The process is as follows: The milk is put into clean glass flasks or bottles with small mouths which are stoppered with plugs of cotton batting, or, as it is sometimes called, "cotton-wool." These are placed in a wire basket, and the basket immersed in a kettle of warm water, the temperature of which is not allowed to exceed 190° Fahr. As soon as the heat is at or near that point the time is marked, and the milk is kept at that temperature for one hour. Then the bottles are removed, cooled quickly, and placed in the refrigerator. If it is desirable to keep the milk an indefinite time, the process should be repeated the second day, and again the third day, a third sterilization being necessary to insure success, since _spores_ of organisms may escape the first and even the second heating. For all ordinary household purposes, however, and as a safe food for the sick, heating once is all that is necessary. Milk thus treated will keep in the temperature of an ordinary room, even in warm weather, from twenty to thirty hours. By using the small-mouthed flasks very little scum is formed, and thus the valuable albuminous portion is preserved in the milk. Also, a small quantity at a time may be used without disturbing the rest. =To Sterilize for Family Use.= Milk may also be preserved by open sterilization in a saucepan or kettle by the following simple process: Heat the milk until a scum forms over it; keep it at, or near, the temperature it then has for one hour, then pour it into a thoroughly washed and scalded pitcher, cool it, and put it into a refrigerator or some cool place. It will remain sweet for twenty-four hours, and, unless the weather be very warm, it will be good at the end of thirty-six hours. Should it sour before the end of twenty-four hours, it indicates that the temperature was too low, or the time of exposure to the heat too short. A chemist's thermometer costs but little, and will be found very useful for testing milk. It should be borne in mind, in this connection, that milk is not rendered _absolutely_ sterile,--that is, free from all possible organisms and spores which may occur in it,--except at a temperature of at least 212° Fahr., or even higher. Sterilized milk diluted with water is a nutritious and wholesome drink for the sick. Of course the water with which it is diluted should be boiled.[32] In hospital practice nurses have told me that patients suffering from sleeplessness will often fall into quiet slumber after drinking hot milk, and that not infrequently the ordered hypodermic of morphine is not needed when hot milk is used. MILK AND SELTZER Mix equal quantities of sterilized milk and seltzer-water. Drink immediately. MILK AND SODA-WATER Into a glass half full of fresh milk put an equal quantity of soda-water. Use at once. This is an agreeable way to take milk, and is a nutritious and refreshing drink. TOAST-WATER