314 ON THE QUANTITY OF FOOD 



persons differ materially according to circum- 

 stances. Upon the average it may be reckoned 

 to consist of 93 or 94 per cent, of water, and 

 the rest is a complication of a great many 

 articles. The carbone contained in these ingre- 

 dients cannot be estimated at more than 1 or 

 1} per cent, from the analyses hitherto made. 

 This will give .5 or .6 of an ounce of carbone 

 upon 481 of urine per day. Berzehus has not 

 neglected the analysis of the faeces; of 100 

 parts, three-fourth may be estimated as water, 

 and the rest do not seem to contain more than 

 ten parts of carbone. This would give half an 

 ounce of carbone in five ounces. Hence we 

 may infer that one ounce, a little more or less, 

 of carbone, is carried off from the body daily 

 through these two channels. The remainder 

 lOi ounces must therefore be spent in the insen- 

 sible perspiration. 



The quantity of insensible perspiration from 

 the skin cannot be easily determined by direct 

 experiment. That from the lungs may be ap- 

 proximated from known facts. 



I have shewn (see Manchester Memoirs, vol. 

 2nd. new series, page 27,) that I produce by 

 breathing in the space of 24 hours, 2.81bs. troy, 

 of carbonic acid gas. This is equivalent to .78 



