Milk is composed mainly of water, casein, lactose, fats and mineral ingredients. The fat is only suspended in it, i.e., it is found in infinitely small globules, which float in the colorless solution of the sugar of milk and the protein corpuscles, and which make the fluid appear white.

The average composition of good, pure cows' milk should be as follows:

The mineral ingredients are chiefly kalium, phosphate of calcium, chloride of kalium, and chloride of sodium.

Milk is one of the healthiest, most nutritive and very digestive beverages, and is prescribed very frequently in cases of diseases of the stomach, of phthisis, etc. In cases of poisoning it serves to coat over the irritated mucous membrane, and thus protect it; it works even as an antidote to metallic poisons by precipitating the metals.

It is justly considered the "model food;" necessary as good milk is, it is a common experience to receive it deprived of its cream, diluted with water, or otherwise adulterated by dishonest dealers. A surplus of wine. 57 water renders the milk thin, and gives it a bluish color, which is often covered by yellow dyestuffs. For preserving, salicylic acid, borax, soda, etc., are added; to give diluted milk more body, different ingredients are dissolved in it, as corn-starch, flour, dextrine, glue and emulsions of hemp, poppy, etc. It is capable of absorbing noxious odors and emanations, and may convey the infection of scarlet and typhoid fevers from infected milk-rooms. Great care, therefore, is to be observed in keeping milk. The store-rooms, as the vessels containing it, should be clean and free from odors.

The appearance of milk, its taste, its change in boiling, and after long standing are, for the majority, the only proofs of its quality. The different lactometers and galactometers furnish satisfactory results only in the hands of experts.