Milk

(milk.) [From A. S. mel ce.] (Chem.) Afluid secreted by the mammary glands of the females of the cla Mammal i a, after they have brought forth their young, and during the period in which their offspring are too immature to live upon ordinary food. This fluid, which is only produced from the body on occasion of suckling, is, notwithstanding, constantly formed. It is the proper sustenance of the animal itself: all the nutritive parts of food being formed into chyle, and chyle into milk. It is of an opaque white color, a mild saccharine taste, and a slightly aromatic smell. When allowed to stand for some time, it undergoes spontaneous changes, and is resolved into its component parts, throwing up a white, thick, unctuous cream to its surface; the fluid beneath becoming thinner than before, and of a pale-bluish color. The proximate elements of M. are:-1. the aroma, or odorous volatile principle, called butyrin, which pa es off, when it is fresh milked, in the form of visible vapor; 2. water, which constitutes the greatest part; 3. fatty matters, from which the cream is formed; 4. curd, which is the caseous matter that coagulates; 5. sugar, which, with the water, ., forms the serum of M.; 6. some neutral salts, such as phosphate of lime, iodide of pota ium, chloride of calcium, ., which are accidental, not being found at all times, nor in all M. Human M. is very sweet and thin; the nearest in resemblance to this is the M. of a es, next that of mares, then that of goats, and lastly that of cows. Rennet, prepared of the juices of such animals as chew the cud, being mixed with M., coagulates it into a uniform ma , which maybe cut with a knife, and which spontaneously separates into whey and curds. When M. contained in wire-corked bottles is cautiously heated to the boiling point in a water-bath, the oxygen of the included small portion of air under the cork seems to be combined, and the M. will afterwards keep fresh for a considerable time; as green gooseberries and peas do by the same treatment. By evaporating to dryne , and powdering, M. can be brought to a condition in which it will keep for a length of time. In this case an artificial M., called condensed M., can be formed by di olving the powder in tepid water, which is useful in sea-voyages, especially for children. The condensed M. exported from the port of New York in 1869, amounted in value to $79,652. In 1870, there were sold in the U. States 235,500,599 gallons of fresh M. See BUTTER and CHEESE. [s. 601]