,0 C, ,f\ ■• — 3H| inn — • W «V' *< 0' 4 o ** ** *j£MZ>S. *^ r oK '^*CV ^ ^ %/■ «**<% 4 o ***** ^°^ * l O o * . , i • V .'/V.I '\ £— «• ^OcJL (X^^/A<-tHs THE ADULTERATION OF MILK HENRY A. MOTT, Jr., E.M., Ph.D. MINING ENGINEER AND ANALYTICAL CHEMIST; MEMBER OF THE AMERICAN CHEMICAL SOCIETY; MEMBER OF THE NEW YORK ACADEMY OF SCIENCES \ FELLOW OF THE GEOGRAPHICAL SOCIETY, ETC., ETC. NEW YORK: TROWS PRINTING & BOOKBINDING CO., 205-213 East 12th Street. 1878. w- THE ADULTERATION OF MILK HENRY A. MOTT, Jr., E.M., Ph.D. MINING ENGINEER AND ANALYTICAL CHEMIST ? MEMBER OP THE AMERICAN CHEMICAL SOCIETY; MEMBER OF THE NEW YORK ACADEMY OF SCIENCES; FELLOW OF THE GEOGRAPHICAL SOCIETY, ETC., ETC. NEW YORK: TROW'S PRINTING & BOOKBINDING CO., 205-213 East 12th Street. 1878. r ^ Br transfer J! 2? "07 THE ADULTERATION OF MILK. BY HENRY A. MOTT, JR., E.M., PH.D. This department of the subject of milk is, without doubt, the most importaut of all. Surely, every effort made to discover or point out the true method for de- tecting the adulteration of this most important fluid, which is so indispensable to the kitchen, the sick-room, and the nursery, cannot help but be received with in- terest. For this reason I shall endeavor in this paper to consider in detail : l s t._The Adulterants of Milk. 2d.— The Instruments and Methods of Detecting Adulteration. Before proceeding with the discussion of the first division of the subject, it will probably be well to con- sider very briefly some of the peculiarities of milk, of which undue advantage are taken by milkmen. Milk contains two elements, water and fat, both of which possess a specific gravity less than that of pure milk itself ; these two elements can vary, and do vary, between certain limits in pure or normal milk ; but when the variations are too great the milk becomes abnormal. Between certain limits, then, a sample of pure milk may have a low specific gravity, owing to a large proportion of water, or it may have a low gravity, owing to a large proportion of fat. In the first case the milk would be poor and thin, in the latter rich and thick. The consistence of two such fluids, a thorough milk- man (I mean one posted up to the tricks of his trade) could easily distinguish, and it is, I suppose, on the business principle, that you should only give a man for his money as little as possible, that the milkman, when he finds or receives a quantity of milk that is rich and thick, partly skims and dilutes it between certain 4 limits, knowing that the fraud cannot be detected, owino'to the fact that the constituents of milk (especi- ally fat) are subject to yariation. I am sorry to have to say that this fraud cannot be detected, but it is a fact, and we must grin and bear it, for science never has nor never ean offer a method for the detection of such adulteration. Neither chemical analysis nor the various instruments used for detecting adulteration can offer any aid. Happily, though, for the consumers of this most valuable fluid, the limits between which such adultera- tion can be carried on are very small, and consequent- ly no very serious results could originate from such adulteration even to infants. If the milkmen would limit their adulteration to this point, we all might be thankful, but unfortunately for us they do not conde- scend to consult any other source but their pockets. Hence there is forced upon the consumers: "Milk di- luted largely with water; skimmed milk; skimmed milk diluted largely with water, and various decoc- tions called milk, containing any number of adulter- ants." Fortunately science can interfere with such adulterations and frauds as these, and when they are detected then a severe and just penalty should be pro- nounced upon the perpetrator, who not only robs the consumers of their rights, but sends many an infant to its grave. 1. — The Adulterants op Milk. The adulterants, said to be used by different writers for the adulteration of milk, are quite numerous. Al- though water and, sometimes, chalk, soda, and caramel are practically the only adulterants that are used, the proper treatment of the subject demands the considera- tion of all the other adulterants, no matter if the con- sideration extends to the brains of the sheep. 1. Water. — This fluid is the most prevalent adulter- ant of milk — it costs nothing, and possessing a speci- fie gravity less than that of pure milk, the gravity of this fluid may be reduced at pleasure. The amount of water added by milkmen ranges between 10 and 50 per cent Dr. Chandler, 1 from numerous and valuable investigations of the milk supply of New York, con- cluded that the average milk sold consisted of three- quarters milk and one-quarter added water. The 120,000,000 quarts of milk sent annually to New York receive an addition of 40,000,000 quarts of water, which, sold at 10 cents per quart, brings $4,000,000 per annum, or $12,000 per day. There are a few persons who are disposed to make light of the adulteration of milk by water, but to an educated mind they only display their ignorance. The addition of water to milk or, worse, to skim milk greatly decreases the percentage of the milk solids (as proven in the following table), and consequently ren- ders the milk not only unfit for the food of infants but in many cases dangerous. If the water used to adulterate the milk is not pure, we have danger arising from another source. There is recorded a case 2 where an epidemic of typhoid fever occurred near G-lasgow, Scotland, in 1872-8 by the milkman adulterating his milk with foul water, and allowing his cows to slake thirst from such water. Thirty -two out of thirty-nine families which were sup- plied with this milk, as also the family of the milk- man, were attacked. Families supplied by other milk- men were not affected. The fever germs were propagated through the adul- terating of the milk with this foul water. Another case is reported : "In one of the healthiest suburban sections of London 500 cases of typhoid fever were found distributed in 104 families, 96 of which were supplied with milk from one dairy. The contagion 1 Johnson's Cyc, article Milk. 2 See Willard's Practical Butter Book, p. 24. » 6 Table of the quantities of milk solids contained in 100 farts of a mixture of water and -pure milk, in differ- ent proportions. 1 BY CESAIRE REYNARD. Milk. Water. Milk solids. Milk. Water. Milk solids. 100 12.9200 64 36 8.2688 99 1 12.7908 63 37 8 1396 98 2 12.6616 62 38 8 0104 97 3 12.5324 61 39 7 8812 96 4 12.4032 60 40 7.7520 95 5 12.2740 59 41 7 7308 94 6 12.1448 58 42 7 2016 93 7 12.0156 57 43 7 1724 92 8 11.8864 56 44 7.0432 91 9 11.7572 55 45 6 8140 90 10 11.6280 54 46 6 6848 89 11 11.4988 53 47 6 5556 88 12 11.3696 52 48 6.4264 87 13 11.2404 51 49 6.2972 86 14 11.1112 50 50 6.2600 85 15 10.9020 49 51 6.1308 84 16 10.8528 48 52 6.0016 83 17 10.7236 47 53 5.9724 82 18 10.5944 46 54 5.9432 81 19 10.4652 45 55 5.8140 80 20 10.3360 44 56 5 . 6848 79 21 10.2068 43 57 5.5556 78 22 10.0776 42 58 5.4264 77 23 9.9484 41 59 5.2972 76 24 9.8192 40 60 5.1680 75 25 9.6900 39 61 5.0388 74 26 9.5608 38 62 4 9096 73 27 9.4312 37 63 4.7384 72 28 9.3024 36 64 4.G532 71 29 9.1732 35 65 4 5220 70 30 9.0440 34 66 4.3928 69 31 8.9148 33 67 4.2636 68 32 8.7856 32 68 4.1344 67 33 8.6564 31 69 4.0522 66 34 8.5272 30 70 3.8760 65 35 8.3980 1 Journal de Chimie Med., p. 358. 1856. was traced directly to the water used for washing the milk cans and retained in the milk, the water being previously polluted by sewer drainage." All stagnant water contains organisms either animal or vegetable, that renders it unsafe to use, or to allow cows to drink. In the case of pure spring water or running water, which likewise contains organisms, there is not sufficient organic matter in suspension to promote their development. In the case of stagnant water the organic matter in suspension or in solution creates in the water the proper mediums suitable for the development of living organisms. "It 1 is no longer mere water — it is a world of microscopic ani- mals and plants which are born, live, and increase with bewildering rapidity. Drink a drop of this water and you swallow millions of minute beings." Use this water to adulterate milk and you furnish more nourish- ment to these little organisms, which continue to mul- tiply, and then give the milk to an infant for food and you supply with it organisms which are capable of producing violent cramping and purging, as also capable of setting up putrefaction in the tissues. 2. Chalk. — This substance is sometimes used to pro- duce a thickness and opacity to milk that has been diluted with water ; it is also used to neutralize the acidity in sour milk. 3. Starch, Flour, Decoction of Barley, Rice, and Emulsion of Almonds and Hempseed are said to be used to thicken milk and to neutralize the blue color caused by dilution. 4. Cane Sugar, Dextrine, Milk Sugar, Gum Traga- canth, Gum Arabic, and Borax are sometimes used to increase the specific gravity of diluted milk and sweeten the same. 5. Salt (sodic chloride) is used to increase the epe- cific gravity of diluted milk and to bring out the flavor. 1 Scientific Conversations by M. Porville. Paris. 8 6. Turmeric, Annatto, Caramel, juice of certain roots, such as the Carrot or the different flowers, Marigold, Saffron, and Safflower, are used to color the fluid so as to hide the blue color due to dilution. 7. Carbonate or Bicarbonate of Soda is used to pre- vent the milk from becoming sour, by neutralizing the acidity; also to increase the specific gravity of diluted milk. 8. Gelatin and Isinglass have been used to thicken diluted milk. 9. Cerebral matter, Sheep's Brains, Calves' 1 Brains, or Horses' 1 Brains, have been detected in milk. They were used to thicken the milk after first watering the same. Having enumerated over the adulterants said to be used for the adulteration of milk, I will now proceed to the discussion of the second division of the subject, namely : 2. — The Instruments and Methods for Detecting Adulteration. The first requisite, before proceeding to apply a rapid and practical test to the examination of milk, is to ascertain the nature of the adulterants used, so as to know what has to be coped with in the examina- tion. If a given sample of milk, known to be adul- terated with several of the adulterants mentioned above, is presented to a chemist to discover the nature of the adulterants, the only method for arriving at the required result is by chemical analysis. Knowing the adulterant or adulterants used, then a more rapid method may be adopted for their detection. It is well though, in large cities, from time to time, to make analyses of the adulterated fluid, to ascertain whether or no the adulterant or adulterants have been changed ; for it might become necessary to change to a cer- tain extent the method of examination. Experience has demonstrated that water is, in 99 cases out of 9 100, the only adulterant used for the adulteration of milk. This has been clearly demonstrated in this country, in England, Scotland, France, Belgium, Germany, and Switzerland. Let us now consider the instruments and methods for detecting its presence in commercial milk. DETECTION OF THE ADULTERANT, WATER. The detection of water, when employed as an adul- terant of milk, is not always possible, for two reasons : 1st, because science does not offer any method for distinguishing the water naturally present in milk and the added water ; 2d, because the percentage of water varies so much in pure milk, that it is only possible to detect added water when the quantity present exceeds the maximum quantity in pure milk. No matter what method we adopt to detect adulterated milk, whether it be chemical analysis, the lactometer, the microscope, or the various other instruments and methods to be described, a standard which shall represent the poorest pure milk has got to be adopted. When it is desired to use the specific gravity of milk as a test for its purity, the specific gravity adopted as a standard must represent the gravity of the whole pure milk. To determine this gravity any number of experi- ments have been made : but, before proceeding to the consideration of the different experiments, let us glance for one moment at the various specific gravities stated by prominent writers which are given to represent the weight of milk : SPECIFIC GRAVITY OF COW'S MILK. 1.030 to 1.039.... Simon. 1 1,0302—1.0396 Vernois & Becquerel. 2 l'.026— 1.032 Scherer. 3 1 Animal Chem., Eng. ed., p. 50. 2 Anal. d'Hygiene Publ., Avril, 1857. s Physiol., von Dr. Wagner, 1850, p. 450. 1* 10 1.0395-1.0343 J Fleischman.' average 1.0317 \ • g 1.0324 (average) Brisson. 2 1 -^-}° m A Quevenne.* 1.0322 (average) \ ^ t0 f n trJ- 0357 J Macadam.' 1.032 (average) ) « 1.032 (average) \ . . Wiggin. 5 1 -" 2 »- 1 ; 040 J-- Mott. 1-032 (average) \ ess 1.02958—1.0354 ) T „ n , , 1.03184 (av'ge) [ Je P son & Gardner. 6 [ 1.02958-1.03538 ) w „ 7 1.03219 (av'ge) f" vvaiier. i 1.029—1.034 (whole milk). . .Hassal. 8 j 1.026—1.031 Hassal. 9 1.028—1.032 Wilson. 10 1.026—1.036 Atcherley. 11 1.029. . . . , Gorup v. Besanez. 12 1.030 (lowest) Marchand. 13 1.029—1.034 C. MiUler. 14 1.031494 (average) J. Blake White. 15 1.027—1.033 ) au i i6 1.030 (average) \ Sharpies. 16 ] 1.026—1.035 Parkes." 1.026—1.032 Klencke. 18 S 1.0271 (average) Orthman. 1.0248—1.0348 Pincus & Struckmann. 1.02958—1.0348 Chandler. 19 1 Jahresb. Th. Chem., XIII.-XV. (3), p. 237. 2 Rees' Ency., 1819, article "Milk." 3 Diet. Ency. des Sci. Med., p. 130. 4 Amer. Chem., 1875, May, p. 419. 6 Report, 1870-71, Providence, R. I. 6 City Record, July 29, Oct. 7, 1875. 7 School of Mines, Columbia College. 8 Adulteration of Pood, new ed., p. 408. 9 Adulteration of Pood, old ed., p. 216. 10 Handbook of Hygiene, p. 42. - 11 Adulteration of Food, p. 61. 12 Physiol. Chemie, p. 332. 13 M^ moires d' Agriculture, Paris, 1858, p. 305. 14 Anleitung zur Prufung der Kuhmilch, p. 47. 15 City Record, Aug. 17-24, 1676. 16 Proc. Amer. Acad. Arts & Sci., p. 149 (vii.). 17 Practical Hygiene, p. 216, London, 1866. 18 Die Verfalschung der Nahrungsmittel und Getrauke, von Herman Klencke, 1S58. 19 Johnson's Cyc, article "Milk." 11 In reviewing the above figures, quite a difference will be observed ; but, fortunately, this difference can be readily explained. The object of most experimenters has been simply to determine the specific gravity of the particular samples they have had under examination, and their results are correct for those particular sam- ples, but incorrect if they are meant to represent the specific gravity of all the milk from a milking thor- oughly mixed together. When I speak of the specific gravity of the milk of a cow, I mean the specific gravity of all the milk from the cow (in perfect health) thoroughly mixed together, obtained at her regular hour of milking, not the spe- cific gravity of the first, middle, or last portion, for each of these portions give an entirely different specific gravity peculiar to themselves. The following are tests of the first and second drawn milk from eight different cows : 1 First drawn milk. Second drawn milk. Cows. Specific Gravity. Cream. Cows. Specific Gravity. Cream. 1.... 2.... 3.... 4.... 5.... 6.... 7.... 8.... 1.027 1.026 1.027 1.029 1.030 1.030 1.029 1.031 9 13 8 7 11 8 H 2 1.... 2.... 3.... 4.,.. 5.... 6.... 7.... 8.... 1.023 1.023 1.025 1.024 1.024 1.022 1.026 1.030 25 22 10 15 32 25 7i 5 Total... 61| Total... 1 141* Schubler found that, on fractioning the milk at a milking, the — 1 London Lancet. 12 Specific Gravity. Cream. First portion showed 1.0340 5 per cent. Second •• " 1-0334 8 " » Third " " 1.0327 11.5 " " Fourth " " 1-0315 13.5 " " Fifth " " 1.0290 17.5 " " Average 1.0321 11.0 " " Jepson & Gardner, Milk Inspectors for New York, found the milk and strippings of two cows : Entire Milk. Strippings. First cow. . .Specific gravity 1.0348. .1.02610 lact. 90 Second cow. " " 1.0319. .1.02668 lact. 92 What, then, is the specific gravity of cow's milk ? Or what is the range of the specific gravity ? I have already stated that a number of experiments have been made to determine this important point, and we will now proceed to consider them : Dr. Fleischman, 1 of Germany, personally inspected the milk of thirteen different dairies in the vicinity of Linden, containing in the aggregate one hundred and twenty-three cows. He noted the specific gravity of the milk of each cow separately and upon each day, in bulk, with the following results: " The mean specific gravity from the 123 cows is 1.0316908." " The maximum specific gravity of any one of the 123 cows is 1.034300, and the minimum specific gravity from any one of the 123 cows is 1.029500." "The milk of 9 per cent, of the cows exceed 1.033 in specific gravity." "The milk of 89 per cent, of the cows ranged from 1.033 to 1.030 in specific gravity, and the milk of 2 per cent, of the cows was below 1.030 in specific gravity." "The mean specific gravity of the milk from the 13 dairies ranged between 1.03065 and 1.03285, or, in round numbers, between 1.031 and 1.030." Quevenne 2 tested the milk from 103 cows, his ex- 1 Jahresb. Th. Chem., XIII.-XV. (3), p. 237. 2 Die. Ency. Sci. Med., p. 130. 13 periraents extending over a period of eleven years. He found the average specifie gravity 1.0322, and for the range 1.0288 to 1.0364. He only found one sample of specific gravity 1.0288 ; he found six samples be- tween 1.029 and 1.030, five samples above 1.035, and ninety-one samples between 1.030 and 1.035. Dr. Steven Macadam * made a number of tests at three large dairies in the neighborhood of Edinburgh. He found the specific gravity to range from 1.0284 to 1.0357; the average of forty-four trials of different milks being 1.03220. The milk was taken direct from the udders of the cows. He found only one sample of specific gravity 1.0284, one of 1.0294, and one of 1.0296. All the other samples had a specific gravity between 1.0304 and 1.0357. Jepson & Gardner 2 tested the milk of 109 cows (45 Harlem and 65 Orange Co., N. Y.) ; they found, for the average, the special gravity 1.03184, for the range 1.02958 and 1.0354. Dr. Waller tested the milk of 86 cows and obtained the average specfie gravity 1.0321, and for the range 1.02958-1.0353. Dr. J. Blake White 3 tested the milk of 129 cows at six dairies, making 142 examinations, and found the total average specific gravity 1.031494. Lastly, Dr. Christian Miiller 4 had made, under his control, " in the newly-erected manufactory of con- densed milk of the Swiss Company, Moleson," a large number of milk tests. Out of the first 280 weighings in the month of March, 1872, only two cases were found under 1.030, namely, 1.0286 and 1.0298. Over 1.033 to and with 1.034 there were twenty cases ; over 1.034 only two, the highest being 1.0344. Two hun- 1 Amer. Chem., May, 1875, 419. 2 City Eecord, July 29, and Oct. 7, 1875. 3 City Eecord, Aug. 17 and 24, 1876. * Anleitung zur Priifung der Kuhmilch, p. 55. 14 dred and fifty-seven weighings varied between 1.029 and 1.033. "As the average of all the tests," he says, "I obtain a figure which is only a very little larger than 1.031. With respect to the milk which gave the specific gravity 1.0286, it came from a spayed cow, which was already fattening and gave daily two quarts of milk that had, moreover, a bitter taste." From the above most elaborate experiments an un- prejudiced mind will not hesitate to say that the speci- fic gravity of the whole milk from cows in perfect health will never fall below 1.029. And if we see stated the specific gravity of a cow's milk below 1.029, we may be sure that either the milk is abnormal, the sample tested not a fair average of all the milk that could be obtained from the cow at her regular hour of milking, the sample has been tampered with, the in- strument used to obtain the specific gravity incorrect, or that the temperature at lohich the specific gravity was obtained could not have been the conventional temper- ature 15.5, O. (60° F.). With respect to the two samples recorded, one by Quevenne and the other by Macadam, which gave a gravity slightly below 1.029 within 6 ten thousandths, it is evident that some of the above-mentioned conditions were overlooked. "No better proof is necessary to my mind than the fact that it took the examination of the milk from over 850 cows to produce two such samples. The minute we find a property of milk that is con- stant, or, if it varies, does so between certain limits that can be definitely fixed, that minute this property becomes a standard and test for the purity of milk. And it is for this reason that an instrument can be constructed, based on the fluctuating gravity of pure healthy cow's milk, the indications of which will be infallible. The original galactometer discovered by Cadet de Vaux, in 1817; the Centesimal Galactometers ; the Lactodensimeter, discovered by Quevenne, in 1842 ; 15 the first instrument called Lactometer, by Mr. Dicas ; l the Lactometer, discovered by Edm. Davy, in 1821 ; the Milk Tester, discovered by G-reiner, in Berlin, in 1834; the Milk Weigher of Mollenkopf, Dorssel, and G-eissler, in Stuttgart ; and the various other lactome- ters are such instruments, which are all hydrometers, and differ from each other in the graduation of their scales. The Centesimal Galactometee, was invented by Dinocourt : it is shown in fig. 1. The stem of the in- strument has two scales: one for pure milk, the other for skim- med milk ; the scale A, in part colored yelloio, serves to weigh the milk with its cream ; the first degree on the top of the scale is marked 50, which cor- responds to the sp. gr. 1.014* The following marks extend from 50 to 100 (sp. gr. 1.029), and over. Each degree starting from one hundred in mounting up to 50, represents a hundredth of pure milk; the degrees formed by a line are equal, as 50, 52, 54, etc. ; the de- grees formed by a dot are un- equal, as 81, 83, 85, etc. To illustrate by an example : If the galactometer is sunk to the 85th degree, that will indicate 85 hundredths of pure milk, and consequently that 15 hundredths of water has been added to this milk ; if sunk to 60 degrees, that will indicate 40 hundredths of >-_/.03£ f.03S Fig. 1. * Agric. Survey of Lancashire, 1815, p. 550. 16 water, or four-tenths of water added. If it is desired to count by tenths, it is only necessary to notice that the first tenth is white, that the second is colored yel- low, the third white, the fourth yellow, and that the fifth is also white; towards the middle of each tenth the figures 1, 2, 3, 4, 5 are placed to indicate their order. The scale, a, is in part colored blue, and is destined to weigh skim milk ; it is, like the first, divided into hundredths (100 degrees), of which the first 50 have been cut off as useless, as in the case of the other scale, each degree commencing from 100 to 50 and mounting upwards represents a hundredth of pure skimmed milk, consequently the manner of estimating the quan- tity of water added to skim milk is absolutely the same as for pure milk with cream. The degree 130 corresponds to a specific gravity 1.038, the degree 120 to 1.035, the degree 110 to 1.032, the degree 100, which is the standard, to 1.029, the degree 80 to 1.023, the degree 70 to 1.020, the degree 60 to 1.017, and the de- gree 50 to 1.014. Another Centesimal Galactometer 1 was in- vented by Chevallier ; it is similar to the above instru- ment. It serves to determine the specific gravity of cream, milk, and skimmed milk. This instrument is used in connection with the *creamometer. The speci- fic gravity of the milk not skimmed is first determined, noting the temperature, then the volume of cream is ascertained by means of the creamometer, and finally the specific gravity of the skimmed milk is determined, noting the temperature. From the data obtained, by referring to tables com- piled by Chevallier, the additional water contents of the milk is ascertained. 1 Jour. Pharm. et Chim., 3d series, 1844, t. v. p. 137; Jour. Chem. Medic, 4th series, 1856, t. 11, p. 343-401. 17 THE LACTODENSIMETER. The lactodensimeter J is an instrument differing from the galactorneter just described only in the division of its scale. It is the production of Bourchardat and Quevenne, and is represented in fig. 2. This instru ment, like all the densimeters, gives immediately and without calculation the density of the liquid in which it is plunged ; its scale comprises only the densities which may be presented by pure or adulterated milk. The shaft bears three distinct graduations. The first, which is the middle one in the figures, contains the whole numbers inter- mediate between 14 and 42. In reality, the whole numbers comprised between 1.014 and 1.042 ought to be inscribed ; but on account of the small size of the shaft the two first figures have been suppressed which do not change. If, consequently, the instrument is sunk in a liquid up to the figure 29, this signifies that a litre of this milk weighs 1.029 grams, and that its den- sity is consequently 1.029. The instrument has been graduated for the temperature of + 15° C. It is necessary, therefore, for obtaining an exact indication, to be assured the liquid under examination is at this temperature. In the contrary case, it may be brought back to this degree by plunging the gauge containing the milk in water that is cold, or in lukewarm water, accord- ing as the thermometer is above or below + 15°. The table given on p. 19 may also be employed, which is easily comprehended on inspection, and which is extracted from the memoir of Bouchardat and Quevenne. 2 1 See Die. Ency. Sci. Med., p. 144— Lait. 2 Repertoire de Pharrnacie, juiliet, 1856. 18 The scale on the right is employed when it is certain that the milk acted on is not skimmed. This scale shows what are the variations of the density of milk in proportion as water is added, and the figures to, A, etc., indicates that the liquid operated upon has been mixed with this proportion of water. The scale on the left contains the same indications relative to skimmed milk. Milk is marked pure on this instru- ment between the specific gravities 1.030 and 1.034, skimmed milk is marked pure between the gravities 1.034 and 1.037. LACTOMETEK. The original instrument that was called a " Lactom- eter" was discovered by Mr. Dicas in 1815. The following is a description of the instrument by the inventor : "It is constructed with ten divisions on the stem, which is similar to the patent brewing hydrometer, and with eight weights, which are to be applied only one at a time upon the top, to obtain the weight of the milk ; an iron sliding rule accompanies this instru- ment, upon the middle or sliding part of which is laid down the lactometer weight of the milk, going from to 80 ; and opposite thereto are placed the various strengths of milk, from water to 160, 100 having pre- viously been fixed upon, from a number of experi- ments, as the standard of good new milk, and each of the other numbers bearing a proportionate reference thereto. "At one end of the slide-rule, the degrees of heat from 40 to 100 are placed with a star opposite as an index to fix the slide to the temperature of the milk. " The whole being graduated to show the exact strength of the milk, as it would appear in tempera- ture 55 degrees of heat, although tried in any inferior or superior temperature between 40° and 100°; thus the great inconvenience which would attend bringing 19 o 1-5 00 CO 00 © 00 O IO IO o" -r I. cm ',•1 1 CM 1 CM o CM CM JO CM to CM to CM to 00 CM 29 5J 50. 6J 31 71 00 Gl lO OS IO IO JO to CM CO IO to CO lO JO »o © CM © CO CO t— 00 ss IS r- CM CM CO IO CM © o CO CM O CM o oo CM CM CM 10 o to IO IO Gl IO o !o r- IO co JO cn CO ro © CO IO © to 00 © IT* JO oo JO © so ©° CM ira CM JO CM CO IO CM r- JO CM CO CM oo CM o o to to Gl Gl to to to to JO JO IO © CO IO IO oo IO t— CM CM © Gl to CO IO 1 to © o ■=- 1 CM to CM to CM CM to CM -o CM JO JO CM JO CO CM JO CM o oo CM r- OJ CM oo o OS lO to to to .CM JO to to CO IO to CO CM © © o oo © o CM CM CM CM CM to CM to ■** CM to JO CM to CD CM to r- CM cS JO CM CD © to t~ IO t~ CM IO oo to IO © 3 © © IO t~ to oo to • 113 oo CO © © oo © © © o CM © CM o to CM CM SO CM CD CM «M CM OO CM to CM o to JO to JO CM IO CO to IO IO 00 so to 00 CD to 00 t- to 5! CO jo CO CO 1— 00 © 1-- o CM CM 00 C» CM oo to 00 51 CO JO CM oo CO CM 03 I— CM o CM o IO CM to CM CM to 10 to to to IO JO to IO CO to JO lO S3 5/5 -0> CO JO JO oo JO © JO © CM JO CM CO CM co to CM co CM CD so' CM CD CO CM t~ CM oo 00 CM 05 Gl en o to 05 to © IO IO to CM IO to CM © to CM r- to CM CM CM JO 0-1 CO to IO IO © ■5-1 IO o CM IO CM CM CM to CM -<* ••J CM <* JO CM CD CM JO CO 00 CM CO Gl CD O IO CD . to to 00 to to © to © to © CO to CM o JO © CO 5 CO © o CM ■<- I CM T- I CM CM 1 CM 3-1 IO CM CM ■«* CM CM JO CM CM CO CM to CM ■5* CO G-l Ci Gl CD IO to JO Gl hi CO ro to © to CO so to © co to O CM CO 00 JO © CD © r— 02 OC © © o o o CM CM O to CM © CM o IO CM o CO CM t— CM CM OO CM CM 1 CM ai o GJ 1 IO G» to to CM lO to IO lO .to -<* to to JO to to CD to o JO © r— oo I— © © 00 CM CO CM Gl 00 to CO 00 JO CD r- G-l C7J co CM as CM 05 o IO © Gl LO © >o to © IO © JO IO © CD to 00 "* «* so JO CO JO CO JO © JO o CM © "CM O CM CM co lO CM CD CM co JO CM CD CO CM CD r-* CM CD CO CM CO o Gl CO o to to I— Gl IO lO IO to J.O to I— Gl •** Gl JO to o to t^ to 00 to © IO o CM CM CM ■<* to CM CM ->* SO fM CO t— Gl OO Gl C5 o IO to CM to "■* to IO •** to JO CO ■«* JO co T< 00 © o CM CM CM CM CM CM IO CM CM CM CM JO CM CM CM Gl CM Gl OO Gl CM CM CM o IO G^ IO Gl Gl to CM to IO Gl Gl JO IO jo © © JO © co © I— o co o © o © CM O CM o CM CM o to CM o CM o JO CM o CO CM o CM o 00 CM O Gl o © to © lO © Gl IO © io © IO © JO to 00 to 00 oo OS CO 00 t— oo 00 00 OS CO O CM S OO CM CM ,00 S3 00 CM 00 SO oo CO Gl oo r- GJ oo oo oo CJ5 Gl CO © to 00 to oc Gl to oo IO IO to «* to ' to I— to -tf t- SO o r- t- I— CO CO © CO O CM CO CD CM CM CD IO CM CD CM CO JO CM o CO Gl o Gl CD 00 Gl CO OS Gl CD © IO co j © ti 1 Gl to 1 lO 20 to to CM 9 t« co IO CO CO jo' CO co 1-- co so J/3 © JO © CM JO CM JO CM 20 IO CM JO CM JO hi JO ' CO' Gl Gl -<* on G. CM ©' IO -<* Gl IO IO IO CM ■*? CO 1 "** lO JO JO JO JO CO JO t- jO 00 CD O CM CM •** to CM to to SO CM to G-l GJ- Gl Gl 50 Gl oa CM Gl ©' IO G3 to G-l Gl ' to IO to © to • 20 the milk at all times to one temperature is avoided, and a simple mechanical method of allowing for the contraction and expansion substituted." "And as skimmed milk, being divested of the par- ticles of butter which existed before skimming, ap- pears to have a less degree of affinity with that than the new milk has, one side of the ivory sliding-rule is adapted to skimmed, and the other to new milk." " Genekal Eulb. — First find the temperature of the milk with the thermometer, and fix the sliding- rule so that the star shall be facing the degree of heat the mercury rises or falls to ; then put in the lactome- ter and try which of the weights, applied to the top, will sink it to some one division on the stem ; add the number of the weights upon the top, and that of the division together, and opposite to the same formed upon the side, will be shown the strength of the milk." " Examples op New Milk. — If in the temperature of 72°, the lactometer with the weight 40 sinks to 9 upon the stem, fix the slide so that the star shall be facing 72° ; then opposite 49 will be found 100°, the strength of the milk. Again if in 60° the lactometer with 50 on the top sinks to 6 upon the stem, the slide being fixed for new milk so that the star shall be at 60° of heat, then facing 56 will be found 110°, the strength of this milk in proportion towards the other, provided it is equally replete with cream." " To discover which, it becomes requisite these two samples should stand a certain time, that the cream may rise, which being taken off, they are to be tried with the lactometer again, and as the cream is evi- dently the lighter part, the milk will appear by its denser or better in quality than before. Supposing the milk in the first sample to be 57 by the lactometer, in 60° of heat, the strength by the skimmed milk side of the rule will be 112°- And admit the second sam- 21 pie of new milk to be 58, in 64° when skimmed, the strength would be 116°. "Asa comparison : Say Number 1, New Milk 100 Skimmed Milk 112 Difference 12 Number 2, New Milk. HO When skimmed 116 Difference 6 "From which it appears that Number 1 has pro- duced a larger quantity of cream than Number 2, and consequently rni^y be deemed the better milk." The next instrument receiving the name of lactom- eter was invented by Prof. Edmund Davy 1 in 1821. It is represented in Fig. 3. It is made of brass, and con- sists of a pear-shaped bulb, at the top of which is a graduated stem, and at the bottom a brass wire, to the end of which a weight is screwed. This instrument is only intended for skimmed milk, and the mark corresponds to the sp. gr. 1.035, which, according to Davy's experiments, represents the lightest genuine skimmed milk. The dots in the figures, which extend from to 35, indicate parts of water in 100 parts skimmed milk at 60°. Of the various lactometers that have been in use, the only difference was the specific gravity represented by the 100 degree of the scale. The specific gravity corresponding to the 100 degree on the centesimal galactometer invented by Dinocourt, as I have already stated, was 1.029, which was intended to represent the proper minimum. This sp. gr. has been adopted by the Board of Health of New York as the standard for their lactometers. The old standard adopted by the milk dealer was 1.030; this was changed by Dr. Chilton to 1.034, and 3 Triloch's Philosophical Magazine, Nos. 57, 58, p. 241. 22 has gradually dropped to 1. 033. So that the standard now employed by the milk dealers to secure for them- selves pure milk is 0.004 higher than that adopted by the Board of Health. Fig. 3J Fig. 4. In graduating the Board of Health lactometer shown in Fig. 4, the 100° is placed at the standard 1.029, 2; and at 1.000 ; the gravity of water, the intermediate spaces being divided into 100 divisions. Great care should be taken to determine with absolute accuracy the degree and the 100 degree; other points may also be determined, but they are not absolutely neces- sary if the space is properly divided. The point to which the lactometer sinks in the milk under exam- ination indicates the percentage of milk in 100 parts. Thus, if the lactometer sinks to 80, the milk must con- sist of, at least, 20 per cent, of water and 80 of milk. This assumes the original milk to have had a specific gravity of 1.029; but, if the milk had originally a gravity of 1.034, it would require 16.67 per cent, of water to bring it down to 1.029, and 20 per cent, more water to lower it to 80° on the lactometer. The tem- perature at which examinations are made with the lactometer should be 60° F., for exact determinations, as the instrument is graduated for that temperature. If it is only necessary to establish the fact of an adul- teration by water, the milk may be cooled to a tem- perature below 60° F., which an expert can easily as- certain by the sense of taste, etc. The lower the milk is cooled the more dense it becomes ; consequently, if the lactometer should sink below 100 in a sample of milk known to be below 60° F., sufficient evidence to establish the fact of its adulteration is indicated. A sample of milk tested by Dr. Chandler, 1 which stood at 100 by the lactometer at 60° F., was found to stand at 106 at 44° F., at 98 at 66° F., at 90 at 80° F., and at 74 at 100° F. 1 Johnson's Cyclopaedia, article " Milk." j 24 Value of the Degrees of the Board of Health Lactometer in Specific Gravity. — By Dr. Waller. Lactometer. Gravity. Lactometer. Gravity. 1.00000 45 1.01305 1 1.00029 46 1.01334 2 1.00058 47 1.01363 3 1.00087 48 1.01392 4 1.00116 49 1.01421 5 1.00145 50 1.01450 6 1.00174 51 1.01479 7 1.00203 52 1.01508 8 1.00232 53 1.01537 9 1.00261 54 1.01566 10 1.00290 55 1.01595 11 1.00319 56 1.01624 12 1.00348 57 1.01653 13 1.00377 58 1.01682 14 1.00406 59 1.01711 15 1.00435 60 1.01740 16 1.00464 61 1.01769 17 1.00493 62 1.01798 18 1.00522 63 1.01827 19 1.00551 64 1.01856 20 1.00580 65 1.01885 21 1.00609 66 1.01914 22 1.00638 67 1.01943 23 1.00667 68 1.01972 24 1.00696 69 1.02001 25 1.00725 70 1.02030 26 1.00754 71 1.02059 27 1.00783 72 1.02088 28 1.00812 73 1.02117 29 1.00841 74 1.02146 30 1.00870 75 1.02175 31 1.00899 76 1.02204 32 1.00928 77 1.02233 33 1.00957 78 1.02262 34 1.00986 79 1.02291 35 1.01015 80 1.02320 36 1.01044 81 1.02349 37 1.01073 82 1.02378 38 1.01102 83 1.02407 39 1.01131 84 1.02436 40 1.01160 85 1.02465 41 1.01189 86 1.02494 42 1.01218 87 1 .02523 43 1.01247 88 1.02552 44 1.01276 1 89 J 1.02581 25 Lactometer. Gravity. Lactometer. Gravity. 90 1.02610 106 1.03074 91 1.02639 107 1.03103 92 1.02668 108 1.03132 93 1.02697 109 1.03161 94 1,02726 110 1.03190 95 1.02755 111 1.03219 96 1.02784 112 1103248 97 1.02813 113 1.03277 98 1.02842 114 1.03306 99 1.02871 115 1.03335 100 1.02900 116 1.03364 101 1.02929 117 1.03393 102 1.02958 118 1.03422 103 1 02987 119 1.03451 104 1.03016 120 1.03480 105 1.03045 The following table by Dr. Voelcker, with an addi- tion by Dr. Chandler, illustrates the effects of watering and skimming: - UNSKIMMED. SKIMMED. Sp. G-r. Lact. Sp. Gr. Lact. 1.0314 108 i 1.0337 117 10 per cent, water added . . 1.0295 102 f 1.0308 106 20 " " " 1.0257 88 I 1.0265 91 30 " " «' . 1.0233 80 1.0248 86 40 " " " 1.0190 66 j 1.0208 72 KQ u u u 1.0163 56 1.0175 60 Thus it is seen that with a sample of pure milk of sp. gr. 1.0314 more than 10 per cent, of water could be added before the gravity is reduced to 1.029 or 100 on the lactometer; and, after skimming, considerable more. That the specific gravity 1.029 is the true minimum standard for 'pure whole cow's mills, I think I have al- ready fully demonstrated ; yet it is interesting to bear in mind that it has been confirmed by Muller, 1 Fleisch- mann, G-oppelsroder, Kramer, and other specialists?' 1 1 Anleitung zur Prufung der Kuhmilch, p. 42. 2 26 k k Muller 1 says: "From more than 6,000 notes by Quevenne and Bouchardat, the minimum is 1.029, and the maximum 1.033. For the hospitals and public institutions in Paris, the minimum is 1.030." He further says: "If" . . . " we go through all Europe, from country to country, from place to place, from dairy to dairy, from Alp to Alp, with the lactodensi- meter in hand, and mix at times the milk of several cows together which have been milked under condi- tions sufficiently touched upon, we shall find that the milk which is divided as a trade commodity from the physiological milk weighs between 1.029 and 1.033." Let us consider, now, if there are any objections to the use of the standard lactometers for the detection of adulteration. I have already stated that a sample of perfectly pure cow's milk, possessing a high specific gravity, can be considerably additioned with water, and the lactometer is unable to detect the fraud. The question naturally arises, is there any method *by which the fraud can be detected ? The answer comes unfor- tunately, no — owing to the variation in the proportion of each constituent, a proper margin has to be left for the maximum and minimum proportions, and between these limits the fraud can be perpetrated, and defy all Science to detect it. Milk may be skimmed, which will increase the speci- fic gravity of the fluid ; it may then be watered, and the sp. gr. reduced to the standard of the lactometer, or the sp. gr. may be still further reduced, and by the addition of some solid substance, such as sugar or salts, increased to the standard specific gravity. The question naturally arises here, can the lactometer de- tect such adulteration ? To answer this question, we must first inquire into the method adopted where the lactometer is used to detect adulteration. It is to be 1 Correspondenz-Blatt des Niederrheinischen Vereins fur oeffentliche Gesundheitspflege. Band vi., p. 82. Dr. Heusner. 27 supposed that an expert commissioned to examine milk for adulteration, using, as a means, the lactometer, will perform the test which is to be made, in connec- tion with the senses — that is to say, the sample under examination should be examined as to its opaqueness and color, its taste and odor, etc. If, on the contrary, he performs the test automatically, simply taking the degree of the instrument, noting the temperature, without examining the sample otherwise — the lacto- meter itself will not detect such adulteration ; but such an experimenter is not fit or competent to make such investigations, for, no matter what the method of examination may be, the common sense is always required to accomplish the object in view. I say it without fear of successful contradiction, that if the lac- tometer is used in connection with the senses, that is to say, regarding the flow of milk from the bulb of the instrument, observing its opacity and color, as also examining as to flavor and odor of the sample under ex- amination, that the lactometer will detect all the 'prac- tical frauds perpetrated oy milkmen. In my opinion there is not one unprejudiced person, with the experi- ence and education that a milk expert should have, that cannot distinguish a fair sample of pure milk from a fair sample of skimmed milk or cream ; and, if such is the case, how readily could be detected an adulterated sample. In the first part of this paper I stated that the indi- cations of the lactometer are infallible; this is the case, for if a sample of milk should indicate a degree less than the standard, there is indisputable evidence that the sample has been tampered with. METHOD OF DETERMINING THE CREAM. Sir Joseph Banks was the inventor of an instrument by means of which the cream in milk may be deter- mined ; this instrument was called by him the Lacto- 28 meter, but it afterwards received the more appropriate name — Creamometer. It consists of a graduated tube, usually eleven inches long and half an inch in diame- ter; ten inches of this are graduated in tenths of an inch — that is, in hundredths of the whole. To make the examination the tube is filled with milk up to the 100 mark, and set aside for twelve hours; the cream rises to the surface, and its volume is determined by the thickness of the stratum formed, and which is as- certained by noting the number of degrees or tenths through which it extends. This method is based on the assumption that all milk, under the same circumstances, would deposit its cream with the same facility, and that the cream so deposited would always have the same proportion of fat in it. As to all milk depositing its cream with the same facility, is evidently a mistake, for experiments have demonstrated that the larger the milk globules the more rapid will they rise, and the more perfect will be the separation of the cream from the milk. Valuable investigations by Dr. Sturtevant 1 have shown that the milk of a butter-cow consists mostly of large globules, whilst the milk of a cheese- cow contains very small globules. So that if two samples of milk, one from a butter-cow and the other from a cheese-cow, were placed in a Creamometer and allowed to rest for 12 hours, the cream from the butter- cow's milk would be far greater than that from the other, owing to the fact that the globules rise more rapidly. Careful trials of this test, made with different sam- ples of milk, whose composition was determined by chemical analysis, have shown that it is untrustworthy. Baumhauer examined 20 different samples of milk in this manner. His results are recorded in the following table: 2 : Ayrshire Cow, p. 239. a See Amer. Chem«. Nov., 1876, p. 199. 29 O I- O ?- lO lO t- 1- WiO lO O « I lC £- t- iO © c- O 00 OP Oi O •<* 3i" OC (N 00 £- CO t- CO 03 •9^T3^S ^It^BH S^I III £* JTj ™ £ ^ ^ 1-5 a "pauiraptg •g^S X'BJtl^'BU sq.i hi coiq s>? t-* id i-' in I I i I 1 I co s* t- t- # ■* © in co id ed "* ■* to -r o P bi) (B 3 r* bffl CO CO CO CO CO cc OOGO loOiOOOOOGOO ' C?OC^OC03it^"C0DOC0l0b , H^CT^C0OrHC0 ^MlflHOrlOMSKH co ot;c)«c:30^ CO m ^n en CO CO CO CO O' CO CO CC CO :o CO CO ~ CO CO ©OOOOOOOOOOOOOOOOO— 'O •s^uan^suoo x*3-*8tnH H C: 00 CS lO HO O Tf lO ^t-H ffi ~_l-i-; « » CO l- 00 CO* £- £-' L-' CO* OO' 00 CO' CO' ©" OS CO* £-' CO 00 CO fc-° t^ L-" •J9}13Ai HI 8tqn[osui sgoire^sqng •ja^BAV ni ajq -tups s9Dut^sqns jsq^o •xeSiis->xiij\[ ^co^cccoTcHco^cttco^r-^cococogico-tfcoco e* t}< co co r— cd © £- in CO O: © i— CN ?r- £r- «Sw3cow«M««wcoci"tcoc ,d ^3 vD »C5 -O ^ P, p, r^ r-t r^ g^l^fi cS S tHH^'WI -3 -3 -3 —■ ^ O S & U U U H U. hi % *i u dcSaSS333fiSS "3 s >;^^>i^>i>p,>i>, rdi'.'df csSSSSScjScs |j-i^3p:333c33^ ! aft" SSS r S«SC 'SS^t-t-L-OSOSt-t-t- 3 3 3 3 £t OJ CO £qts. Whole quantity of milk said to be 10 qts. per day. Cow in perfect health. Sample obtained Jan. 15, 1877, in the presence of Dr. Waller. ANALYSIS NO. 2. Name of Cow—" Strawlerry." Age— 6 years. Feed of cow— Fresh brewer's grain, Indian meal, brand with some salt. Quantity of milk (evening), 5 qts. Whole quantity of milk said to be 10 qts. per day. Sample obtained Jan. 15, 1877, in the presence of Dr. Waller. Lactometer 106°=1.03074 Cream 12>£# by vol. (16 hours). Whey 92° =1.02668 Average of two Analyses. Water 87.202 Milk solids 12.798 100.000 3.389 4.743 3.854 0.812 Lactometer 103°=1.02987 Cream by vol. 8.7$ (16 hours). Whey 92°=1.02668 Average of two Analyses. Water 87.240 Milk solids 12.760 100.000 12.798 Fat 3.684 Milk sugar 4.828 Casein ^1^ Inorganic salts 0.730 12.760 The first of the following tables was compiled by Dr. Jos. C. Rowland, Assistant Sanitary Inspector of K Y. All the milk from each cow, at the time of milking, was collected in the presence of Dr. Rowland, was thoroughly mixed together by him, a sample cooled to 60° F., then tested with the lactometer with the 38 a H IS •a 8 So «© o ■<*< oi so rH W CO O fc" T-( C> O CO CO -* coo co t> ■■* "*iCtH i> t> OS fc- rjH «4H O o CO .-eo -+3 t> o o h- en r» t- r- 00 o y; ■t— i r- 1 „ A ^ i — i +3 "9 © CO u 43 k. O £ o rd ^d GJ CI • co o -s aj T3 a .2 r- ^ a e« ri g tf M ' H g g Eq o rd O 05 T3 r-l O ft M ci O h^OPS «co tiho :o i> co aOri "* o 39 u >>a «0005W««'*QO T—i i—l OCSGSOOOOCSO c 1 o .2-8 t— 1 rH i— * r- 1 t— 1 i— ( T-I tH M j p 43 HiM r^N Ha 0> a OOOI>rP«!OOf'HT-iT|i tH H CM CM N H M 03 CM «N«H 1 CM o o rlHHHHiHHrlriTiHH tH h3 -+3 . ■o" "3 PI PI t> CD o CD eg *i ^---*---'-*~ n a§ c3 CD ft CD ft OOOKCOO^OCSff! CO t-I H H N O) « H T-I O '3 b3 H^ioio^MWONiONt' CO K>1 COTHf>OJOCOGOQOCClOCOCO cs ®OOi>©OCOOi>CO"JOOX 00 O CO M OOOOtHOtHOOOOC o .a t-ONOCB^COlOMOOC CO Ot«C100^WOrlOQN cs s QOCO'^OOOO'^t-iO'^COC JO cs o CO tH rjH tH -^ ^ CO tH* IO tH ^' cc TJH O »C CO 'O tH CO *> "■* O CM CO -<+ J> a «NffiOJOi>OriOOOOCC CO CC OC35QCOCOO©Cii>OQffi 1 00 g 10'^-^-^'>*-^'*-^-^)0^^ tH 9 owaoooooowoicoic IO • OWM^lOOOlOhOHr- CO "8 OCSOJ^HIOONMICWIC 1 i> ICC^riHrtHOOiOr^iCCO'^Ot TjH 01C550MHO^CSHO>0' p ■*THi>^THlOHCOCMGOCOC o £ OCl-*HOrl0JO'*O'*C OS c8 •^OlOLOCOCOHlOOOOlOt" tH OOOOOOOOOQOOOOOOGOGOOOOC 00 ! p . o :■& . Pi : a a i3 . c3 '. 5 CD . .'SSffl S o a CD 3 i-( OJt CO* Tji IO CO* t" 00* OS O tH i-i u 05 n ? 0) 1-1 $-1 & g -p o o bcj ppr Wei But Liti 01 o ppr Wei But Liti R - v £ P-( O C.c. of Milk required. O PS nffl ® u ?4 o C.c. of Milk required. s +> a) -a Ph o 1.00 23.43 6.75 3.66 17.00 1.60 1.50 15.46 7.00 3.54 18.00 1.52 2.00 11.83 7.25 3.43 19.00 1.45 2.50 9.51 7.50 3.32 20.00 1.39 2.75 8.73 7.75 3.22 22.00 1.28 3.00 7.96 8.00 3.13 24.00 1.19 3.25 7 41 8.25 3.04 26.00 1.12 3.50 6.86 8 50 2.96 28.00 1.06 3.75 6.44 8.75 2.88 30.00 1.00 4.00 6.03 9.00 2.80 35.00 0.89 4.25 5.70 9.25 2.73 40.00 0.81 4.50 5.38 9.50 2.67 45.00 0.74 4.75 5.13 9.75 2.61 50.00 0.69 5.00 4.87 10.00 2.55 55.00 0.64 5.25 4.66 11.00 2.43 60.00 0.61 5.50 4.45 12.00 2.16 70.00 0.56 5.75 4.26 13.00 2.01 80.00 0.52 6.00 4.09 14.00 1 88 90. CO 0.4S 6.25 3.94 15 00 1.78 100.00 0.46 6.50 3.80 16.00 1.68 Dr. Lauder Brunton ! says: "Before applying this test, it must be ascertained by microscopical examina- tion that the milk does not contain starch granules, or Physiol. Laboratory, Sanderson, p. 529. 48 any other impurity in suspension which might increase its opacity." This method has been highly recommended for its accuracy by good authorities. Kuhn, in his prize essay on stock feeding, says that, as he has proved by his own experience, "this method enables one in a short time, and with but little trouble, to determine the fat in a large number of samples of milk with accu- racy." Caldwell 1 says : " After a little practice the whole analysis can be executed in three or four minutes, even to the cleaning of the apparatus to have it ready for another trial." If cream is to be tested, only one cubic centimetre is to be added at first and a half c.c. at a time after- wards. Vogel found that about 6 c.c. of pure cow's milk, or 3.7 of cream, added to 100 c.c. of water were sufficient to form a mixture which quite obscured a candle flame. When 8 c.c. are required, the milk contains about 30 per cent, more water than it ought, either from the addition of water, or of creamed milk. When 12 c.c. are necessary, the milk contains 50 per cent, too much water. Hoppe-Seyler 2 alters this process so, that to a mix- ture of 5 c.c. of milk and 95 c.c. of water he keeps adding water until through a layer of 1 c.c. thickness the candle-light becomes visible. Dr. Heeren 3 has very carefully examined into the merits of the optical test and- says: " The four ex- periments performed by me with the most scrupulous care were the following : "I. Pure milk from quite a fresh milking cow, milked in my presence, showed at 14" R., a spec, gravity of 1.0316. The chemical examination gave fatty con- 1 Eeport for 1871, Amer. Dairymen's Assoc, p. 50. 2 Physiol. Chern., Band III., Milch, Gorup Besanez. 3 Dingler's Polytechnisches Journ., Vol. 193, 1869, p. 403. 49 tents at 3.160 per cent. Examined with one of Vo gel's galactoscopes, obtained from the mechanician Greiner in Munich, 8 cubic centimetres of milk were used, cor- responding by the table to 3.14 per cent. The milk was divided into two parts; these were kept for 24 hours in a cellar and the milk of one part was taken away from under the cream by means of a siphon. This skimmed milk showed at 14° R. 1.0343 spec, gravity, and gave 0.701 per cent, by the chemical test; by the optical 22 K. C, corresponding to 1.28 percent. The second unskimmed portion was now uniformly mixed by gently moving about, its specific gravity was sought for, which showed itself exactly the same as the day before=1.0316, and then by the "addition of water it was diluted to a weight 4.508 times as much, by which its fatty contents became equal to those of the skimmed milk. " This diluted milk of 0.701 per cent., fatty con- tents showed 0.690 per cent, by the optical test. "II. Milk, not milked in my presence, but by the statement of the seller asserted to be still intact. . Spe- cific gravity = 1.0270. Fatty contents chemically de- termined — 5.018; optically 5.61 per cent. Skimmed, specific gravity = 1.0312 ; fatty contents chemically ,1.670; optically 2.8 percent. The unskimmed milk reduced by dilution to equal the fatty contents with the skimmed gave optically 14 K. C, corresponding to 1.88 per cent "III. Milk procured from a milkman, probably somewhat skimmed. Specific gravity = 1.0265 ; fatty contents chemically 4.225 ; optically 5.0. Skimmed, specific gra^ity=1.0312; fatty contents chemically 0.225 ; optically 1.0. The unskimmed portion diluted to 0.225 fatty contents, consequently now of equal fatty contents with the skimmed, gave optically over 2.00 K. C. "IV, Milk from another milkman, without doubt partly skimmed. Specific gravity -= 1.0260. Fatty 3 50 contents chemically 2.312; optically 1.66 per cent. The unskimmed milk, reduced by dilution to the fatty contents of the skimmed, showed optically 24 K, C. f corresponding to 1.19 per cent. " A glance at these figures furnishes first of all a proof of the actually surprising exactness of the opti- cal test, as long as we have to do with whole, intact milk, for the diiference between the chemical and optical determination in No. I., 3.16 and 3.14, is cer- tainly smaller than one might expect, when the grad- ual disappearance of the visibility of a candle-flame serves as the measure. In No. II. the agreement 5.018 and 5.61, or 100 : 112, is still less, but the possibility is by no means excluded, that the milk, in spite of the statement of the seller, may have suffered a slight ad- dition of skimmed milk. In Nos. III. and IY., where more considerable differences presented themselves between the chemical and optical test, 4.225 and 5.0 (or 100 : 118) and 2.312 and 3.2 (or 100 : 139), proba- bly, or indeed without doubt, a partial skimming had taken place. " In all four investigations the deviations of the optical test showed themselves far more strongly in the skimmed than in the milk examined before the skimming, as the following table shows : "Relation of the actual to the optically found fatty contents r Before Skimming After SMmming^ In. No. I. 1:0.997 ' 1:1.82 " II 1 : 1.12? 1 : 1.7a " III 1 : 1.18 1 : 4.44 "■ IV ... 1 :1.39- 1 1.1..95. "By this, the above-made m p)*iori assertion is con- firmed, that the optical test will not prove right m skimmed milk, because^ owing to the smallness of th@ * That is, before the skimming performed by me, without any regards a & skimming psrhaps previously performed by the producer.. 51 fat-globules, it appears more transparent than it must be according to the actual contents. When in these experiments the unskimmed milk was diluted by ad- dition of water, so far, that it possessed equal fatty contents with the skimmed, considerable differences were shown optically. There were here, consequently, two milks of fully equal fatty contents, which, how- ever, were optically different, and must have been so naturally, as is shown by the following table : Optical test showed. Actual contents in the in the of both milks. diluted, skimmed. No. 1 0.701 0.690 128 " II 1.67 1.88 2.80 " HI 0.225 0.268 1.00 " IV 0.85 1.19 1.66 "If the milks II., Ill, and IV. had not been already partially skimmed by the producer, the figures of the second column must have agreed with those of the first just as well as in the milk No. I., which was cer- tainly not previously skimmed. " If we go a step further, the possibility is shown of calculating approximately from the combination of the chemical with the optical examination, how much a milk has been skimmed. Without, however, going into this somewhat unfruitful calculation, I will only briefly remark that a difference of the optical from the chemical examination indicates in any case a skimming has taken place, and the greater this differ- ence, the more extensive skimming is indicated. Thus it results from table A, that the milk No. I. was in- tact, next to it the milk No. II. on account of the difference, 1 : 1.12, indicates a slight skimming, while in III. and IV. the differences, 1:1.18 and 1 : 1.39, show that these milks, just as they were received from the milkmen, had been already skimmed in a very percep- tible degree. " Recapitulation. 1 — To facilitate a survey of the 1 Loc. cit., p. 407. 52 somewhat complicated investigations the principal points may be again briefly recapitulated : "1. Skimmed milk contains smaller fat globules than unskimmed milk. " 2. Smaller globules cause a greater cloudiness, in proportion to the existing quantity of fat, than larger ones. "3. As the optical milk test is based upon the de- gree of untransparency, it can give no serviceable re- sults for milk wholly or partially skimmed. "4. Careful experiments have confirmed the great exactness of the optical test, of the galactoscope of Vogel, and of the table calculated by him, but only for intact, unskimmed milk. " 5. The more the milk has been skimmed, the more the optical statement differs from the true fatty con- tents. " 6. Two portions of the same milk, one by skim- ming, the other by dilution brought to exactly equal fatty contents, show considerable differences by the optical test, and this test gives the fatty contents cor- rectly in the diluted milk, but too high in the skimmed. " 7. The possibility is given, of ascertaining, by combination of the chemical with the optical examina- tion, what part of the fat of a milk was withdrawn by skimming. " 8. The observed increase of the specific gravity of the milk by skimming agrees exactly with the increase, calculated from the loss of fat, it being supposed that the specific gravity of the milk globules is assumed as equal to that of the pure butter- fat. If, on the other hand, on account of the supposed membranous cover- ing, it be assumed as only a little greater, the experi- ments do not agree as well. In any case the covering must be supposed as of such immeasurable fineness that it can scarcely be imagined as existing. " However excellent, indeed unsurpassed, the opti- cal test, especially Vogel's galactoscope, and, perhaps, 53 too, Feser's improvement on it, shows itself for farmers and all such persons as can examine the milk in a positively unskimmed condition, it cannot be recom- mended in the ordinary milk trade, where the milk offered for sale is so often, indeed usually, in a partially skimmed state, and in such cases I consider conse- quently the creamometer always as the most serviceable instrument, as the errors of its data do not go so far as those noted in the above table A, found by means of the optical test, which gave the fatty contents in unskimmed milk too high by 1.82, 1.73, 4.44, and 1.95 times the actually existing." M arch and 1 s (de FScamp) Process.— This process is based on the determination of the butter by means of the lacto-lutyrometer shown in Fig. 10. The instru- ment consists of a glass tube closed at one end, having an interior diameter of 0.010 m. to 0.012 m. It is divided into three equal parts of 0.10 m., the upper part being divided into hundredths. The operation is conducted as follows: A cubic decimetre of milk is introduced in- to the tube so as to be even with the first line of the graduation, and a drop of potassic hydrate is added to hold the casein in solution. Ether is then added in equal quantity to that of the milk, and the mixture is shaken, when a cubic deci- metre of alcohol is added, and the mix- ture is again shaken, when the tube is put into a water-bath at 40° C, and there kept vertical, until the oleaginous layer rising to the surface no longer increases ; but as this layer contains some ether, and as a small amount of butter may still be retained in the lower aqueous fluid, a correction of the results is necessary. The following table, compiled by Marchand, facilitates this correc- -iO Fig. 10. Maechand's Lactobtjty- ROMETER. 54 ^3 s aq ^ s k5 to to 6 5sa <» rO s O a io *, *j <^ <3 c> V <5» <0 -si »~«i Weight of the Butter. bo fc~ 2> i> £> i> O £> C- f l> fc- i> fc- t- fc- i> J> •saaiSad OOOiOrKMCO^lOtDb'OOQOHCiO:^ Weight of the Butter. b£ OCDOOi>t>t-i>G0000000G0C50i0505 •saaaSaQ OHNCOlHOOi>00050H«W'omNOMi>oeoi>oo:oow© NC'iXXlCOflOCOXOJfflOJOOOOOH •saaiSaci ©0S05050J050501OOOOOOOOO Weight of the Butter. £ rt<£>CSTHTj05C rlHHiHrlrlHHTHrlHrlrlHHHrl Weight of the Butter. u bo ©QOHM»0000(M^i>©H-*COQOHCO aaooooHriHWHNUiiNiMtoco CO CO "^ ^ "^ ^ '^ ^ ^* ^ "^ "^ "^t* "*f "^ ^ "^ •saaaSaQ «Ci>0005OH«C0^1O?0J>0005OH01 T-trHi-l'i-l«'r-ITtiC-OTj0'<*I>OT^J>OCOi>0 COCOCOCOCOCOCOCOCOCOCOOOCOCOOtiCOCO •saaaSad ooaoHWn^iocot-QOQOHCdm-* t^i>COOOQOOOOOOOOOG00000050505CSOS Weight of the Butter. be OD«W050110QO(M1CCOWWQOHWQOH OOHCOOOOOCOiOi>OWiff>QrH^ O1W03CQC*i01010iOiCiO Weight of the Butter. u be OCOOOCOOOCO«5 0COOOCOOOiCO OG0OC010J>OC01i-H^OX)OC0 «WCOMOTKlTt<'^'*Tt(^iOlOlOUOOO HHHHHrlHHHi-lrtHT-lrlrtHH •8aaj3aQ[ OH«W*IOOi>XlC50HNC0^100 OOOOOOOOOOTHTHT-(i-trHTHT-( 00 OlOHWOOrHlOOt'COOOHWM^OCD^K OS —. ' I '. '. ' ^' ^' _I _J _J h N W W W W W W W N W fcj £>' $>' i> t-' t> i> J> J> 00 00 00 CO 00 00 GO GO CO GO OS OS ffim©oiWcoffl«fflcs«caNWfflW|OC5W>o §»OwSt-05«^OQHMOCOOWiOb;0« J J j J j ^' ^ lO lO lO lO ® O S3 00 t- t; t" t- 00 CO 00 ^ W to t- 00 OS O tH « M ^ lO ffl i> GO OS C H W CO CO CO CO* CO CO CO CO* Tt" rH "*' -*' ^ ^ ^' 3* 3 2J S 12 S S r«THlffl\o»OlCffitD©CD!>i>f>t-00C000a)C005Q COCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOOt) JOOt-OOCJSOHffiM^lOfflt-COOJOHWMTlllO OS QfflffifflO'o'ddo'oOOOOWHHrjrjH )rim 1 -nnQOiHTHflOH'^ , 0O'- l ' , *00HT}t!>'H , *t-H'^ §&OHW§ooo«Io?OiO^©C5HMOCoomra inin'«Dtofflffli>!>!>i>i>oocooococioffiq®qo Ci>00 050H(MX^lOOt'a)05 0H«CO'^ffi!Ot- id id id id to cd dddoddddt-£-t-fc-!>J>i>t- eocot-t-t-t-t-oooooooooscscsosooooo^T-j t-t»0>OH«M^iOCOb-00050H«M-^lCOt-CO ,_(' ,_| t-I 05 cq> Ci C3 «' Ol CNi d CO CO 00 CO CO CO CO CO CO 56 tion. (The relation between the weight of the butter and degrees of the lacto-butyrometer are in the fol- lowing table established according to the formula : p = 12 grms. 60 -+- n degrees x 2 grms. 33.) According to March-arid a litre of pure milk must give from 30.55 gr. to 35.43 gr. of butter. These quantities were obtained from 126 analyses made by Marchand, and are nearly the same as those found by Que venue : 34 grms. for the average, and 30 grms. for the minimum. Chevallier and Henri give the average 31.3. Mar- chand states 1 that he agrees with Quevenne, " that all commercial milk, containing less than 30 grms. of butter a litre (kilogramme), does not have a normal proportion of cream, and that it has experienced a par- tial skimming. When the milk is obtained from a sin- gle cow, the minimum may be admitted at 27 grms." " Milk containing 27 grms. of butter per kilogramme marks 6.2° on the lacto-butyrometer, and that contain- ing 30 grms. indicates 7.5°. "These figures are the smallest that can be admitted, and the last (7.5°) has constantly served me as a basis in the investigations with which I have been commis- sioned. "For the authorized inspectors, therefore, the ques- tion will always be limited to determine whether the milk, which they may have to examine, indicates or does not indicate 7.5°. This is an easy verification to make ; but when it conducts them to negative results, thsy should take care to have the suspected sample ex- amined by an expert chemist. This is a measure of prudence from which they should never depart." Sallbron's Process. — The lacto-butyrometer of Sal- leron 2 is shown in Fig. 11. It only differs from that of 1 Jour, de Pharm. et de Chimie, III. Serie, Tome xxvi. Annee, 1854, 2a Partee. Page 351. 2 Nouveau Diet., Des Falsifications et des Alterations des Aliments et des Medicaments, par J. Leon Soubeiran, 1874, p. 107. h 57 - — -Alcohol f -~\ C 5 > ■JEthef. —Milk Flo. 11. — Sallebon (Lacto-Butyrometer). Marchand in having a graduated index, which gives directly the butter-contents of the milk ; the first divi- sion of the index indicates, instead of 0, 12.6, and cor- responds to 12.6 grms. of butter remaining in solution. The instrument has a tin tube for a case, which serves as a water-bath, and is supplied with a cup at its base, in which the alcohol is burned. Lecojsttb's Process. — This process con- sists in putting into a graduated tube (shown in Fig. 12) five cubic centimetres of milk, then twenty cubic centimetres of crystallized acetic acid and then closing the upper orifice of the tube, and shaking for several minutes. The casein that had been coagulated is dissolved little by little, and the butter floats rapidly on the liquid in the form of white flakes. The butter is liquefied by means of the flame of an al- cohol lamp, and a liquid layer is thus ob- tained, whose volume is easily ascertained by means of the graduations on the tube. The apparatus is composed of a tube of Fig. 12. about 0.025 m. in diameter, closed at one appabatus. 58 1 of its extremities, and divided into five parts, each presenting a capacity of five cubic centimetres; to the upper part of this tube is joined another tube of much smaller diameter, and divided into twen- tieths of a cubic centimetre ; then, to the upper part of this second tube a third tube of the same diameter as the first, but much shorter and not divided, serving as a funnel, is joined. This last tube receives the liquids which are dilated during the operation. HOItSELEY'S INSTRUMENT. This instrument consists of a tube, which is divided so that every degree is one-hundredth of the whole. The milk to be tested is poured into the tube until it measures 250 grains, opposite which is a mark, A. Methylated ether is then added until the next mark, B, is reached, and the whole well shaken together for five minutes ; methylated spirits is next poured in to 10° of the graduation, (7, and again shaken for five minutes. On placing the tube in the stand the fat will rise to the top as a bright yellow oil, the measure of which will indicate the weight, because each gradu- ation is equal to 4.15 grains of fat. The casein sep- arates and falls to the bottom of the tube as a white mass, capable of being strained off, dried, and weighed. The remaining fluid after evaporation to dryness will give the amount of sugar and salts. As an example : a rich sample of milk from an Al- derney cow gave four graduations of fat from 250 grains of milk. Therefore, 4x4x4.15 = (mfat> 10 The sediment equalled 10.8 grains ; so that 10.8 x 4 , 00 — — 4.32 casein. 10 59 Residue after evaporation, 7 14.2 x 4 *°=™ — = 5.68 salts and sugar. Total solid contents = 16.G4 per cent. A sample of diluted milk. No. 2 gave three gradations for fat, — — — - = 4.98 per cent. It has had 25 per cent, of water added. No. 3 gave one gradation, 1 x4x4.15 i „„ = l.oo per cent. 10 L It has had 50 per cent, of water added, and had 25 per cent, of fat removed. No. 4 gave two gradations, 2 x 4 x 4.15 Q 00 , 3.32 per cent. 10 F This had had 50 per cent, of water added. W. W. Stoddart, speaking of Horsley's instrument, says: J It " shows the fat or cream distinct and per- fectly separated. By it you can calculate the weight per cent., and estimate the casein, the sugar and salts with great ease and rapidity. Indeed, the whole operation only takes ten minutes, or the quarter of an hour, and the results may be kept for observation for any length of time ; an advantage of no mean impor- tance when legal consequences are dependent on the analytical evidence. CHAMELEON TEST. E. Monier 2 has founded a peculiar optical process for testing milk on the fact that potassjc permanga- nate is equally discolored by casein and albumen. A 1 Pharm. Jour, and Trans., September, 1874, p. 188. 2 See Die Milch, von Benno Martinez, Vol. I., p. 174 ; or Monier, Nou- velle methode pour Tanalyse du lait au moyen de liqueurs titrees, Compt. Bend., xlvi., 1858, p. 236. 60 two per cent, normal solution of casein is compared with the milk to be tested, and the volumes of a solu- tion of potassic permanganate are determined, which must be added on one hand to the solution of casein, on the other to the milk, in order to obtain a lasting color of equal intensity in both. As these volumes are proportional to the existing quantities of casein and albumen, the contents of the milk in the two latter may be calculated from them. If the contents of casein and albumen are to be separately ascertained, the casein is first separated from a second portion of milk by means of a little acetic acid under warming to 40° to 50° C, and the albumen in the remaining liquid is determined as before. If the fatty contents of the milk are to be ascertained, the previously obtained precipitate is dried, and the already known casein con- tents are subtracted from it, the remainder giving the fatty contents. Experiments are wanting to show the utility of this method. HALTMETRIC TEST. Reichelt, of Ausbach, 1 has applied the halimetric test, proposed by Fuchs for the examination of beer, to the determination of the aqueous contents of milk. The method is grounded on the fact that 100 parts of water will dissolve 36 parts of pure salt. If we suc- ceed, therefore, in finding how much salt comes to solu- tion in a known fluid, whose entire water will dissolve the same, the water contents of this fluid may be calcu- lated from it. Fuchs has constructed a halimeter for this determination of salt (see Fig. 13), which consists of a graduated spindle, open at the upper, thickejr end, and closed at the lower, thinner end, whose di- visions give in grains of the old Prussian apothe- caries 1 weight the quantities of the residue of salt re- maining undissolved in a liquid. Applied to milk the process is as follows : 1 Die Milch, von Benno Martinez, 61 Fig. 13. Reichelt-Haumetbic Test. One thousand grains (= 62.5 grm.) of the milk to be tested are mixed in a flask with 324 grains (= 20. 25 grm.) of salt, and 240 grains (=15 grm.) of tinc- ture of litmus saturated with common salt, and re- peatedly shaken at 25° to 30° K., then poured off into the halimeter, so that none of the undissolved salt re- mains behind in the flask ; and after this has set- tled in the halimeter, and has been shaken close to- gether, its quantity is read off, the water contents of the milk are then calculated from the grains of dis- solved salt found. These — n, after the equation 36 : 100 = n : x, or the same by multiplication of n. 2.7778. The addition of the tincture of litmus is merely for the purpose of making the limit of the salt- 62 residue more distinctly recognizable, partly by the coloring, partly by the dilution of the milk. 1 In one experiment the salt-residue amounted to four grains. One thousand grains of milk, therefore, dis- solved 320 grains of salt, corresponding to 888.89 gr. water, or 111.11 gr. dry substance. The determina- tion of the dry substance of the same milk by evapora- tion with quartz-addition, and drying at 100° to 110° C, gave 11.033 per cent., consequently a differ- ence of 0.078 per cent. In an examination of cream the halimetric test gave 14.308 per cent, dry substance ; the evaporating test, 14.696 per cent, dry substance ; difference, 0.390 per cent. Another milk of 10 per cent, contents in dry sub- stance was diluted with two per cent, in weight of water. The halimetric examination of this diluted milk gave 9.722 per cent, dry substance, while from calculation there should be 9.804 per cent.; difference, 0.082. Benno Martinez 2 says : " The method furnishes quite exact results, and is besides easily and rapidly per- formed. From its nature, however, it can be of use only where one has to do with notoriously adulte- rated milk, and here of but slight use, as it can give no information on the relation of the parts of the dry substance to one another." [method of vernois and becqtjerel. Vernois and Becquerel proposed to determine the milk-sugar in milk, and thus to judge of its quality. This was accomplished by means of a polarimeter, which consists, according to Yogel 3 of a hollow tube Reichelfc Wagner, Jahresbericht iiber die Fortschritte und Lusfcun- gen der chemise aen Technologie fur 1859, S. 443 ; aus Jahresber. iib. d. k. Landw. u. G-ewerbesclrale zu Ausbach, 1858-59, u. 1859-60, Aus- bach, 1859 u. 1860. , ^ a Loc. cit. ^, 3 Eine neue Milcbprobe, Erlangen, 1862, p. 11. j 63 0.3 metre long and 0.02 metre in diameter, both ends of which are provided with Nicol prisms. The rays of light fall in through the front prism or the polarizer ; the second or analyzer is brought before the eye. If the entering light is examined in the empty tube, and with such a position of the prisms that their principal surfaces are parallel with one another, the rays of light are seen in their highest intensity. If the analyzer be turned about the axis of the tube and the parallelism of the prisms thus removed, every trace of light ceases, as soon as the principal surfaces stand at right angles with each other. If a fluid is now introduced into the tube which has an influence on the plane of polar- ization, the analyzer must be turned in a different way, sometimes more and sometimes less, in order to bring back darkness again. METHOD PROPOSED BY POGGIALE. 1 Poggiale proposed to ascertain the sugar in milk by means of the Soleil saccharometer, and thus to judge of its richness. He proceeded as follows : The milk was coagulated with acetic acid at 40 to 50° C, a few drops of acetate of lead added to the serum, and again filtered, the filtrate poured into a tube 22 centimetres long and after closing up put into the apparatus. In this apparatus 201.9 grm. of sugar of milk dissolved in 1,000 cub. cent. (1 litre) of water indicate 100 degrees. If we denote by g the number of the degrees found in the testing of whey as to the sugar of milk, the sugar of milk contents in a litre are calculated according to the formula 100: 201.9= g : x. The following table is founded on this for- mula: 1 Dosage du sucre de lait au moyen du sacharimetre de M. Soleil et determination de la rechesse du lait Comptes Rendus, xxviii., 1849, p. 584. 64 Degree Gramme Degree Gramme found. Milk-Sugar. found. Milk-Sugar. 18 36.84 26 52.49 19 38.36 27 54.51 20 40.38 28 56.53 21 42.39 29 58.55 22 44.41 30 60.57 23 46.43 31 62.58 24 48.45 32 64.60 25 50.57 According to Poggiale the serum of pure milk should show 28°, corresponding to 56.5 gr. of sugar of milk in the litre of serum and 52.7 gr. in the litre of milk. TEST OF MILK BY MEANS OF CENTRIFUGAL FORCE. C. J. Fuchs, Professor of the Veterinary School in Karlsruhe, proposed (1859) the employment of a cen- trifugal apparatus. He states his process as follows : Common cylindrical test-glasses divided into centi- metres are enclosed in paper, placed in correspond- ingly formed tin boxes, and the latter are so fastened on a centrifugal disk accelerated ten-fold by carrying over, that they can assume a horizontal position in swinging around. Fresh milk from a dealer showed -£s of cream on the average after 300 turns or 3,000 rotations, and just as much was obtained from the same milk, when left in the same glass it had stood from twelve to twenty-four hours. Also, milk which had been diluted with a definite quantity of water showed a diminution of the cream corresponding to this quantity of water. If the milk was fatter than usual, a correspondingly greater quantity of cream was found by the centrifugal machine, as well as by spontaneous separation, namely, from 6 to 10 per cent. All the butter-globules were not, however, brought to the surface of the milk by the centrifugal machine. 65 The turning of the glass cylinders, instead of in the centrifugal machine, fastened on a rod seven to eight feet long with a wire four or five feet long on a loose ring, did not give the desired success, probably, as Fuchs says, because the rotations could not be effected quickly enough, and the greater length of the arch of rotation could not make up for the more rapid revo- lution of the centrifugal machine; besides, it was hard work, and much practice was necessary for an easy motion. Fuchs constructed therefore a particular small centrifugal machine especially for the test of milk. On a stand a disk lying horizontally 60 cm. in diameter is fastened and set in motion by a winch. Opposite to this disk stands a second, 6 cm. in diam- eter, which is moved ten times more rapidly by a cord running over both from the first disk. Through the smaller disk goes an angle projecting over it about one foot, on which there is an iron cross horizontally at the top, and on its ends the tin boxes for contain- ing the milk vessels are hung by means of wires, so long that in turning round they describe a circle of two to three feet in diameter. This machine furnished the same result as the previously employed centrifugal apparatus ; but after frequently repeated experiments, as it was made mostly of wood, its motion was ir- regularly distributed. 1 REMARKS. I must again call to mind the fact, that before we can adopt the method for determining the quality of milk, a standard must be recognized which will repre- sent the poorest pure healthy milk. In the case of the specific gravity of milk, this standard has been accu- rately determined, and is recognized by those who have the most right to speak on this subject, but un- fortunately, as yet, for the other methods I have 1 Die Milch, von Benno Martinez, p. 176. 66 described, there is no recognized standard, and al- though many of them may be of great value until the true standard is obtained, they remain perfectly useless for the purposes they are intended for. DETECTION OF CHALK. When chalk is added to milk, it readily subsides if the sample is allowed to remain at rest for some time, particularly if a little water be added. So that, if in a tube a sample of milk is put, containing this adul- terant, and allowed to remain at rest, we will have two layers formed, one on top and the other at the bottom ; if to this bottom layer (which I suppose the milkman means us to consider an extra layer of cream), hydrochloric acid is added, effervescence takes place, and the chalk is dissolved to a solution, in which the characteristic properties of a lime-salt can be recog- nized. STARCH, FLOUR, DECOCTION OF BARLEY, RICE, EMUL- SION OF ALMONDS AND HEMPSEED. By boiling the sample of milk suspected to contain one or more of these adulterants, and adding tincture of iodine, the amylaceous substances, if present, will produce a blue coloration in the fluid. For the detection of starch in milk and cream the microscope is much to be preferred. A little of the milk is spread out to a very thin stratum and then examined under the microscope. The examination is aided by tincture of iodine. It is considered better to coagulate the milk with acetic acid, and search the feculain the coagulated casein. DEXTRINE. Dextrine may be detected by adding to the sus- pected fluid iodine water, where a more or less vio- 67 let-blue coloration appears. It is better to act on the milk coagulated by acetic acid. The dextrine can also be inverted by means of sul- phuric acid, and tested by means of the polarimeter. In this way Adrian has established for Pure Milk. Density. Rotation to the Eight. 0.10 of solution of dextrine. 1.0305 22. 0.20 of water, 0.10 " 1.032 32.25 0.15 " 0.10 " 1.0305 31.5 Laury found that if iodine be added to pure serum, it will be colored yellow, but, if the serum is mixed with 0.39 of dextrine, it will be colored dark blue; with 0.10, it is violet-blue, with 0.01, it is orange. CANE-SUGAR. To detect the presence of cane-sugar, the milk should be coagulated, and the serum evaporated at a gentle heat ; if the residue is darker than usual, the presence of sugar may be suspected (as brown sugar is generally used). The residue may then be dissolved in distilled water, and a little yeast added, when the fluid should be exposed for some hours at a tempera- ture of between 70° and 80° F. If fermentation en- sues, " it is a sure sign of the presence of sugar, for milk sugar cannot ferment, at least in so short a time, as the fermentation is never brisk. But the smallest proportion of sugar, either grape or cane-sugar, very speedily gives rise to a tumultuous fermentation." — Normandy. The carbonic acid may be collected, and the sugar calculated either from it or from the alcohol formed. GUM ARABIC AND GUM TRAGACANTH. To detect gum araoic, the serum of milk must be evaporated, and the residue boiled and digested with alcohol, which will take up the sugar and leave the gum. Or, the alcohol may be poured into the whey, when the gum will be precipitated in a white opaque OS flock, which, when collected and dried, may be identi- fied by its appearance. To detect gum tragacanth, it has been " recommended to boil the milk, and leave it at rest for some hours, when a gelatinous translucid deposit will be formed, which, being washed with a small quantity of water and tested by a few drops of solution of iodine, produces a blue color because gum tragacanth contains starch. The starch is plentiful and is in the form of starch corpuscles; these are rather small, but vary much in size ; many are irreg- ular, some are rounded, others are somewhat polyg- onal, while a few are muller-shaped ; in the more perfect grains a rounded hilum is distinctly visible." [salt. To detect the addition of salt, the most accurate method is to determine the percentage of chlorine. The ash may also be tasted, which, if strongly saline, indicates the addition of salt. DETECTION OP CARBONATE AND BICARBONATE OP SODA. When these salts are used the milk possesses a strong alkaline reaction, furnishes a serum having a sharp, bitter taste, and leaves a residue of the salt upon evap- oration, which can be recognized by the usual tests, DETECTION OP ANNATTO. If the milk, when evaporated to a small volume, possesses a reddish or orange-red color, annatto may be suspected. If by the addition of an acid the color is rendered purplish, or by an alkali rendered brighter red, its presence is certain. The color may be ex- tracted from the soft residue by means of alcohol, and tested with an acid and alkali as above. The color of the serum may also be observed. 69 DETECTION OF TURMERIC. In some cases turmeric cells may be detected by the microscope. It is best to examine the fluid in the same manner as for annatto. The turmeric is rendered deep brown by alkalies, and may be thus distin- guished. DETECTION OF GELATIN. Gelatin and isinglass have been detected in milk by Morin, at Rouen. It may be detected by treating the serum with tannin, when it will be precipitated. To the precipitate is then to be applied the usual tects. detection of cerebral matter. Wheu a sample of milk containing cerebral matter is examined under the microscope, portions of nerve tubules are readily discovered. Professor Queckett obtained a sample of milk adulterated by this sub- stance. 286 78 54?