56 FERMENTATION. 



by experiment that fermentation might be completed 

 in carbonic acid or hydrogen gas, without a trace of 

 oxygen; but they never saw fermentation commence 

 without it. That little or no air is necessary to the 

 continuance of fermentation is certain, for it was the 

 custom for many years in France, in order to prevent 

 the loss of alcohol during fermentation, to cover the 

 wine-coops with a cask lid, provided with a long pipe, 

 wherein the alcoholic vapours were condensed. 



In this manner the admission of air to the ferment- 

 ing liquid was completely cut off, for both cask 

 and pipe were speedily filled, and kept filled, with 

 carbonic acid. But this apparatus has fallen into 

 disuse since G-ay-Lussae proved that when open 

 vats were used, scarcely - 2 outh part of alcohol was lost 

 in consequence. Neither before, during, nor after its 

 use, was any change found in the quality of the wine ; 

 and yet such must have been the result, if a large 

 quantity of air were necessary to the preparation of 

 wine. After an account of the method of preparing 

 Bavarian beer, where the air is allowed to enter freely, 

 Liebig recommends the same in the case of wine, and 

 suggests that a large opening should be made in the 

 cask^ in which fermentation takes place. Yon Babo, 

 a vine-grower in Baden, " in accordance with this ad- 

 vice, allowed wine to ferment in casks provided with 

 large openings."* 



This experiment was made in 1841, with red wine, 



+ Liebig. Ch. Briefe, 1851, s, 302. 



