.552 



THE SUGAR OF GRAPES. 



ferments 

 though freed 

 from fecula. 



The cause of 

 the fermenta- 

 tion is in the 

 liquid sugar. 



1st stage of 

 fermentation. 



5d stage. 



Sd stase. 



cause it retains in solution a pordon cf the fecula that has 

 • been mentioned, and the nature of which has been com. 

 pletely ascertained by Fabbroni and Thenard. This fecula 

 is retained there apparently by the intervention of acidsj 

 since we do not find it in the juice, that has been saturated 

 hy the carbonate, and clarified with whites of eggs- in 

 which way alone it is obtained perfectly clear. 



Fabbroni and Thenard have considered this fecula as a 

 ferment indispensable to the change of the saccharine mat- 

 ter: but when the juice of the grape has been carefully 

 freed from it, the fermentation takes place as briskly as in 

 must not clarified, and we find it pass through all its stages 

 in the same period, without depositing any thing but tar- 

 trite of lime. 



The true cause of fermentation in juices, whether clari- 

 fied or not, does not reside in this fecula therefore, but in 

 the fluid sugar, the only principle of fruits that is truly fer- 

 mentable of itself, and capable of imparting this movement 

 to solid sugar, Deyeux appears to me to be the first who 

 observed this difference, and it must be confessed, that all 

 the phenomena of fermentation tend to confirm his opinion. 

 Let us take a rapid view of them. 



The first effect of fermentation on a juice that has beeii 

 clarified but not saturated is the absorption of tht^ first por- 

 tions of carbonic acid, that begins to be evolved. This 

 product occasions the honied sweetness to be succeeded by 

 a brisk taste, which, without being spirituous, renders the 

 must far more pleasant than it was before; and j,t is in this 

 state, that children like it so much. 



The second is the increase of the bulk of the liquor with 

 a temperature exceeding that of the atmosphere, though 

 diminished hy all the heat the carbonic acid gas carries off, 

 and the opacity of whey not well clarified. 



At the third period the spirit of wine begins to appear, 

 and then the presence of this frees the must from its fecula, 

 and a great part of its tartar. The gum, extractive matter, 

 and malic acid subsist amid the fermentation, without tak- 

 ing the least part in it, since we find them in the same pro- 

 portions after it is over. 

 T If 



