Butter, which contains from 5 to 10 per cent. of water, 11.7 per cent. fat, 0.5 per cent. casein, 0.5 per cent. milk sugar (Konig). The addition of salt to butter prevents fermentation. Butter will not support life when taken alone, but with other foods is highly nutritious and digestible. CREAM. Cream is one of the most wholesome and agreeable forms of fat. It is an excellent substitute for cod liver oil in tuberculosis. Ice cream when eaten slowly is very nutritious. LARD. Lard is hog fat, separated by melting. SUET. Suet is beef fat surrounding the kidneys. COTTOLENE. Cottolene is a preparation of cotton-seed oil. OLEOMARGARINE. Oleomargarine is a preparation of beef fat provided as a substitute for butter. OLIVE OIL. Olive oil is obtained from the fruit, and is considered to be very wholesome; in some cases being preferred to either cod-liver oil or cream for consumptives. COTTON SEED OIL. Cotton seed oil is frequently substituted for olive oil. NUTS. Nuts contain a good deal of oil. CHAPTER VII. Carbohydrate Foods. The idea of starchy foods is usually connected with such substances as laundry starch, cornstarch, arrow root, etc. These are, of course, more concentrated forms of starch than potatoes, rice, etc. Many starchy foods contain other ingredients, and some are especially rich in proteids. The following table may help to make this clear (Atwater):-- PERCENTAGE OF STARCH IN VEGETABLE FOODS. -----------------+----------- | Per Cent. -----------------+----------- Wheat bread | 55.5 Wheat flour | 75.6 Graham flour | 71.8 Rye flour | 78.7 Buckwheat flour | 77.6 Beans | 57.4 Oatmeal | 68.1 Cornmeal | 71.0 Rice | 79.4 Potatoes | 21.3 Sweet Potatoes | 21.1 Turnips | 6.9 Carrots | 10.1 Cabbage | 6.2 Melons | 2.5 Apples | 14.3 Pears | 16.3 Bananas | 23.3 -----------------+----------- It is estimated that starch composes one-half of peas, beans, wheat, oats and rye, three-fourths of corn and rice, one-fifth of potatoes. Vegetable proteids, as already stated, are less easily digested than those belonging to the animal kingdom, therefore it must be remembered that a purely vegetable diet, even though it may be so arranged as to provide the necessary protein, is apt to over-tax the digestive organs more than a mixed diet from both the animal and vegetable kingdoms. Much depends upon the cooking of the starchy foods in order to render them digestible. (Study chapter on Digestion in the Public School Physiology.) STARCH.