Absolute cleanliness is necessary for the preservation of milk; vessels in which it is to be kept must be thoroughly scalded with boiling water, not merely washed out with warm water. _Methods of Preserving Milk._ STERILIZED MILK. Milk to be thoroughly sterilized and germ free must be heated to the boiling point (212 deg. F.). This may be done by putting the milk into perfectly clean bottles and placing in a rack, in a kettle of boiling water, remaining until it reaches the necessary degree of heat. The bottle should be closely covered _immediately_ after with absorbent cotton or cotton batting in order to prevent other germs getting into the milk. PASTEURIZED MILK. The difference between pasteurizing and sterilizing is only in the degree of heat to which the milk is subjected. In pasteurizing, the milk is kept at a temperature of 170 deg. F. from 10 to 20 minutes. This is considered a better method for treating milk which is to be given to young children, as it is more easily digested than sterilized milk. All milk should be sterilized or pasteurized in warm weather, especially for children. CHEESE. Cheese is one of the most nutritious of foods, and when meat is scarce makes an excellent substitute, as it contains more protein than meat. Cheese is the separated casein of milk, which includes some of the fats and salts. EGGS. Eggs contain all the ingredients necessary to support life. Out of an egg the entire structure of the bird--bones, nerves, muscles, viscera, and feathers--is developed. The inner portion of the shell is dissolved to furnish phosphate for the bones. The composition of a hen's egg is about as follows (Church):-- ----------------------+------------++---------------------+------------ | White--In || | Yolk--In | 100 parts. || | 100 parts. ----------------------+------------++---------------------+------------ Water | 84.8 || Water | 51.5 Albumen | 12.0 || Casein and albumen | 15.0 Fat, sugar, | || Oil and fat | 30.0 extractives, etc. | 2.0 || Pigment | Mineral matter | 1.2 || extractives, etc. | 2.1 | || Mineral matter | 1.4 ----------------------+------------++---------------------+------------ The albumen--or the "white"--of an egg is greatly altered by cooking. When heated beyond boiling point it becomes a very indigestible substance. Eggs cooked at a temperature of about 170 deg. F., leaving the whites soft, are easily digested. A raw egg is ordinarily digested in 1-1/2 hour, while a baked egg requires from 2 to 3 hours. Eggs _baked_ in puddings, or in any other manner, form one of the most insoluble varieties of albumen. GELATIN.