[54] The following mineral substances occur in both cow's and woman's milk: potassa, soda, lime, magnesia, iron, phosphoric acid, sulphuric acid, and chlorin.
[55] It is worthy of notice, in this connection, that children have been known to be made ill by drinking water which has stood for a length of time—such water containing great numbers of bacteria, but none of the so-called disease-producing organisms. The same water, when boiled, produced no ill effects.
[56] Stated by Sedgwick.
[57] Welsh.
[58] Since writing the above I have learned that Prof. Vaughan has isolated a poisonous matter—the product of the growth of certain organisms which multiply readily in milk—which caused active vomiting, purging, collapse, and death when injected into the lower animals.
[59] In England and America many cases of scarlatina, typhoid fever, and diphtheria have been traced to the milk supply. But there is no satisfactory evidence that those diseases were transmitted from the cow; more probably the milk, which is an especially good nutritive medium for bacteria, became infected after leaving the cow. In October, 1891, an epidemic of diphtheria prevailed in Melrose, Mass. Thirty-three cases were reported. On investigation it was found that every case could be traced to the milk supply. The farm from which it came was situated in an adjoining town, and the family of the dealer had been afflicted with diphtheria, two of the children having died. The use of the milk was, of course, promptly stopped.
[60] A simple and inexpensive apparatus for sterilizing milk consists of a covered tin kettle ten inches in height by eight inches in diameter, a wire basket, which fits easily into the kettle, supplied with supports or legs projecting one and a half inches from the bottom, one dozen eight-ounce nursing-bottles, and a bundle of fresh cotton wadding. The whole apparatus, costing about $1.25, is kept in most drug stores.
Milk for twenty-four hours' use is properly sweetened and diluted with water in a clean pitcher, and as much of this as the child will take at one feeding is poured into each bottle, and the bottle stopped with cotton wadding, which should fit only moderately tight in the neck of the bottle. The kettle is filled to the depth of one half to one inch with water, the basket containing the bottles placed in it, the kettle covered and placed over a fire until the steam comes out from the sides of the top for half an hour, when the basket containing the bottles should be removed and put in a cool place. When the milk is to be used, it should be heated by placing a bottle in warm water for a few minutes. The cotton is then removed, and a sterilized nipple attached. After the feeding the bottle is cleansed and kept in an inverted position until used again. The above directions are those of Dr. Booker, specialist of children's diseases, Johns Hopkins Hospital.
[61] In the Walker-Gordon Milk Laboratory, in Boston, milk is sterilized at 175° to 180° Fahr. for fifteen minutes, and it is claimed that this temperature gives the best results for milk to be used within twenty-four hours. If the milk has to be kept a longer time, a higher temperature is necessary, as only the bacteria and not the spores are destroyed by 175° Fahr.
Machines are in use in France which will heat great quantities of milk to about 155° Fahr. and then rapidly cool it. Not all, but nearly all, forms of bacteria likely to be found in milk are destroyed at the temperature of 155°, and the good flavor of the milk is not injured. Such milk is known as Pasteurized milk.