72 COMPANION TO TROPICAL READERS 



III. Cultivation of Crops 



For general notes on the study of Economic Plants 

 see pp. 24-29 of this Companion. 



IV. Health 



WHY WE EAT 



(See Tropical Readers, Book II, pp. 136-140.) 



Expt. 148. Functions of Foods. In a tabular form 

 set out the functions of foods. In the first column put 

 the names of the different types, in the second, examples 

 of each class, and in the third column their functions. 



Expt. 149. Kinds of Foods. Collect two samples 

 each of the different kinds of foods: 



(a) Carbonaceous, e.g. starch, sugar. 



(b) Nitrogenous, e.g. lean meat, white of egg. 



(c) Mineral, e.g. salt. 



Expt. 150. Carbon and Nitrogen in Foods. To 



illustrate the presence of these important elements in 

 foods 



(a) Carbon: Heat meat and bread, and the carbon will 

 be noticed as they char. 



(b) Nitrogen: Powder cheese, and mix it with lime; 

 apply heat, and test for ammonia with a piece of mois- 

 tened litmus or turmeric paper. (Red litmus will be 

 turned blue, and yellow turmeric will be reddened, if 

 ammonia is present.) 



