NOEMAL PEOCESSES OF ENEEGY METABOLISM 557 



Multiplying each of these quantities of oxygen by the respective thermal 

 quotients (see table above) for the different foodstuffs: 



185.9 gm. O 2 X 3.19 = 593.1 Cal. 

 356.2 " " X 3.29 == 1172.0 " 

 574.7 " " X 3.56 = 2046.0 " 

 Sums 1116.8 " " = 3811.1 " 



From this calculation 1 gm. O 2 = 3.41 cafories. 



For a liter of oxygen at 18 C. the mean thermal quotient would bo 

 4.60 1 Cal. (nearly). 



Laulanie(a) conducted experiments on small animals at or near this 

 temperature by means of a small calorimeter and computed the oxygen ab- 

 sorbed by analysis of the air of the chamber after a short period of con- 

 finement. The average value of the thermal quotient found by him was 

 4.71 Cal. per liter as calculated from the metabolism and 4.75 Cal. as 

 measured by the calorimeter. 



Atwater and Benedict (c) in a series of 12 experiments on mixed 

 diets found as an average a heat production for 24 hours of 2238 calories 

 and an oxygen absorption of 652.1 gm. The mean thermal quotient in 

 this series was 3.43 Cal. per gram, which agrees very well with the the- 

 oretical value based upon a mixed diet. At 18 C. the heat value per 

 liter of O 2 would be 4.61 Cal. 



TABLE 3 

 THERMAL QUOTIENT OF 2 BASED UPON EXPERIMENTS ON MAN (ATWATER AND BENEDICT) 



The greatest deviation from the mean is represented by experiment 

 No. 9 where it is only 3.9 per cent. 



In the case of a man on a lacto-vegetarian diet containing 39 gm. pro- 

 tein, 25 gm. fat and 265 gm. carbohydrate Atwater and Benedict found 

 that 1800 Cal. of heat were eliminated and that the absorption of oxygen 



'The weight of a liter of oxygen at 18 C. is 1.341 gm.; that of CO a is 1.804 gm. 



