ANIMAL HEAT 581 



combustion of the food substances. From careful experiments, 

 it has been found that a gramme of dry protein (egg-albumin), 

 when burned in a calorimeter, yields 5- 735 calories of heat, a 

 gramme of dextrose 3*742, and a gramme of animal fat 9*500 

 calories (Stohmann). 



Calories. 



Heat-equivalent of i gramme of albumin 5 '73 5 



Albumin (minus urea produced from it) 4'949 



Cane-sugar 3 '95 5 



Kreatin (water-free) - 4' 275 



Starch - 4-182 



In applying such results to the calculation of the heat-production 

 of the body, it is not sufficient to deduct from the heat of combustion 

 of the proteins the heat which the residual urea would yield if fully 

 oxidized. For other incompletely oxidized products arise from 

 proteins when consumed in the body, and Rubner has shown, by 

 actually determining the heat of combustion of the urine and faeces, 

 that the real equivalent of a gramme of albumin is at most only 

 4-420 calories. The heat-equivalent of our less liberal specimen diet 

 (p. 545) will be approximately : 



Calories. 



Protein, 95 grammes x 4*420 4i9'9 



Fat, 80 grammes x 9' 500 760*0 

 Carbo-hydrate (reckoned as 



dextrose), 320 grammes x 3'742 1,197-4 



2,377'3 



The heat-equivalent of the more generous specimen diet (p. 546) 

 would be 2,878 calories. 



But this is the diet of a man doing a fair day's work, and to 

 get the quantity of energy which actually appears as heat, the heat- 

 equivalent of the mechanical work performed must be deducted. 

 A fair day's work is about 150,000 kilogramme-metres that is, an 

 amount equal to the raising of 150,000 kilogrammes to the height 

 of a metre. Now, a kilogramme-degree or calorie of heat is 

 equivalent to 425-5 kilogramme-metres of work, and a kilogramme- 

 metre to calorie. The heat-equivalent of the day's work 

 425'5 



is, therefore, 150,000 x - - = 352 calories. Deducting this from 



4 2 5 '5 



the heat-equivalent of the food, we get in round numbers 2,520 calo- 

 ries as the heat given off on the more liberal diet. This corresponds 

 fairly well with the calculated heat-loss (p. 579). 



The following table, based on the direct calorimetric observations 

 of Atwater and Benedict, shows the average heat-production in a 

 large number oi experiments on several individuals at rest and doing 

 measured amounts of work, with a stationary bicycle, for instance. 

 This was connected with a small dynamo, which transformed the 

 greater part of the work into electrical energy. The electrical energy 

 in its turn was changed into heat, the current passing through a 

 lamp : 



