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The tincture, or, as the Distillers call it, the Wash, being prepared, as in the foregoing Chapter, it is next to be fermented; for, without this Operation, no vinous Spirit can be produced.

By Fermentation is meant that intestine Motion performed by the instrumental Efficacy of Water, whereby the Salt, Oil and Earth of a fermentable Subject, are separated, attenuated, transposed, and again collected, and recomposed in a particular Manner.

The Doctrine of Fermentation, is of the greatest Use, and should be well understood by every Distiller, as it is the very Basis of the Art; and, perhaps, if more attended to, a much purer Spirit, as well as a greater Quantity of it, might be procured from the same Materials than at present. We shall therefore lay down a concise Theory of Fermentation, before we proceed to deliver the Practice.

Every fermentable Subject is composed of Salt, Oil, and a subtile Earth; but these Particles are so small, that, when asunder, they are imperceptable to the Senses; and, therefore, when mixed with an aqueous Fluid, they leave it transparent; neither have fermentable Bodies any Taste, except that of Sweetness.

These Particles are each composed of Salt, Oil and Earth, intimately mixed in an actual Cohesion, Connexion, and Union; and, therefore, when any one of those Principles too much abounds in any Subject, so that an intimate Union is prevented, the whole Efficacy of the Fermentation is either stopped or impaired, or at least limited to one certain Species.

This equal Connexion of Salt, Oil and Earth into a single compound Particle, forms a Corpuscle soluble in Water; or, to speak more philosophically, this compound Corpuscle is, by means of its saline Particles, connected with the aqueous Corpuscles, and moved up and down with them. But where these Corpuscles are not thus connected with the Water, a Number of them join together, and form either a gross, or a loose, chaffy, and spungy Matter.

When these compound Particles are diluted with a small Quantity of an aqueous Fluid, they feel slippery, clammy, and unctuous to the Touch, and affect the Taste with a kind of ropy Sweetness. And when a proper Quantity of the Fluid is added, a Commotion is presently excited, and afterwards a subtile Separation.

This Commotion and Separation first begins in the whole Substance; for before the Addition of Water, the Subject may remain in dry, solid, and large Pieces, as in Malt, Sugar, &c. which being reduced to Powder, each Grain thereof is an Aggregate of many smaller compound Corpuscles; these being put into Water, dissolve, and separately float therein, till at length, they be come so small as to be invisible, and only thicken the Consistence of the Liquor.

These Corpuscles being thus separated from one another, there next ensues a Separation of their component Particles; that is, the Salt, the Oil, and the Earth, are divided by the Interposition of the aqueous Particles.

The first Commotion is no more than a bare Solution; for the saline Particles being easily dissolvable in Water, they are immediately laid hold of by the aqueous Particles, and carried about with them. But the succeeding Separation, or fermentative Motion, is a very different thing; for by this the saline Particles are divided from those of Oil and Earth, partly by the Impulse of the others in their Motion, and partly by the Force of the aqueous Particles, which are now continually meeting and dashing against them.

This Motion is performed by the Water, as a Fluid, or Aggregate of an infinite Number of Particles, in actual and perpetual Motion; their Smallness being proportionable to that of the fermenting Corpuscles, and their Motion, or constant Susceptibility of Motion, by Warmth, and the Motion of the Air, disposing them to move other subtile moveable Corpuscles also. The certain Agreement of Figure, or Size between the aqueous Particles, and those of the Salt in the fermentable Subject, tends greatly to increase this Commotion; for, by this means, they are readily and very closely connected together; and therefore move almost like one and the same compound Corpuscle; whilst the Water is not at all disposed to cohere immediately with either the Oil or Earth. And thus an unequal Concussion is excited in the compound Corpuscles of the fermentable Subject; which Concussion at length strikes out the saline Particle, loosens the others, and finally produces a Separation of the original Connexion of the Subject.

An aqueous Fluid, therefore, is the true, and indeed the only, Instrument for procuring a fermentable Motion in these compound Corpuscles of the Subject: For were an oily Fluid poured upon any fermentable Subject, no vinous Fermentation would ensue; as the Oil could neither give a sufficient Impulse on the compound Corpuscles, which are grosser than its own constituent Particles, nor divide the oily or saline Particles of the Subject from their Connexion with the others, which detain, and, as it were, envelope, or defend them from its Action.

The compound Corpuscles of the fermentable Subject being affected by the perpetual Motion of the Particles of the aqueous Fluid, a proper Degree of Motion is necessary, or that the Particles move with a proper Degree of Velocity, which principally depends on external Heat. A considerable Degree of Cold, indeed, will not absolutely prevent Fermentation, though it will greatly retard it; and a boiling Heat will prevent it still more. A tepid, or middle Degree of Heat between Freezing or Boiling, is therefore the most proper for promoting and quickening the Operation.

The Admission of Air, also, though not of absolute Necessity, yet greatly promotes and quickens the Action, as being a capital Instrument in putting in a proper Degree of Motion the oily Particles of the Subject. But whilst the Air thus contributes to hasten the Effect, it causes at the same time by its Activity some remarkable Alterations in the oily Particles; for it not only moves, but absolutely dissolves and displaces them from their original Connexions; and thus carries them off with itself from the whole Mass. And, therefore, though the Consideration of the Air does not so properly belong to Fermentation in the general, yet it does in particular; as having an accidental Power to alter every Species of this Operation: Consequently its Agency ought to be well understood, either to procure Alterations at pleasure in the fermenting Mass, or to prevent and correct impending Dangers.

The oily Particles thus separated and dissolved by the Air, are also elastic, though they probably derive that Property from their Intercourse with the Air itself, and their being rendered extremely minute.

When, therefore, an aqueous Fluid is added to a fermentable Subject exposed to a temperate Heat, a fermentative Struggle immediately arises, the saline Part of the compound Particles being dissolved by the continual intestine Motion of the Water, and carried up and down with it in all Directions, amidst an infinite Number of other Particles, as well fermentable, as aqueous ones; whence, by this Collision and Attrition, the saline Particles are dissolved, and separated from their Connexion with the oily and earthy. And as the oily Particles are the most subtle and elastic, they would, by this means, be thrown up to the Surface of the Liquor, and carried off by the Air, were they not closely connected with the earthy ones, whose Gravity prevents their Evaporation, and, by coming in contact with others of the same kind, form Aggregations, and sink down, with the oily Particles, to the Bottom. But before these can form a Bulk too large to be supported by the Water, many of the oily Particles are, by their frequent Collisions with the aqueous Fluid, separated from the earthy ones; and, by Degrees, more strongly connected again with the saline ones; whilst, on the other hand, the same saline Particles imbibe some of the earthy ones, which being left single, upon their Separation from the oily Particles, floated about separately in the Fluid.

And hence proceed the several different Consequences of Fermentation; viz. 1. From the Separation of the saline Particles of the fermentable Subject proceeds the tart, saline, or acid Taste of the Liquor; which is more sensible at first, before the Liquor is duly composed and settled, or the due Arrangement and Connection of the saline Particles with those of the oily and earthy Kinds, completed: After which the Liquor proves milder, softer, or less pungent. 2. From the oily Particles being set at liberty, proceeds the strong Smell of the Liquor, and the Head or shining Skin upon the Surface. 3. The earthy Particles collecting together in Clusters, cause the Fluid to appear turbid, and afterwards a visible earthy, or clay-like Matter to be precipitated: And some of the earthy Parts, in their Motion, arriving at the Head, or oily Skin on the Surface, cause it to thicken; and afterwards taking it down along with it, thus constitute the Lees which abound in Oil. 4. From this new Struggle or Collision, which is productive both of Solution, and a new Connection in the saline and earthy Corpuscles, proceeds the Ebullition in Fermentation. And, lastly, by the same repeated Coalition of the oily with the aqueous and saline Particles, the inflammable Spirit is produced.

Having thus laid down a concise Theory of Fermentation, we shall now proceed to the Practice.

The Wash being brought to a tepid, or lukewarm State in the Backs, a proper Quantity of a good-conditioned Ferment is added; but if the Ferment be solid, it should be previously broke into small Pieces, and gently thinned either with the Hand, Whisp, &c. in a little of the tepid Liquor. A complete and uniform Solution, however, should not be attempted, because that would greatly weaken the Power of the Ferment, or destroy its future Efficacy. The whole intended Quantity, therefore, being thus loosely mixed with a moderate Parcel of the Liquor, and kept in a tepid State, either by setting it near the Fire, or otherwise, and free from the too rude Commerce of the external Air; more of the insensibly warm Liquor ought to be added, at proper Intervals, till, at length, the whole Quantity is properly set to working together. And, thus, by dividing the Business into Parts, it may much more speedily and effectually be performed, than by attempting it all at once.

The whole Quantity of Liquor being thus set to work, secured in a proper Degree of Warmth, and defended from a too free Intercourse of the external Air, Nature itself, as it were, finishes the Process, and renders the Liquor fit for the Still.

By Ferments, we mean any Substance, which, being added to any rightly disposed fermentable Liquor, will cause it to ferment much sooner and faster than it would of itself; and, consequently, render the Operation shorter; in contradiction to those abusively called so, which only correct some Fault in the Liquor, or give it some Flavour. Hence we see, that the principal Use of Ferments is to save Time, and make Dispatch in Business; whilst they only occasionally, and, as it were, by Accident, give a Flavour, and increase the Quantity of Spirit. And, accordingly, any fermentable Liquor, may, without the Addition of any Ferment, by a proper Management of Heat alone, be brought to ferment, and even more perfectly, though much slower, than with their Assistance.

These Ferments are, in general, the Flowers and Fæces of all fermentable Liquors, generated and thrown to the Surface, or deposited at the Bottom, either during the Act of Fermentation, or after the Operation is finished.

Two of these are procurable in large Quantities, and at a small Expence; we mean, Beer-Yeast and Wine-Lees; a prudent and artificial Management, or Use of which, might render the Business of Distillation much more facile, certain and advantageous.

It has been esteemed very difficult, and a great Discouragement, in the Business of Distillation, to procure a sufficient Stock of these Materials, and preserve them at all times ready for use. The whole Secret consists in dexterously freeing the Matter from its superfluous Moisture; because in its fluid State, it is subject to a farther Fermentation, which is productive of Corruption; in which State it becomes intolerably fœtid and cadaverous.

The Method of exposing it to the Air till it has required a proper Consistence, is subject to great Inconveniencies; and so peculiar and careful a Management necessary, that it rarely succeeds.

The best Way, therefore, is to press it very slowly and gradually, in a thick, close, and strong Canvas Bag, after the manner of Wine Lees, by the Tail-press, till it becomes a kind of Cake; which, though soft, will easily snap, or break dry and brittle between the Fingers. Being reduced to that Consistence, and closely packed up in a tight Cask, it will remain a long Time uncorrupted, preserve its Fragrancy, and consequently, fit to be used for fermenting the finest Liquor.

The same Method is also practicable, and to the same Advantage, in the Flowers or Yeast of Wine; which may be thus commodiously imported from abroad: Or, if these cannot be procured, others of equal Efficacy may be procured from fresh Wine Lees, by barely mixing and stirring them into a proper warm Liquor; whence the lighter, or more volatile and active Parts of the Lees, will be thrown to the Surface, and may easily be taken off, and preserved, by the above-mentioned Method, in any desired Quantity. And hence, by a very easy Process, an inexhaustible Supply of the most useful Ferments may be readily and successively procured, so as to prevent for the future all Occasion of Complaint for want of them, in the Distiller’s Business.

Experience has demonstrated, that all Ferments abound much more in essential Oil, than the Liquor which produced them; and consequently they retain, in a very high Degree, the Smell and Flavour of the Subject. It is therefore requisite, before the Ferment is applied, to consider what Flavour is intended to be introduced, or what Species of Ferment is most proper for the Liquor.

The Alteration thus caused by Ferments is so considerable, as to render any neutral fermentable Liquor, of the same Flavour with that which yielded the Ferment. This Observation is of much greater Moment than will presently be conceived; for a new Scene is hereby opened, both in the Business of Distillation, and others depending upon Fermentation. It must, however, be observed, that its Benefit does not extend to Malt, treated in the common Method; nor to any other Subject but what affords a Spirit tolerably pure and tasteless: For, otherwise, instead of producing a simple, pure, and uniform Flavour, it causes a compound, mixed, and unnatural one. How far the fine Stiller may profit by it, well deserves his Attention; and whether our native Cyder Spirit, Crab Spirit, &c. which have very little Flavour of their own, may not, by this Artifice, be brought nearly, if not intirely, into the State of some foreign Brandies, so highly esteemed, is recommended to Experience.

It is common with Distillers, in order to increase the Quantity of Spirit, give it a particular Flavour, or improve its Vinosity, to add several things to the Liquor, during the Time it is in a State of Fermentation; and these Additions may properly be reduced to Salts, Acids, Aromatics, and Oils.

All rich vegetable Juices, as Treacle, Honey, &c. which either want a natural Acid, have been deprived of it, or contain it in too small a Quantity, will be greatly improved by adding, at the Beginning of the Operation, a small Quantity of the vegetable or fine mineral Acids; as Oil of Sulphur, Glauber’s Spirit of Salt, Juice of Lemons, or an aqueous Solution of Tartar. These Additions will either give, or greatly improve the vinous Acidity of the Subject, but not increase the Quantity of the Spirit, that Intention being performed by Aromatics and Oils.

All pungent Aromatics have a surprising Quality of increasing the Quantity of the Spirit, as well as in altering, or improving the Flavour; but their Use requires that the Fermentation should be performed in close Vessels. And if a large Quantity be intended to be added, Care must be taken not to do it all at once, lest the Oiliness of the Ingredients should check the Operation. But if the Flavour be the principal Intention, they should not be added till the Operation is nearly finished. After the same Manner a very considerable Quantity of any essential vegetable Oil may be converted into a surprisingly large Quantity of inflammable Spirit; but great Caution is here also necessary not to drop it too fast, or add too large a Quantity at a time, which would damp the Fermentation; it being the surest Method of checking, or totally stopping this Operation, at any Point of Time required. The best Method, therefore, of adding the Oil, so as to avoid all Inconveniencies, is to rub the Oil in a Mortar with Sugar, which the Chemists call making an Olæosaccharum, by which Means the Tenacity of the Oil will be destroyed, and the whole readily mix with the Liquor, and immediately ferment with it. The Distiller would do well to consider these Observations attentively, as he may thence form an advantageous Method of increasing the Quantity of Spirits, and at the same Time greatly improve their Quality and Flavour.

But in order to put these Observations in practice, particular Regard must be had to the containing Vessel in which the Fermentation is performed, the Exclusion of the Air, and the Degree of the external Heat or Cold.

With regard to the containing Vessel; its Purity, and the Provision for rendering it occasionally close, are chiefly to be considered. In cleansing it, no Soap, or other unctuous Body should be used, for fear of checking the Fermentation; and, for the same Reason, all strong alkaline Lixiviums should be avoided. Lime-water, or a turbid Solution of quick Lime may be employed for this Purpose, without producing any ill Effect; it will also be of great Service in destroying a prevailing acetous Salt, which is apt to generate in the Vessels when the warm Air has free Access to them; and tends to pervert the Order of Fermentation, and, instead of a Wine or Wash, produce a Vinegar. Special Care must also be had, that no Remains of Yeast, or cadaverous Remains of former fermented Matters, hang about the Vessels, which would infect whatever should be afterwards put into them; and cannot, without the utmost Difficulty, be perfectly cured and sweetened.

The occasional Closeness of the Vessels may in the large way, be provided for by Covers properly adapted; and, in the small way, by Valves, placed in light Casks. These Valves will occasionally give the necessary Vent to preserve the Vessel, during the Height of the Fermentation; the Vessel otherwise remaining perfectly close, and impervious to the Air.

It is a Mistake of a very prejudicial Nature, in the Business of Fermentation, to suppose, that there is an absolute Necessity for a free Admission of the external Air. The express contrary is the Truth, and very great Advantages will be found by practising according to this Supposition. A constant Influx of the external Air, if it does not carry off some Part of the Spirit already generated, yet certainly catches up and dissipates the fine, subtile, or oleaginous and saline Particles, whereof the Spirit is made, and thus considerably lessens the Quantity. By a close Fermentation this Inconveniency is avoided; all Air, except that included in the Vessel, being excluded. The whole Secret consists in leaving a moderate Space for the Air at the Top of the Vessel, unpossessed by the Liquor. When the Liquor is once fairly at work to bung it down close, and thus suffer it to finish the Fermentation, without opening or giving it any more Vent than that afforded it by a proper Valve placed in the Cask; which, however is not of absolute Necessity, when the empty Space, or rather that possessed by the Air, is about one tenth of the Gage; the artificial Air, generated in the Operation being then seldom sufficient to open a strong Valve, or at most not to endanger the Cask.

This Method may be practised to good Advantage by those whose Business is not very large; but it requires too much Time to be used by the large Dealers, who are in a manner forced to admit the free Air, and thus sustain a considerable Loss in their Quantity of Spirit, that the Fermentation may be finished in the small Time allowed for that Purpose. It may, however, be said, that the silent, slow, and almost imperceptible vinous Fermentation, is universally the most perfect and advantageous.

During the whole Course of this Operation, the Vessel should be kept from all external Cold, or considerable Heat, in an equal, uniform, and moderate Temperature. In the Winter, a Stove-Room, such as is com mon in Germany, would be very convenient for this Purpose; the Vessel being placed at a proper Distance from the Stove: But at other Seasons no particular Apparatus is necessary with us in England, if the Place allotted for the Business be but well defended from the Summer’s Heat, and the ill Effects of cold bleak northern Winds.

The Operation is known to be perfected when the hissing, or small bubbling Noise can be no longer heard, upon applying the Ear to the Vessel; and also by the Liquor itself appearing clear to Eye, and having a pungent Sharpness on the Tongue. And that it may fully obtain these Properties, and be well fitted to yield a pure and perfectly vinous Spirit by Distillation, it should be suffered to stand at rest in a somewhat cooler Place, if practicable, than that in which it was fermented; till it has thoroughly deposited and cleansed itself of the gross Lee, and become perfectly transparent, vinous and fragrant; in which State it should be committed to the Still, and the Spirit obtained will not only exceed that obtained in the common Way in Quantity, but also in Fragrance, Pungency, and Vinosity.