338 On I he Cultivation of the Vine, 



bottles before their fermentation was completed. This gas, 

 being slowly developed in the liquor, remains compressed in 

 it till the moment when, the effort of the compression having 

 ceased, by the opening of the vessels it can escape with force. 

 This acid gas gives to all liquors impregnated with it a 

 tartish savour. Those mineral waters called gaseous waters 

 are indebted to it for their principal virtue. But it would be 

 having a very incorrect idea of its real state in wine, to com- 

 pare its effects to those which it produces by its free solution 

 in water. 



The carbonic acid disengaged from wine holds in solution 

 a pretty considerable portion of alcohol. I think I was the 

 first who made known this fact, when I showed that, by ex- 

 posing pure water in vessels placed immediately above the 

 chapeau of the vintage, at the end of two or three days this 

 water is impregnated with carbonic acid, and that, to obtain 

 very good vinegar, nothing is necessary but to put it into 

 uncorked bottles, and to leave it to itself for a month. At 

 the same time that the vinegar is formed, abundance offtakes, 

 which are of a nature analogous to fibrous matter, are preci- 

 pitated in the liquor. When water containing earthy suU 

 phats, such as well-water, is employed instead of pure water, 

 there is disengaged at the moment of acetification an odour 

 of sulphurated hydrogen gas, which arises from the decom- 

 povsition of tlie sulphuric acid itself. This experiment suffi- 

 ciently proves that the carbonic acid gas carries with it al- 

 cohol and a little extractive matter; and that thes(^ two prin- 

 ciples, necessary for the production of the acetous acid, being 

 afterwards decomposed by the contact of the atmospheric air, 

 produce acetous acid. 



But is the alcohol dissolved in the gas, or is it volatilised 

 merely by the heat ? This question cannot be determined by 

 direct experiments. Gentil observed in 177 J), that when a 

 glass bell was inverted over the vintage in fermentation, the 

 inside of it became covered with drops of a liquid which had 

 the smell and properties of the first phlegm that passes when 

 spirits are distilled. Humboldt has proved that if the vapour 

 of champagne be received under bells, in an apparatus for 

 collecting gas, surrounded with ice^ alcohol is precipitated on 



the 



