MEASUHE OF THE WHOLE WORK DONE IN THE LIVING BODY. 497 



force exerted in a living body. If, then, it could be easily 

 ascertained how much carbonic acid is thrown off by an animal 

 in 24 hours in the process of respiration, the other channels by 

 which carbon or carbonic acid is eliminated being barely ma- 

 terial, a numerical index would be afforded of the sum of all 

 the several kinds of work (before enumerated) performed by 

 the animal in that time. This, doubtless, can be accomplished, 

 yet not so easily as to afford a practical method. Neverthe- 

 less it is not without its use in theory. Again, if it could be 

 easily ascertained how much heat is dissipated by an animal 

 to the surrounding medium in 24 hours, that quantity would 

 indicate the proportion of the whole carbonic acid formed in 

 that time which had become subservient to the mere preserva- 

 tion of the temperature of the body. And if the quantity 

 of carbonic acid so indicated were deducted from the whole 

 quantity of carbonic acid produced in 24 hours, the remain- 

 der would represent the sum of the vital, the mechanical, 

 and the mental work performed by the frame of such animal 

 in the period referred to. The proportion of vital and mental 

 work cannot as yet be exactly estimated ; yet if it were 

 ascertained how much external mechanical work the animal 

 in question had performed in the given time as by raising 

 a known weight of matter to a certain height then the 

 quantity of carbonic acid corresponding to the whole work, 

 vital, mechanical, and mental, being diminished by the quantity 

 corresponding to the ascertained amount of carbonic acid de- 

 rived from the mechanical work, would represent the carbonic 

 acid generated during the vital and mental work. Thus the 

 whole amount of carbonic acid produced by the animal in 24 

 hours might be divided duly into three portions, representing 

 (1) the vital and mental work, (2) the mechanical, and (3) 

 the heat work. This, then, can in truth be done, but by 

 methods that do not deserve the name of practical. 



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