CARBOHYDRATES, ACIDS, FATS, OILS 



69 



TABLE XXI 



88. Classification of non-nitrogenous compounds. 

 The non-nitrogenous compounds of foods are usually 

 divided into two main classes, viz., carbohydrates and 

 similar bodies and fats and oils. The first class often 

 bears the name nitrogen-free extract, but the carbohy- 

 drates are its principal members. Crude fiber belongs in 

 this class. The second is known by the chemist as ether- 

 extract, because ether is used to extract the fats or oils 

 from the vegetable substances in which they are con- 

 tained. The actual fat obtained from vegetable foods is 

 always less, however, than the ether-extract, because the 

 ether takes into solution other compounds than the fats. 

 It should be noted that the last two compounds of the 

 above table, which are fats, are relatively richer in car- 

 bon and hydrogen and poorer in oxygen than the other 

 compounds mentioned, which are carbohydrates. This 

 fact has an important relation to nutritive value. 



89. The carbohydrates. In order to understand the 

 carbohydrates as individual compounds and in their 

 relations to each other and to the processes of nutrition, 

 it is necessary to consider them, in general outlines at 

 least, from the standpoint of the chemist. 



The term carbohydrates, as it is used, like the term 

 protein, is collective and includes a great variety of com- 

 pounds. By their common names we know them as sugars, 



