DAILY LOSS OF CARBOX AND XITROGEX. 253 



For the sake of example, we may now take only two 

 elements, carbon and nitrogen, and, if we discover what 

 amount of these is respectively discharged in a given time 

 from the body, we shall be in a position to judge what 

 kind of food will most readily and economically replace 

 their loss. 



The quantity of carbon daily lost from the body amounts 

 to about 4,500 grains, and of nitrogen 300 grains; and - 

 if a man 7;6uld be fed by these elemenls, as such, the 

 problem would be a very simple one; a corresponding 

 weight of charcoal, and, allowing for the oxygen in it, 

 of atmospheric air, would be all that is necessary. But, 

 as before remarked, an animal can live only upon these 

 elements when they are arranged in a particular man- 

 ner with others, in the form of an organic compound, as 

 albumen, starch, and the like; and the relative propor- 

 tion of carbon to nitrogen in either of these compounds 

 alone, is, by no means, the proportion required in the 

 diet of man. The amount, 4,500 grains of carbon, repre- 

 sents about fifteen times the quantity of nitrogen required 

 in the same period; and, in albumen, the proportion of 

 carbon to nitrogen is only as 3*5 to I. If, therefore, a man 

 took into his body, as food, sufficient albumen to supply 

 him with the needful amount of carbon, he would receive 

 more than four times as much nitrogen as he wanted ; 

 and if he took only sufficient to supply him with nitrogen, 

 he would be starved for want of carbon. It is plain, 

 therefore, that he should take with the albuminous part 

 of his food, which contains so large a relative amount 

 of nitrogen in proportion to the carbon he needs, sub- 

 stances in which the nitrogen exists in much smaller 

 quantities. 



Food of this kind is provided in such compounds as 

 starch and fat. The latter indeed as it exists for the most 

 part in considerable amount mingled with the flesh of 

 animals, removes to a great extent, in a diet of animal 



