192 



MAX KLEIBER 



where aQ/ M — rate of heat loss in calories per second, s = specific heat of 

 medium, water in this case, in calories per oram per degree Centigrade, 

 aW / M = rate of flow of the medium, in grams per second, T^.^ = tempera- 

 ture of outflowing water, and Tu^i = temperature of inflowing water. 



If the weight of the water, W, is measured in metric units, s is nearly unity 

 (depending slightly on the temperature). 



Trap for 

 HgO vapor 



Sodo 

 Lime 



HgSO^ 



Og meter 



COj trap 



Fig. 4. Schematic diagram showing principle of Atwater- 

 Rosa, respiration calorimeter. 



To the heat carried away by the water must be added the heat 

 given off as latent heat of water vaporization. For a temperature of 

 20° this latent heat is: 



Q, = 585 W, 



(15) 



where Qc = latent heat of evaporation in calories and We = grams of 

 water evaporated. 



The latent heat of evaporation for other temperatures is found in 

 the literature {5-7). 



The amount of evaporated water is measured by the increase in 



