FERMENTATION. 79 



ing the deposit, O013 (0*2 grs.), and in a gramme of 

 ferment, which had been rubbed in water for six 

 hours, 0*056 (0'86 grs.) phosphate of ammonia and 

 magnesia. There are, therefore, decomposed ferment- 

 ing matters in the ferment ; but there is also another 

 substance contained in it, which is still decomposing, 

 and this only requires to come in contact with the air 

 in order to be resolved into ammonia. 



Schubert* instituted a variety of investigations 

 upon the subject of fermentation, which must serve as 

 critical reviews of those earlier ones undertaken by 

 Liidersdorff t and others. 



Liidersdorff thought he had observed that ferment 

 ceased to operate if its particles were subjected to 

 friction, and believed with Cagniard la Tour, and 

 others, that the action of the ferment depended as a 

 general rule on the cellular structure of its parts. 



Schubert, on the contrary, attempted to prove that 

 even vegetable particles are unnecessary to fermen- 

 tation. He ascribes its operation solely to the 

 peculiar capacity possessed by ferment of absorbing 

 gas, and he thought that when he substituted other 

 bodies possessing the same capability in an equal 

 degree, he really perceived a fermentation of sugar. 

 He was led to make these experiments by the follow- 

 ing statements. 



According to Rousseau, whose opinion is confirmed 



* Fogg's Ann. Bd. 69, s. 157 and 542; Bd. 77, s. 197. 

 t Ibid. Bd. 67, s. 408. 



