846 
On the Cultivation of the Vine*, 
firmed by a sufficient number of observations to merit 
full belief, is., that fermentation is slower as the tempera* 
ture has been colder at the time of collecting the grapes . 
Rozier found in 1769* that grapes collected on the 7th, 
8th, and 9th of October remained in the vat till the 19th 
without showing the least sign of fermentation : the ther- 
mometer in the morning had been at 3J degrees below 
freezing, and maintained itself at + 4. The fermenta- 
tion was not completed till the &5th; while similar 
grapes collected on the I6tli, at a temperature much less 
cold, terminated their fermentation on the Slst or 22 &» 
The same thing was observed in 1740. 
In consequence of these principles, it has been recom- 
mended to place the vats in covered places ; to re- 
move them from damp and cold places ; to cover 
them, in order to moderate the cold of the atmosphere ; 
to heat again the mass by introducing boiling must ; and 
to make choice of a warm day for collecting the grapes, 
or to expose them to the sun, &c. 
2. Influence of the Air on Fermentation . 
We have seen in the preceding article that fermenta= 
tion may be moderated and retarded by withdrawing the 
must from the direct action of the air, and keeping it ex- 
posed to a cool temperature. Some chemists, in conse- 
quence of these facts, are of opinion that fermentation 
can take place only by the action of the atmospheric 
air ; but a more attentive observation of all the pheno- 
mena it presents in its different states, will enable us to 
set a just value on all the opinions which have been en- 
tertained on that subject. 
The air, no doubt, is favourable to fermentation. This 
truth seems established by a concurrence of all the facts 
known ; for, when preserved from the contact of the air, 
must will keep a long time without any change or altera- 
