends, calculating at cheese
factories, 215 ; at creameries,
205 ; of both milk and cream at
the same factory, 211.

Dividers, use of, 37.

Double-necked test bottles, 92 ;
value of divisions of, 93.

Draining-rack for test bottles, 42.

Eichler's Saurepillen, 125.
Expansion coefficient of butter fat.
36.

Failyer and Willard's test, 4.

Farrington's alkaline tablet test,
124.

Fat, 11 ; color of, an index to
strength of acid used, 67 ; con-
tent, causes of variation in, 146 ;
determination of, in butter, 231 ;
in cheese, 244 ; in milk, 221 ;
globules, 11 ; Gottlieb's method
for determining, 222 ; influence
of temperature on separation of,
69 ; measuring of, in cream test-
ing, 86 ; in milk testing, 35 ;
pounds in 1-10,000 Ibs. of milk,
testing, 3 to 5.35 per cent., 266 ;
speed required for complete sep
aration of, 59.

294

Testing Milk and Its Products.

Fat-saturated alcohol, use in

cream testing, 88.
Fermentation test, the, 139.
Filled cheese, detection of, 245.
"Fitch's Salt Analysis," 239.
Fjord's centrifugal cream test, 8.
Fluorids, detection of, 252.
Food, influence of on quality of

milk, 144, 146, 150.
Food standards, Government, 254.
Fool pipettes, 46.
Formaldehyd, detection of, 252.
Frozen milk, sampling of, 27.

Gauges of cream, 176.

Gelatine in cream, detection of,
249.

Gerber's acid-butyrometer, 7 ; fer-
mentation test, 139.

Glassware used in the Babcock
test, 37 ; calibration of, 48.

Globulin, 15.

Glycerids of fatty acids, 13.

Glymol, use in cream testing, 88.

Goat cheese, 14.

Gottlieb method, the, 222.

Government food standards, 254.

Gray's test for water in butter,
2J55. *

Grain-feeding, heavy, influence of,
on quality of milk, 155.

Hand separator cream, gathering

and sampling, 185.
Hand testers, 60.
Hart's test for casein in milk,

226.

Hemi-albumose, 14.
Herd milk, variations in, 153 ;

ranges in variations of, 154.
Hydrostatic balance, 82.
Ilypoxanthin, 18.

Ice-cream, test of, 100 ; definitions,
255 ; apparatus for determin-
ing overrun, 101.

Immersion refractometer, use of
for detection of watered milk,
245.

Introduction, 1.

Iowa station test, 5.

Irish test for water in butter, 237.

Kumiss, 256.

Lactic acid in milk, 16.

Lactocrite, 5, 7.

Lactose, 15.

Lactochrome, 18.

Lactometer, the, and its applica
tion, 102 ; bi-chromate, influence
on, 108 ; cleaning of, 108 ; de-
grees, 101 ; N. Y. board of
health, 106, 261 ; Quevenne,
103 ; reading the, 106 ; testing
accuracy of, 108 ; time of tak-
ing readings, 107.

Lecithin in milk, 18.

Leffrnann and Beam test, 5.

Legal standards for milk, 112, 259.

Liebermann's method, 5.

Macroscopic impurities in milk,
250.

Manns' test, 121 ; testing outfit,
124.

Marschall acid test, 131 ; rennet
test, 141.

McKay sampling tube, 165.

Measuring fat column in testing
cream, 86, 87 ; in testing milk,
35.

Mercury, calibration with, 51 ;
cleaning, 52.

Metric and customary systems of
weights and measures, compar-
ison of, 284.

Michels' cream sampling tube, 165.

Milk, acidity of, 119, 132 ; albu-
men in, 12 ; adulteration of,
111 ; amphoteric reaction of,
119 ; ash, composition of, 17;
blended, definition, 254 ; boiled,
detection of, 249 ; casein in,
13 ; chemical analysis of, 217 ;
cholesterin in, 18 ; churned,
sampling of, 24 ; citric acid in,
18; colostrum, 18; composition

Index.

295

of, 10, 18, 258; composite
sampling of, 160 ; condensed, 22,
98, 258 ; correction table for
specific gravity, 262 ; defini-
tions, 254 ; detection of coloring
matter, 247 ; of preservatives,
135, 251 ; determination of acid-
ity, 132 ; of ash, 227 ; of casein
and albumen, 223 ; of fat, 221 ;
of milk sugar, 226 ; of solids,
221 ; of specific gravity, 217 ;
of water, 220 ; fat in, 11 ; from
cows in heat, 112 ; from sick
cows, 112 ; from single cows,
sampling of, 150 ; variations in,
142 ; frozen, sampling of, 27 ;
gases, 18 ; hypoxanthin, 18 ; lac-
tochrome, 18 ; lactose, 15 ; leci-
thin, 18; legal standards, 112,
259 ; macroscopic impurities,

250 ; mineral components, 17 ;
partially churned, sampling of,
24 ; pasteurized, detection, 248 ;
preservatives, detection, 136,

251 ; quality of, influence of food,
155 ; of heavy grain feeding,
155 ; of pasture, 156 ; method of
improving, 158 ; sampling, 23,
29 ; scale, Richmond's, 110 ;
scales, 150 ; serum, 10 ; skim-
ming, 116 ; solids, 10 : calcula-
tion of, 109 ; specific gravity of,
113 ; souring of, 15 ; sour, sam-
pling of, 26 ; standards, 112,
254 ; sugar, 15 ; tests for adul-
teration : nitric acid test, 245;
sp. gr. of skim milk, milk serum,
or \rhey, 247 ; testing on the
farm, 142 ; testing purity of,
137 ; urea, 18 ; water, 11 ; water-
ing of, 116 ; detection of, by re-
fractometer, 245 ; watering and
skimming, 117.

Milk test, a practical, need of, 1 ;
requirements of, 6 ; bottle, use
of, in testing cream, 84 ; Rus-
sian, 71.

Milk tests, Babcock, 4, 6; Beim-
ling (Leffmann and Beam), 5;

Cochran, 5 ; DeLaval butyrome-
ter, 8 ; Failyer and Willard, 4 ;
Fjord, 8 ; foreign, 7 ; Gerber
acid-butyrometer, 7 ; introduc-
tion of, 4 ; lactocrite, 5,7; Lie-
bermann, 5 ; Lindstrom, 9 ;
Nahm, 5 ; Parson, 4 ; Patrick
(Iowa station test), 5; Rose-
Gottlieb, 5, 222 ; sal-method, 5 ;
Schmied, 5 ; Short, 4 ; sin-acid,
7 ; Thorner, 5 ; Wollny refracto-
meter, 9.

Milk products, composition of, 19,
258.

Monrad rennet test, the, 140.

Milk testing, 28 ; on the farm, 142.

Mitchell-Walker test, 236.

Nahm's test, 5.

N. Y. board of health lactometer,

105; degrees corresponding to

Quevenne lactometer degrees,

261.
Nitric acid test for adulteration of

milk, 245.

Non-fatty milk solids, 10.
Normal solutions, 121.
Nuclein, 14.

Official tests of cows, 150.

Oil-test churn, 2, 177.

Oleomargarine, detection of, 240,
242 ; cheese, detection of, 245 ;
tests for artificial coloring mat-
ter in, 243.

One-third sampling pipette, use of,
166.

Organization of co-operative cream-
eries and cheese factories, sug-
gestions concerning, 285.

Overrun, 190 ; calculation of, 195 ;
factors influencing, 190 ; table,
199, 280 ; from cream, 194 ;
from milk, 190.

Parsons' test, 5.

Pasteurized milk or cream, detec-
tion of, 248.

296

Testing Milk and Its Products.

Pasture, influence on quality of

milk, 156.

Patrick's test, 5 ; method for de-
termining water in butter. 236.
Percentages, average, methods of
calculation, 172 ; fallacy of aver-
aging, 171.
Phenolphtalein, 122.
Physician's centrifuge, use of, in

milk testing, 72.

Pipettes, 30. 45 ; proper construc-
tion of points, 45 ; proper meth-
od of emptying, 31 ; calibration,
54.

Pooling system, 3.
Potassium bi-chromate, 168.
Power testers, 61.
Preservaline, 135, 251; detection

of in milk, 135, 251.
Preservatives, for composite sam-
ples, 167 ; in milk, detection of,
135, 251.
Primost, 14.

Process butter, detection of, 242.
Proteose, 14.

Quevenne lactometer, the, 106
degrees corresponding to scale of
N. Y. board of health lactome-
ter, 106, 261.
Readings of cream tests, 86; of

milk tests, 35.

Recknagel's phenomenon, 107.
Refractometer, Wollny, 9 ; immer-
sion, use of for detection of
watered milk, 245.
Reich ert number, 242.
Reichert-Wollny method, 241.
Relative-value tables, 209, 274.
Rennet tests, 140.
Renovated butter, detection of,
242 ; boiling test, 242 ; Water-
house test, 242.
Reservoir for water in Babcock

test, 70.

Richmond's milk scale, 110.
R8se-Gottlieb's method, 5, 222.
Russian milk test, the, 71.

Salicylic acid, detection of, 252.
Salt, estimation in butter, 239.
Sampling cheese, 97 ; milk, 23, 20 ;

milk from single cows, 150.
Sampling tube, for cream, 181 ;
McKay, 165 ; Michels, 165 ; Sco-
ville, 163.
Scales for weighing cream, 80 ;

milk. 150.

Schmied method, the, 5.
Scovell sampling tube, 163.
Serum solids, 10.
Short's test, 4.
Siegfeld's modification of Babcocfc

test, 72.

Sinking fund, 209.
Separator cream, 19.
Skimming of milk, detection of,

116.

Skim milk, 19; Babcock test for,
90 ; chemical analysis of, 228 ;
composition of, 258 ; condensed,
255 ; definition, 255 ; sp. gr.,
102; test bottles, 92.
Solids not fat, 10; formulas for
calculating 110 ; tables show-
ing, corresponding to 0-6 per
cent, fat and 26-36 lactometer
degrees, 263.
Sour milk, sampling, 26 ; analysis,

228.

Space system, the, 176.
Specific gravity, 102 ; cylinders,
103, 107 ; influence of tempera-
ture, 104 ; of butter fat, deter-
mination of, 240 ; of butter milk,
229 ; of condensed milk, 230 ; of
milk, 217 ; of milk solids, 113 ;
of sour milk, 229 ; temperature
correction table, 262.
Speed required for complete sepa-
ration of fat, 57 ; ascertaining
necessary speed in Babcock
test, 59.

Spillman's cylinder, 131.
Standard measure for calibrating

test bottles, 50.

Standards for Babcock glassware,
257, 258.

Index.

297

Standards of purity, Government,
for milk and its products, 254.

Starch in cream, 250.

Steam turbine testers, 61.

Stokes' acidity pellets, 125.

Storch's test, 248.

Sulfuric acid, 64; table showing
strength of, 67 ; testing strength
of, 65.

Sweetened condensed milk, Bab-
cock test for. 99.

Swedish acid bottle, 47.

Swedish acid tester, 67.

Tank for cleaning test bottles, 43.

Temperature of turbine testers,
36 ; of fat when tests are read,
36 ; of milk, influence on tests,
152.

Test bottles, 30, 38 ; apparatus
for cleaning, 41, 44 ; calibration,
48 ; cleaning, 41 ; cream, 79 ;
draining-rack for, 42 ; marking,
39 ; skim milk, 92 ; rack for use
in creameries and cheese facto-
ries, 166 ; tank for cleaning, 43.

Testers, 54 ; ascertaining speed of,
58 ; electrical, 63 ; hand, 60 ;
power, 61.

Testing cows, number of tests re-
quired during a period of lacta-
tion, 147.

Testing milk and its products, 1 ;
on the farm, 142.

Test sample, size of, 153.

Tests of cows, official, 150.

Thermometer scales, comparison
of, 282.

Thorner's method, 5.

Total solids in milk, 10; determi-
nation, 221.

Trowbridge method of calibration,
49.

Turbine testers, 61 ; hot, errors in.

Volatile acids in butter fat, de-
termination, 241.

Wagner skim milk bottle, 94.

Waste acid jar, 40.

Water, calibration with, 48 ; deter-
mination of, in butter, 231, 233 ;
in cheese, 243 ; in milk, 220 ;
reservoir for, 70 ; to be used in
the Babcock test, 69.

Waterhouse test, 243.

Watering of milk, detection of,
116 ; watering and skimming, de-
tection of, 117.

Weights and measures, comparison
of metric and customary, 284.

Westphal balance, 219.

Whey, 22; Babcock test for, 94;
chemical analysis, 228 ; composi-
tion, 258; definition, 256.

Winton cream bottle, the, 79.

Wisconsin creamery butter, sum-
mary of analyses, 189.

Wisconsin curd test, the improved,
137.

Wisconsin high-pressure oven test,
for water in butter, 238.

Wollny refractometer, 9.

World's Fair breed tests, compo-
sition of butter from, 188 ; vari-
ation in quality of milk, 153.

Yield of butter, calculation of,
187, and butter fat test, 187 ;
from different grades of milk,
192 ; table showing, from 1 to
10,000 Ibs. of milk, testing 3 to
5.3 per cent., 278.

Yield of cheese, calculation of,
199 ; relation between, and qual-
ity of milk, 200 ; table showing,
corresponding to 2.5 to 6 per
cent, of fat, with lactometer
readings of 26 to 36, 281.

THE "FACILE"

Iron Frame Babcock Milk Testers

FACILE JR. TESTER

Two BoUle

FACILE JR. TESTER
Four Bottle

FA'ILE STEAM TUR

BINE TESTER

36 Bottles

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

Testing Specialties

We furnish everything for the commercial testing of milk and
its products. No other concern makes so varied a line. Among
our specialties we describe the following :

Wizard Turbine Babcock Tester

Made for factory use. Enclosed case ; top turbine 7 inches in
diameter in separate compartment ; center spindle has bearings
at both ends ; friction brake for stopping ; all wearing parts re-
newable. Made for six and nine inch bottles, 12, 24, 32 and 40
bottles, seven sizes in all. Two distinct styles of stands
furnished if wanted, painted or vitrified porcelain enamel.

20th Century Hand Babcock Tester

For dairy use and where steam pressure is not available ; en-
closed case ; long center spindle with two bearings ; top drive ;
wearing parts renewable ; noiseless cut gears : made in 6, 8, 10,
12. and 24 bottle sizes for 6 in. (regular bottles) and in 12, 24
bottle size for 9 in. bottles. We also furnish this tester in
aluminum for travelers' use.

Electric Drive Babcock Tester

Same as Wizard and 20th Century tester except that it is
driven by electric motor mounted on top of case. Furnished in
any regular size, and with motor as required according to the
current used.

"Official" Hand Babcock Tester

For dairymen and travelers. Made to clamp to table or
bench or may be permanently fastened with screws ; bottles set
in deep brass pockets ; noiseless cut spur and worm drive.
Made in two and four bottle sizes.

Hart Casein Test

Hand power, similar to 20th Century tester ; made for six and
twelve tubes. Furnished with all necessary equipment.

Farrington Moisture Test

Wisconsin High Pressure Oven principle. Two styles of oven
furnished ; the Farrington tests from two samples upward at
one time ; Farrington Junior tests a single sample.

The Ames Moisture Test

Paraffine method. Complete outfit consists of jacketed par-
affine container, aluminum sample cup ; high reading thermom-
eter and stand.

C. P. Salt Test

A simple, practical and accurate test for the per cent, of salt
in butter. Furnished complete with full directions for use.

For circulars and prices on the above and other testing ap-
paratus mention this book and address

The Creamery Package Mfg. Co.

SALES BRANCH HOUSES— Write to one nearest you

CHICAGO, 61-67 W. Kinzie St. OMAHA. 113 S. Tenth St. KANSAS CITY, 931 W. Eighth St.

PHILADELPHIA, 1907 Market St. NEW YORK, 47 W. 34th St. WATERLOO IOWA, 406 Sycamore St.

TOLEDO, OHIO, 119 St. Clair St. MINNEAPOLIS, 318 Third St., N. SAN FRANCISCO, 53 California St.

5

Grand Victories

Five Years in Succession
1910 - 1911 - 1912 - 1913 - 1914

NATIONAL DAIRY SHOW

CHICAGO, ILLINOIS

Our Customers took all the First Prizes

for American, Brick and Limburger Cheese

This unparalleled record during the last five years,
shows what the best cheese-makers think of the

Marschall Rennet and Color

WE HAVE THE LARGEST AND ONLY
UP-TO-DATE AND SANITARY REN-
NET FACTORY IN AMERICA, AND
OUR RENNET AND COLOR HAVE
NEVER BEEN EQUALLED.

QUALITY FIRST

The Marschall Dairy Laboratory

MADISON, WISCONSIN

Chr. Hansen's Laboratory

HEADQUARTERS FOR DAIRY PREPARATIONS
UNEQUALED IN PURITY AND STRENGTH

Chr. Hansen's Danish Rennet Extract
Chr. Hansen's Danish Cheese Color

VEGETABLE BUTTER COLOR
and LACTIC FERMENT CULTURE

RENNET TABLETS AND CHEESE COLOR TABLETS
FOR CHEESE-MAKING ON THE FARM|

JUNKET CREAM TABLETS for Ice Cream Manufacturers
JUNKET TABLETS for Dainty Desserts

JUNKET BRAND COLORS and FLAVORS

JUNKET BRAND BUTTERMILK TABLETS
NESNAH, the New Milk Dessert

Chr. Hansen's Laboratory, Inc.

Branch Office: Milwaukee, Wis. Little Falls, N. Y.

New Style Torsion Cream Test Scales

equipped by

"Sliding

Revolving

Tare"

Butter Moisture
and Print Scales.

Cream Test Scales
for one, two, four
and twelve bottles.

Analytical Bal- £~r-

ances and Weights. style NO. 4500

THE TORSION BALANCE COMPANY

Factory and Shipping Address Office

Jersey City, N. J. 92 Reade Street, New York

Pacific Coast Branch: 49 California Street, San Francisco, Cal.

Cream -Weighing Scale

FOR USE fN CONMECTION
WITH THE BABCOCK TES r
'THIS SCALE Is especially designed for
•*• very a curate weighing of cream, bnt-
ler and cheese. All bearings are agate:
plates are porcelain: base and nndercon-
nections are galvanized, making a rust-
proof scale. It has a side bar In front to
balance the t< st b ttle and is provided with
the necessary weights. Base of ncaie 10 1-2
in. long: porcelain plates 3 in. square.

PRICE $10.00

Manufactured by HENRY TROEMNER, 911 Arch St., PHILADELPHIA, PA.

All Text and Reference Books used in
AMERICAN DAIRY SCHOOLS

may be obtained from
MENDOTA BOOK COMPANY, Madison, Wisconsin

SEE LIST ON FOLLOWING PAGE

The Accuracy and Quality of
Nafis Scientific Glassware

have insured its steady use in the
largest Creameries, Cheese Fac-
tories and Condensing Plants as
well as Dairy Schools and Experi-
ment Stations.

When so ordered, Test Bottles and Pipettes
are made in accordance with the specifications
formulated by the U. S. Bureau of Stand-
ards and the various State Laws.

Write for Catalogue

LOUIS F. NAFIS

544 Washington Blvd. Chicago, Illinois

BOOKS

The following books on dairying and related topics will be sent, postage prepaid,

on receipt of the price given

Farrington-Woll, Testing Milk and Its Products,
Twenty-third ed. Madison, Wis., 1915, 304 pp 1 25

Woll, Handbook for Farmers and Dairymen. Fifth ed.

New York, 1912, 488 pp 1 50

Woll, Productive Feeding of Farm Animals. Phila-
delphia, Pa., 1915, 362 pp 1 50

Grotenfelt-Woll, Principles of Modern Dairy Practice.
Third ed., revised. New York, 1910, 286 pp 2 00

Wing, Milk and Its Products. New ed., rev. New

York, 1912. 433 pp 1 50

Fleischmann, The Book of the Dairy. London and New

York, 1896, 344 pp 4 00

Snyder, Dairy Chemistry. New "Fork, 1906, 190 pp.— 1 25

Meyer, Modern Butter-Making. Madison, Wis., 1910,

306 pp. 1 50

Eckles. Dairy Cattle and Milk Production. New York,

1911, 342 pp. 1 60

Larsen and White, Dairy Technology. New York, 1913,

298 pp. 1 50

Michels, Creamery Butter-Making. Lansing, Mich.,

1904, 271 pp 1 50

Russell, Dairy Bacteriology. Fifth ed. Madison, Wis.,

1903, 214 pp 1 00

Conn, Practical Dairy Bacteriology. New York, 1907,

340 pp. 1 25

Gurler, The Farm Dairy. Chicago, 1909, 164 pp 1 00

Decker, Cheese Making. Rev. ed. by F. W. Woll. Madi-
son, Wis., 1909, 211 pp 1 75

Winslow, The Production and Handling of Clean Milk.
Second ed. New York, 1909, 207 pp 3 25

Belcher, Clean Milk. New York, 1903, 146 pp 1 00

Monrad, ABC in Buttermaking. Winnetka, 111., 1900,

68 pp. 50

Monrad, ABC in Cheesemaking. Winnetka, 111., 1900,

68 pp. 50

Schoenman, Butter Fat and Dividend Calculator 2 00

Henry, Feeds and Feeding. Tenth ed. Madison, Wis.,

1910, 613 pp. 2 25

Plumb, Types and Breeds of Farm Animals. New York,

1907, 563 pp. 2 40

Jensen, Essentials of Milk Hygiene. Second ed. Phila-
delphia, 1909, 275 pp 2 00

Craig, Judging Live Stock. Tenth ed. Des Moines,
la., 1912, 193 pp 1 50

King. Physics of Agriculture. Fourth ed. Madison,

Wis., 1907, 604 pp 1 75

Boss, Instructions for Traction and Stationery Engi-
neers. Minneapolis, 1906, 319 pp 1 25

MENDOTA BOOR GO., Madison, Wisconsin

WILL

SFSTsr*3* ON

OVERDUE

SEP
SEP 25 1932

191933

OCT

LD2l-SOm-

355208

UNIVERSITY OF CALIFORNIA LIBRARY