Foods and household management

Comparison of milk and beans. — A moment's thought enables us to see that in milk we have a food that must have all the elements needed in nutrition, since it is the only food taken by many young animals. The baby and the young calf find in it everything that is needed to build the growing body, and to give them energy. If you see a young calf frisking about the field, you can appreciate how well his food supplies his needs. A simple experiment will help us to find some of the substances contained in milk. Let the milk stand until the cream rises on the top. Skim the cream, warm it slightly and beat it with an egg beater. Butter will soon " come," and butter, we know, is a form of fat. Warm a pint of the skimmed milk, add to it a dissolved rennet tablet, and set it in a warm place. In a short time, the milk becomes solidified to a consistency like that of jelly. If allowed to stand longer, a watery liquid will separate itself from the solid portion. These are the " curds and whey '' that result, also, from the souring of milk. The whey can be squeezed out of the curd, leaving it quite dry. We have now fouad at least three constituents of milk, — water, fat, and curd. You may then surmise from the sweet taste of milk that sugar is present; the chemist knows how to obtain it in pure form as " sugar of milk." The chemist also finds cer- 1. Whole milk. 2. Wattr. 3 Fat. Flo. 1. — Compositioii of milk. G. CHrbobrdrate. 6. Mineral matter tain mineral substances which remain behind when all the water is evaporated and the curds and sugar burned away. These mineral substances are spoken of by the chemist as " ash," because this is what remains after burning the other portions of a food material, as ashes remain from a wood fire. Figure 1 shows you these substances in the amounts in which each occurs in a pint of milk. The sugar is one of a class of substances to which the chemist gives the name carbohydrate. To the substance in the curd that is different from all the other substances in the milk the name " protein " is given. We will now turn to the composition of beans, for in beans we find food stored up to nourish the young plant, which we, also, appropriate as food. The composition of both the milk and the beans' is given in this table. Compare also Figures 35 and 41. CoMPOsmoN OF Milk and Beans Food Materials Water Per Cent Protein Per Cent Fat Per Cent Carbohydrate Per Cent Ash Per Cent Milk . . . . . Beans, dried . . 87.0 12.6 3.3 22.5 4.0 1.8 5.0 59.6 0.7 3.5 Notice that the substances in the beans are the same in g^aeral nature as those in the milk, although the amounts are different. The water that the young plant needs is, of course, supplied from the earth. There is another difference to note although this is not shown in the table ; in the beans the carbohydrate is of two kinds, sugar and starch. Foodstuffs ^