The question of preservation and pasteurization can be treated here but briefly. Preservatives are forbidden by law in most states. Pasteurization is heating at a temperature sufficiently high to kill any disease germs present, but not high enough to give a cooked taste. This process, while it destroys most of the bacteria, does not kill the spores of all. The chief arguments against pasteurization are (1) that on a commercial scale it is difficult to really accomplish this, and (2) that it is easily used to cover the sale of unclean milk. The argument for it is, that it is impossible to obtain as yet an ideal supply for a large city in hot weather, and that pasteurization, if properly conducted, kills nearly all of the dangerous bacteria and saves the lives of many babies. Clean milk that needs no pasteurization is our ultimate aim, and we must remember that milk pasteurized under unknown conditions needs to be kept cold and treated with even more care than fresh milk, for it “spoils” quite as easily, only we may not know it because it may not taste sour. In the last few years the question of pasteurization has been studied with very great care. It is found best to heat the milk for 20 to 30 minutes at a temperature of 140° to 155° F. If it is certain that this method has been used, one need not hesitate to trust the milk, for the arguments against pasteurization do not properly apply here. =How to buy.=——Investigate by question and inspection, if possible, the available milk supply. Be sure to do this in the country in the summer. Always buy bottled milk. Where the income is small, good quality milk should be used for the little children and invalids, and skim milk purchased for cooking. In many places skim milk is supplied in bottles by reliable firms. The usual price for bottled milk in the city is 8 to 10 cents, and this is of good average quality. Keep milk cold. If there is no ice, use an ice substitute (page 74), and in very hot weather pasteurize or scald the milk, cooling afterward as quickly as possible by placing in cold water and stirring the water. GENERAL METHODS AND RECIPES =Principles of cookery.=——Clean, sweet milk is an ideal food, which requires no cooking. Heating milk to 212° F. changes its properties in some way, so that it is not considered an ideal food for babies’ regular diet. If it must be used, for reasons of safety, some uncooked food, such as orange juice, should also be given. This is the reason for pasteurizing milk instead of boiling it. Heating milk in an open vessel causes some of the protein to harden into a thin “skin” on the top. This can be prevented by stirring the milk until it is cool. =1. To pasteurize milk.=