MILK.
Owing to the very important sanitary relations of milk as a model food, the subject of its sophistication has during the past ten years received particular notice at the hands of the food-chemist. The investigations of our public sanitary authorities have shown that milk adulteration is exceedingly common. It is stated upon good authority that until quite recently (1883) the 120 millions of quarts of milk annually brought into New York city were intentionally diluted with 40 millions of quarts of water, the resulting product rivalling in richness the famous compound once lauded by the philanthropic Squeers.
The results of the examination of milk instituted by the New York State Board of Health are given below, in which, however, the specimens of skimmed milk are not included:—
| Year. | Number of Samples tested. | Number showing addition of Water. | Per cent. of Adulterated. |
| 1880 | 1514 | 167 | 11·0 |
| 1881 | 1110 | 51 | 4·6 |
| 1882 | 1775 | 120 | 6·7 |
From October 1883 to March 1884, of 241 samples of milk examined by the Public Analyst of Eastern Massachusetts, 21·37 per cent. were watered; of 1190 samples tested during the year 1884, 790 were watered.[18] Over 73 per cent. of the milk supplied to the city of Buffalo in 1885 was found to be adulterated. A very marked improvement in the quality of the milk received in New York city has taken place since the appointment of a State Dairy Commissioner (1884). Under the direction of this official the metropolitan milk supply has been subjected to a most rigid inspection, and with very satisfactory results. During the years 1884 and 1885 nearly 45,000 samples of milk were examined.
A very common sophistication practised upon milk consists in the partial or complete removal of its cream. This process of skimming is conducted at establishments called “creameries,” of which sixty-three were formerly known to send their impoverished product to New York city. The State Dairy Commissioner has likewise accomplished much towards stopping this form of adulteration.
Milk is the secretion of the mammary glands of female mammalia. It is an opaque liquid, possessing a white, bluish-white, or yellowish-white colour, little or no odour, and a somewhat sweetish taste. At times it exhibits an amphigenic reaction, i. e. it turns red litmus blue and blue litmus red. From the examination of nearly one thousand cows in the States of New York, New Jersey, and Connecticut, the minimum specific gravity of milk was found to be 1·0290, the maximum being 1·0394. The opacity of milk is only apparent, and is due to the presence of fatty globules held in suspension; these under the microscope are seen to be surrounded by a transparent liquid. Upon allowing milk to remain at rest for some time it experiences two changes. At first, a yellowish-white stratum of cream rises to the surface, the lower portion becoming bluish-white in colour and increasing in density. If this latter is freed from the cream and again set aside, it undergoes a further separation into a solid body (curd), and a liquid (whey). This coagulation of the curd (caseine) is immediately produced by the addition of rennet, and of many acids and metallic salts.
The essential ingredients of milk are water, fat, caseine, sugar (lactose), and inorganic salts. The following table, collated by Mr. Edward W. Martin,[19] exhibits the results obtained by numerous authorities from the analysis of pure cow’s milk:—
| Authority or Analyst. | Number of cows. | Water. | Total solids. | Fat. | Solids not fat. | Sugar. | Caseine. | Salts. |
| per cent. | per cent. | per cent. | per cent. | per cent. | per cent. | per cent. | ||
| James Bell | 216 | 87·17 | 12·83 | 3·83 | 9·00 | .. | .. | 0·71 |
| James Bell | 24 dairies | 86·78 | 13·22 | 4·12 | 9·10 | .. | .. | 0·72 |
| C. Estecourt | 22„ | 87·26 | 12·74 | 3·37 | 9·37 | .. | .. | .. |
| J. Carter Bell | 183 | 86·40 | 13·60 | 3·70 | 9·90 | .. | .. | 0·76 |
| J. Cameron | 42 | 86·53 | 13·47 | 4·00 | 9·47 | .. | .. | .. |
| C. Cameron | 40 | 87·00 | 13·00 | 4·00 | 9·00 | 4·28 | 4·10 | 0·62 |
| C. Cameron | 100 | 86·75 | 13·85 | 4·60 | 9·25 | .. | .. | .. |
| Fleischmann and Veith | 120 | 87·78 | 12·22 | 3·20 | 9·02 | .. | .. | .. |
| Veith | 60 | 87·20 | 12·80 | 3·10 | 9·70 | .. | .. | .. |
| Veith | 9120 | 86·97 | 13·03 | 3·52 | 9·51 | .. | .. | .. |
| Wanklyn | Average | 87·50 | 12·50 | 3·20 | 9·30 | .. | .. | .. |
| A. Wynter Blyth | „ | 86·87 | 13·13 | 3·50 | 9·63 | .. | .. | .. |
| Marchand | „ | 87·15 | 12·85 | 3·55 | 9·30 | .. | .. | .. |
| Henry and Chevalier | „ | 87·02 | 12·98 | 3·13 | 9·85 | 4·77 | 4·48 | 0·60 |
| Vernois Becquerel | „ | 86·40 | 13·60 | 3·60 | 10·00 | .. | .. | .. |
| Payen | „ | 86·60 | 13·40 | 3·50 | 9·90 | .. | .. | .. |
| O. C. Wiggin | 58 | 85·92 | 14·08 | 4·01 | 10·07 | 4·29 | 4·99 | 0·79 |
| E. Calder | 27 | 87·23 | 12·77 | 3·32 | 9·45 | .. | .. | .. |
| Sharpless | 34 | 85·85 | 14·15 | 4·62 | 9·53 | 4·82 | 4·06 | 0·65 |
| Haidlen | Average | 87·30 | 12·70 | 3·00 | 9·70 | .. | .. | .. |
| Letherby | „ | 86·00 | 14·00 | 3·90 | 10·10 | 5·20 | 4·10 | 0·80 |
| J. König | „ | 87·30 | 12·70 | 3·00 | 9·70 | 5·00 | 4·00 | 0·70 |
| Boussingault | „ | 87·40 | 12·60 | 4·10 | 8·50 | 5·10 | 3·20 | 0·70 |
| Muspratt | „ | 86·43 | 13·57 | 4·43 | 9·14 | 4·73 | 3·74 | 0·67 |
| Dieulafait | „ | 87·64 | 12·36 | 3·11 | 9·25 | 4·22 | 4·18 | 0·85 |
| Gorup-Bezanez | „ | 85·70 | 14·30 | 4·31 | 9·99 | 4·04 | 5·40 | 0·55 |
| Brinton | „ | 86·00 | 14·00 | 4·50 | 9·50 | 3·50 | 5·50 | 0·70 |
| Chandler | 1700 qts. | 87·45 | 12·55 | 3·83 | 8·72 | .. | .. | .. |
| Newton | Average | 87·50 | 12·50 | 3·50 | 9·00 | .. | .. | .. |
| Bartley | „ | 87·50 | 12·50 | 3·50 | 9·00 | .. | .. | .. |
| White | „ | 87·50 | 12·50 | 3·50 | 9·00 | .. | .. | .. |
| Waller | „ | 87·50 | 12·50 | 3·20 | 9·30 | .. | .. | .. |
| Babcock | „ | 85·53 | 14·47 | 5·09 | 9·39 | 5·15 | 3·57 | 0·67 |
| Church | „ | 86·30 | 13·70 | 3·70 | 10·00 | 5·10 | 4·10 | 0·80 |
| Edward Smith | „ | 86·40 | 13·60 | 3·61 | 9·90 | 3·80 | 5·52 | 0·66 |
| Martin | „ | 86·50 | 12·50 | 3·20 | 9·30 | .. | .. | 0·67 |