90 FORMATION OF FAT. 



degrees of heat during a period of 120 hours. In each 

 hour there is, therefore, set free an amount of heat ca- 

 pable of raising the temperature of each pound of 

 liquid 2-4 degree ; a rise of temperature which is very 

 powerfully counteracted by external cooling and by the 

 vaporization of alcohol and water. 



The formation of fat, like other analogous phenom- 

 ena, in which oxygen is separated in the form of car- 

 bonic acid, is consequently accompanied by a disen- 

 gagement of heat. This change supplies to the animal 

 body a certain proportion of the oxygen indispensable to 

 the vital processes ; and this especially 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. 



This excess of carbon, as it cannot be employed to 

 form a part of any organ, is deposited in the cellular 

 tissue in the form of tallow or oil ; and the production 

 of this fat, explains the fact, that the oxygen given out 

 in the shape of carbonic acid and water is more than 

 equal to that directly absorbed in respiration. 



At every period of animal life, when there occurs a 

 disproportion between the carbon of the food and the 

 inspired oxygen, the latter being deficient, fat must be 

 formed. Oxygen separates from existing compounds, 

 and this oxygen is given out as carbonic acid or water. 

 The heat generated in the formation of these two pro- 

 ducts contributes to keep up the temperature of the 

 body. Every pound of carbon which obtains the oxygen 

 necessary to convert it into carbonic acid from sub- 



