256 YEAST OR FERMENT. 



depends solely on its presence, and its presence is 

 necessary, until the last atom of sugar is decom- 

 posed. 



These facts and observations point out the exist- 

 ence of a new cause, which effects combinations and 

 decompositions. This cause is the action which 

 bodies in a state of combination or decomposition 

 exercise upon substances, the component parts of 

 which are united together by a feeble affinity. In its 

 action it resembles a peculiar power, attached to a 

 body in the state of combination or decomposition, 

 but exerting its influence beyond the sphere of its 

 own attractions. 



We are now able to account satisfactorily for 

 many known phenomena. 



A large quantity of hippuric acid may be obtained 

 from the fresh urine of a horse, by the addition of 

 muriatic acid ; but when the urine has undergone 

 putrefaction, no trace of it can be discovered. The 

 urine of man contains a considerable quantity of 

 urea, but when the urine putrifies, the urea entirely 

 disappears. When urea is added to a solution of 

 sugar in the state of fermentation, it is decomposed 

 into carbonic acid and ammonia. No asparagin 

 can be detected in a putrified infusion of asparagin, 

 liquorice-root, or the root of alihcpa officinalis. 



It has already been mentioned, that the strong 

 affinity of nitrogen for hydrogen, and that of car- 

 bon for oxygen, are the cause of the facility with 

 which the elements of azotised compounds are dis- 



