It is in the first place necessary to consider whether the existing
state of fermentation be the original or secondary stage of that
process which comes on after the former has ceased for several days,
and is indeed the commencement of acetous fermentation. That of the
former kind rarely proceeds beyond what is necessary for the perfect
decomposition of the saccharine and other parts of the vegetable
substances necessary for the production of spirit, unless the liquor
be kept too warm, or is too weak, and left exposed to the air after
the vinous fermentation is completed. The means to correct these
circumstances are sufficiently obvious. The heat for spirituous
fermentation should not be above 60 degrees Fahrenheit; when it is
much above that point, the liquor passes rapidly through the stage
of vinous fermentation, and the acetous immediately commences. When
too long-continued fermentation arises from the liquor having been
kept in a warm situation, it will be soon checked by bunging, after
being removed into a cold place; the addition of a small proportion
of spirits of wine or brandy, previously to closing it up, is also
proper. A degree of cold, approaching to the freezing point, will
check fermentation of whatever kind. Fermentation of this kind cannot
be stopped by any chemical agent, except such as would destroy the
qualities of the liquor intended to be produced.
The secondary stage of fermentation, or the commencement of the
acetous, may be stopped by removing the liquor to a cool situation;
correcting the acid already formed; and if the liquor contain but
little spirit, the addition of a proper proportion of brandy is
requisite.
The operation of racking is also necessary to preserve liquor in
a vinous state, and to render it clear. This process should be
performed in a cool place.