Encyclopaedia Britannica > Volume 7, ETM-GOA

F E R [21
Ferments- have feen a bottle opened in a cold day, that has been
, tl“n' quite vapid, which was made bnfk and lively by cork-
Vt' ing it up tight again, and fetting it for ten or twelve
minutes in a bafon of water a little more than milk
,, warm.'’
His theory Oar author’s theory of fermentation is to the fol-
cf fermen- lowing purpofe. 1. The heat occurring in the mix-
tation. ture, he explains on Dr Black’s principle of latent
heat. 2. In the fermenting procefs, he fuppofes the
inflammable part of the mixture to have a tendency to
combine with pure air, and thus to form what is call¬
edfixed air. 3. The pure air is fuppofed to be derived
fectn the atmofphere, while inflammable air is furnifhed
by the fermenting liquor. 4. The fixed air found in
fuch plenty above the liquid while in a ilate of fermen¬
tation, does not exift in it originally, but is farmed by
a combination of the two ingredients juft, mentioned.
5. On thefe principles the heat which takes place in
the mixture may be particularly explained in the fol¬
lowing manner. “ Suppofe that the quantity of heat
in the two airs before combination was in each as teh-,
or, in other words, that they were capable of contain¬
ing that quantity in a latent ftate effential to their ex-
iftence as matter in that form ; when they unite, they
form a very different kind of air, which is not capable
of combining with fo much heat, and perhaps quite
foreign to its exiftence as that kind of matter : we
will fuppofe then, that it can combine with but a
quantity of that heat as five; the confequence muft
then be, that there is a quantity of redundant heat, as
fifteen ; and there being no bodies at hand undergoing
any changes in their properties, by which their capa¬
cities to unite with heat as a principle are increafed, it
becomes mechanically diffufed among thofe bodies which
are neared to it; it gives the redundant heat to the
I4 band,” &c.
General re- We fltall conclude this article with one obvious re¬
mark. mark, vix. that the difpute concerning Mr Henry’s
method of inducing fermentation, may be eafily de¬
cided by a comparative trial. Let, for inftance, two
gallons of wort, the quantity he ufed in his experi¬
ment, be put into a certain veffel without addition,
and kept in a moderate heat for a certain time ; take
other two gallons, and impregnate the whole or any
part of it with fixed air, according to Mr Henry’s me¬
thod : put the whole then into a vefltl fimilar to the
other, /Kid fet it in the fame place ; and if the fermen¬
tation begins in the one impregnated with fixed air
fooner than the other, we have good reafen to believe
that the fixed air was the caufe of its doing fo. This
experiment is eafily made, and muft be of confiderable
importance to the public: for, as Mr Henry juftly
obferves, his experiments “ may be of extenfive uti¬
lity, and contribute to the accommodation, the plea-
fure, and the health, of men in various fkuatiorts, who
have hitherto been precluded in a great meafure from
the ufe of fermented liquors; and be the means of
furniftiing important articles of diet and of medicine.”
Even as matters Hand, we muft confider this end as
accomplifhed; though, -if the mere circumftance of
heat, without fixed air, would bring on fermentation,
it would undoubtedly render the procefs confiderably
eafier, by laving the trouble of impregnating the liquor
with fixed aii% With regard to bread, his method
feems to be entirely decifive..
8 ] f E n
The bufinefs of fermentation is one of the great pre- Ftrmenta-
patations to the diftillery. What we ufually call vi- tion-
nous fermentation in particular, is the kind in which » , y.
it is principally concerned. By this we ufually under-
ftand that phyfical action, of inteftiue commotion of
the parts of a vegetable juice, tincture, or foliition,
which render them fit to yield an inflammable fpirtt on
diftillation.
This fermentation in the hands of the di(filler differs
from the common one that is ufed in the making of
potable vinous liquors, as being much more violent,
tumultuary, active, and combinatory than that. A
large quantity of yeaft, or other ferment, is added to
the diftiller’s fermentation; the free air is admitted,
and every thing is contrived to quicken the operation,
fo that ft is fometimes fiuifhed in two or three days.
This great difpatch, however neceffary to the large
dealer, has its inconveniences attending it; for the
fpiri't is by this means always fouler, more grofs, and
really terreftrial, than it would have been if the liquor
had undergone a proper fermentation in a flower man¬
ner. It alfo fuffers a diminution in its quantity, from
the violent and tumultuary admiffion, conflict, and agi¬
tation of the free air, both in the body and upon the
furface of the liquor, efpecially if the liquor be not
immediately committed to the ftill as foon as the fer¬
mentation is fairly flacked or fully ended. It is a very
difficult talk to render the bufinefs of fermentation at
once perfect and advantageous. To ferment, in per¬
fection, nedeffarily requires length of time and care¬
ful attendance, and clofe veflels, befide feveral other
articles of nice management, which cannot be expect¬
ed to be received and praftifed in the large way, on
account of the trouble and expence, unltfs it could be
proved to the diftillers, as potfibly it fometime may,
that the quantity of fpirit would be fo ntuch greater
from the fame quantity of materials managed thus,
than by the common way, that it will more than pay
its own expence : to which may be added, the very
well known advantage of the fpirit thus procured by
perfeft fermentation, being much finer than that ob¬
tained in the common way. Till this fhaftbe made out,
it may not be amifs to try how much of the more per-
feCt art of vinous fermentation is profitably practicable
by the difttller in the prefent circumftances of things.
The improvements to be made in this affair will prin¬
cipally regard, 1. The preparation or previous difpo-
pofition of the fermentable liquor. 2. The additions
tending to the general or fome particular end. 3. The
admiffion or exclufion of the air. 4. The regulation
of the external heat or cold. And, 5. A fnitable de¬
gree of reft at laft. When proper regard is had to
thefe particulars, the liquor will have its due courfe of
fermentation, and it will thence become fit to yield a
pure and copious inflammable fpirit by diftillation.
The tin&ure, folution, or liquor, intended for fermen¬
tation, for the ftill, ftrould be confiderably thin and:
aqueous. Thatlfort of riehnefs there is in the twelve-
{hilling fmall beer, is the utmoft that ought to be al¬
lowed to it. This property not only fits it to ferment
readily, but alfo to yield a larger quantity in propor¬
tion of a pure vinous, fpirit, than it would do if it
were more rich or clammy : tire grofs, foul, vifeid,.
and earthy particles of fuch glutinous liquors, being
after fermentation apt to rife up with the boiling heat
which.