=Adulteration of Food.=--Sometimes _cheaper materials_, of little or no value as food but of no great injury to health, are added to foods. _Examples:_ water added to milk, sawdust to ground spices, chicory to coffee, glucose to maple syrup. Other forms of adulteration not only cheat the purse but _tend to destroy health_, or actually do so. _Examples:_ Boracic acid or formalin added to milk to prevent souring, copper to canned peas, etc., to give a bright green color; salicylic acid or borax used in minute quantities as a preservative with canned corn, tomatoes, etc.; acids added to “apple” vinegar; dried fruit treated with sulphur to prevent a dull color. Pure food laws tend to repress these evils. It is best to buy foods in their original form. For instance, lemons are more reliable than vinegar. A bit of lemon at each plate, in households that can afford it, is far preferable to vinegar. We should always buy from neighbors when possible. Farmers and gardeners should do their own drying and canning. For purity of water, see Chap. X. =The Daily Ration.=--_A quarter of a pound_ (4 oz.) _of proteid foods and one pound_ (16 oz.) _of fuel foods_ (total 20 oz. of water-free foods) are needed to replace the daily =waste= of the body. Hence a _balanced ration_ has proteid and fuel food in the ratio of 4 to 16, or 1 to 4. But recent experiments at Yale University indicate that 2 oz. of proteid daily are more strengthening than four. _Appetite is a perfect guide for those who lead an active life and eat slowly of simple food._ Highly seasoned food and complex mixtures deprave the appetite; it then leads astray, instead of guiding safely. Of course the appetite cannot guide one to eat the right kind and quantity of food at a table where the food lacks any of the four necessary food stuffs, or where innutritious or indigestible food is provided. It is well to select one food for a meal because it is rich in proteids, another because it is rich in fat, and the third because it is rich in starch or sugar. (See table, p. 95.) Intelligence in regard to diet enables a housekeeper to provide nourishing food for less money than an ignorant housekeeper often pays for food deficient in nourishing qualities. =A Balanced Ration.=--A deficiency of starch may be supplied by an excess of fat or sugar. It is most essential to provide proteid as it cannot be replaced by any other food stuff. An excess of proteid is most harmful. An excess of starch or fat is oxidized into water and carbon dioxid, which are harmless waste products; an excess of proteid is changed into urea which may become harmful by overworking the liver and kidneys which excrete it. COMPOSITION OF ONE OUNCE OF VARIOUS FOODS IN FRACTIONS OF AN OUNCE