This section is from the book "Scientific Feeding", by Mrs. Dora C. C. L. Roper. Also available from Amazon: Scientific feeding.
Put the desired amount of milk or cream, or mixed milk and cream, into a clean sauce-pan, stir over a hot fire until it reaches the boiling point or to about 200°F. Then pour into a pitcher and set in a pan of cold water; stir until the milk is cold. Set on ice or in a cold place for 24 hours. Milk prepared in. this way is the only wholesome kind to use in addition to boiled cereals and fruit puddings. It is also often preferrable to raw cream and milk, in combination with raw fruits. If the milk is to be used on cereals for the morning meal, it can be reheated or used directly after boiling. If hot milk is added to cereals, the sugar will not be missed.
If boiled milk or cream has stood for 24 hours it has become unfit for further use unless it is reboiled. If putrefaction has set it, boiled milk can become more dangerous as a food than raw milk which has stood for the same length of time; therefore careful handling of boiled milk as well as other boiled foods is of the utmost importance. (See Chapter on Hygiene and Economy, under Left-Overs.)
In many foreign countries it is a general custom in every household to boil milk directly after delivery, for the infant as well as for table use. To do differently means uncleanliness. Modern invention of coolers and ice-boxes in every house, and delivery of milk in bottles, has gradually done away with this custom. Many of our present generation of house-wives are so little acquainted with practical housekeeping that they consider food fit for use as long as it has not soured, notwithstanding the many changes it has undergone on the pantry shelf. Raw cream is fit for use only directly after it has left the separator. Raw milk should not be considered fresh and wholesome for table use longer than eight or ten hours after milking, and then only with the most careful handling. Following this precaution, morning milk, which is delivered during the day, should not be used raw later than five or six o'clock in the evening. Remember that all milk begins to turn acid as soon as it comes in contact with the air. The longer it stands the more acid it will be, besides being laden with germs. The process of cooking or scalding raw milk checks the fermenting processes and renders the food more alkaline, especially if it is to be taken with cereals or fruit puddings and gelatines.
Cooked milk is not a natural food, but neither are cooked cereals. Raw milk is quickly digested, while boiled milk takes several hours to digest, and so do boiled cereals. A combination of raw milk, or cream, and cooked cereals will force the stomach to absorb the milk immediately, while the remainder, poorly masticated and filled with germs, will tend to produce an acid process rather than an alkaline. If sugar is added to raw milk and cereals, the process of intestinal fermentation is complete. If the glandular system and the eliminating organs are strong, they will work harder in order to rid the system of this excess of acid; but if the constitution is not able to stand the strain of wasteful nervous expenditure, discomfort and disease will be the result! Enlarged tonsils are often the first sign of danger. We cannot invent customs of feeding that interfere with natural laws without paying the penalty.
 
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