DAILY LOSS OF CARBON AND NITROGEN. 261 



facts and considerations. Thus, the food a man takes 

 into his body daily, represents or ought to represent, 

 the quantity and kind of matter necessary for replacing that 

 which is daily cast out by way of the lungs, skin, kidneys, 

 and other organs. To find out, therefore, the quantity 

 and kind of food necessary for a healthy man, it will, 

 evidently, be the best plan to consider in the first place 

 what he loses by excretion. 



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 could be fed by these elements, 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 



