To secure the whey, 5 grams (1 teaspoonful) of rennet should be used to each quart of milk. The mixture must be kept at a temperature of about 100 F. until it separates into a liquid and a solid portion. It is then strained through cheesecloth. Practically all the casein is left on the cloth, the fluid being the whey. The curd should be broken up before straining, in order to obtain, as nearly as possible, the casein. However, about two-thirds of the milk fats remain in the curd. The whey, besides the whey proteins, thus contains only about one-third of the fats, but nearly all of the milk-sugar and salts. The whey still contains the rennet and, to destroy this, the whey must be heated to at least 140 F. for thirty minutes. The average composition of whey according to Wachenheim is as follows: Proteins 0.8 per cent. Fats 1.0 ” ” Milk-sugar 4.5 ” ” Salts 0.7 ” ” Water 93.0 ” ” Sometimes sugar is the primary cause of intestinal fermentation, due to the concentration of the whey and the relative proportions of casein and sugar in the mixture. According to Finkelstein and Meyer, to prepare a food which will combat intestinal fermentation there must be: A diminution in the quantity of milk-sugar, a diminution of the salts through dilution of the whey, and an increase in the casein, with varying, and, under certain circumstances, not inconsiderable amounts of fat. After improvement has begun, an easily assimilable and consequently little fermentable carbohydrate should be added. They developed a food to meet these requirements to which they gave the name of “_Eiweissmilch_.” This food is prepared as follows: * * * * * Heat one quart of whole milk to 100 F.; add four teaspoonfuls of essence of pepsin, and stir. Let the mixture stand at 100 F. until the curd has formed, then strain. Press the mass of curd through a rather fine sieve two or three times by the means of a wooden mallet or spoon. Add one pint of water to the curd during this process. The mixture should now look like milk and the precipitate must be very finely divided. Add one pint of buttermilk to this mixture. Finkelstein and Meyer used buttermilk in the preparation of this food: (1) Because of the small amount of milk-sugar which it contains; (2) To obtain the good effects of the lactic acid; (3) Because buttermilk can be kept for a longer time. The composition of this food is: Fat 2.5% Sugar 1.5% Protein 3.0% Salts 0.5% One quart of this milk contains about 360 calories. They call attention to the low caloric value of this food and to the necessity of increasing it as soon as possible by the addition of dextrin-maltose mixtures.