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WINE.
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as shown by the froth or scum which forms on
the surface, and increases in thickness, caused
by the more solid parts being thrown to the
surface, by effervescence created by the escape
of carbonic acid gas. This scum is called the
head.
After the lapse of some time this scum
is removed with a skimmer, and the thin liquor
returned to the vat; sometimes two or three
coats are removed in this manner. When the
regular vinous fermentation has begun, all the.
remaining froth is taken off; the liquor having
acquired a strong vinous taste, and beco1ne per–
fectly clear, is considered formed, and is trans–
ferred into barrels. The fermentation, however,
still progresses for several months longer. The
precipitates form a deposit, which constitutes
the wine-lees.
Grape juice does not ferinent in the grape
itself; this is owing to the exclusion of atmo–
spheric oxygen, the contact of which is neces–
:.;:ary to effect some change in the gluten, to
enable it to set up the fermentating process.