A SOURCE OF ANIMAL HEAT. 93 



French weight, contains 16 per cent, of sugar, in all 

 384 Ibs., then, during the fermentation of this sugar, 

 an amount of heat must be generated equal to that 

 which would be produced by the combustion of 

 51 Ibs. of carbon. 



This is equal to a quantity of heat by which 

 every pound of the liquid might be heated by 

 297'9; that is, supposing the decomposition of 

 the sugar to occur in a period of time too short 

 to be measured. This is well known not to be 

 the case; the fermentation lasts five or six days, 

 and each pound of liquid receives the 297*9 de- 

 grees of heat during a period of 120 hours. In 

 each hour there is, therefore, set free an amount 

 of heat capable of raising the temperature of each 

 pound of liquid 1'4 degree ; a rise of tempera- 

 ture which is very powerfully counteracted by ex- 

 ternal cooling and by the vaporization of alcohol 

 and water. 



The formation of fat, like other analogous phe- 

 nomena in which oxygen is separated in the form 

 of carbonic acid, is consequently accompanied by a 

 disengagement of heat. This change supplies to 

 the animal body a certain proportion of the oxygen 

 indispensable to the vital processes ; and this espe- 

 cially in those cases in which the oxygen absorbed 

 by the skin and lungs is not sufficient to convert 

 into carbonic acid the whole of the carbon adapted 

 for this combination. 



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