S50 



OS FERMENTATION. 



TTrifi opmion 



of anhrsa} and 

 •wgetsbie sub- 



siuines. 



The air jnl^ij- 

 ««trcs fermeut- 

 atrw.n. 



ExperrtBcrat 

 ^ith grape 

 juice. 



Fermentation 

 e-xcite.i by the 

 contact of air. 



Th«? same 

 »!!)«iT!jn by 

 *aoti5cr expe. 

 riiiiejil. 



for an excellent paper on fermentation*, has accorciingljr 

 adopted the opinion, that the ferment was in all cases iden- 

 tic^}. The experiments 1 have made have led me to a dif- 

 ferent opinion ; and the principal object of this paper will 

 be to show, that the fermentation of grape must .cannot take 

 place without the assistance of oxigen gas. Hence it follows, 

 that the ferment of the grape is not of the same nature as 

 yeast ; or rather, that they are not both in the same state. 



I was led to this inquiry by an examination of the pro- 

 cesses employed by jNlr. Appert for preserving vegetable 

 and animal substancesf. 1 had observed with surprise, that 

 grape must, which had been kept unaltered a whole year, 

 began to ferment in a few days after being poured into 

 fresh vessels. It is in this way Mr. Appert prepares spark- 

 ling winej \vins moiisseux] at aU seasons of the year. This 

 fact led me to suspect, that the air had some influence on 

 fermentation, and suggested to nie the following experi- 

 ments. 



I took a bottle of grape must that had been kept a year, 

 and was perfectly limpid ; poured it into another bottle, 

 which I corked tight; and exposed it to a temperature from 

 15* to 30° [59° to 86° F.]. In a week's time the must had 

 lost its transparency ; fermentation had taken place in it ; 

 and it was soon converted into a vinous liquor, sparkhng 

 like the best champagne. A second bottle, that had been 

 kept a year, like the preceding, but was not exposed to the 

 contact of air, gave no signs of fermentation, though placed 

 in the most favourable circumstances for producing it, 



I then took this bottle of grape must, cut it pretty deeply- 

 round the neck with a file, inverted it in a mercurial trough, 

 and then broke oif the neck, without suffering the must to 

 come into contact with the air. One portion of the must 

 I passed through the mercury into ajar containing a small 

 quantity of oxigen gas, and another portion into a jar 

 perfectly void of air. The first fermented in a few days: 



♦ Ann. de Chim vol. XLVI, p. 291. See Journ. vol. VII, p. 33.| 

 t These processes, which are extremely simple, consist in puttirjg 

 the iubstances to be preserved into bottles, corking them very close, and^ 

 t]\on exposing them to the heal of boiling water for a longer or shorter 

 time. See tiie instructions published by Mr. Appert. 



the 



