ON FERMENT ITION. 251 



the seconci gave no sign of fermentation in forty. On ab« 

 soVbing by potash the carbonic acid gas evolved during the Oxigenab* 

 fermentation of the first portion, a very little residuum was s^''''^'^- 

 left ; consequently the greater part of the oxigen gas I had 

 added was absorbed. 



Thpse results evidently prove, that must kept along time Farther con. 

 cannot ferment without the contact of oxigen gas. But to ^^'^^ '°°*' 

 obtain still greater certainty on this point, I analysed with 

 Volta's eudiometer the air found in several bottles of must, 

 that had been kept a year, and found in them no oxigen. 



I proceeded in the same way with the juice of goose- Similar results 

 berries and grape must recently prepared, which had been jujce. 

 exposed in well-corked bottles to the heat of boiling water, 

 and obtained precisely the same results. 



It is very remarkable, that, when a fermentable juice. Fermentation 

 which has been kept a long time, is poured into another j,eatand ex^ 

 vessel, so that-it would ferment from having been exposed to elusion of air. 

 the contact of the air, it may readily be deprived of this 

 property, by exposing it anew, in bottles closely corked, to 

 the heat of boiling water. Ey this operation we perceive it 

 loses its transparency, and afterward lets fail a slight sedi- 

 ment. During the fermentation of a very limpid juice a Sediment, 

 sediment is also deposited : but there is this difference be- 

 tween them ; that of the latter is capable of exciting fer- 

 mentation, but that of the former no longer enjoys this 

 property. 



From these several results I have considered it as very Grapejuice 



probable, that grape must recently obtained would not fer- P']=ssedout 

 . ' , 1 . , , ,. without the 



ment, it the grapes were pressed without the contact ot contact of w 

 air. Accordingly I took a jar, into which I introduced ^*>'* "ot fee- 

 some small bunches of grapes perfectly whole; inverted it ~ ' 

 wnder mercury; and filled it live times following with hi- 

 drogen gas, in order to expel the smallest portions of at- 

 mospheric air. I then bruised thegrapesinthejar by means 

 of an iron rod, and exposed them to a temperature of 15° or 

 20° [59° or 68]. Twenty-five days after no fermentation 

 appeared ; though must, to which I had added a litUe oxi- 

 gen, had begun to ferment the first day, and in a short time 

 after fermented very briskly. In these last two experiments 

 I observed, that the oxigen was almost wholly absorbed ; 



but 



