ANIMAL HEAT 499 



From careful experiments, it has been found that a gramme of 

 dry proteid (egg-albumin), when burned in a calorimeter, yields 

 5,735 millicalories of heat, a gramme of grape-sugar 3,742, 

 and a gramme of animal fat 9,500 millicalories (Stohmann). 



Calories. 



Heat equivalent of r gramme of albumin - - 5>735 

 Albumin (minus urea produced from it) 4,949 

 Cane-sugar - . 3,955 



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 proteids the heat which the residual urea would yield if fully 

 oxidized. For other incompletely oxidized products arise from 

 proteids 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 millicalories. The heat-equivalent of our specimen diet (p. 476) 

 will be approximately : 



Millicalories. 



Proteid, 140 grammes x 4,420 = 618,800 



Fat, 100 grammes x 9,500 = 950,000 



Carbo - hydrate (reckoned as 



glucose), 350 grammes x 3,742 = 1,309,700 



2,878,500 



But this is the diet of a man doing a fair day's work; and tc 

 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 equiva- 

 lent to (say) 427 kilogramme-metres of work, and a kilogramme- 

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



427 



is, therefore, 150,000 x = 351,000 millicalories. Deducting this 



427 



from the heat-equivalent of the food, we get in round numbers 

 2,530,000 millicalories as the quantity of heat given off. This cor- 

 responds fairly well with the calculated heat-loss (p. 497). Calori- 

 metric observations have given results in some cases not widely 

 different, in others considerably higher. Thus, Him found that a 

 man of 73 kilos weight produced 140,000 millicalories per hour 

 during rest, and 229,000 during an hour's work of 32,550 kilogramme- 

 metres. At the same rate for the twenty-four hours these numbers 

 would correspond respectively to 3,360,000 and 5,496,000 small 

 calories. But it is not legitimate to apply the results of compara- 

 tively short observations in this way; for, on the one hand, the heat- 



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