=Kumyss= is milk slightly soured and fermented with one species of yeast. This is a Russian method. These preparations are excellent for invalids and exhausted people, for they can sometimes be assimilated because of the fine curds when sweet milk cannot. =Condensed milk= is a practical method of preserving milk. The milk is evaporated under pressure at a high temperature in apparatus constructed for the purpose. Cane sugar or glucose is sometimes added. A new patent process condenses the milk at low temperature, preserving it for a short period, as compared with the condensed milk in tins, but it keeps well for several days, and bears transportation. Condensed milk may be used in cooking, when clean fresh milk is not available. The unsweetened kinds are most useful, but, like pasteurized milk, must be treated with care after the cans are opened. =Cheese.=——Cheese is made from the curd of milk, and contains the most nutritive parts of the milk in highly concentrated form. In the process of manufacture, the milk is first curdled by rennet, and the whey strained out. The curds after preliminary treatment, varying according to the style of cheese to be made, are finally pressed together very slowly in a cheese press, which is screwed down more tightly as the cheese becomes dryer. The cheeses are then covered with cheesecloth and “ripened” slowly, the ripening process giving characteristic consistency and flavor. This ripening is due to the action of bacteria and molds. (See page 97.) Foreign varieties of cheese, made originally in some one locality, have marked colors, quality, and flavors, as Brie, Camembert, Roquefort, and the Swiss cheeses. Parmesan is an Italian cheese, excellent with macaroni and spaghetti. _American cheeses_ vary in color, in strength of flavor, in creaminess, and in degree of hardness. Much the greater part is, however, of the general type known as “American cheddar” or “standard factory” cheese. _Club cheese_ is an American cheese of good quality, put up in small jars. It is a soft cheese, excellent to serve with crackers, but is too expensive for common use. _Cottage cheese_ is a home product made from sour milk, and used at once. =Composition and nutritive value.=——Cheese is high in protein, and usually in fat. (See Fig. 40.) Note the small amount of water, which makes cheese a very concentrated food. The protein content makes it a meat substitute, for those with whom cheese does not disagree. Being a dense as well as concentrated form of food, it should be eaten in small quantities, and in combination with other food materials in such a way that it will become finely divided, or it will not be easily digested. The ash content is high, the most valuable of the ash constituents of the milk being retained in the cheese. =The cost of cheese.=——The foreign cheeses are expensive, but American cheeses may be classed among the moderate priced foods and they compare favorably with other protein foods.