34 THE GRAPE. 



albuminous matter. But even Thenard's examination 

 cannot be regarded as conclusive and decisive, par- 

 ticularly as he asserts that this matter is soluble in 

 boiling water. 



It is, however, very necessary to know what albumi- 

 nous matter is found in grape juice, in order to under- 

 stand rightly the mode in which the ferment is pro- 

 duced in the juice. 



The existence of this matter has been ascertained 

 in the following manner : 



First, we must distinguish between the albumen 

 found in the juice, and that which exists perhaps in 

 the walls of the cells of the pulp, in the walls of those 

 cells in which the juice is enclosed. These crushed 

 cell- walls ferment with the juice, and exercise an im- 

 portant influence upon the fermentation. 



The pulp of white grapes was freed from stones and 

 skins, finely strained, and the juice then passed through 

 filter paper. The pulp was rubbed and treated with 

 water, until nothing but pure water passed through. 

 The remaining cell-walls, after being warmed with 

 potash, and strained, yielded, on addition of acid, 

 pectic acid, as a product of the decomposition of 

 pectose. The^ residuum was cellulose. The prin- 

 cipal ingredients of the cell-walls seem to be pectose 

 and cellulose. 



A part of these cell-walls was boiled with acetic 

 acid, the liquor so obtained was neutralized with 

 ammonia after filtration. A white flocculent preci- 



