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 as well as a tissue builder. We could burn beans and peas as well as the strictly fuel foods, starch and fat, in an engine, and get heat to move the engine. If one takes up athletics or hard physical labor, he should increase the amount of fats and carbohydrates eaten, but not of proteid. Muscular activity increases the carbon waste but not the nitrogen waste of the body.

Minerals.—The iron of the blood and the mineral salts in bone (carbonate and phosphate of lime) must enter the body in organic form in order to be used. Water and salt are mineral foods. The body is about two thirds water. The cells must do their work under water. They cannot live when dried. Water enables the blood to flow; and the blood is not only the feeder, but also the washer and cleanser of the tissues. Some persons get out of the habit of drinking plenty of water, and their health suffers thereby. In such a case drinking plenty of water will be safer and more effective than taking poisonous drugs to restore health.

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 house-