464 



APPLIED BIOLOGY 



but with gelatin alone they soon begin to lose weight and 

 to show other evidences of starvation. Hence, gelatin must 

 be used with protein foods. 



382. Inorganic or Mineral Foods, and Water. The in- 

 organic foods are the only ones not formed by animals or 

 plants. As we have seen, water plays an important part in all 

 living matter. In the human body it is especially important 

 in dissolving foods during digestion, and also as the circulating 

 medium in the blood- and lymph-systems. 



Common salt (sodium chloride, NaCl) is only one of a num- 

 ber of mineral salts necessary in the human body. A com- 

 pound containing iron gives the red color to blood ; lime 

 (calcium) is necessary in the bones; and less noticeable 

 quantities of other elements (P, K, S, Mg) are needed in the 

 human body. Most animal and vegetable foods which we 

 commonly use contain these necessary elements, and so we 

 do not have to give any special attention to obtaining them. 

 Common salt is the only mineral food which is regularly added 

 to our diet in addition to what is naturally in our organic 

 foods; and it is probably true that we use this greatly in 

 excess of what the body actually requires. 



383. Testing Foods for the Nutrients. (D or L) Apply the tests 

 for starch, proteins, and grape-sugar to oatmeal, flour, white-of-egg, 

 egg-yolk, potato, onion, rice, beans, peas, lean meat, apple, honey, 

 corn-syrup, pears, corn-meal, and other common articles of food. 

 Place each food to be tested in some water in a test-tube, boil for a 

 few minutes, and then pour in the testing reagent to be used. 

 Make a table in your note-book and record the results of the tests 

 by making a mark in the proper columns for the nutrient found to 

 be present. 



