202 Metabolism of Healthy Man. 



as the heat of urine and feces, and 22 per cent in the water vaporized from the 

 lungs and skin. The 77.3 per cent apportioned to radiation and conduction 

 may still further be subdivided, since it has been computed in previous experi- 

 ments 1 that during rest, about 2 per cent of the total heat is required to warm 

 the inspired air. Furthermore, an apportionment can be made of the water 

 vaporized from the lungs and skin on the basis that of the 22 per cent of heat 

 absorbed in vaporizing water, 9.8 per cent is from the lungs and 12.2 per cent 

 from the skin. Consequently a more accurate apportionment would be 75.3 per 

 cent as heat eliminated by radiation and conduction, 2 per cent required to 

 warm the inspired air, 0.7 per cent for the heat of urine and feces, 9.8 per cent 

 as heat of vaporization of water from the lungs and 12.2 per cent as heat of 

 vaporization of water from the skin. 



Considering the work experiments, we have a proportionately smaller amount 

 as the sensible heat of excreta, urine and feces, and a larger amount in the water 

 vaporized from the lungs and skin, while the fourth path, namely, the heat 

 equivalent of muscular work, here plays an important role. The average of all 

 the work experiments shows 45.5 per cent for radiation and conduction, 0.4 per 

 cent for urine and feces, and 43.6 per cent for the water vaporized from the 

 lungs and skin, and 10.5 per cent for the heat equivalent of external muscular 

 work. 



1 Benedict, Carnegie Institution of Washington Publication No. 77, 1907, p. 476. 



