and the Method of making Wines. 411 
As in fermentation there is no absorption of air, nor ad- 
dition of any foreign matter, it is evident that all changes 
which take place in the operation can be referred only to 
the departure of those substances which are volatilised 
or precipitated. 
Thus, by studying the nature of these substances, and 
ascertaining their constituent principles, it will be easy 
for us to judge of the changes which must have been pro- 
duced in the nature of the first materials of fermentation. 
The materials of fermentation are the sweet and sac- 
charine principle diluted in water. This principle is form- 
ed of sugar and extractive matter. 
The substance volatilised is the carbonic acid gas, and 
that precipitated is a matter analogous to the ligneous fi- 
bre mixed with potash. 
The principal product of fermentation is alcohol. 
It is evident that the transition of the saccharine prin- 
ciple to alcohol cannot be conceived but by calculating 
the difference which must be produced in the saccharine 
principle by the departure of the principles that form car- 
bonic acid gas which is volatilised, and the deposit which 
is precipitated. 
These principles are, in particular, the carbon and the 
oxygen : here, then, we find carbon and oxygen taken 
from the saccharine principle by the progress of fermen- 
tation ; but in proportion as the saccharine principle loses 
its oxygen and its carbon, the hydrogen, which forms the 
third constituent principle, remaining the same, the char- 
acters of the latter element must predominate, and the 
fermenting mass must attain to that point at which it will 
only present an inflammable fluid. 
In proportion as the alcohol is developed, the liquid 
changes its nature ; it no longer has the same affinities, 
nor, consequently, the same dissolving power. The small 
quantity of extractive principle which remains after haw 
