F E R
tion'd to that of the liquor, to its tenacity, and the de-
gree
of flavour it is intended to
rive, and to the difpatch re-
quired in the operation. From thefe confiderations lie will be able to form a rule to himfelf ; but till fuch a rule is formed, or, in order to the forming of it, proper trial will fiiew how much fuffices for the purpofe. The way is to begin with a little, and to add more occasionally, the weight of the whole being noted beforehand; fo that on weighing the remainder after the proper quantity is taken away, it will be found how much exactly has been ufed out of it for the bufinefs. Among the feveral ingredients of which fermentable liquors are made for the fervice of the diftillery, treacle requires more ferment than almoft any other. This is not wonderful on a juft confideration of the nature of the fubject, fince the manner in which that concrete juice is made, muft render it greatly unfit for fermentation afterwards, though the original product of a vegetable juice very much difpos'd to it in its own nature. The Strength of the fire ufed in the fugar-making, and its long continuance and almoft immediate contact, and the lime and other alkalies ufed in refining the fugar, that is, in making the treacle, do fo condenfe, indurate, and fcorch the body of this juice, and abforb its acid, that it is fcarce to be expected that it fhould ferment at all, even with the ad- dition of jalap, or other powerful faline and acid or acrid fti- mulators, which tend to break the viicous and aduft connecti- ons of the particles.
The greateft circumfpedtion and care are neceffary in regard to the quality of the ferment, if a pure and well flavoured fpirit be required. It muft be chofen perfectly fweet and freih, for 2W ferments are liable to grow mufty and corrupt ; and if in this ftate they are mixed with the fermentable li- quor, they will communicate their naufeous and filthy flavour to the fpirit, which will fcarce ever be got off by any fubfe- quent refining. If the ferment be fower, it muft by no means be ufed to any liquor, for it will communicate its flavour to the whole, and even prevent its rifing to a head, and give it an acetous, inftead of a vinous tendency. When the proper quantity of a fuitable and well conditional ferment is got ready, it muft be put to the fermentable liquor in a ftate barely tepid, or fcarce lukewarm. The beft manner of putting them to- gether, fo as to make the fermentation ftrong and quick, is this : When the ferment is folid, it muft be broke to pieces, and gently thinn'd with fome of the warm liquor : but a compleat or uniform folution of it is not to be expected or defired, as this would weaken its efficacy for the future bufinefs. The whole intended quantity being thus loofely mixed in fome of the lukewarm liquor, and kept near the fire, or elfe where, in a tepid ftate, free from too rude commerce of the external air, more of the infenfibly warm liquor ought at proper inter- vals to be brought in, till thus by degrees the whole quantity is fet at work together.
When the whole is thus fet at work, and fecured in a proper degree of warmth, and kept from a too free intercourfe with the external air, it becomes as it were the fole bufinefs of na- ture to finifh the operation, and render the liquor fit for the frill. In this eafy manner the whole end of fermentation would be anfwered. But during the whole courfe of the operation, there are feveral other things that may be added with fome par- ticular view, as either to increafe the quantity of fpirit, or give it fome agreeable flavour. Thefe additions may fome- times require fome alteration in the general method laid down above, though upon the whole it is right. Show's EfTay on Diftilling. See Additions.
Ferments in the Earth. It is very probable, that the natural ferments in the earth may be of more confequence than is ge- nerally fuppofed, and tend to elucidate many things, which at prefent appear very myfterious. The different fruitfulnefs of different fpots of the fame fort of land may be owing to this, as alfo the different temperature of the air at the fame time in places very little diftant from one another. The effluvia fent up by fome of thefe, not only diffolve fnow that falls on them, but even melt it in the air as it approaches, and caufe it to fall in rain, not in fnow. And often in two places with- in a mile or two of each other, there {hall be a difparity of heat and cold no way elfe to be accounted for, fince there is often no difference of fhade or Shelter.
In Scotland there are large tracts of land, where the ferment is fo ftrong, that the earth lets a perfon in up to the ankles as he walks ; and generally, at about a foot depth under- this, there is found a ftratum of pebbles, fo clofe ramm'd together, that they fecm an artificial caufeway. This land, though of no greater depth than a foot, is found very rich for gar- den plants, and even for fruit-trees, Phil. Tranf. N Q no.
FERMENTATION {Cyd.) is often confounded with Effer- vefcence, but a great difference is made between thefe by the chemifts.
Fermentation is that fpontaneous inteftine motion, which, in the degree of heat of the univerfal temperature of fubterraneous caverns, will, in a few hours, bring on fuch a change in ve- getable juices, or in water charged with a ftrong tincture of vegetable particles, (for fermentation is confined to the vegeta- ble kingdom folely) as from a vapid inuft or wort quenching
FER
fire, to make It become more or lefs inflammable. aS \i is jmpregiiated with more or fewer of the vegetable par- ticles, and m the alembic to afford that volatile, fubtill inflammable liquor commonly called vinous fpirit. The heat produced by fermentation never exceeds that of the hu- man body. Phil.Tranf. N a 4 7 b. p. 474. feq. See Effer- vescence.
The juices of plants are ftrangcly alter'd by fennentatieii, and are fufceptible of many, and thole very various changes from it. And it is not only the juices of fruits that are thus to be wrought upon, as thofe of apples, pears, grapes, and the like, in the common way ; but there is an artificial change to be made in the feeds of plants by what is called malting. And it is not grain alone that is thus to be wrought upon, but any other feed whatever may be made to yield its juices and virtues freely to water by this procefs. The juices of roots alfo, for inftance, that of liquorice, will be wrought upon in the fame manner ; and the juices of the bodies of trees, as of the birch; and the like. If in the month of March a hole be bored in- to the body of a birch- tree, and this hole be flopped with a cork, through the middle of which there is thruft a quill open at both ends, the juices of the tree will drop out at the quill at the rate of a large drop every fecond of a minute, and a great quantity will in fine be obtained in this manner. This liouor is not unpleafant to the tafte, and looks tolerably clear, refembling water into which a little milk had been fpilt. There are ma- ny ways of fermenting this juice, by all of which it is convert- ed into a fort of wine. Thefe are well known ; but there is another remarkable property in our maples, both the common fmall kind, and the great one which we call the fycamore : thefe being tapp'd in the fame manner, will bleed freely in winter ; and their juices, after a hard froft breaks, will flow out in fo copious a manner, as is fcarce to be conceived. The willow, the poplar, and the wallnur-tree will all bleed alfo; and fermentation, of which their feveral juices areeafily fufcep- tible, will turn them all into palatable and ftrong wines. Some of the proceffes in chemiftry feem to prove, that fer- mentation is not confined to animal and vegetable fubftances, but that minerals are alfo liable to fometbing of it. If an ounce of lead and an ounce of bifmuth be melted together in an iron ladle, and an ounce of quicklilver be heated in ano- ther ladle, and all three mixed together, this makes an amal- gamation, which appears perfectly homogeneous, and pafies through leather in a running form, without leaving any thing behind. But this mixture being fuffer'd to ftand quiet for fome hours, a grofs matter will feparate from it by degrees, and float upon the reft, which will now run eafily throueh leather, and leave the grofs matter behind, Here appear all the requifites of fermentation: I. A fluid form. 2. An uni- form matter. 3. An inteftine motion ; and, 4. An actual feparation of a grofTer matter leaving a thinner behind. Shah's Lectures, p. 139. FERMENTED Liquors. All fermentcil liquors abound with an over-proportion of water; and if a very confiderable quantity of it were taken away, they would become not only richer, but more durable, provided that fo much of the aqueous hu- midity was retained, as was juft fufficient to preferve the vi- nous confiftence, to keep the faline part fluid, and to retain the flimy and unctuous parts expanded and mixed among the reft. But as an actual and truly faline matter abounds in wine and in vinegar, and that of an acid, auftere, and tarra- rous kind; when the fpirituous part is drawn away, the wine becomes furprifingly more auftere ; and when a large quantity of the watery part is feparated, this fuperabundant faline, tar- tarous matter coagulates into a crvftalhne form, and either falls to the bottom, or fticks to the fides of the cask. For the fubtile, oily matter, which makes the fpirituous part in winej blunts and takes off from a tartarious acidity, in the fame man- ner that the addition of fpirit of wine blunts, fheathes, and dulcifies the acid, corrofive parts of fpirit of nitre in making the fpiritus nitri dulcis. But this tartarious fait abound- ing alfo with an over proportion of fo grofs and unctuous matter, cannot be diffolved or diluted without a very large proportion of water, which being taken away, it prefently converts into dry and folid cryftals, as is the known cafe of cream of tartar. Hence proceeds the effea before obferv- ed, that the aufterity and roughnefs of wine, are the more preferved, the more the wine is deprived of its fpirituous parts. This experiment is familiar in our kitchens where wine being burnt or boiled into fauce, is found to have a much greater degree of aufterity, than the fauce and wine had before it had undergone the action of the lire, and loft its fpirituous part. When the water is even by diftillation plentifully drawn off from wine, not of a rerreftrial and chalky, but of a tartareous nature, a beautiful tartar will be found to cryftalizc, among the remaining mafs, in a confiderable proportion. But the? this fuperfluous water, that generally dilutes the wine and weakens its tafte might be advantageoufly fparcd from it, and it would then become much more rich and noble, and at the fame time more fmooth and loft, through the fpfs of fume confiderable portion of its tartar ; yet this feparation cannot be effected by diftillation, becaufc that carries away other parts
