TESTING MILK AND ITS PRODUCTS FARRINGTON AND WOLL This book is DUE on the last date stamped below. JJL* 193V FEB 1 1924 APR 7 1926 MAY 14 NOV 1 5 1929 OCT 1 5 193C 1951 28 ^211947 DEC1819 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 Profettor in Charge. of Dairy School Profeisor of Animal Nutritic UNIVERSITY OF WISCONSIN UNIVERSITY OF CALIFORNIA With Illustrations TWENTY FOURTH REVISED AND ENLARGED EDITION MADISON, WIS. MENDOTA BOOK COMPANY ALL RIGHTS RESERVED COPYRIGHT, 1897, 1899, 1901, 1904, 1909, 1911, 1913, AND 1918 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 givem; 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 be 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 been prepared and are included in the Appendix. Madison, Wis., October 1, 1897. PREFACE TO REVISED 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. 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 CF MILK 137 Chap. IX. TESTING MILK ON THE FARM 142 Chap. X. COMPOSITE SAMPLES OF MILK 160 Chap. XI. CREAM TESTING AT CREAMERIES 176 Chap. XII. CALCULATION OF BUTTER AND CHEESE YIELDS___ 187 Chap. XIII. CALCULATING DIVIDENDS 203 Chap. XIV. CHEMICAL ANALYSIS OF 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- 1005 ^ 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 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. v Table IX. Amount due for butter fat, in dollars and cents, at 12 to 2o 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, con- densaries and city milk plants multiplied, and farm- ers in the dairy sections of our country 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 2 Testing Milk and Its Products. from different sources, or even from the same sources at different times, varies greatly in butter-producing capacity, as will be shown under the subject of cream testing (203 1 ). 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. Wis. Expt. Station, bulletin 12 (see also under 208). 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. The problem of just payment for the milk fur- nished by different patrons at cheese factories, con- densaries and city milk plants is no less perplexing than in the case of gathered-cream factories. By the pooling system formerly adopted, each patron re- ceived payment in proportion to the number of pounds of milk delivered, irrespective of its quality. Patrons delivering rich milk naturally will not be sat- isfied with this system when they find that their milk is richer than that of their neighbors. The temptation to fraudulenty increase 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 difficult to prove any fraud committed, from lack of a reliable and practical method of milk analysis, rendered this pooling system still more ob- jectionable. 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 done 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 1 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,* Parsons' method,' Cochran's test,* the Patrick or Iowa 1 See 48, footnote. 2 Kansas experiment station report, 1888, p. 149. N. H. experiment station jeport, 1888, p. 69. 'Journal of Anal. Chem., Ill (1889), p. 381. Introduction. 5 station test, 1 and the Beimling (Leffmann and Beam) test.* Of foreign methods published at about the same time, or previously, the Lactocrite, 8 Liebermann's method, 4 the Schmid,* Thorner,* Nahm, 7 Rose-Gottlieb, 8 sin-acid method, 9 and the Gerber sal- me'thod 1 ' 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-five years it has now been in almost exclusive use in creameries, cheese factories, condensaries, and city milk plants in this country, where payments are made 1 la. exp. sta., bull. No. 8, Feb. 1890 ; Iowa Homestead, June 14, 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. 0. 4 Fresenius' Zeitschr., 22, 383. 5 Ibid., 27, 4G4. 8 Chem. Centralbl., 1892, 429. T Milch-Zeitung, 1894, No. 35 ; 1897, No. 50. 8 Landw. Vers. Stat., 40, 1. Milch-Zeitung, 1904, No. 27. 'Milch-Zeitung, 1906, No. 8. 6 Testing MUk and Its Products. on the basis of the quality of the milk delivered, 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 several practical milk and cream tests, besides the Bab- 1 For 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-Flechtl, Mllchzeltung, 1896, p. 183 et seq. 'The Babcock test, like the ether-extraction method gives, however, somewhat too low results in the case of skim milk and other dairy products low In fat (97). Introduction. 7 cock test, are in the use at the present time, viz: Gerber' s acid-butyro meter, the sin-acid (or no-acid) test, the lactocrite, De Laval's butyrometer, 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 ,., . , , Fio. 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. 1 la. The sin-acid test was invented by the German chemist A. Sichler and published in 1904. In place of the sulfuric acid used in the Babcock and Gerber tests, Sichler employs a solution of 1 The Lister-Iiabcock 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 Ahllorn-Babcuck and the Krugmann-Babcock methods. 1 Gerber, Die praktiscbe Milch priifung, 7th edition, 1900. 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 ec. 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. Fio. 2. De Laval's butyrometer. , 13. In the De Laval butyrometer (fig. 2) the same acid is used as in the Babcock test, but the tubes employed and the manipulations of the method differ materially from this test; a smaller sample of milk is taken (only 2 cc.) and a correspond- ingly small quantity of acid used. Where a large number of ' 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 tester 1 ( fi g- 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 55C (131F.). 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 7 s^entrlfugal cream outside of these limits the test tester. 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 1. COMPOSITION OF MILK AND ITS PRODUCTS. Before taking up the discussion of the Babcock 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 at manufacturing and distributing plants 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 muk solids or total solids, and the total solids less the fat, i. e., casein, albumen, milk sugar, and ash, are often spoken of as solids not fat or the non-fatty milk solids. The milk serum includes all components of the milk less the fat; the serum solids are therefore another name for the solids not fat; when given, they are, however, generally calculated to per cent, of milk serum, not of milk. If, e. g., a sample of milk contains Composition of Milk and Its Products. 11 nine per cent, of solids not fat, and three per cent, of fat, the milk serum will make up 97 per cent, of the milk, and the serum solids, 9X10 =9.28 per cent, of the milk serum. 16. Water. The amount of water contained in cow's milk ranges from 82 to 90 per cent. Normal cow's milk will not, as a rule, contain more than 88 per cent, of water, nor less than 84 per cent. In states where there- are laws regulating the sale of milk, as is the case in 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 herd 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 wjth 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 varies 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, 100 15.7 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 : C 12 H 23 U H 2 (lactose) =4 C 3 H 6 3 (lactic acid}. 1 Ordinarily the souring of milk is, however, more complicated, and other organic bodies, like butyric acid, alcohol, etc., and gases like carbonic acid are formed, resulting in a 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 (H 2 O). 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. Thr 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 (K 2 O) .19 per ct. 25.64 per ct. Sodium oxid ^Na,O) .09 12.45 Lime (CaO) .18 24.58 Magnesia (.MgO; .02 3.09 Iron oxid (FejO,) .002 .34 Phosphoric anhydrid (P 2 O B )_ .16 21.24 Chlorin (01) .12 16.34 .762 per ct. 103.68 per ct. chlorin__. .012 3.68 Less oxygen, corresponding to " " rin_. .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 separated out by means of Chamberland filters (18), or by long- continued centrifuging (Babcock 1 ). 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. Pat 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 coajrii 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, ice cream and con- densed milk are obtained. When milk is left standing for some time or subjected to centrifugal force, it will separate into two distinct parts, cream and skim milk. The proportion of each part which is obtained, and their chemical composition, will depend on the method by which the separation is effected; in the so-called gravity process where the cream is separated on standing either in shallow pans in the air, or in deep cans, submerged in cold water a less complete separation is reached, and 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 .4 per cent, when obtained by the gravity process, and less than .2 per cent, in the case of separator skim milk. Milk set in shallow pans in the air, or in deep cans in water above 60 P., 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 for the manufacture of cheese and casein. 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 qf 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 not less than 8% fat, and must be free from pre- servatives and other foreign substances (except sugar). Tables are given in the Appendix showing the aver- age composition of the various milk products. Questions. 1. What is the average composition of cow 's milk ; state briefly the properties of the various constituents. 2. What is meant by total solids; solids not fat; milk serum; serum solids f 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 tost 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 ce.) 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 J^Q 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. $2. 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- fore interfere with its being tested by the Babcock test or with the accuracy of the results obtained. In order to facilitate the sampling of sour or lop pered milk, some chemical may be added which will re- dissolve the coagulated casein and produce a uniform mixture that can be readily measured with a pipette. Any alkali (powdered potash or soda, or liquid ammo- nia) will produce this effect. Only a very small quan- tity of powdered alkali is necessary for this purpose. The complete action of the alkali on sour milk requires a little time, and the operator should not try to hasten the solution by adding too much alkali. An excess of alkali will often cause such a violent action of the sul- furic acid on the milk to which the acid is added (on account of the heat generated or the presence of car- 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. lOfi. Testing Milk 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 milkf Give reasons. 2. How can a fair sample be taken of (a) partially churned milk, (b) sour milk, (c) frozen milkf 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 milkT 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 niilk 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 FIG. 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 with. 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- pjstte 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 .S.Babcockmllk 11 P 1&Ced in the Deck f 9 Fio. 6 test bottle. Babcock test bottle (fig. 5), 17 p 6 et c t c e p1 ' 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 FIG. 7. The right way of emptying the milk is allowed to pipette into test bottle. run into the test bottle. 37- Adding acid. The acid cylinder (fig. 9) hold- ing 17.5 cc., is filled to the mark with sulfuric acid 01 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- ^ 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 on this small portion of the milk, and thus char the fat contained therein. The appear- ance of black flocculent matter in or below the col- umn of fat which generally results, in either case renders a correct measurement difficult and at times even impossible; if the black specks occur in the fat column itself, the readings are apt to be too high; if below it, the difficulty comes in decid- ing where the column of fat begins. 38. Mixing milk and acid. After add- ing the acid, this is carefully mixed with the milk by giving the test bottle a rotary motion. In doing this, care should be 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 sulfurie acid on the nitrogenous constituents and the sugar in the milk. 34 Testing MUk and Its Products. Colostrum milk or milk from fresh cows will form a violet colored mixture with the acid, due to the action of the latter on the albumen present in such milk in considerable quantities (23). When milk samples are preserved by means of potas- 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 j the fat. 41. Measuring the fat. The amount of fat in the neck of the bottle is measured by the scale or graduations on the neck. Each division of the scale represents two-tenths of one per cent of fat 2 and the space filled by the fat shows the per cent, of butter fat contained in the sample tested. FIG. 10. Measuring the The fat is measured from the Babcock "test* "botXe. & lower line of separation between the fat and the water, to the top of the fat column, at the point 6, shown in the figure, the reading being thus taken from a to 6, and not to c or to fl. Comparative See under 204. 2 One-tenth of one per cent, in rase of 8 per cent, bottles. 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% bottles (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 P. ; too low results will be obtained if the fat is allowed to cool below 120 P., and too high if readings are taken above 150. The fat separated in the Babcock test solidifies at about 100 P. 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 mado, this difference of 40" P. (22.3 C.) would mane 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 dojiree Centigrade between 50 and 100 The Babcock Test. 37 42. Readings of tests of milk made in steam turbine testers with tightly closed covers which prevent the free escape of exhaust steam (71), will come .2 to .3 per cent. 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 b 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. (Zvne, Analyse des Beurres, 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 Its 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 to 10 per cent. 10 per cent, of 18 grams is 1.8 grams. As the specific gravity of pure butter fat (i. e., its weight compared with that of an equal volume of pure water) at the temperature at which the readings are made (about 140 P.), is 0.9, then 1.8 grams of fat will oc- cupy a volume of iv8=2 cubic centimeters. The space between the 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. 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 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 lost, 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 Jd.Hk 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 precipitate 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 L . _ r~ rv- ~~ ^ ^ e bottles should occasionally be wiped clean and dry. 47. The amount of unseen fat that clings to test bottles used FIG. 14. Draining rack for test bottles. . for testing milk or cream, is generally not sufficient to be noticed in test- ing whole milk, but it plays an important part in test- ing samples of separator skim milk. It may be readily brought to light by making a blank test with clean water in bottles used for testing ordinary milk, which have been cleaned by simply draining the contents and rinsing once or twice with hot water; at the conclusion of the test the operator will generally find that a few 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 occasional bath in some weak alkali or other grease-dissolving solution. Persons doing con- siderable milk testing will find it of advantage to pro- vide themselves with a small copper tank, fig. 15, which can be filled with a weak alkali-solution. After 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, Lewis' 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 FIQ 15 Tank for c]eanlnjr t * 1 See Wis. exp. station, report 17, p. 81. 'First constructed by Mr. J. J. Nnssli.nnmer, of Illinois; now manu- factured by various flrron. Babcock Test for other Milk Products. 93 one per 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 skim 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 tester they should be put with the filling tube toward the center, so as to avoid any of the fat being caught between this tube and the side of the bottle when it resumes a verti- cal position. i AVisc. exp. sta., bull. 52; Penna. exp. sta., repot-t 1896, p. 221. 94 Testing Mtik 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 (See fig. 38.) 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- *A double-necked copper test bottle with a detachable graduated rlass neck was designed and tried by one of us a few years ago, but It was not found to possess any special advantage over .the glass bottle. FIG. 38. The double-bore kim 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 ccols, 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 Babccck test can be used with only 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. Fairly accurate results can only be obtained by taking great care in all the manipulations, especially in weigh- ing the butter and in reading the fat at the proper tem- perature. Small errors in making tests have a marked influence on the results, because the butter fat is such a large per cent of the butter. Tests should always be made in duplicate, and even then results are only approximately correct. 2 1 See bull. 154, Wisconsin exp. sta., p. 10. * 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. 58b) is at-Jhand 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. For inspection purposes the rind may be rejected, but for investi- gations, where the absolute quantity of fat in the cheese is required, the rind shouLl be included in the sample. 1 The following method of sampling cheese is recommended. 105. Draw a plug from a sound portion of the cheese with a cheese trier; this should be taken at a point that is not near the rind, a cut surface of the cheese, a de- fective spot or an old trier hole. Cut off the top one-half inch of the trier plug and replace it in the trier hole to protect the cheese ; then cut the plug of cheese length- wise into four pieces and slip two of these into the neck of a cream test bottle which has been previously weighed empty. After adding 8 to 10 grams of the cheese in this way the test bottle should be weighed again and the exact weight of cheese taken for testing is obained by sub- traction. 10 ec. of boiling water is then added to the test bottle by using a- wide tipped pipette, and acid is added im- mediately in portions of about 1 cc. each at first, shak- ing the bottle for a second after each addition of acid. on the market, e. g., the Wagner Butter Test Bottle and the form Bug- srested by H. R. Wright, given in the 18th report of the Iowa Stnt- Dairy Commissioner, 1904, p. 40. 1 TL S. Dept. of Agriculture, Chemical Division, bull. 46, p. 37. 7 98 Testing Milk and Its Products. This method of adding the acid gradually to the hot water and cheese in the test bottle produces a temper- ature high enough to melt the cheese immediately so that the test bottle may be placed in the centrifuge at once and the fat separated and measured in the usual way for testing cream. 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. TTunxiker 2 recommends adding hot, dilute sulfurk- ?i<-il 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. 1 Ind. erpt. 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 using the methods given for testing ice cream. The Mojonnier Tester. This is an apparatus de- signed especially for determining butter fat and total solids in condensed milk, ice cream, milk powder and other dairy products. It is based on the Rose-Gottlieb method (254). The manipulations of the method are much facilitated, and the time required for making the determinations are greatly reduced, by the use of this tester which includes a chemical balance, electric ovens, hot plates, motors, etc. 108. Ice cream. Methods for determining the per cent, of fat in ice cream have been worked out by Holm, 2 Howard 3 and others. On account of the ten- dency of ice cream to foam when melted, it should be mixed carefully by pouring a number of times from one l 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. o C. P. sulfuric acid, and proceeding as given above (Amott). 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, 1906, p. 50. s Journ. Am. Chem. Soc., 1907, p. 16. Methods of analysis of ice < roam have also been proposed by White, (Penna. exp. sta., rept. 1910, p. 243), Baird, (N. Y. Prod. Rer., Feby. 26, 1913), and Halvorsen. s., this can will hold a smaller weight of water, say 100 Ibs., as milk is heavier than water; the specific gravity of this milk will then be ~ =1.032. 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 IDS., 1 gal. of milk will weigh s.34Xl-32 or 8.6 Ibs. : 1 gal. of skim milk, 8.7 IDS., and 1 gal. of cream from 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. 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, 1.0345X10001000= 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-f-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 warmed or cooled, if need be, so that its temperature does not vary ten degrees either way from 60 degrees P, 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 P. 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 P., 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 P.; and 34.0 at 52 P. will be about 34.0 .8=33.2 at 60 P. 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.* 115. Reading the lactometer. For determining the specific gravity of milk in factories or private dairies, tin or copper cylinders are recommended, l 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. Chem., 1911. p. 40fi). 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 r IG. 4U. Hp6- contact with the lactometer stem will rise erne-gravity cylinder. 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 (Beck- nagel's phenomenon}.* 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 Milchztg. 1883, 419 ; bull. 43, Chem. Div., U. S. Dept. of Agriculture, p. 191 ; Analyst, 1894, p. 76. See also Flelgcbmann and Wlegner, Jr f. T,dw.. 1913, pp. 283-828. 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-chromate, corrosive sublimate, etc., is added to milk samples to preserve them from souring (190), the specific gravity of the milk will be increased; with the quantity usually added (y 2 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- loff 1 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, or when a few drops of formaldehyd are used as a 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 P. of solutions thus ob- 'Technlk dor Milchfriifung, p. 98. The Lactometer and Its Application. 109 tained are 1.022, 1.029, and 1.036, for 3, 4, and 5 per cent, solutions, respectively. CALCULATION OF 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, Pleischmann, Hehner and Eichmond, Richmond, Bab- eock) 1 are very involved, and require rather lengthy calculations, tables facilitating the figuring have been prepared. The formulas in rise at the present time, in this country and abroad, are those proposed by Pleisch- 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 to 6 per cent. The formula, as amended in 1895, 2 is as fol- lows, S being the specific gravity and / the per cent, of fat in the milk. Solids not fats = -l(100-f)2.5 Agricultural Science, vol. Ill, p. 139. Wisconsin rxporimont station, twolfth roport. 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=J4 L -f .2 f Total solids=:% L + 1.2 f , L being the lactometer reading at 60 P. (specific gravity X 1000 1000), and / the per cent, of fat in the milk. Rule: 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. 121. Methods of adulteration. The problem of de- termining whether or not a sample of milk is adulter- ated becomes an important one in the work of milk in- spectors and 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 or high per cent, of solids not fat, it is skimmed; if the fat and solids not fat are below nor- mal, it is watered; and if both these percentages are abnormally IOAV, the sample is most likely both watered and skimmed (126). ] Dairy Chemistry, p. 69 (second ed.) 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- Blythe, Foods, 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 = 100 s-100 * s S being the sp. gr. of the milk solids, a 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 ^!l^gz!?2_ =3.101; 13.0-3.101=9.899; ^^ =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, 3=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 - - 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 -.ontains 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 0.00 13, the figure 3.316, which is the value for 10 8 ~ 100 when s=] 0343. Introducing this value and that of the total solids in the formula, the calculation is 12.25 3.316=8.934; 12.25-f- 8.934=1.37, which is the specific gravity of the solids in this case, 726. 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 th( 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 Mows the milk is sp. gr. of milk i \ fat and solids not fat \ l01 I watered sp. gr. of solids normal j sp. gr. of milk and of solids__ - , . , ) solids not fat. } hlgil \ skimmed fat and solids low J 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 iti 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: ^y ion r=10 -~iegal standard for fat 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-, 3 S ?i 100 ,. (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 -^g =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 -g -100 (IV) In the example given above, 1 -^- 9 100=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 MUk Products. 117 ascertained by means of formula (III) or (IV), ana the fat abstracted found according to the following formula : Per cent, fat abstracted= 3 f A l e g- stand, for sol. not fat leg. stand, for fat Xf . . (V) o Example: A. sample of milk contains 2.4 per cent, of fat and 8.1 per cent, solids not fat; then Extraneous water in milk=100- JLl^M. =10 per cent. Fat abstracted=3 -^~- =.33 per cent, or 11 per cent of total fat in milk. 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? H. 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 P. 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, the amount of acidity found in milk fresh from the cow or nearly so is on the average about .07 per cent. 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 clay 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, 1. 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 d6 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 P., 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. Chemle, 1872, p. 6, 19. Testing the Acidity of Milk and Cream. 121 worked out by Soxhlot an dITenkel has since been in general use by 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 solution 1 (see below). In this country, Dr. A. G. Manns in 1890 pub- lished the results of work done in the line of testing the acidity of milk and cream, 2 and the method of pro- cedure and apparatus proposed by him has become known under the name of Manns' test, and is being advertised as such by dealers in dairy supplies. 131. Manns' test. The acid in milk or cream is measured by using an alkali solution of 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 solution 8 of caustic soda is the alkali solution used most frequently in de- 1 Klrisohmiinn. I.plirb. d. Milchwirtscbaft, 3rd ed., p. 57. 1 Illinois experiment station, bulletin 9. s Xormal 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 (NaOlij is made up of an atom each of pndimu (Xa), oxygen (O), and hydrogen (II) ; 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 cj. : a one-tenth normal solu- tion will contain one-tenth of this amount of soda, or 4 g~a~s 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 CsHeOs (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 phenolphtalein, a light yellowish powder; its compounds with alkalies are red, in weak alkaline solutions pink colored, while its acid compounds are colorless. The phenolphtalein solu- tion used is prepared by dissolving 10 grams in 300 cc of 90 per cent, alcohol (Mohr). 132. In testing the acidity of either milk or cream it is necessary to 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- Fl ' Vn MiSSS' Pa t2t. n8ed 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 would be 32x - 009 XlOO=.58 per cent. A / oO 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-f-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-=-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 oont. 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.* 135. The alkaline tablet test. Solid alkaline tab- lei s 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 50tb 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. * Derarrta'* nciilinieler (Mik-hzeitung 180(5. p. 7S5) is based on the same principle as Manns' tost: one-tenth soda solution is added to 100 cc. of milk in a glass-stoppered granulated flask. ^ cc. of a 4 per cent, phenolphtnlein solution being used as an indicator. The graduations on the neck of the flask give the "degrees acidity" directly. 1 Illinois oxperimcnt station, bulletin 3'J, April. 1894. Testing ike 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'sSaurepillen (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 Fio. 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 oxfimino The tablets are sold by dealers in dairy Milchzeitung, 1895, pp. 513-16. wpplit 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 6c. 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, Hoard's Dairyman, Sept. 8, 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 per cent, of acidity directly, without tables or calculations, but being weaker, the unavoid- able errors of determination are decreased by its use. Since a 17.6 cc. pipette is found in creameries and dairies with the Babcock test outfit, no new apparatus is necessary for making the acidity test in the manner given. 140. The preparation of the standard solution is as follows: Five tablets are placed in the 100 cc. cylinder which is filled to the 97 cc. mark with clean soft water. 2 The cylinder is tightly corked, shaken and laid on its side, as the tablets dissolve more quickly when the cyl- inder is placed in this position than when left upright with the tablets at the bottom. Several cylinders con- taining the tablet solution may be prepared at a time; as soon as one is emptied, tablets and water are again added, and the cylinder is corked and placed in a hori- * Illinois experiment station, bulletin 32 ; Wisconsin experiment sta- tion, bulletin 52. * 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 may be depended upon to be accurate. Testing the Acidity of Milk and Cream. 129 142. Making the acidity 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 '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. I 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 Bach 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 represehts 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. 'Chicago Dairy I'rodm-e. April 21, 1900, p. 30 ; Iowa expt. sta., buK 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. _: Tn shaking the graduate, give it a rotary motion J?IQ. 43. gpili- to prevent .spilling any of the liquid. Continue *' B ln cyl !,?| adding the tablet solution until a permanent pink mining the acid- color can be detected in the milk. The level of y , k 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. Tt 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 Tt is used with a tenth-normn 1 alkaline Washington experiment station, bulletin 24. ' SPP Wig. exp. sta.. bnll. 129. 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 1 icing graduated to two-tenths cf one cc. The burette is filled by tipping tlie bottle and the surplus of the "neutrali/er" 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, FKJ. 44. The Marschnll 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 & Ounce Bottle. "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., 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 twice 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. ^35 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- ple tested. 1 150. b, Cream. Cream can be tested in the way al- ready described for testing the acidity of fresh milk, by adding to one measureful of cream in the cup as many measures of tablet solution as are necessary to change the color of the cream when the two liquids are thor oughly mixed. If one measure of tablet solution colors one measure of cream, this contains less than .1 per cent, acid; if five measures of tablet solution are re- quired, the cream contains about .5 per cent, acid, etc. By proceeding in the manner described, the operator can estimate the acidity to within .05 per cent, of acid, if half measures of tablet solution are added. The re- 1 In European creameries and city milk depots the alcohol test is often applied to every can of man received ; milk that is sufficiently sour to be noticed by the taste, will coagulate when mixed with an equal folume 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 cent; two packages of square paper; one glass of about 10 cc. capacity, and one small glass bottle. An investigation of these "Tabs" soon disclosed the fact that they were entirely inaccurate, and that no dependence could therefore be placed on the results obtained by their use. Questions. 1. Tf 20 cc. cream require 12 cc. alkali for neutralization, what per cent, acid in the sample t 2. If 1 cc. -^- 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 f 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. Tf cream testing 20% fat has an acidity of .6%, what will be the correppon' u? acidity of cream testing 40% fatt CHAPTER VI11. TESTING THE PURITY OF MILK. 153. The Wisconsin curd test. Cheese maken. 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 ; Slats, Unters. landw. wicht. Stoffe, 1903, p. 140. * Wisconsin" experiment station, twelfth report, p. 148. The appar- atus used for the test was greatly improved in 1898, and a description of the improved test is given in bulletin No. 67 and the annual report of the Station for 1898 (fifteenth report, 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 P. 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 PIG. 46. Cross-section of the Wisconsin curd test, T.T-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 pall. 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 tke 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. *55> 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. 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 j j- 11 * x Fi 47> - Thp Orher fermentation test, two-thirds full of water; the temperature of the water is kept at 104-106 P., for six hours, when the rack is taken out, the tubes gently shaken, and the appearance of the milk, its odor, taste, etc., carefully noted in each case. The tubes are then again heated in the tank at the same tem- perature as before, for another six hours, when observations of the appearence of the milk in each tube are once more taken. The tainted milk may then easily be discovered by the abnormal coagulation of the sample. According to Gerber, 1 good and prop- erly handled milk should not coagulate in less than twelve hours, when kept under the conditions described, 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 FIG. 48. The Monrad rennet test wa ter. 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 coagulating the milk is shown di- rectly by a Scale On the FlG - 49 - Thc Marschnll rennet test. inside wall of the cup (see fig. 49). 1 Decker, Cheese Making-, Revised ed., 1909, p. 39. 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 Cooke 1 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 1800. p. !>< : Woll's Hand- book for Farmers and Dairymen, Fifth od.. p. 2.",0. 144 Testing MUk and Its Products. and the milk sugar and ash content increases but little (about .69 per cent.) within the range given. 6. A test of only one milking may give a very erro- neous impression of the average quality of a certain cow's milk. A composite sample (see 179) taken from four or more successive milkings will represent the average quality of the milk which a cow produces at the time of sampling. 161. The variations that may occur in testing the milk of single cows, are illustrated by the following fig- ures obtained in an experiment made at the Illinois ex- periment station, 1 in which the milk of each of six cows was weighed and analyzed daily during the whole period of lactation. Among the cows were pure-bred Jerseys, Shorthorns and Holsteins, the cows being from three to eight years of age and varying in weight from 850 to 1350 Ibs. During a period of two months of the year 2 the cows were i'ed 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. 'See 175. Testing Milk on the Farm. 145 Average results obtained in weighing and testing a milk daily during one period of lactation. Daily milk Test of Yield of fat yield one day's milk per day MONTH 1 Id & !R ^ |j IN 11 "8 a I . >~ ^ * I si ^ it ^5 ^ M 13 ^ W S ! n a - ^ C ' ^ H )3 920 12 1 16 10 3 8 4 9 3 46 60 34 927 16.0 17.7 14.0 3.7 4.6 .59 .76 .44 February 1035 1047 16.1 14 3 17.7 16 13.5 12 5 5.8 4 7 fl'l .58 54 .84 61 .51 50 March April 1054 13.8 16.5 11.5 4.0 5.8 g3.0 .55 .72 .46 May- 1079 1105 14.5 12 1 14 10.0 9 2 3.8 3 g 4.6 4 6 I''* .55 47 .70 57 .44 35 July 1180 9.3 12.2 6.0 4.2 6.2 9 .39 .60 .27 1130 6.4 9.3 3.5 4.7 7.9 1.2.9 .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 -=- 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 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 tell from the tests made, if these are continued for several days, whether or not the cows are in a normal healthy condition or have been subjected to excitement or abuse in any way. 165. Number of tests required during a period of lactation in testing cows. The daily records of the six cows referred to on page 142 furnish data for com- paring their total production of milk and butter fat dur- ing one period of lactation, as found from the daily weights and tests of their milk, with the total amount calculated from weights and tests made at intervals of 7, 10, 15 or 30 days. The averages of all results ob- tained with each of the six cows show that weighing and testing the milk of a cow every seventh day gave 98 per cent, of the total milk and butter fat, which according to her daily record was the total product. Tests made 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 butter fat. Selecting every thirtieth day of her record as testing day, the total production of milk and fat is shown to be as follows: Production of milk and butter fat per day. Testing day Weight of Milk Test of milk Yield of butter fat Nov 4 20.5 4.7 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 4.4 .81 May 2 17 7 4.8 85 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 the 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 8 " 8-10" " " 6^-7% mos. after calving 6 -7 " " 5^-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. 1 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 sunnner-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 lie taken (,10'J). "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 placed on the market, but so far as known 1* IG. oU. .Milk scnie. 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 cows 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 or for a week. If continued for a week, the jars will contain at the end of this time a mixture of the milk of fourteen milkings. The composite sample is then carefully mixed by pouring it gently a few times from one jar to another, and is tested in the ordinary man- ner. The result of this test shows the average quality of the milk produced by the cow during the time the milk was sampled. As the amounts as well as the quality of the milk pro- duced by single cows vary somewhat 'from day to day and from milking to milking, it is desirable in testing single cows, especially when the test includes only a few days, to take a proportionate part (an aliquot} of each milking for the composite test sample. This is easily done by means of a Scovell sampling tube, the use of which is explained in another place (183), or by a 25 cc. pipette divided into _1 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 " 4.5 " 3.8 " July 18, 1893 47 " 4.4 " 3.8 " July 19, 1893 46 " 46 " 37 " 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 Pleischmann, 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- age b^y 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+ ^ X 4.0=5.2, or may go below 2.8 per cent, (viz., 4.0 ^ 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+ T y> X31=34.1; 31 jiA, x 31=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 co'w, 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 l For further data on this point, see Cornell (N. Y.) exp. sta. bulle- tins 13, 22, 36 and 49; N. D. exp. sta., bull. 16; Kansas exp. sta., re- port, 1888 ; Hoard's Dairyman, 1896, pp. 924-5 ; W. Va. exp. sta., b. 109. - 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 of improving the qual- ity of the milk produced by our cows. It may be well in this connection to call attention to the fact that the quality of the milk which a cow pro- duces is only one 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 milkf 4. Between which limits is the test of milk of single cows and of a herd likely to vary? 5. Will it introduce any error in the test of a cow's milk to measure out the sample directly after milking ?If so, how much? 6. How many times should the milk of a cow be weighed and tested to calculate the total production of milk and butter fat by the cow during a whole period of lactation! 7. What is an official test of a cow? 8. How does the test, as a general rule, change during the first couple of 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 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 aklng test samples at ta-takc. samp , es . & Uge of tin dipper. Either pint or quart fruit jars, or milk bot ties provided with a cover, are used for receiving the daily samples. One of these jars is supplied for each '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 thp 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 milk 2 (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 Scovell representing exactly the quality of the milk saSmKng 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 J A recent Wisconsin law (Chap. 99. laws of 1907) provides that hi sampling cream or milk from which composite tests are to be made to determine the per cent of butter fat therein, no such sampling shall be lawful, unless a sample be taken Irom each weighing, and the quantity thus used shall be proportioned to the total weight of cream or milk tested. 2 Kentucky experiment station. Sth 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 2 inch, the quan- tity of milk secured in the tube will always stand in the ratio to that of the milk in the pail, of (i/ 2 ) 2 to 8 2 , 1 that is, as 1 to 256, no matter how much or how little milk there is in the pail, the sample will represent _L 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 n cylinder are represented hy the formula ^ r ! h. r being the radius of the cylinder, and 7? Its height. The relation be- tween two cylinders of the same height, the radii of which are It and r. Is therefore as 1J K 2 h to rh. or as I{* to r 2 . Composite Samples of Milk. 1U5 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. 1 86. 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 \\ill 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 e Scovell omposite sample 4.0 per cent. 4.0 per cent. 4.04 per cent. 4.06 per cent. tube composite sample 187. d. The McKay sampler (fig. 53), constructed by Professor (>. L. McKay, formerly of I own 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. Ei'kli s in lireeder's Gazt-tt-', May 19, 1897. 1 See also 199 et siq. K;G 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 PI ' ?ampr e McKa> ' 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 there are patrons; there is no 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 f 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 M.^lk 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 % inch long, or a .32-inch caliber shell i/4 inch long, when loosely filled, will hold enough pow- dered bi-chromate to preserve y 2 pint, and a .32-inch caliber shell % i neh lon g will hld 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. "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 lrn-a 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, Ix2i^> 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, vrhich 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 1 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. Mil) s varying and test in weights i II. Mil k of unifo and tests rm weight s Lot ij i! jj Lot I! 1* |3 = I Ibs. 120 per ct. 5 Ibs. 4 2 I Ibs. 250 per ct. 4 2 Ibs. 10 5 II... 570 5.0 28.5 II... 225 4.0 9.0 Ill 360 18.7 Ill 240 4.3 10.3 IV 55 3 1 6 IV 238 4 1 9 7 V... 82 4.0 3.2 V 234 4.4 10.3 Total 1187 56.2 Total 1187 49.8 ' Average True average test 237 4.14 4.73* 11.24 Average True average test 237 4.20 4 22 10.0 '56.2X100 .,, 1187 =473 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 1 In the experiment srivcn <>n p. 14S, the arithmetical mean of the tests is 5.15 per cent., wliilp 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 vras to show him that while 5.1 was the correct average of the figures representing the tests of his twenty-one cows, it was not a correct average test of the mixed milk from all his cows, as he had not considered, in calculating this average, the quantities of milk yielded by each cow; the following illustration was used: Cow No. 1, yield 25 Ibs. of milk, test 3.6 per cent, =0.9 Ib. of butter fat. Cow No. 2, yield 6 Ibs. of milk, test 5.0 per cent, =0.3 Ib. of butter fat. Total 31 Ibs. 2)8.6 1.2 Ibs. 4.3 per cent The two cows gave 31 Ibs. of milk containing 1.2 Ibs. of fat; the test of the mixed milk would therefore not be 4.3 per cent. /3.6+5.0\ but 1.2X100 _ g 8? ccnt , f fhe fat j n the mixe( , \ 2 / 31 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 -^^ =4.56 per cent, of fat, and the night milk, 4 -^ =3.80 per cent, of -fat. The sum of the morning and night milkings gave: milk, 244.2 Ibs., fat 10.15 Ibs. The mixed morning and night milk, there fore, contained 10 ' 2 ^ X 2 100 ^-4.1 per cent, of fat. This is the true average test of the morning and night milkings of these twenty- one cows, as found by weighing and testing separately the milk of each cow at both milkings. The total milk was strained into a large cav at the farm, both in the morning and in the evening. A sample ^f 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 fained by the different methods of sampling. Questions. 1. What is a composite sample of milkt 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 following methods of sampling 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 f Mention the more common preservatives usetl and quantities to be added. CHAPTER XL 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, except that tests are made of each lot of cream and -not of composite samples. This method has now largely replaced those formerly used for this pur- pose, such as the oil -test churn or the space (or gauge) system. 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, 1 Bartlett, 2 Lindsay, 3 and Hunziker. 4 201. The space system. The space is the volume of a cylinder, 8V> inches in diameter and 10 of an inch , ' 64 high. The number' of spaces in each can of milk is read off before skimming by means of a scale marked on a strip of glass in the side of the can. Numerous tests have shown that one space or gauge of cream does not contain a definite, uniform amount of fat. In over 100 comparisons made by "Winton it was found that one space of cream 5 contained from .072 to .170 Ib. of butter 'Conn, exprrtment station (New Haven), bull. 108 and 11!); report l?94, pp. 214-244. * Maine experiment station, bull. 3 and 4 (S. S.) * Ilntch experiment station, report 1894, pp. 02-103: 1805, pp. 67-70. 4 Indiana experiment station, cir. 42. 6 Conn. exp. sta.. bull. 119. Cream Testing at Creameries. 177 fat, or on the average .13 lb., and the number of spaces required to make one pound of butter varied from 5.01 to 11.72. It is also claimed that in the winter season when cream is gathered at long intervals, like once a week, it is necessary for the buyer to accept the seller's statement 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) was formerly used quite extensively a m o n-g gathered-cream fac- tories ; this system is based on the number of inches of cream which the various pa- trons 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 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 Inches, and two inches in n 8%-inch pail 113.49 cubic inches. 12 FIG. 56. The oil-test churn. was supposed to make one 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 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 Fahr., where they are left for at least ten minutes to melt the butter and "cook the butter milk into a curd." 'The oil 'will now be seen mixing through the mass. The test tubes are then 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 F., 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 en 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 churnable 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. 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 creameries in this country. On account of the great varia- tion in both the richness and the acidity of farm separator cream it has been found in practice that com- posite samples of cream are not so satisfactory to either buyer or seller as the testing of a sample taken from each lot of cream gathered. The following method of collecting and sampling cream is now commonly used by creameries. 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), collecting bottles (5), and a record book. At each patron's farm he takes from his wagon the sampling pail and tube, the scales, and one small collecting bottle. He should find in the dairy of the patron the cans of perfectly sweet cream, kept at a temparature of 40 to 50 degree F., and protected from dirt and bad a 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 23 per cent, of butter fat in the cream. Testing Cream at Creameries. 181 odors. 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 the dial will stand at zero 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 FIG. 58. Outfit for cream testing jred- cream factories. by the Babcock test at gather 205. Thin, sweet cream is comparatively easy to mix, either by pouring or by using a tin stir- rer attached to an iron rod about, two feet long. Many lots of cream, however, are thick and sour when the cream gatherer col- lects them, and satisfactory weigh- samples can only be obtained by repeated mixing by pouring; in some cases it is necessary to warm the cream and even to pour it through a strainer to get a uniform mixture. 'The necessity of care in mixing the cream is shown by the follow- ing illustration given by the authors referred to. Percent of /at in cream which stood for 24 hours. Sample drawn FIG. 58a. Crear ing pail. Surface. Bottom. Not mixed 28.00 5.00 Poured once 23.75 22.00 roured twice with sampling tube. 19.25 22.50 22.25 182 Testing Milk and Its Products. J8b. Cream sample bottles. After mixing as well as possible, each lot of cream is poured into the cream- f(l A I weighing pail (Fig. 58a), from which a sample for testing is taken by means of a sampling tube of about one-half inch diameter. This tube is emptied into a num- bered bottle (Fig. 58b) in which the cream is kept Until tested. The weighing pail is sometimes cleaned after emptying, by using a rubber scraper and the tube must be completely drain- ed and cleaned before another lot of cream is sampled. A combined stirrer and sampler is sometimes used in- stead of the sampling tube. 206. T ne samples of cream in the small bottles, be- sides furnishing the means of testing the richness of the cream, give the creamery man an opportunity to in- spect the flavor of each lot of cream, and the condition in which this has been kept by the various patrons. If the cream samples are tested soon after being collected no preservative is needed and the cream left after fil- ling the test bottles may be saved, but if the samples must be kept sometime before testing, a small quantity of some preservative (193) should be added to the samples to keep them in as good condition as possible until they are tested. Testing Cream at Creameries. 18^ The samples are tested by weighing either 9 or ] 8 grams of the carefully mixed sample into cream-test bottles, as explained in chapter IV (91). 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. FIG. 58c. Cream sample bottle case. 208. When this system of Vesting cream 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 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. 184 Testing Cream and Its Products. 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. 209. Small 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 standing for a time before being set, or submerged in the creamer immediately after milking and straining, diameter of creaming cans, etc. Bartlett states 1 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, but even though the separator can be regulated to deliver cream of nearly uniform richness from all kinds of sweet milk, considerably var- 1 Bull. 3 (S. S.), Maine experiment station. Testing Cream at Creameries. 185 iatidns in the richnes of the cream from the same farm may occur because of variations : 1, in the speed of the separator bowl; 2, the temperature of the milk; 3, the rate of the flow of milk into the separator bowl, and 4, the amount of water or skim milk used to flush out the bowl when through skimming. 210. At creameries where both milk and cream are delivered, somewhat of an injustice is done to patrons de- livering cream, by paying for the amounts of butter fat furnished by the different patrons, since the milk patron receives pay for all the fat in the milk including that in the skim milk. 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 concerned 3 (239). 211. Gathering and sampling hand-separator cream. A still more satisfactory method is to provide separate cans for each patron, the cream gatherer leav- 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 * Spillman (Dairy and Creamery, Chicago, April 1, mends the use of the factor 1.044. This subject is discussed in detail in the 17th annual report of Wis. experiment station, pp. 90-92 ; see also the 20tb report of that Station, pp. 130-31. 186 Testing Milk and Its Products. and relieves the cream gatherer of all these details 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 testt '2. Describe the method of testing cream by the Babcock test nt 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 water, curd, ash salt and ash Average of 350 analy- Per cent Per cent Per cent Per cent Per cent ses 11.57 84.70 .95 2.78 15.30 Lower and upper lim- its 8.63-15.00 76.53-88.26 .50-2.14 1 01-8 58 Analyses of fifty samples of creamery butter taken in 1896, from the tubs ready for market at as many Wis- consin creameries, showed that no two of them were ex- actly alike in composition, but varied within the limits given on the following page :* Wisconsin experiment station, bul'. 5t5. Calculation of Butter- and Cheese Yield. 189 Summary of analyses of Wisconsin creamery butter. Sum of Salt and water, curd, \Vater Fat Curd ash 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 12.77 88.03 1.28 2.87 16.92 The preceding analyses shew 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, more butter than there was butter fat, since 83 : 100 : : 100 : x ; therefore 100X100 x= =120.a. 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 percent., but will never exceed 25 percent., un- less 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, in the condition of the butter when the churn is stopped ; and in the manner of working the butter ; 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 4.0 " " " 100 " " " 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 under good management (219). Fat available for butter in different grades of milk. Grade of milk Whole milk Skim milk Butter milk Waste Total loss Fat available forj [ butter 2.5 per cent Fat. . 4000 Ibs. 2.5 per ct. 3400 Ibs. .1 per ct. 400 Ibs. .3 per ct. Lbs. 3.0 Lbs. 7.6 Per_ct. 92.4 IOC Ibs. 3.4 Ibs. 1.2 Ibs. 3.5 per cent Fat 2857 Ibs. 3.5 per ct. 2429 Ibe. .1 perxct. 286 Ibs. .3 per ct. 3.0 6.3 93.7 100 Ibs. 2.4 Ibs. .9 Ibs. 4.0 per cent Fat 2500 Ibs. 4 per ct. 2125 Ibs. .1 per ct. 250 Ibs. .3 per ct. 3.0 5.8 94.2 100 Ibs. 2.1 Ibs. .71b. 6.0 per cent Fat- 1666% Ibs. 6 per ct. 1417 Ibs. .1 per ct. leribs. .3 per ct. 3.0 4.9 95.1 100 Ibs. 1.4 Ibs. .Sib. The table shows that with 2.5 per cent.-milk, there is a loss of 3.4 Ibs. of fat in the skim milk, a loss of 1.2 Ibs. of fat in the butter milk, and of 3.0 Ibs. in the creamery waste, for every 100 Ibs. of fat in the whole milk, or a total loss of 7.6 Ibs. from these sources. In case of 6 per cent, milk these losses are 1.4 Ibs., .5 Ib. and 3.0 Ibs. for skim milk, butter milk and waste, re- spectively; a total loss of 4.9 Ibs., or 2.7 Ibs. less than the losses with poor milk. This difference in the losses 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: IOC Ibs. of fat from Available fat Butter cent. 83 per ct. fat Overrun Lbs. Lbs. Per cl. 2,857 Ibs. 93 7 1130 13.0 2 500 Ibs 94 2 113 5 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 Babcock test shows it to contain butter fat, but it is impossible to know ex- actly, except by chemical analysis, how much butter fat is lost in the skim milk and the butter milk, and how much water, salt nnd ourd tlio butter \\ill nontnin. 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 1 per cent, has been assumed in these calculations: 100 Ibs. fat in cream Av?ilable fat Butter of 83 per ct. fat Overrun Per cent 20 30 40 Lbs. 96.8 97.3 97.6 Lbs. 116.6 117.2 117.6 Per cent 16.6 17.2 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 fnt available for butter will be 98.8. 00 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 83.0% 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, vi/., 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. 25% 15.5 20% "1.0 3.5% 17.1 4.0% 17 8 60% 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 amounl 196 Testing Milk and Its Products. of butter made from it, and linding 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 4C ^ =15.1 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: x= (b-f)lOO 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: (iso-awxioo =15.1 percent. 304 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 100; or 54 ^ 100 =21.8 per cent.. 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, on the average, contained 82.37 per cent, butter fat; in other words, 117.3 pounds of butter were made from each 100 pounds of butter fat in the whole milk. 1 The exact conversion factor 'When 82.37 Ibs. of butter fat will make 100 Ibs. of butter, how much butter will 06.67 Ibs. of butter fat make? 82.37: 96.67 : : 100: x, x = 117.3. Calculation of Butter- and Cheese 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, aa 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 fer 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 if? =1.19. If B therefore designate the yield of but- ter from 100 Ibs. of milk, the following formula will express the relation between yield and fat content, provided there are no other factors entering into the problem, viz.: B=(f .20) 1.19 Prom 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 100; the amount of butter which the total milk of this average fait 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 OP YIELD OP CHEESE. 223. a. From fat. The approximate yield of green Cheddar cheese from 100 Ibs. of milk may be found by multiplying the per cent, of fat in the milk by 2.7 ; if / 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 Slyke x 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=l. 58 f A_ +.91 f) . _ (II) 1 N. Y. experiment station (Geneva), bulletins 65 and 82. 2 Investigations as to the relation between the quality of tho 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, 12, bull. 197, 276; Ont. ~Agr. College, reports 1894-'96, incl.; Minn. exp. sta., b. 19, reports 1892-'94, incl.; Iowa exp. sta., bull. 21; Hoard's Dairyman, 1892, p. 2400. 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. (-1^=1.54), 40 per cent. M=1.67, etc. bo 60 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-j-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 varyT 2. What is the difference between the churn yield and the re suits obtained by the Babcock testt 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. fail 8. Why is the overrun from cream greater than from milkT 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% fatf 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% f 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%. Ff 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 MUk 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 iy 2 cents, below the average market price of butter, for each pound of butter fat received in the milk. 1 Bull. 56, p. 26, Wisconsin exp. station ; see Report 18, Iowa State Dairy Commissioner, p. 33. Calculating Dividends. 205 229. II. Co-operative creameries. Where the cieamery 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. In 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. The average test of this milk may be found by multiplying the total weight of milk delivered by each patron by bis 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 aa the average test, or the average amount of butter fat in each 100 Ibs. of milk received during the month. So far the method of calculation is common for 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. It the net returns for the 6650 Ibs. of butter sold during the month were $2394, 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 $2394 $266 =$2128. This sum, $2128, 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: $2128-=- 5700 = 37% cents. This price is paid to all patrons for each pound of butter fat delivered 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 Fourto week Total Milk Average test Milk Test Milk Test Milk ~Lbs7 3600 720 1850 Test Milk Test No. !___. No. 2 No. 3 Lbs. 3500 700 2480 ti 3.8 4.2 Lbs. 3000 2000 3?5 3.8 3.8 3i6 4.0 Lbs. 3450 750 1500 3.45 3.7 3.6 Lbs. 13,550 2.825 7,830 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 .37% 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. ^81 Cents 37 H $179 41 No 2 2 8b5 3 7 104 5 37 j 38 98 No. 3 7,830 3.9 305! 4 37 H 113.91 232. 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 $2.50 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 $2.50-f-4 = 62.5 cents, and the amount due each patron is found by multi^ plying 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, saj 1 cent 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 cent there- from. If the four weekly market prices were 37, 38, 37 and 40 cents, the average of these would be 38 cents, and this less 1 cent gives 37 cents as the price per pound of fat to be paid to the patrons; this price is then used in calculating the di- vidend as in case of first method. Patron Total milk Average test Butter fat Price of fat per Ib. Amount due Xo. 1 Lbs. 13,550 Per cent 3.55 Lbs. 481.0 Cents 37 $177.97 No. 2 2,825 3.7 104.5 37 38.67 No 3 7,830 3.9 305.4 37 113.00 234. 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 linking 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 $2394, and the running expenses of the factory $285, the amount to be divided among the patrons is $2109; the quan- tity of butter fat received was 5700 Ibs., and the price per pound of butter fat will therefore be 37 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 tlie 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 3V-} 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 7 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. 3.6X25=90c. per 100 Ibs. 3.7 X 25=92 5c. 3.8X25=95.0c. " 3.9X25=97.5c. 4.0X25=100c. " etc. .TOX25:=75c. per 100 Ibs. 3.lX25=77.5c. 3.2X25=80c. 3.3X25=82.5c. 3.4X25=85.0c. 3.5X25=87.5c. By continuing this multiplication, or adding the mul- tiplier each time for each tenth of a per cent, up to 5 210 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 Ibe. 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 Lbs. Per cent Cents So. 1... 13,550 3.55 58.5 $79.26 o. 2... No. 3. . 2,825 7,830 3.7 3.9 61.1 64.0 17.23 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 abou' 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 equalixa- 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 contain* ( ^y^-) =202 Ibs. butter fat. If the price paid ilie pntrons 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. ( ^jjjp ) =106.7 Ibs. but 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 patrous 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. oxp. station, p. !)0 : COtli report, pp, 1,'W-lf!1. 2 Wisconsin exp. station, llth report, p. 134. "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. Aer College: we also Dean. Canadian Dairying, o. 146, and Sammis, Wisconsin station, bull. 276. 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 20 cents a pound, the gross receipts would be $3,000. 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 2 cents per pound of green cheese, this would amount to $300 in the example given. Subtracting this sum from the gross receipts, $3,000, leaves 1 Wisconsin oxpt. station, null 107 216 Testing Milk and Its Products $2,700 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 ba 2,700-^5,700 = .2111, or 21 cents. Taking the figures for the three patrons al- ready mentioned under Creamery Dividends, we then have : Patron Total milk Average test Butter fat Price per Ib. of fat Amount due No. I... Lbs. 13,350 Per cent 3.55 Lbs. 481.0 Cents 21 $101.01 No. 2 2*825 3.7 104.5 21 21 .94 No 3 7 830 3.9 305.4 21 64 . 1 3 245. 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% fat; 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 those 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 hut 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 l>y tho Association of Official Agricultural Chemists are published l>y tho r?ur. of Chemistry of the U. S. Department of Agriculture; see Hull. No. 107. pp. I17-12S. 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 mill? 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. 239 the milk then found by dividing the weight of the milk by that of the water. Example: Weight of Bp. gr. bottle-f water . . .146.9113 grams. Weight of sp. gr. bottle empty. . . 46.9423 grams. Weight of water 99.9690 grams. Weight of sp. gr. bottle+milk 149.8708 grams. Weight of sp. gr. bottle empty... 46.9423 grams. Weight of milk 102.9285 grams. Sp. gr. of mite 1 -||||p =1.0296. 249. If a plain picnometer without a thermometer attached is available, the method of procedure is similar to that described, with the difference that the temperature of the water and of the milk must be brought to 60 F. before the picnometer is filled, or the picnometer filled with either liquid is placed in water in a small beaker, which is very slowly warmed to 60 F. and kept at this temperature for some time so as to allow the liquid in the picnometer to reach the temperature desired; the temperature of the water in the beaker is as ertained by means of an accu- rate 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 ex- panding liquid will flow on to the balance pan, with a result- ant 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 tnbe 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 C. 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-j-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+beaker+milk 29.3004 grams. Weight of tube+beaker 24.1772 grams. Milk weighed out 5.1232 grams. Weight of tube+beaker+milk 29.3004 grams. Weight of tube+beaker+milk,dry 24.9257 grams. Weight of water 4.3747 grams. Per cent, of water in milk= 4 '*^ =85.39 per cent. 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=H.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-ffat ............. 15.8039 grams. Weight of flask ................. 15.5171 grama. Weight of fat ............... 2868 gram. Milk weighed out ............... 5.1232 grams. Per cent, of fat in milk= =5.60 per cent. 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 y 2 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 Roese-Gottlieb method. The Mojonnier tester (108) is based on this method and is largely used in milk-condensing factories for determining solids and butter fat in condensed milk and other dairy products. 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 -L cc.) into a re- ceiving flask and the flask connected with a distillation apparatus. At the other end, the Jena flask containing 'Fresenius' Zeltschrlft, 22, p. 366; TT. S. Bept. Apr. Bur. of Chom . Rull. 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- solution 1 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 Jl alkali N solution are used in titrating back the excess of acid. 1.55 cc. of ~ alkali = l ~ =.51 cc. -^-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. I cc. semi-normal HCl-solution corresponds to 7 milligrams or .007 gram of nitrogen; 4.67 cc. HC1 therefore represents .-Q3269 gram of nitrogen. This quantity of nitrogen was obtained from the 5.1465 grams of milk measured out; the milk therefore contains ^ 26 ^ x _ 100 .535 per cen t. O f nitrogen, and .635X6.25=3.97 per cent, of casein and albumen. 1 Sutton, Volumetric Analysis, 4th edition, p. 31. 1 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 s 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 2573. 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 (Wls. expt. station, research bull. 11). 15 2i!6 Testing Milk and Its Products. Olson 1 : P=T JL 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 70 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 iy 2 ' 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 .Tourn. Ind. and Eng. Chemistry, I. 1909, p. 253. * Report 24, p. 117: "A simple method for the estimation of casein in cow's milk." * See also Clrc. 10. Wis. expt. sta.. Operating the casein tost 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 Wiley, 1 will be given here. The specific gravity of the milk is accurately deter- mined, and the following quantities of milk are meas- ured out by means of a 100 cc. pipette graduated to .2 cc. (or a 64 cc. pipette made especially 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. Cbem. Jour, 6, p. 289 et seq. 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 chic rids 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 grama Weight of dish 28.3538 grams. Weight of milk ash 1499 gram Per cent, of ash= '-~~ .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 ""Ik ia mixed with a certain amount (say 10 per cent.) of ammonia of a definite specific gravity, and the specific gravity of the liquid determined after thorough mixing and subsequent standing for an hour. If A designate the volume of butter milk taken, B that of ammonia, and C that of the mixture; and if furthermore S designate the specific gravity of the butter milk, * a that of the ammonia, and *, that of the mixture, we have Cs 2 - Bs! Klein 1 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 S- ^; Sj - 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 Milch zeitung, 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 mUk 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)= -1L_ where a and s designate the solids not fat and specific gravity, respectively, of the condensed milk, and a a and s l the corresponding data for the milk used. If s,= *A second extraction following leaching and subsequent drying of the tubes Is necessary to extract all the fat In condensed milk ; se* Bull. 104, Bur. of Chem., U. S. Dept. of Agr., p. 102 and 154. Bulletin 54, Laboratory Inland Rev. Dept., Ottawa, Canada. Chemical Analysis of Milk and Its Products. 231 1.030 and a i =9 per cent., then c= gives the con- centration. C. BtJTTER. 265. Sampling. A four- to eight-ounce sample of butter is melted in a tightly-closed pint fruit jar, shaken vigorously and cooled until the butter is hard-' ened, the jar being shaken vigorously at short 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- porcelain 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 FIG. 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. References 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- 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- Dairy Chemistry, p. 252. *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 Patrick's, 4 the Wisconsin high- pressure oven method, 5 the Benkendorf moisture test, 6 the Ames method, 7 the Mitchell- Walker test, 8 and the Cornell moisture test- 9 274. 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. 59) 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 weighed J-^%, Aiumujum^gr and 8.45 grams after heating, trlck test - the loss in weight of 1.55 grams represents 15.5 per cent, of the weight of the sample, and the butter there- 1 Dept. of Agr., Ottawa, Dairy Com'r Branch, bull. 14, pp. 6-8. * Ontario Agr. College, rept. 1906, p. 120. * Clrc. 100, Bur. An. Ind., U. S. Dept. of Agr. Journal Am. Chem. Soc., 28, 1906, p. 1611. Bull. 154, Wis. exp. sta. Bull. 220, Wis. exp. sta. T Bull. 97, Iowa exp. sta. Bull. 167, Dairy Branch, Ont. Dept. of Agr. Bull. 281, Cornell exp. sta. 236 Testing Milk and Its Products. fore contained 15.5 per cent, of water.- The results ob- tained by this method seldom vary more than .2 per cent, from those of chemical analysis, and often less than .1 per cent, when proper care in sampling and weighing has been taken. A few points need special attention in using this method: First, care must be taken not to heat the beaker too fast so that spattering occurs ; there is not so much danger from this source when an alcohol lamp is used as with a gas burner, which easily raises the tem- perature too high, causing a fine spray of -material to be thrown about, and thus giving too high results for water content. Second, it is important to discontinue the heating at the exact point when all the water has been driven 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 * 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.. 1908, p. 530). Chemical Analysis of Milk and Its Products. 237 sample is heated with a paraffine bath, while in the Cor- nell test a thin sheet of asbestos is placed between the flame and the dish holding the samples. 275. Dean's method. Three cc. of a melted sample }f butter are placed in an ordinary "patty-pan" tin dish (about 2y 2 inches in diameter and % inch deep) ind accurately weighed; the dish is then placed in a steam oven provided with a pop safety valve, a steam pressure gauge, and a thermometer. The oven used by Professor Dean of Guelph (Ont.) Dairy School, the originator of this method, was 6x8 inches. It was made of galvanized iron by a local tin-smith at a cost of about $5.00, exclusive of safety valve and steam gauge, and was made to withstand a pressure of about 10 pounds. After five or six hours' drying in the oven, 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. 276. The Wisconsin high-pressure oven method (see fig. 60). 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 238 Testing Milk and Its Products. 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 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. \ is. 60. The Wisconsin 5g(J and 58e ) high-pressure oven. wo./ Chemical Analysis of Milk and Its Products. 239 277. TheBenkendorf moisture tester consists of a small cast-iron oven (3l/ 2 x3i/2 inches, 1 inch deep) which is heated by an alcohol or gas lamp. A thin piece of asbestos is placed on the bottom of the oven. This aids in distributing the heat so that the butter which is weighed into a shallow, _ , Fig. 61. The Benkendorf tester. fl a t-b o 1 1 o m aluminum dish, about three inches in diameter, is heated from above as well as from below. 10 grams of butter are commonly used in this test and the moist- ure evaporates in about five to ten minutes. 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 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 \v>is '('Ire. 14, Wisconsin cxpt. station. 240 Testing Milk and Its Products. 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 back and forth repeatedly from a small warm beaker into the flask, and the quantity wanted is then drawn off with a warm pipette. 1 Wis. experiment station, report 17, pp. 98-101 : Hoard's Dairyman. February 15. 1001. "Uniform Salting of Butter." Chemical Analysis of Milk and Its Products. 241 281. 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. H 2 SO 4 per liter) are added to the soap solution to decompose the soap into free fatty acids and glycerol. A few pieces of pumice stone (prepared by throwing the pieces at white heat Lie 242 Testing Milk and Its Products. 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 thfr so-called Reichert or Reichert-Meissl number thus obtained. The Keichert number for pure butter fat will ordi- narily ccme 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 Reichert number of 1 to 2 cc. ; and mixtures of artificial and natural but- ter will give intermediate numbers. TESTS FOB THE DETECTION OF OLEOMARGARINE OB 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 Pntrirk. Household tests for the detection of oleomargarine and renovated butter. Fanner's Bulletin. No. 131. For detection and examination of renovated or "process" butter, see also Cochran. Jnurn Franl-l. Inst., 1899, p. 94; Analyst, 1899, p. 88. 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 nnf.il 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.- 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- 1 Farmers' Bulletin No. 131, p. 7. For tests for artificial coloring matter In oleomargarine, see Clrc. 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. In cheese factories the Wisconsin high-pressure oven (276) is now used for making moisture tests of cheese. A 10-gram sample requires about five hours' heating to expell all the moisture in the cheese. The rapid methods for moisture testing of butter do not give satisfactory results with cheese. 1 286. 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 Babcock test for cheese (105). 287. c. Casein (total nitrogenX6.25). About 2 grams of cheese are weighed out on a watch glass and trans- ferred to a Jena nitrogen flask, and the nitrogen in the sample determined according to the Kjeldahl method 1 See also Dean's method for determining water in butter, curd and cheese, 276, ami the Walker casein test, N. Y. Produce Rejr. 1913, p. 1154. Chemical Analysis of Milk and Its Products. 245 (253) ; the percentage of nitrogen multiplied by 6.25 gives the total nitrogenous components of the cheese. 288. d. Ash. The residue from the water determina- tion is taken for the ash ; it is preferably set fire to, in the same manner as explained under determination of ash in butter (270), before it is placed in the muffle oven and incinerated. The increase in the weight above that of the empty dish-)-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 Reich ert-Meissl method, as already ex- plained under Detection of Artificial Butter (282). 1 TESTS FOR ADULTERATION OF MILK AND CREAM. 291. Use of the refractometer. The immersion re- fractometer furnishes a delicate apparatus for the de tection of watered milk. 2 100 cc. of milk and 2 cc. of 1 See Arb. Kais. Ges.-Amt., 14, 506-598. 1 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. 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 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 Richmond 2 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 H^SO* (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. 1 Uffelmann, Deutsche Vierteljahresschr. f. 6ff. Ges.-pfl., 15, p. 663. 2 The Analyst, 1893, p. 272. Chemical Analysis of Milk and Its Products. 247 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. H 2 SOJ is poured down the side of the tube so it will form a layer under the milk. If nitrates or nitrites are present, a violet ring will form at the place of contact. This is Hehner's test for for- maldehyd reversed, see (304). 292. Besides by the methods given in the preceding (pp. 121-127), watering or skimming of milk may be de- tected by determining the specific gravity of a, the skim milk, b, the milk serum, and c, the whey. a. Specific gravity of skim milk. The milk is set in a flat porcelain or glass dish for 12 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. Tf both skimming and watering had been practiced, the difference given above might be obtained, but the analysis of the milk would in such case easily disclose the adul- teration. b. Specific gravity of the milk serum. To 100 ce. 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 ita 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 iu 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 1 K8nlg, Menschl. Nahrungsmittel, II, p. 276. 248 Testing MUk and Its Products. 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. 2 293. 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 Wallace 1 is claimed to detect one part of coloring matter in 100,000 of milk. Inorganic coloring matter like chromates and bi-chro- mates have, although fortunately rarely, been used to impart a rich color to adulterated milk or poor cream. Chromates may be detected by the reddish yellow color produced when a little 2 per cent.-silver nitrate solution is added to a few cubic centimeters of the milk. 294. Detection of pasteurized milk or cream. Prof. Storch, of Copenhagen, Denmark, 2 in 1898, published a simple method for ascertaining whether milk, cream, * Slats, Unters. landw. vrlcht. Stoffe, p. 88. 1 N. J. Dairy Commissioner, report 1896, p. 36. 1 40th report, Copenhagen experiment station. Chemical Analysis of Milk and Its Products. 249 or other dairy products have been heated to at least 176 F. (80 C.). The test is made as follows: A teaspoonful of the milk is poured into a test tube, and 1 drop of a weak solution of peroxid of hydrogen (2 per cent.) and 2 drops of a paraphenylenediamin-solu- tion (2 per cent.) are added. The mixture is then shaken; if a dark violet color appears at once, the milk has not been heated, or at any rate not beyond 176 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- 1 See also Slats, Unters. landw. wlcht. Stoffe, p. 60, and Molkerel- Ztg. (Hlldeshelm), 1899, p. 677. 250 Testing Milk and Its Products. pected cream is mixed with warm water, and acetic acid is added to precipitate the casein and fat (1.5 cc. of 10 per cent.-acetic acid per 10 cc. of cream is sufficient). The precipitate is filtered off, and a few drops of a strong tannin solution are added to the clear filtrate. Pure cream will give a slight precipitate, while in the presence of gelatine a copious precipitate will come down. The picric-acid method has also been proposed for the detection of small quantities of gelatine in cream. 1 297. Starch in cream. Starch is mentioned in the dairy literature as an adulterant of milk find fronm. Tt is doubtful, how- ever, if it is ever used for the pur- pose 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 suchacasebe readily detected by means of the iodin FIG. 62. The Wisconsin Milk Sediment Test. reaction. A Solu- 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. 'The Analyst, 1897. p. .V_>0. Chemical Analysis of Milk and Its Products. 251 298. 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 bee,n 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 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 Li A modification of the apparatus used has been published by Wisconsin experi- ment station. 2 About one pint of milk is strained through a cotton disc which is held in the lower opening of a small metal cylinder (see Fig. 62). This disc is then removed and Milk Sediment Test Discs. Hoard's Dairyman. Nov. _>. 1907. *Bu!l. 195 and fMreular 41. 252 Testing Milk and Its Products. furnishes evidence of the degree of cleanliness with which the milk has been handled. A rubber bulb is attached to the top of the cylinder to force the milk through the cotton 'disc. 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.) :* 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. 4 301. 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- *N. J. Dairy Commissioner, report, 1896 p. 36. See also par. 161. Chemical Analysis of Milk and Its Products. 253 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 staling 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 frith ether; the ether solution is evaporated, and the residue treated with alcohol and a little iron-chlorid solution; a deep violet color will be obtained in the presence of salicylic acid. 304. e. Formaldehyde (a forty-per cent, solution in water) . The following method by Hehner is stated to show the presence of one part of formaldehyde in 200,000 1 Chromates In dairy products may be readily determined by the use ol a silver-nitrate solution, see Molkerei-Ztg. (Berlin) 1899, p. 603. 254 Testing Milk and Its Products. parts of milk: the milk is diluted with an equal volume of water, and strong H 2 S0 4 (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 Pe 2 Cl 6 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. GOVERNMENT STANDARDS OF PURITY FOR MILK AND ITS PRODUCTS. 1 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 stituents. 3. Skim milk is milk from which a part or all of the cream has been removed and contains not less than nine and one-quarter (9.25) per cent, of milk solids. 4. Pasteurized milk is milk that has been heated below boil- : 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, sweetened evaporated milk, sweetened concentrated milk, is the product resulting from the evaporation of a considerable portion of the water from the whole, 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, to which sugar (sucrose) has 1 Circular No. 19, Office of the Secretary. TJ. S. Dept. of Agriculture, June 26. 1906. 256 Testing Milk and Its Products. been added. It contains, all tolerances being allowed for not less than twenty-eight per cent (28%) of total milk solids, and not less than eight per cent (8%) of milk fat. 8. Condensed skimmed milk, evaporated skimmed milk, concentrated skimmed milk, is the product resulting from the evaporation of a considerable portion of the water from skimmed milk, and contains, all tolerances being allowed for, not less than twenty per cent (20%) of milk solids. 9. Sweetened condensed skimmed nr'k, sweetened evap- orated skimmed milk, sweetened concentrated skimmed milk, is the product resulting from the evaporation of a consider- able portion of the water from skimmed milk to which sugar (sucrose) has been added. It contains, all tolerances being allowed for, not less than twenty-eight per cent (28%) of milk solids. 10. Dried milk is the product resulting from the removal of water from milk, and contains, all tolerances being al- lowed for, not less than twenty-si* per cent (26.0%) of milk fat, and not more than five per cent (5.0%) of moisture. 11. Dried skimmed milk is the product resulting from the removal of water from skimmed milk and contains, all toler- ances being- allowed for, not more than five per cent (5.0%) of moisture. 12. Malted milk is the product made by combining whole milk with the liquid separated from a mash of ground barley malt and wheat flour, with or without the addition of sodium chlorid, sodium bicarbonate, and potassium bicarbonate in such a manner as to secure the full enzymic action of the malt extract and by removing water. The resulting product contains not less than seven and one-half per cent (7.5%) of butterfat and not more than three and one-half per cent (3.5%) of moisture. 13. Buttermilk is the product that remains when butter is re- moved from milk or cream in the process of churning. 14. 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. Government Standards of Purity. 257 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, clottedjcream, is cream from which a considerable portion of water has been evaporated. C. MILK FAT OR BUTTER PAT. 1. Milk fat, butter fat, is the fat of milk and has the Reich- ert-Meissl number not less than twenty-four (24) and a specific gravity of not less than 0.905 d. BUTTER. T 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. 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 17 258 Testing Milk and Its Products. 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 less than twelve (12) per cent, of milk fat. g- MISCELLANEOUS MILK PRODUCTS. 1. Whey is the product remaining after the removal of fat and casein from milk in the process of cheese-makiug. 2. Kumiss is the product made by the alcoholic fermentation of mare's or cow's milk. 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 grams. 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% D- 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 258b Specifications for Glassware. 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. Bulb: (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 bottJe 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. 50% 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% 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.i) 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 SMljTMt Want Fst Cucin and ilbamtn Milk Ask Authority Cow' 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 91.87 93.381 93.lt 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 .12 .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 t& 3.50 3.20 1 3. 51* 3.40 17.64* 3.76 Pf. Ct. 4.88 4.60 5.10 'i!85 2.67 4.23 pt. ct. .71 .75 .70 .71 .75 1.56 .53 .62 .70 K6nig' Fleischmanu Van Slyke Holland* Richmond K5nig Holland* K6nig Holland* Van Slyke K6nig Holland* K6nig Van 81yk ESnig* 44 Well K5nig Won Farrington Konig- Van Slyk* Drew Shntt K6nig S torch .7 ^5. 44 5,552 2,173 200,000 42 43 203 56 354 14 II II II Colostrum milk Cream Cream, Cooley Skim milk (gravity).. Skim milk (centrifugal) Butter milk 3.26 4.74 3.55 4.03 5.25 4.04 .80 ;72 57 31 46 14 Whey .. .86 .81 11.92 11.79 1.3 .61 .81 1.5 .8 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 5 1.02 1.43 5. 2.95 5. 1.79 - .65 to 2.18 .19 .58 .25 .19 .12 .78 .10 .97 51 3.58 >1 4.73 4.87 5.2 TTIWJ Condensed milk, (no sugar added)... Condensed milk, (sugar added) ...... 36 64 1,676 10 11 242 350 127 143 Butter salted " sweet cream.. " sour cream... " nnsalted " World'. Fair. 1893 Cheese cream ... " full cream.... " eheddar, green " eheddar, cured " World's Pair Mam'th, 1893 44 half-skim .... " skim. 27 1 21 41 " centrifugal skim . 1 .70 per cent, albumen. * 18.60 per cent, albumen. * Forty-two analyses. * Mostly European samples. * Right analyses. * Massachusetts' samples. 260 Testing Milk and Its Products. Legal Standards for Dairy Products (Cir. 218. Bur. An. Ind. U. S. Dept. of Agric.) States Milk Skim milk Cream But- ter Whole milk cheese Condensed milk lee cream Plain Fruit and nut Total solids Solids not fat Fat Total solids Fat Pr.ct. 18.0 Fat Fat Total solids Fat Fat Fat Pr.ct. Cal Pr.ct. 11.5 Pr.ct. 8.5 Pr.et. 3.0 Pr.ct. 8.8 Pr.ct. 80.0 Pr.ct. 50 Pr.ct. n Pr.ct. <*) Pr.ct. 12 Colo 3.0 '16.0 80.0 150 14 12 Conn. 11.75 8.5 3.25 16.0 Dint. Col 12.5 9.0 3.5 9.3 20.0 83.0 Fla 11.75 8.5 3.25 9.25 18.0 82.5 150 *28.0 7.7 12 Ga 11.75 8.5 3.25 9.25 18.0 82.5 150 28.0 1 27. 66 14 12 Hawaii* 11.5 8.5 3.0 28.0 7.7 Idaho 11.2 8.0 3.2 9.3- 18.0 8.25 30 W ( 2 ) 14 12 Ill 11.5 8.5 3.0 9.25 18.0 82.5 150 (*) (*) 8 Ind 8.5 3.25 9.26 18.0 82.5 150 28.0 127.5 8 Iowa 12.0 3.0 16.0 6 80.0 12 Kans 11.75 8.5 3.25 9.25 18.0 80.0 150 (') ( 2 ) 14 12 Ky 12.5 8.5 3.25 9.26 18.0 82.5 150 28.0 126.76 14 12 La 8.5 3.5 8.0 18.0 P) (') Me 11.75 8.5 3.25 18.0 Md. 12.5 3.5 9.25 18.0 (') P) 4 6 Mass 12.15 3.25 9.3 15.0 ?.. Mich 12.5 3.0 12 Minn 13.0 9.75 3.25 20.0 145 (*) W 12 Mo 12.0 8.75 3.25 9.25 18.0 8.25 150 28.0 7.76 14 Mont 11.75 8.5 3.25 20.0 8.25 150 14 Neb 3.0 18.0 14 12 ' Percentage of fat based on total solids. Fat, 7.8 per cent; total solids plus fat, 34.3 per cent For buttermaking, 25 per cent fat. 4 Thii standard for sweetened condensed milk: "Evaporated milk," solids, 24 per cent; fat, 7.8 per cent. So report; 1910 rtandard given. Appendix. LEGAL STANDARDS FOR DAIRY PRODUCTS Continued 261 States Milk Skim milk Cream But- ter a- cheese Condensed Ice cream Plain Fruit and nut Total solids Solids not fat Fat Total solids Fat" Fat Fat Total solids Fat Fat Fat N. H Pr.et. 12.0 Pr.ct. Pr.ct. Pr.et. 8.5 Pr.ct. 18.0 Pr.et. 80.0 Pr.ct. Pr.ct. Pr.d. Pr.d. 14 Pr.d. N. J 11.5 3.0 16.0 N. Y 11.5 3.0 18.0 (') '25.0 Nev 11.75 8.5 -3.25 9.25 18.0 82.5 >50 26.5 7.8 14 N. C 11.75 8.5 3.25 9.25 18.0 82.5 50 28.0 27.5 14 12 N. Dak 12.0 9.0 3.0 15.0 14 Ohio 12.0 3.0 80.0 () 25.0 Okla 12.51 0.5 3.0 18.0 81.5 14 Ore 9.0 3.2 20.0 30.0 ( 7 ) 12 Pa....: 12.0 3.25 18.0 32.0 8 6 Porto Rico.. 12.0 9.0 3.0 R. I 12.0 2.5 S. Dak 8.5 3.25 9.25 18.0 80.0 >50 28.0 27.5 14 12 Tenn 8.5 3.25 Texas 8.5 3.25 Utah 12.0 9.0 3.2 9.0 18.0 80.0 >50 (') (*) 14 12 Vt 12.5 9.25 Va 11.75 8.5 3.25 9.25 18.0 82.5 (') P) 8 Wash 12.0 8.75 3.25 9.3 18.0 30 Wis 8.5 3.0 9.0 18.0 82.5 >50 28.0 8.0 14 Wyo 8.5 3.25 9.25 18.0 82.5 '50 28.0 () 14 12 1 Percentage of fat based on total solids. J Fat, 7.8 per cent; total solids plus fat, 34.3 per cent. 1 Not more than 0.2 per cent "filter." 4 Must correspond to 11.5 per cent solids in crude milk. If artificially colored. 8 Must correspond to 12 per cent solid in crude milk. 7 23-24 per cent solids, 7.9 per cent fat; 24-25 per cent solids, 7.8 per cent fat; 25-26 per cent solids, 7.7 per cent fat; 26 per cent solids, 7.6 per cent fat. > In May and June, solids 12 per cent. Fat. 27.5 per cent of total solids. 262 Testing Milk and Its Products. lactometer degrees corresponding to N. Y. Board of Health degrees. (See par. 114) Bd. o< Health degrees. *sr Bd. of Health Qutvennc 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 18.0 83 24.1 103 29.9 63 18.3 84 24.4 104 80.2 64 1S.6 85 24.6 105 80.5 65 18.8 86 24.9 106 80.7 66 i.i 87 25.2 107 8LO 67 19.4 88 25.5 108 81.8 68 19.7 89 25.8 109 31.6 69 20.0 90 26.1 110 31.9 70 20.3 91 26.4 111 82.2 71 20.6 92 26.7 112 82.6 72 20.9 93 27.0 118 32.8 73 21.2 94 27.3 114 88.1 74 21.5 95 27.6 116 83.4 75 21.7 96 27.8 118 83.6 76 22.0 97 28.1 117 83.9 77 22.8 98 28.4 118 84.1 78 22.6 99 28.7 119 84.6 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. .*r.(g)= 0.0000 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 1.019 1.864 1.874 1.884 1.894 1.903 1.913 L922 L932 1.941 1.951 .020 1.961 L970 1.980 1.990 1.999 2.009 2.018 2.028 2.038 2.047 .021 2.057 2.066 2.076 2.086 2.095 2.105 2.114 2.124 2.183 2.143 .022 2.153 2.162 2.172 2.181 2.191 2.200 2.210 2.220 2.229 2.239 .028 2.249 2.258 2.267 2.277 2.286 2.296 2.306 2.815 2.825 2.334 .024 2.344 2.353 2.363 2.372 2.382 2.391 2.401 2.410 2.420 2.430 .025 2.439 2.449 2.458 2.468 2.477 2.487 2.496 2.506 2.515 2.525 .026 2.534 2.544 2.553 2.563 2.573 2.582 2.591 2.601 2.610 2.620 .027 2.629 2.638 2.648 2.657 2.667 2.676 2.686 2.695 2.705 2.714 .028 2.724 2.733 2.743 2.752 2.762 2.771 2.781 2.790 2.799 2.809 .029 2.818 2.828 2.837 2.847 2.856 2.865 2.875 2.884 2.893 2.903 .030 2.913 2.922 2.931 2.941 2.951 2,960 2.969 2.979 2.988 2.997 .031 3.007 3.016 3.026 3.035 3.044 3.054 3.063 3.072 3.082 3.091 .032 3.101 3.110 3.120 8.129 3.138 3.148 3.157 3.166 3.176 3.185 .033 3.195 3.204 3.213 3,223 3.232 3.241 3.251 8.260 3.269 3.279 .034 3.288 3.298 3.307 3.816 3.326 3.335 3.344 3.354 3.363 3.372 .035 3.382 8.891 3.400 3.410 3.419 3.428 8.438 3.447 3.456 3.466 .036 3.475 3.484 3.494 3.503 8.512 3.521 3.531 3.540 3.549 3.559 (See direction* for UM, Appendix. 263 Table V. Correction-table for specific gravity of milk. f* Temperature of milk (In degrees Fahrenheit). J! 51 62 63 64 66 56 67 68 69 60 20 19.3 19.4 19.4 19.5 19.6 19.7 19.8 19.9 19.9 20.0 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> 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 2!) 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 66 66 67 68 69 70 20 20. 20.2 20.2 20.3 20.4 20.5 20.6 20.7 20.9 21.0 21 21. 21.2 21.3 21.4 21.5 21.6 21.7 21.8 22.0 22. 22 22. 22.2 22.3 22.4 22.6 22.6 22.7 22.8 23.0 23. 23 23. 23.2 23.3 23.4 23.5 23.6 23.7 23.8 24.0 24. 24 24. 24.2 24.3 24.4 24.5 24.6 24.7 24.9 25.0 25. 25 25. 25.2 25.3 25.4 25.5 25.6 25.7 25.9 26.0 26. 26. 26.2 26.3 26.5 26.6 26.7 26.8 27.0 27.1 27.2 27 27. 27.3 27.4 27.5 27.6 27.7 27.8 28.0 28.1 28.2 28 28. 28.3 28.4 28.5 28.6 28.7 28.8 29.0 29.1 29.2 29 29. 29.3 29.4 29.5 29.6 29.7 29.9 30.1 30.2 30.3 30 30. 30.3 30.4 30.5 30.7 30.8 30.9 81.1 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. 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 85.9 36.1 36.2 36.4 36.6 DIRECTIONS. Bring the temperature of the milk to within 10 of 80 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- erved, 31.0 at 67 F. ; corrected reading, 81.9 264 Testing Milk and Its Products. Table VI. Per cent, of solids not fat, corresponding to to 6 per cent, of fat, and lactometer readings of 26 to 36. (See directions for use, par. 120) s LACTOMETER READINGS AT 60 P. 3 J I JL 26 27 28 29 30 31 32 33 34 35 36 y 6.50 6.75 7'. oo 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00 0.1 6.52 6.77 7.02 7.27 7.52 l.TJ 8.02 8.27 8.52 8.77 9.02 0.1 0.2 6.54 6.79 7.04 7.29 7.54 7.79 8.04 8.29 8.54 8.79 9.04 0.2 0.3 6.56 6.81 7.06 7.31 7.56 7.81 8.06 8.31 8.56 8.81 9.06 0.3 0.4 6.68 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 6 6 6'? 6 87 7 191 7 37 7 69, 7 87 8 V> 8 37 8 6? 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 8 6 66 6 91 7 16 7 41 7 66 7 91 8 16 8 41 8 66 8 91 9 16 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 i .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 6 79, 6 97 7 9,9, 7 47 7 7? 7 97 8 W 8 47 8 7?, 8 97 9 22 1.1 2 6 74 6 99 7 94 7 49 7 74 7 99 8 94 8 49 8 74 8 99 9 94 1 2 .3 6.76 7.01 7.26 7.51 7.76 8.01 8.26 8.51 8.76 9.01 9.26 1.3 .4 6.78 7.03 7.28 7.53 7.78 8.03 8.28 8.53 8.78 9.03 9.28 1.4 .5 6.80 7.05 7.30 7.55 7.80 8.05 8.30 8.55 8.80 9.05 9.30 1.5 .6 6.82 7.07 7.32 7.57 7.82 8.07 8.32 8.67 8.82 9.07 9.32 l.C .7 6.84 7.09 7.34 7.59 7.84 8.09 8.34 8.59 8.84 9.09 9.34 1.7 .8 6 86 7 11 7 36 7 61 7 86 8 11 8 36 8 61 R 86 9 11 9 37 1 8 .9 6.88 7.13 7.38 7.63 7.88 8.13 8.38 8.63 8.88 9.13 9.39 1.9 2.0 6.90 7.15 7.40 7.65 7.90 8.15 8.40 8.66 8.91 9.16 9.41 2.0 2.1 6.92 7.17 7.42 7.67 7.92 8.17 8.42 8.68 8.93 9.18 9.43 2.1 2.2 6.94 7.19 7.44 7.69 7.94 8.19 8.44 8.70 8.95 9.20 9.45 2;2 2.3 6.96 7.21 7.46 7.71 7.96 8.21 8.46 8.72 8.97 9.22 9.47 2.3 2.4 6.98 7.23 7.48 7.73 7.98 8.23 8.48 8.74 8.99 9.24 9.49 2.4 2.5 7.00 7.25 7.50 7.75 8.00 8. 25 8.50 8.76 9.01 9.26 9.51 2.5 2.6 7.02 7.27 7.52 7.77 8.02 8.27 8.52 8.78 9.03 9.28 9.53 2.6 2.7 7.04 7.29 7.54 7.79 8.04 8.29 8.54 8.80 9.05 9.30 9.55 2.7 2.8 7.06 7.31 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 7.58 7.83 8.08 8.33 8.59 8.84 9.09 9.34 9.-V) 2.9 Appendix. Table VI. Per cent, of solids not fat (Continued"). LACTOMETER READINGS AT 60 F. 11 is * 26 27 28 29 30 31 32 33 34 35 86 X* 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 1? 7 37 7 6? 7 87 8 13 8 38 8 63 8 88 9 13 9 38 9 64 3.1 3.2 7.14 7.39 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 7.79 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 4.5 7.40 7.66 7.91 8.16 8.41 8.66 8.92 9.17 9.42 9.68 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 .51 7 76 8.01 8 ?fi 8 51 8 76 9 0?, 9 ft? 9 52 9.78 10.03 5.0 6.1 .53 7.78 8.03 8.28 8.53 8.79 9.04 9.29 9.54 9.80 10.05 5.1 5.2 .55 7.80 8.05 8.30 8.55 8.81 9.06 9.31 9.56 9.82 10.07 5.2 5.3 .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 .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. 11 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 6.6 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 at of cream in table VIII; the first or last horizontal row ol fig- ures, the amounts of fat in ten thousand, thousands, hundreds, tens, and units of pounds of milk are then given in this verti- cal column. By adding the corresponding figures for any given quantity of milk or of cream, the total quantity of butter fat contained therein Is obtained. Example: How many pounds of fat Is contained In 8925 IDS. of milk testing 3.85 per cent.? On p 264. -econd column the test 3.63 ii found, and by going downward in this coiiunu we have: 8000 IDS ..... .. .................... 292. Ibs. 900 Ibs ........ 82.9 Ibs. 20 Ibs! ...... .'. .............. .... .7 Ibs, 5 Ibg ............................ 2 Ibs. 8925 Ibs. of milk. 825.8 Ibs. of fat 8925 Ibs. of milk testing 3.65 per cent., therefore, contains 325.S Ibs. of batter fat. TABLL 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 the table is, otherwise, as explained above. Example: How much money Is due for 825.8 Ibs. of batter fat at 15% cents per pound T In the horizontal row of figures beginning with 16^ on p. 247, we find : 100 Ibs ____ ..... ------- $46.50 20 Ibs ..................... - 8.10 825. 8 Ibs. S50.49 825.8 Ibs. of butter fat at 15> cents per pound, therefore, Is worth 850.4*. 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 wi 11 5845 Ibs. of milk testing 8. 8 per cent. be apt to make under good creamery conditions ? In the column headed 3.8, we find : 6000 Ibs ........................... 209.0 Ibs. 800 Ibs ........................... 33;4 Ibs. 40 Ibs ........................... 1.7 Ibs. 6 Ibs ......................... .. .2 Ibs. 8845 Ibs. 244.8 Ibs. 5848 Ibs. of milk tost ng 3.8 per cent, of fat will make about 244.8 Ibs. of utter, under oondltioua 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 3.4013.45 3.50 3.55 J_ Milk Milk Ibs. Ibs. 10,000 300 305 310 315 320 325 330 335 340 345 350 355 10,000 9,000 270 275 279 284 289 293 297 302 306 311 315 320 9,000 8,000 240 244 248 252 256 2GO 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 U)5 198 201 204 207 210 213 6,000 5.000 150 153 155 158 160 163 165 168 170 173 175 178 5.000 4.000 120 122 124 126 128 130 132 134 136 138 140 142 4.000 3,000 90.0 91.5 93.0 94.5 96.0 97.5 99.0 101 102 104 105 107 3,000 2,000 60.0 61.0 62.0 63.0 64.0 65.0 66.0 67.0 68.0 69.0 70.0 71.0 2,000 1,000 30.0 30.5 31.0 31.5 32.0 32.5 33.0 33.5 34.0 34.5 35.0 35.5 1,000 900 27.0 27.5 27.9 28.4 28.8 29.3 29.7 30.2 30.6 31.1 31.5 32.0 900 800 24.0 24.4 24.8 25.2 25.7 26.0 26.4 26.8 27.2 27.6 28.0 28.4 800 700 21.0 21.4 21.7 22.1 22.4 22.8 23.1 23.5 23.8 4.2 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 10. 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 .30(1 200 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 2J 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 ? 1 9, 1 ? 1 3 1 3 1 3 1 3 1 3 1 4 1 4 1 4 1 4 40 80 .9 .9 .9 .9 1.0 1.0 1.0 1.0 1.0 1.0 1.1 1.1 30 20 6 6 i* ft 6 7 7 7 7 7 7 7 20 10 .3 .3 .3 .3 .8 '.3 .3 .3 .3 .3 .4 .4 10 9 .3 .3 .3 .3 .3 .3 .3 .8 .8 .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 g 2 2 .2 2 2 2 ? ft 2 Q 2 6 5 '.2 '.2 .2 .'2 .2 .2 .2 .2 .2 .2 .2 5 4 .1 .1 .'l .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 I 3.00 J 3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 1.50 ! . 5f> 268 Testing Milk and Its Products. Table VII. Pounds of fat in I to 10,000 Ibs. of milk (Continued). 1 3.60 3.65 3.70 3.75 3.80 3.85 3.90 3.95 4.00 4.05 4.10 4.15 I Milk Milk Ibs. Ibs. '0,000 360 365 370 375 380 385 390 395 400 405 410 415 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 1 ~i r 154 156 158 160 162 164 166 4,000 3,000 108 110 111 113 114 116 117 119 120 122 123 125 3,000 2,000 72.0 73.0 74.0 75.0 76.0 77.0 78.0 79.0 80.0 81.0 82.0 83.0 2,000 1,000 36.0 36.5 37.0 37.5 38.0 38.5 39.0 39.5 40.0 40.5 41.0 41.5 1,000- 900 32.4 32.9 33.3 33.8 34.2 34.7 35.1 35.6 36.0 36.5 36.9 37.4 900 800 28.8 29.2 29.6 30.0 30.4 30.8 31.2 31.6 32.0 32.4 32.8 33.2 800 700 25.2 25.6 25.9 26.3 26.6 27.0 27.3 27.7 28.0 28.4 28.7 29.1 700 600 21.6 21.9 22.2 22.5 22.8 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 y 12.5 300 200 7.2 7 3 7 4 7 5 7.6 7.7 7.8 7 9 8 8 1 8 ? 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 1.0 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 50 40 1 4 1 fi 1 5 1 "> 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 ft ft ft ft ft 3 4 4 4 4 4 4 9 8 .3 .3 .3 .3 .3 .3 .3 .3 .3 .3 .8 .3 8 7 .3 .3 .3 .3 .3 .3 .3 .3 .8 .8 .3 .3 7 3 .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 .2 .2 .2 .2 .2 .2 .2 .2 .2 4 3 .1 1 1 1 1 1 1 1 1 1 1 1 8 2 .1 .1 .1 !i !i .1 .1 .1 .1 .1 .1 .1 1 1 3.60 i 3.65 3.70 3.75 3.80 3.85 3.90 3.95 4.00 4.05 4.10 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. 10,000 420 425 430 435 440 446 450 455 460 465 470 475 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 7,000 294 298 301 305 308 312 315 319 322 326 329 383 7,000 ti.OOO 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 5.0CO 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 45.6 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 31.0 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 2-5.2 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 lo 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 2 5 5 5 5 10 9 .4 .4 .4 .4 .5 .6 .5 .5 .5 .5 .5 .5 9 8 .4 .4 .4 .4 .4 .4 .4 .4 .4 .4 .4 .4 8 y ^ T T ^ 4 4 4 4 4 4 4 4 7 6 .3 .3 .3 .3 .3 .3 .3 .3 .3 .3 .3 .3 G 5 .2 .2 .2 .2 .3 .3 .3 .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 5.20 j 4.80 4.85 4.90 4.95 5.00 5.05 5.10 5.15 5.25 5.30 5.35 I Appendix. 271 Table VIII. Pounds of fat in I to 1000 Ibs. of cream testin 12.0 to 50.0 per tent. 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 120 180 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 800 900 108 117 126 135 144 153 162 171 180 189 198 207 216 225 234 248 252 261 270 800 96 104 112 120 128 186 144 152 160 168 176 184 192 200 208 216 224 232 240 700 84 91 98 105 112 119 126 133 140 147 154 161 168 175 182 189 196 203 210 800 72 78 84 90 96 102 108 114 120 126 182 138 144 150 156 162 168 174 180 600 00 66 70 75 80 85 90 95 100 105 110 115 1201 125 130 1351 140 145 150 400 48 62 66 60 64 68 72 76 80 84 88 92 96 100 104 108 112 116 120 MO 88 39 42 45 48 61 64 57 60 63 66 69 72 75 78 81 84 87 90 900 24 26 28 82 84 86 88 40 42 44 46 48 50 62 54 66 68 60 100 12 18 14 16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 80 90 80 10.8 9.6 11.7 10.4 12.6 11.2 11.5 12.0 14.4 12.8 15.3 13.6 16.2 14.4 17.1 15.2 18.0 16.0 18.9 16.8 19.8 17.6 20.7 18.4 21.6 19.2 22.5 20.0 23.4 20.8 24.8 21.6 25.2 22.4 26.1 23.2 27.0 24.0 TO 8.4 9.1 9.8 10.5 11.2 11.9 12.6 13.3 14.0 14.7 15.4 16.1 16.8 17.5 18.2 18.9 19.6 20..3 21.0 00 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 8.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.6 13.0 13.6 14.0 14.5 15.0 <0 4.8 5.6 6.0 6.4 6.8 7.2 7.6 8.0 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 6.1 5.4 5.7 6.0 9 3 6.6 6.9 7.2 7.5 7.8 8.1 8.4 8.7 e.o 90 2.4 2.6 2.8 3.0 8.2 8.4 8.6 3.8 4.0 4.2 4.4 4.6 4.8 6.0 5.2 6.4 5.6 6.8 6.0 10 l.f 1.8 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 8.0 9 1.08 1.17 1.26 1.85 1.44 1.58 1.62 1.71 1.80 1.89 1.98 2.07 2.16 2.25 2.34 1.48 2.52 2.61 2.70 g .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 j .84 .91 .98 1.05 1.12 1.19 1.26 1.33 1.40 1.47 1.54 1.61 l.8 1.75 1.82 1.89 1.96 2.03 2.10 1 .72 .78 .84 .90 .96 1.02 1.08 1.14 1.20 1.26 1.32 1.88 1.44 1.50 1.56 1.62 1.68 1.74 1.80 i .00 .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 .48 .52 .56 .60 .64 .68 .72 .76 .80 .84 .88 .92 1.00 1.04 1.08 1.12 1.16 1.20 1 .80 .89 .42 .46 .48 .51 .64 .67 .60 .63 .66 .69 .72 .75 .78 .81 .84 .87 .90 .24 .12 .26 .18 .28 .14 .80 .15 .82 .16 .84 .17 .86 .18 :!S : .42 .21 :8 .52 .26 .54 .27 .00 M 272 Testing Milk and Its Products. Table Vltl. Pounds of fat in I to 1000 Ibs. of cream (continued}. 1 81 82 33 84 85 86 87 88 39 40 41 42 43 44 45 46 47 48 49 69 II 1000 810 820 380 940 350 860 870 880 390 400 410 420 480 440 450 460 470 490 490 500 900 279 288 297 306 315 824 833 342 351 360 869 378 887 896 405 414 423 482 441 450 800 248 256 264 272 280 288 296 304 312 820 328 336 344 352 860 368 876 884 892 400 700 217 224 231 238 245 252 259 266 273 280 287! 294 301 308 315 329 886 850 600 186 192 198 204 210 216 222 228 234 240 246 252 258 264 270 276 282 288 294 300 500 165 160 165 170 175 180 185 190 195 200 205 1 210 215 220 225 230 235 240 245 250 400 124 128 132 136 140 144 148 152 156 160 164 168 172 176 180 184 188 192 196 200 93 96 99 102 106 108 111 114 117 120 128 126 129 132 135 188 141 144 147 150 100 62 64 82 66 33 68 34 70 86 72 36 74 87 76 38 78 80 82 84 86 88 90 92 94 96 98 100 90 27.9 28.8 29.7 30.6 81.5 82.4 38.8 34.2 35.1 86.0 36.9 87.8 38.7 39.6 40.5 41.4 42.3 48.2 44.1 45.0 80 24.8 25.6 26.4 27.2 28.0 28.8 29.6 30.4 21.2 82.0 32.8 33.6 34.4 35.2 86.0 86.8 37.6 88.4 .39.2 40.0 70 60 21.7 18.6 22.4 19.2 23.1 19.8 23.8 20.4 24.5 21.0 25.2 21.6 25.9 22.2 26.6 22.8 27.8 28.4 28.0 24.0 28.7 24.6 29.4 25.2 30.1 25.8 SO. 8 26.4 31.6 27.0 32.2 27.6 82.9 28.2 33.6 28.8 84.3 29.4 35.0 30.0 50 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.6 21.0 21.5 22.0 22.6 23.0 23.6 24.0 24.6 25.0 12.4 9.8 12.8 9.6 13.2 9.9 13.6 10.2 14.0 10.5 14.4 10.8 14.8 11.1 15.2 11.4 15.6 11.7 16.0 12.0 16.4 12.8 16.8 12.6 17.2 12.9 17.6 13.2 18.0 18.5 18.4 18.8 18.8 14.1 19.2 14.4 19.6 14.7 20.0 15.0 30 6.2 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 3.1 8.8 8.4 8.5 8.6 .7 3.8 8.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 6.0 9 2.79 2.88 2.97 3.06 3.15 3.24 8.88 3.42 8.51 8.60 8.69 8.78 3.87 8.96 4.95 4.14 4.28 4.82 4.41 4.50 8 7 2.48 2.17 2.56 2.24 2.64 2.81 2.72 2.38 2.80 2.45 2.88 2.52 2.96 2.59 3.04 2.66 3.12 2.73 3.20 2.80 3.28 2.87 8.86 2.94 3.44 5.01 3.52 3.08 8.60 8.15 3.68 3.22 8.76 3.29 3.84 8.86 3.924.00 8. 433.50 E 1.86 1.55 1.92 1.60 1.98 1.65 2.04 1.70 2.10 1.75 2.16 1.80 2.22 1.85 2.28 1.90 2.34 1.95 2.40 2.00 2.48 2.05 2.62 2.10 2! 15 2,64 2.702.76 2.252.80 2.82 2.35 2.88 2.40 2.948.00 2.45J2.50 4 1.24 1.28 1.82 1.36 1.40 1.44 1.48 1.52 1.56 1.60 1.64 1.68 1.72 U76 1.801.84 1.88 1.92 1.062.00 8 .96 .99 1.02 1.05 1.08 1.11 1.14 1.17 1.20 1.28 1.26 1.29 1.32 1.361.88 1.41 1.44 1.471. GO 2 '.62 .64 .66 .68 .70 .72 .74 .76 .78 .80 .82 .84 .86 .88 .90 .92 .94 .96 .981.00 1 .SI .82 .34 .36 .86 .87 .88 .89 .40 .41 .42 .48 .44 .45 .46 .47 .48 Appendix. Amount due for butter fat, in dollars and cents, at 12 to 25 cents per pound. (See directions for use, page ((.) 3 o M. Pounds of builcr fat. 3 j.o 'a H c 1 1,000 900 800 700 600 500 400 300 200 100 11 12 120.00 108.00 96.00 84.00 72.00 60.00 48.00 36.00 $ 24.00 $ 12.00 12 12J 122.50 110.25 98.00 85.75 73.50 61.25 49.00 36.75 24.50 12.25 -1 12J 125.00 112.50 100.00 87.50 75.00 62.50 50.00 37.50 25.00 12.50 2J 12$ 127.50 114.75 102.00 89.25 76.50 63.75 51.00 38.25 25.50 12.75 -I 13 130.00 117.00 104.00 91.00 78.00 65.00 52.00 39.00 26.00 13.00 3 131 132.50 119.25 106.00 92.75 79.50 66.25 53.00 39.75 26.50 13.25 sj 13 J 135.00 121.50 108.00 94.50 81.00 67.50 54.00 40.50 27.00 13.50 :U 13| 137.50 123.75 110.001 96.25 82.50 68.75 55.00 41.25 27.50 13.75 13J 14 140.00 126.00 112.00 98.00 84.00 70.00 56.00 42.00 28.00 14.00 4 141 142.50 128.25 114.00 99.75 85.50 71.2-5 57.00 42.75 28.50 14.2-5 q 14i 145.00 130.50 116.001101. 50 87.00 72.50 58.00 43.50 29.00 14.50 4J wi 147.50 132.75 118.00 103.25 88.50 73.75 59.00 44.25 29.50 14.75 1*3 15 150.00 135.00 120.00 105.00 90.00 75.00 60.00 45.00 30.00 15.00 15 151 152.50 137.25 122.00 106.75 91.50 76.25 61.00 45.75 30.50 15.25 151 154 155.00 139.50 124.00 108.50 93.00 77.50 62.00 46.50 31.00 15.50 loj 16| 157.50 141.75 126.00 110.25 94.50 78.7563.00 47.25 31.50 15.75 1,31 16 160.00 144.00 128.00 112.00 96.00 80.00 64.00 48.00 32.00 16.00 16 161 162.50 146.25 130.00 113.75 97.50 81.25 65.00 48.75 32.50 16.25 161 16] 165.00 148.50 132.00 115.50 99.00 82.50 66.00 49.5033.00 16.50 LBi 163 167.50 150.75 134.00 117.25 100.50 83.75 67.00 50.25 33.50 16.75 16| 17 170.00 153.00 136.00 119.00 102.00 85.00 68.00 51.0034.00 17.00 17 17} 172.50 155.25 138.00 120.75 103.50 86.25 69.00 51.7534.50 17.25 171 17) IT) 175.00 177.50 157.50 159.75 140.00 142.00 122.50 124.25 105.0087.50 106.5087.75 70.00 71.00 52.50i35.00 53.2535.50 17.50 17.75 17* 173 18 180.00 162.00 144.00 126.00 108.0090.00 72.00 54.00136.00 18.00 18 18 ', 182.50 164.25 146.00 127.75 109.5091.25 73.00 54. 75136.50 18.25 IS* 18 i 185.00 166.50 148.00 129.50 111.00,92.50 74.00 55.5037.00 18.50 18} 18| 187.50 168.75 150.00131.25 112.50 93.75 75.00|56^25 3- 50 18.75 18J 1,000 900 800 700 600 500 400 300 2UO 100 274 Testinn M*lk and Its Products. IX. Amount due for butter fat (Continued}. Price per | pound, cenU. Pounds of butter fut. P 19 19J 19i 19? 1,000 900 800 700 600 500 400 300 200 100 19 19* 19} 195 190.00 192.50 195.00 197.50 171.00 173.25 175.50 177.75 152.00 154.00 156.00 158.00 133.00 134.75 136.50 138.25 114.00 115.50 117.00 118.50 95.00 96.25 97.50 98.75 76.00 77.00 78.00 79.00 57.00 57.75 58.50 59.25 38.00 38.50 39.00 39.50 19.00 19.25 19.50 19.75 20 3 205 200.00 202.50 205.00 207.50 180.00 182.25 184.50 186.75 160.00 162.00 164.00 166.00 140.00 141.75 143.50 145.25 120.00 121.50 123.00 124.50 100.00 101.25 102.50 103.75 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 20J st 21 21i 21j 21J 210.00 212.50 215.00 217.50 189.00 191.25 193.50 195.75 168.00 170.00 172.00 174.00 147.00 148.75 150.50 152.25 126.00 127.50 129.00 130.50 105.00 106.25 107.50 108.75 84.00 85.00 86.00 87.00 63.00 63.75 64.50 65.25 42.00 42.50 43.00 43.50 21.00 21.25 21.50 21.75 21 211 21 J 213 22 I 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 22 221 224 22| 23 23* 23* 23} 230.00 232.50 235.00 237.50 207.00 209.25 211.50 213.75 184.00 186.00 188.00 190.00 161.00 162.75 164.50 166.25 138.00 139.50 141.00 142.50 115.00 116.25 117.50 118.75 92.00 93.00 94.00 95.00 69.00 69.75 70.50 71.25 46.00 46.50 47.00 47.50 23.00 23.25 23.50 23.75 23 23J 23* 23| 24 ill y 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 97.00 98.00 99.00 100.00 72.00 72.75 73.;>0 74.25 75.00 48.00 48.50 49.00 49.50 50.00 24.00 24.25 24.50 24.75 25.00 24 24 3 241 24$ 25 1,000 900 800 700 600 500 400 300 200 100 Appendix. 275 Table X. Relative-value tables. (See directions for use, par. 238.) ll 3.0 3.1 3.2 3.3 3.4 8.5 3.6 R 7 Price of milk per 100 pounds, In dollars and cents. .30 .31 .32 .33 .34 .35 .36 37 .31 .33 .34 .35 .36 .37 .38 .39 .33 .34 .35 .36 .37 .38 .40 41 .34 .36 .37 .38 .39 .40 .41 .43 .36 .37 .38 .40 .41 .42 .43 44 .37 .39 .40 .41 .42 .44 .45 46 .39 .40 .42 .43 .44 .45 .47 48 .40 .42 .43 .45 .46 .47 .49 .50 .42 .43 .45 .46 .48 .49 .60 .52 .43 .45 .46 .48 .49 .61 .52 54 .45 .46 .4f- .46 .61 .6 .54 fifi 3.8 3.9 4 .38 .39 40 .40 .41 42 .42 .43 44 .44 .45 46 .46 .47 48 .47 .49 50 .49 .51 52 .51 .53 54 .53 .55 56 .55 .57 58 .57 .68 6f 4 1 41 43 45 .47 49 51 53 55 57 59 61 4.2 H 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5 4 .42 .44 46 48 50 52 .55 .57 59 61 6? .43 44 .45 .46 .47 48 .49 51 .52 .53 .54 55 .56 .67 .58 .59 .60 .62 .62 .64 .64 6< : .45 .47 .49 .52 .54 .56 .58 .61 .63 .65 6: .46 .47 .48 .49 .50 .51 .52 .53 54 .48 .49 .50 .51 .62 .54 .55 .56 .57 .51 .52 .53 .54 .55 .56 .57 .58 59 .53 .54 .55 .66 .57 .59 .60 .61 62 .55 .56 58 .59 .60 .61 .62 .64 65 .57 .59 .60 .61 .62 .64 .65 .66 67 .60 .61 .62 .64 .65 .66 .68 .69 70 .62 .63 .65 .66 .67 .69 .70 .72 73 .64 .66 .67 .69 .70 .71 .73 .74 76 .67 .68 .70 .71 .72 .74 .75 .77 .78 .6^ .7C .72 .73 .75 .7C .78 .79 81 5.5 5.6 5.7 .55 .56 57 .58 .59 60 .60 .62 63 .63 .64 66 .66 .67 68 .69 .70 71 .71 .73 .74 .74 .76 .77 .77 .78 .80 .80 .81 .83 .8$ .84 8fi 5.8 5.9 6.0 .58 .59 .60 .61 .62 .63 .64 .65 .66 .67 .68 .00 .70 .71 .72 .72 .74 .75 .75 .77 .78 .78 .80 .81 .81 .83 .84 .84 .86 .87 .87 .88 .90 276 Testing' Milk and Its Products. Table X. Relative-value tables ( Continued). 3 li Price of milk per 100 pounds, In dollar* and cents. 8.0 .46 .48 .49 .51 .52 .54 .55 .57 .58 .60 8.1 .48 .50 .51 .53 .54 .56 .57 .69 .60 .62 8.2 .50 .51 .53 .54 .56 .58 .59 .61 .62 .64 3.3 .51 .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 .6 .66 .68 .69 .CL .68 .66 .67 .68 .70 .72 .7 .67 .69 .61 .68 .66 .67 .68 .70 .72 .74 .8 .61 .68 .66 .66 .68 .70 .72 .74 .76 .9 .60 .62 .64 .66 .68 .70 .72 .74 .76 .78 .0 .62 .64 .66 .68 .70 .72 .74 .76 .78 .80 .1 .64 .66 .68 .70 .72 .74 .76 .78 .80 .82 .2 .65 .67 .69 .71 .73 .76 .78 .80 .82 .84 .3 .67 .69 .71 .73 .75 .77 .80 .82 .84 .86 .4 .68 .70 .73 .75 .77 .79 .81 .84 .86 .88 .5 .70 .72 .74 .76 .79 .81 .83 .85 .88 .90 ft .71 .74 .76 .78 .80 .83 .85 .87 .90 92 7 .73 .75 .78 .80 .82 .85 .87 .89 .92 94 .8 .74 .77 .79 .82 .84 .86 .89 .91 .94 .96 4.9 .76 .78 .81 .83 .86 .88 .91 .98 .96 .98 5.0 .77 .80 .82 .85 .87 .90 .92 .95 .97 1.00 6.1 .79 .82 .84 .87 .89 .92 .94 .97 .99 1.02 6.2 .81 .83 .86 .88 .91 .94 .96 .99 1.01 1.04 6.3 .83 .85 .87 .90 .93 .95 .98 1.01 1.03 1.06 6.4 .84 .86 .89 .92 .94 .97 1.00 1.03 1.05 1.08 6.5 .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). 1* Price of milk per 100 pounds, in dollars and cento. 3.0 .61 .63 .64 .66 .67 .69 .70 .72 .73 75 8 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 .00 4.1 .84 .86 .88 .90 .92 .94 .96 .98 1.00 03 4.2 .86 .88 .90 .92 .94 .97 .99 .01 1.03 05 4 3 88 90 92 .95 97 99 1 01 03 1 05 08 4.4 .90 .92 .95 .97 .99 1.01 1.03 .06 1.08 .10 4 5 92 .94 97 .99 1 01 1 03 1 06 08 1 10 .13 4.6 .94 .97 .99 1.01 .03 1.06 1.08 .10 1.13 .15 4 7 96 99 1 01 .03 .06 1.08 1 10 13 1 15 18 4 8 98 1.01 1 03 1 06 .08 1.10 1 13 15 1 18 20 4.9 1.00 1.03 1.05 .08 .10 1.13 1.15 .18 1.20 .23 5.0 1.02 1.05 1.07 1.10 .12 .15 1.18 .20 1.23 .25 5 1 1 05 1 07 1 10 .12 .15 .17 1 20 22 1.25 27 5.2 1.07 1.09 1.12 .14 .17 .20 1.22 .25 1.27 .30 5.3 .09 1.11 1.14 .17 .19 .22 1.25 .27 1.30 .32 5.4 .11 1.13 1.16 .19 .21 .24 1.27 .30 1.32 .35 5.5 .13 1.15 1.18 .21 .24 .26 1.29 .32 1.35 .38 5.6 .15 1.18 1 l> .23 .26 .29 1.32 .34 1.37 .40 5.7 .17 1.20 1.23 .25 .28 .31 1.34 .37 1.39 .43 5.8 .19 1.22 1.25 .28 .30 .33 1.36 .39 1.42 .45 5.9 .21 1.24 1.27 .30 .33 .36 1.39 .42 1.45 .48 6.0 .23 1.26 1.29 .32 .35 .38 1.41 .44 1.47 .50 273 Testing Milk and Its Products. Table X. Relative-value tables (Continued). q 3 Price of milk per 100 pounds, In dollars and cents. 76 78 79 81 82 .84 .85 87 .88 90 3.1 .79 .81 .82 .84 .85 .87 .88 .90 .91 .93 3.2 .82 .83 .85 .86 .88 .90 .91 .93 .94 .96 3.3 .84 .86 .87 .89 .91 .92 .94 .96 .97 .99 3.4 .87 .88 .90 .92 .93 .95 .97 .99 1.00 1.02 3.5 .89 .91 .93 .94 .96 .98 .00 .01 1.03 1.05 3.6 .92 .94 .95 .97 .99 1.00 .03 .04 1.06 1.08 3.7 .94 .96 .98 .00 1.02 .03 .05 .07 1.09 1.11 3.8 .07 .99 1.01 .03 1.04 .06 .08 .10 1.12 1.14 3.9 .99 1.01 1.03 .05 1.07 .09 .11 .13 1.15 1.17 .0 1.02 1.04 1.06 .08 1.10 .12 .14 .16 1.18 1.20 4.1 1.05 1.07 1.09 .11 1.13 .15 .17 .19 1.21 1.23 .2 .07 1.09 1.11 .13 1.15 .18 .20 .22 1.24 1.26 .3 .10 1.12 1.14 .16 1.18 .20 .23 .25 1.27 1.29 .4 .12 1.14 1.17 .19 1.21 .23 .25 .28 1.30 1.32 .5 .15 1.17 .19 .21 1.24 .26 .28 .30 1.33 1.35 .6 .17 1.20 .22 .24 1.26 .29 .31 .33 1.36 1.38 4.7 .20 1.22 .25 .27 1.29 .32 .34 1.36 1.39 1.41 4.8 .22 1.25 .27 .30 1.32 .34 .37 1.39 1.42 1.44 4.9 .25 1.27 .30 .32 1.35 1.37 .40 1.42 1.45 1.47 5.0 .27 1.30 .32 .35 1.37 1.40 1.42 1.45 1.47 1.50 5.1 .30 1.33 .35 .38 1.40 1.43 1.45 1.48 1.50 1.53 5.2 .33 1.35 .37 .40 1.43 1.46 1.48 1.51 1.53 1.56 5.3 .35 1.38 .40 .43 1.46 1.48 1.51 1.54 1.56 1.59 5.4 1.38 1.40 .43 .46 1.48 1.51 1.54 1.57 1.59 1.62 5.5 1.40 1.43 .46 .48 .51 .54 1.57 1.60 1.62 1.65 5.6 1.43 1.46 .48 .51 .54 .57 1.60 1.62 1.65 1.68 5.7 1.45 1.48 .51 .54 .57 .60 i.62 1.65 1.68 1.71 5.8 1.48 1.51 .54 .57 .59 .62 1.65 1.68 1.71 1.74 5.9 1.50 1.53 .56 .59 .62 .65 1.68 1.71 1.74 1.77 6.0 1.53 1.56 .59 .62 .65 .68 1.71 1.74 1.77 1.80 Appendix. 279 .Me XI. Butter chart, showing calculated yield ot buiier < m 5bs.) from I to 10,000 Ibs. of milk, testing 3.0 to 5.3 per cent. (See directions for use, p. 26C.) a 3.00 3.10 3.20 3.30 3.40 3.50 3.60 3.70 3.80 3.90 4.00 4.10 f Milk, Milk, Ibs. Ibs. 10,000 325 836 348 860 371 883 394 406 418 429 441 452 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 8,000 2 000 65 07 f, 69 6 7? 74 ? 76 6 78.8 81.2 83.6 85 8 88.2 90.4 2,000 1,000 32.5 33.6 34.8 36.0 37.1 38.3 39.4 40.6 41.8 43.9 44.1 45.2 1,000 900 29.3 30.2 31.3 32.4 33.4 34.5 35.5 36.6 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. ] 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 18.1 400 300 9.7 10.1 10.4 10.8 11.1 11.5 11.8 12.2 12.5 12.9 13.2 13.6 300 200 6.5 6.7 6.9 7.2 7.4 7.6 7.9 8.1 8.3 8.6 8.8 9.0 200 100 3.2 3.4 3.5 3.6 3.7 3.8 3.9 4.1 4.2 4.3 4.4 4.5 100 90 2.9 3.0 8.1 3.2 8.3 3.4 3.6 3.6 3.7 8.8 3.9 4.1 90 80 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.8 8.4 8.4 3.5 3.6 80 70 2.3 2.8 2.4 2.5 2.6 2.7 2.8 2.8 2.9 8. 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. 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 2.3 60 40 1.3 1.8 1.4 1.4 1.5 1.5 1.6 1.6 1.7 1. 1. 1.8 40 30 20 1.0 1.0 1.0 1.1 1.1 1.2 g 1.2 g 1.2 8 1. 1. 1. 1.4 9 80 20 10 | ft 4 4 4 4 4 4 .ft 10 g .8 .SO I 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 3;>S) 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 2i)9 306 313 320 327 334 341 348 355 6,000 5,000 232 238 244 250 255 261 267 273 279 284 290 296 5,000 4,000 186 190 15)5 200 204 209 214 218 223 227 232 237 4,000 3,000 139 143 146 150 153 157 160 164 167 170 174 178 3,000 2,000 92.8 )3.2 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 5fl 9, 53 4 54 5 55 7 56 8 58 ~>9 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 29.6 510 400 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 8 .4 4 .4 4 .4 4 .5 4 .5 4 .5 4 .5 4 .5 4 .5 5 .5 5 .5 5 .5 6 9 8 7 6 .3 .3 .3 .3 .1 .3 .3 .3 g .3 .3 .3 .4 .4 .4 .4 7 6 5 2 V) o ^ 3 3 ' tj Q 3 3 3 5 4 .2 In .2 c J f] 2j .2 .2 c . ^ .2 .2 '.2 '.2 4 g 1 1 f) cy o 2 ' f 9 2 9 2 3 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 2 1 1 1 1 i 1 .1 1 1 i 1 1 1 1 4.40 1 4.20 4.30 4.50 4.60 4.70 4.80 4.90 5. CO 5.10 5.20 5.30 1 H s* 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 3.42 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 3.93 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 3.89 3.92 3.96 3.99 4.03 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 (> 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.'? 3.8 4.18 4.22 4.26 4.29 4.33 4.C? 4.41 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 .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 .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 .62 4.66 4.70 4.75 4.79 4.83 4.87 4.91 4.96 5.00 5.04 4.2 4.3 .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 84 4 88 4 93 4 97 5 O? 5 06 5 10 5 15 5 19 5 ?4 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 .5 4 6 5 06 5 11 5 15 5 ?0 5 94 - OH 5 34 5 38 5 43 5 47 5 52 .6 4 7 5 17 5 ?9 5 26 5 31 5 36 5 41 5 45 5 49 5 ,55 5 59 5 64 .7 4.8 5.28 5.33 5.38 ").42 5.47 5.52 5.57 5.62 5.66 5.71 5.7H .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 .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 6.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 6.94 5.99 6.05 6.10 6.16 6.21 6.26 6.32 ti.37 6.43 6.48 5.4 6.5 6.0-5 6.11 6.16 6.22 6.27 6.33 6.38 6.44 6.49 6.55 6.60 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 8.55 6.61 6.67 6.73 6.79 6.84 6.90 6.96 5.8 5.9 6.0 6.49 6.6C 6.55 6.66 6.61 6.72 6.67 6.78 6.73 f>.84 6.79 6.90 6.84 6.96 6.90 7.02 6.96 7.08 7.02 7.14 7.08 7.20 5.9 6.0 282 Testing Milk and Its Products. Table XIII. Yield of Cheese from 100 Ibs. milk with 2.5 to 6 per cent, of fat, and lacometer readings from 26 to 30. (See par. 224) =s LACTOMETEK DEGREES. 3 5.4 11.76 11.89 12.02 12.16 12.29 12.42 12.55 12.69 12.83 12.97 13.01 5.4 5.5 11.91 12.04 12.17 12.31 12.44 12.58 12.71 12.85 12.99 13.12 13.25 5.5 ) . i 12.07 12.20 12.33 12.47 12.60 12.73 12.87 13.00 13.14 13.28 13.41 5.6 5.7 12.22 12.35 12.48 12.62 12.75 12.89 13.02 13.16 13.30 13.44 13.57 5.7 5.8 12.38 12.61 12.64 12.77 12.91 13.05 13.18 13.31 13.45 13.59 13.72 5.8 5.9 12.53 12.66 12.79 12.93 13.06 13.19 13.33 13.47 13.60 13.74 13.87 5.9 6.0 12. 6912.82 12.95 13.09 13.22 13.35 13.49 13.62 13.75 13.89 14.02 6.0 Appendix. 283 Table XIV. Comparisons of Fahrenheit and Centigrade (Celsius) thermometer scales. Fahren- heit Centi- grade. Fahren- heit OnU- frade. *E?r Oentt- trade. +212 +100 +178 +80 +140 +60 211 99.44 178 79.44 139 59.44 210 98.89 174 78.89 188 58.89 209 98.33 178 78.33 137 58.33 208 97.78 172 77.78 136 57.78 207 97.22 171 77.22 136 67.22 208 96.67 170 76.67 134 56.67 205 96.11 169 76.11 133 56.11' 204 95.55 168 75.55 132 55.55 203 95 167 76 131 65 202 94.44 166 74.44 130 64.44 201 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 62.22 197 91.67 161 71.67 125 61.67 196 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 88.33 156 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 86 149 65 113 46 184 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 82.78 146 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 60.55 106 40.65 284 Testing Milk and Its Products. Table XIV. Comparisons of thermometer scales ( Continued. ) Fahren- heit. , Centi- grade. Fahren- heit. Centi- grade. Fahren- heit. Centi- grade. +104 +40 +68 +20 +32 +o 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 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 deg. Centigrade: Subtract 32, multiply difference by 5, and divide by 9. Example: Which degree Centigrade corresponds to 110 F.T 110-82 = 78; 78 X 6 = 390; 390 + 9 = 43.33. To convert deg. Centigrade" to corresponding deg. Fahrenheit: Multiply by 9, divide product by 5, and add 32 to quotient. Example: Which degree Fahrenheit corresponds to 95.5 C.? 96.5 X 868.5; MJ5 * 6 = 171.8; 171.0 + 32 = 203.6. 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 1 meter 39 37 inches 1 foot 3048 meter 1 meter 1 0936 yards 1 mile 1 6094 kilometers kilometer 6214 mile 1 square inch.. 1 square foot .. 1 square yard. 1 acre 6.452 sq. centimeters. 9.29 sq. decimeters. .836 sq. meter. 4047 hectare sq. centimeter square meter. . square meter- hectare .155 sq. inch. 10. 764 sq. feet. I.l96sq. yards. > 471 acres 1 cubic inch 16 387 cc cc 061 cubic inch 1 cubic foot.... 1 cubic vard... 1 bushel .0283 cub. meter. .7<>o cub. meter 355 hectolitei cub.decimeter cub. meter hectoliter til. 023 cubic inchea 35.314 cub. feet. %) 8377 bushels. 1 fluid ounce 29 57 cc cc 0338 fluid ounce. 1 quart 9464 liter liter 1 0567 quarts. 1 gallon 1 grain 1 ounce (av.)-. 1 pound (av. ) 3.7854 liters. 64.8 milligrams. 28. 35 gnu as. .4536 kilogram. decaliter gram. grain kilogram 2.'>417 < marts. 15.43 gniins. .035274 ounce. 2.2046|>ounds(av. 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 Ibs. Per cent of fat in cream Specific gravity of cream Weight of one' t gallon Ibs. 1.036 8.6391 35 0.9963 8.3076 10 .0243 8.5417 36 0.9952 8.2985 15 .0186 8.4938 37 0.9941 8.2894 16 .0174 8.4843 38 0.9930 8.2804 17 .0163 8.4749 39 0.9919 8.2714 18 .0152 8.4654 40 0.9908 8.2621 19 .0140 8.4560 41 0.9897 8.2534 20 .0129 8.4465 42 0.9886 8.2444 21 .0118 8.4372 43 0.9875 8.2354 22 .0107 8.4278 44 0.9864 8.2265 23 .0096 8.4184 45 0.9854 8.2176 24 .0085 8.4090 46 0.9843 8.2087 25 .0073 8.3997 47 0.9832 8.1998 26 .0062 8.3905 48 0.9821 8.1909 27 .0051 8.3812 49 0.9811 8.1821 28 .0040 8.3719 50 0.9801 8.1733 29 .0029 8.3626 51 0.9790 8 . 1646 30 .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. SLGGLSIIO\S regarding the organization of co-operativ 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 nidi us of four to five miles from the proposed factory. 1 Small cheese factories can be operated with less milk, and gat he red -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 u 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 cento, (usually five cents) per hundred pounds of milk received at the factory shall be reserved for the payment of this borrowed, money. 1 Bull. 64, 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 OR ARTICLES OP AGREEMENT OF THE ASSOCIATION.' 1. The undersigned, residents within the Counties of , State of , herebyagree 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- J The 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 hall 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 testa of the milk or cream received from each patron, 89 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. Alcohol test, 135. 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, 236. 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. Ash, determination of, in butter, 232; in cheese, 245; in milk, 227. Babcock glassware, standard, spe- cifications for, 258. Babcock test, the, 4, 28; Bart- letts modification, 71; direct- 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, 258a; modifications of, 71; scales for weighing cream, chesee, 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 modification of Babcock test, 48, 71. Bausch and Lomb centrifuge, 71. Beimling test, 5. Benkendorf moisture test, 239. 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. 252. Borax in dairy products, 252. Butter, artificial, 12 ; detection of, 240. Butter chart, 279: 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, 259: creamery methods of estimating water in, 233; definition, 257; determination of ash, 232 ; case- In, 231 ; fat, 231 ; salt, 233, 239 ; water, 231 ; rapid estimation of water 233; Ames method, 236; Benkendorf moisture tester, 239: Cornell test, 237 ; Dean's meth- od, 237; Cray's method, 235; Irish test, 236; Mitchell-Walker test, 235; Patrick's method, 235; Wisconsin high-pressure oven method, 237; processs, 255; renovated, 255 ; sampling for analysis, 95, 231 ; scales for weighing, 81, 233; standard, 257. 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, 257; test and yield of butter, 187. Butter making, quantities of prod- ucts obtained in, 21. Butter milk, 21 ; Babcock test for, 94; chemical analysis of, 228; composition, 259; definition 256; 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 ; Trowbridge 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. Chamber-land 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, 259; chemical analysis of, 243 ; definitions, 257; determination oi ash. 245; 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 ef 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, 259; but- ter milk, 259; cheese, 259; col- ostrum milk, 259; condened milk, 259; cream, 259, milk, 18; 259; milk ash, 17; skim milk, 259; whey, 259. Condensed milk, 22 ; analysis of, 229; composition of, 259; de- termination of concentration, 230 ; of sp. gr. of, 230 ; testing of, 98. Control samples of milk, 111. Conversion factor for butter fat, 196. 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, 180 ; bottles, 79; care In sampling, necessity of, 182 ; clotted, 255 ; definition, 257; determination of acidity of, 125, 135 ; errors of measuring in testing, 76 ; evap- orated, 257; fat in 1 to 1000 Ibs., testing 12 to 50 per cent., 271; gelatin in, detection of 249 ; 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, 257; 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. 285; 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, 255. DeLaval's butyrometer, 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. 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. Flourids. detection of, 253. Food, influence of on quality of milk, 144, 146, 150. Food stannas, Government, 255. Fool pipettes, 46. Formaldehyne, detection of 253. 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, 255. Gray's test for water in butter, 235. Grain-feeding, heavy, influence of, on quality of milk, 155. Hand separator cream, gathering and sampling, 185. Hand testers, 00. Hart's test for casein in milk, 226. Hemi-albumose, 14. Herd milk, variations in, 153 ; ranges in variations of, 154. Hydrostatic balance, 82. Hypoxanthin, 18. Ice-cream, test of, 100 ; definitions, 257: 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, 236. Kumiss, 258. 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. Leffmann and Beam test, 5. Legal standards for milk, 112, 260; for dairy products, 260. 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 fa^ 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, 255; boiled, detection of, 249 ; casein in, 13 ; chemical analysis of, 217 ; cholesterln In, 18 ; churned, sampling of, 24 ; citric acid in, 18; colostrum, 18; composition Index. 295 of |[10, 18, 259; composite sampling of, 160 ; condensed, 22, 98, 259; correction table for specific gravity, 262; defini- tions, 254 ; detection of coloring matter, 247; of preservatives, 135, 252; 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, 260; macroscopic impurities, 251; nrneral components, 16; partially churned, sampling of, 24 ; pasteurized, detection, 248 ; preservatives, detection, 130, 252; 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 whey, 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 . Milk tests, Babcock, 4, 6; Beim- ling (Leffmnnn and Beam), 5; Cochran, 5 ; DeLaval butyrome- ter, 8 ; Failyer and Wlllard, 4 ; Fjord, 8 ; foreign, 7 ; Gerber acid-butyrometer, 7 ; introduc- tion of, 4 ; lactocrite, 5, 7 ; Lle- bcrmann, 5 ; Llndstrom, 9 ; Nahm, 5 ; Parson, 4 ; Patrick (Iowa station test), 5; RSse- Gottlieb, 5, 222 ; sal-method, 5 ; Schmied, 5 ; Short, 4 ; sin-acid, 7 ; Thorner, 5 ; Wollny rcfracto- meter, 9. Milk products, composition of, 19, 259. Milk testing, 28 ; on the farm, 142. Mitchell-Walker test, 235. Mojonnier test, 99. Monrad rennet test, the, 140. 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, 246. Non-fatty milk solids, 10. Normal solutions, 121. Nuclein, 14. Official tests of cows, 150. Oil-test churn, 2, 177. Oleomargarine, detection of, :MO, 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. 235. 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, 252; detection of in milk, 135, 252. Preservatives, for composite sam- ples, 167 ; in milk, detection of, 135, 252. 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. Reichert 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, 243. Reservoir for water in Babcock test, 70. Richmond's milk scale, 110. R8se-Gottlleb's method, 5, 222. Salycalic acid, detection of, 253. 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- vell, 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 Babcocs test, 71. 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, 259; condensed, 256; 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, 264. 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, 258a. Index. 297 Standards of purity, Government for milk and its products, 255. 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, 86 ; 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, 283. ThSrner'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, 285. Westphal balance, 219. Whey, 22; Babcock test for, 94; chemical analysis, 228 ; composi- tion, 259; definition, 258. 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, 237. Wisconsin sediment test, 251. 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., 279. 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, 282. Accurate Tests as well as rapid tests are now essential for testing milk for butter fat and total solids. It is now possible to obtain the same high degree of accuracy within but a fraction of the time necessary by the official method, by using the Mojonnier Tester Its working parts are so carefully designed and co-ordinated that a laboratory assistant can make accurate butter fat tests in a half hour; solids determinations in 25 minutes. Hundreds of the large milk plants have Mojonnier Efficiency Products in successful operation, and profit by their use. Write for Illustrated Circulars. MOJONNIER BROS. CO. Milk Engineers 833 W. Jackson Blvd. Chicago, 111. THE "FACILE" Iron Frame Babcock Milk Testers 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 Increase the Efficiency of your Plant by using NAFIS CREAMERY GLASSWARE In Your Testing Room It will save you money because of its accuracy and quality If your dealer cannot supply you with Nafis Glassware, write for our illustrated catalogue and list of our distributors LOUIS F. NAFIS, INC. Manufacturers of Scientific Glassware 542-548 Washington Blvd. Chicago, Illinois 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- ances and Weights. Style No. 4500 THE TORSION BALANCE COMPANY * , j Office Factory^an Dipping ^ Q2 Reade Street, New York Pacific Coast Branch: 49 California Street, San Francisco, Cal. OP THE MARSCHALL NEVER l:\EQUALLED J* ^aooooooc" Cream-Weighing Scale For Use in Connection with the Bahcock Test "THIS SCALE is especially designed for very accurate weighing of cream, butter and cheese. All bearings are aate; plates are porcelain; base and underconnections are galvanized, mak- ing a rust-proof scale. It has a slide bar in front to balance the test bottle and is provided with the necessary weights. Base of scale 10'i in. long; porcelain plates 3 in. square. PRICE $14.50 Manufactured by HENRY TROEMNER, 911 Arch St. PHILADELPHIA..PA. CHR. HANSEN'S LABORATORY, INC., Little Falls, New York Headquarters for coagulants for milk in Cheese Mak- ing, Rennet Extract, R-P Extract and Pepsin Extract Rennet Tablets and Cheese Color Tablets; Liquid Butter and Cheese Color; Lactic Ferment Culture and Bulgarian Milk Culture. Also Junket Tablets and Nesnah Desserts, Buttermilk Tablets, Pure Food Colors, etc. UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. Form L9-Series 444 SOUTHERN REGIONAL LIBRARY FACILITY