254 



ON THE SOURCE OF MUSCULAR POWER. 



whereas, when muscle is most completely consumed in the body, the 

 products are carbonic acid water and urea ; the whole of the nitrogen 

 passes out of the body as urea — a substance which still retains a con- 

 siderable amount of potential energy. Dry muscle and pure energy 

 yield, under these circumstances, almost exactly one-third of their 

 weight of urea, and this fact, together with the above determination 

 of the actual energy developed on the combustion of urea, enables us 

 to deduce with certainty the amount of actual energy developed by 

 muscle and albumen respectively when consumed in the human body. 

 It is as follows : — 



Actual energy developed by one gram of each substance when con- 

 sumed in the body. 



The second point, viz., the amount of mechanical force exerted by 

 the muscles of the body during a given time, was ascertained from 

 the experiments of Fick and Wislicenus, during their ascent of the 

 Faulhorn, from the Lake of Brienz. The third point, viz., the 

 amount of muscle oxidized in the body, as ascertained from the ex- 

 periments of the above-named observers, on the quantity of nitrogen 

 secreted in the urine, both before, during, and after the ascent. 



From the above data the following table was constructed : — 



