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A TREATISE ON
those grapes that produce the most perfect wines,
the relative proportions of the exciters of fermenta–
tion and the sugar are so accurately proportioned
by nature, that the whole of the former are decom–
posed, and nearly the whole of the latter converted
into alcohol; so that the liquid (wine) is left in a
state not liable to future change. The chiefproduct
of the vinous fermentation is alcohol, but there are
other substances simultaneously produced and which
remain associated with fermented liquor. Among
the principal of these are renanthic acid and renan–
thic ether; neither of which exists previous
to
fer–
mentation, and are generally supposed
to
result from
the action of the nitrogenizcd matters of the solution
on the sugar.
It has been determined by the researches of
HK.
Colin
and
ThenMd,
and more recently by those of
Fremy
and
ROU8seau,
that the peculiar condition of
the nitrogenized matter constituting the ferment
materially influences the nature of the fermentation.
The essential condition of a ferment, to be able to ex–
cite the vinous fermentation,· is to be sufficiently
acidulous to
a~t
on colored paper ; and this acidity
should arise from the presence of certain vegetable
acids and salts, capable of conversion into carbonic
acid and carbonates, by their spontaneous decompo–
sition. Those acids and salts which are found to
Digitized
by