A SOURCE OF ANIMAL HEAT. 91 



of the carbon and of the hydrogen have united with 

 those of the oxygen, to form carbonic acid and water. 



Now, so far as chemical researches have gone, 

 our knowledge of the constitution of starch, and of 

 the varieties of sugar, will justify no other conclu- 

 sion than this, that these substances contain no ready 

 formed carbonic acid. 



We are acquainted with a large number of pro- 

 cesses of metamorphosis of a similar kind, in which 

 the elements of carbonic acid and water are sepa- 

 rated from certain pre-existing compounds ; and we 

 know with certainty that all these processes are 

 accompanied by a disengagement of heat, exactly 

 as if the carbon and hydrogen combined directly 

 with oxygen. 



Such a disengagement of carbonic acid, for ex- 

 ample, occurs in all processes of fermentation or 

 putrefaction, which are, without exception, accom- 

 panied with the generation of heat. 



In the fermentation of a saccharine solution, in 

 consequence of a new arrangement of the elements 

 of the sugar, a certain part of its carbon and oxygen 

 unite to form carbonic acid, which separates as gas ; 

 and as another result of this decomposition, we ob- 

 tain a volatile combustible liquid, containing little 

 oxygen, namely, alcohol. 



If we add to 2 equivalents of sugar the elements of 

 12 equivalents of water, and subtract from the sum 

 of the atoms 24 equivalents of oxygen, there re- 

 main 6 equivalents of alcohol. 



