858 On the Cultivation of the Vine , 
ed, that by exposing pure water in vessels placed imme- 
diately above the chapeau of the vintage,' at the end of 
two or three days this water is impregnated with carbo- 
nic 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 of hakes, which are of a 
nature analagous to fibrous matter, are precipitated in the 
liquor. When water containing earthy sulphats, such as 
well- water, is employed instead of pure water, there is dis- 
engaged at the moment of acetification an odour of sulphu- 
rated hydrogen gas, which arises from the decomposition 
of the sulphuric acid itself. This experiment sufficient- 
ly proves that the carbonic acid gas carries with it alco- 
hol and a little extractive matter ; and that these two 
principles, 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 volatil- 
ised merely by the heat ? This question cannot be de- 
termined by direct experiments. Gentil observed in 1779, 
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. Hum- 
boldt has proved that if the vapour of champagne be re- 
ceived under bells, in an apparatus for collecting gas, 
surrounded with ice, alcohol is precipitated on the sides 
merely by the impression of the cold. It appears, then, 
that the alcohol is dissolved in the carbonic acid gas, and 
it is this substance which communicates to the vinous gas 
a part of its properties. Every one feels, by the impres- 
sion which the vapour of champagne makes on our or- 
gans, how this gaseous matter is modified, and differs 
from pure carbonic acid. 
