Chapter 5

To any one well acquainted with the nature of fermentation, it must be manifest, that the malt distillers have paid more attention, and made greater progress in the improvement of the process than any other class of men interested in the success, though far from having arrived at their _ne plus ultra_.

The introduction of raw or unmalted corn; the close compactness of their working tun, or fermenting backs; the order and progressive succession with which they conduct the process; and the pains they necessarily take to arrive at a perfect attenuation, by a long protracted fermentation, with the early conviction of a reward proportioned to their diligence, and the success attending their best endeavours, when not frustrated by intervening causes, must be stronger inducements with them to delight in this instructive process of nature's formation, than with the brewer, who has not these immediate tests to encourage his labours, which the others daily derive from distillation, and which so quickly and uniformly terminates their hazards and success. The principal object in their view being a high and deliberate attenuation, with a full vinosity, without any further regard to the quality or flavour of their mash, as the combination of these qualities alone produces the required strength, in the cleanest manner.

The brewer's cares are many, and of longer duration: he is the vintager of our northern climates: his porter or ale should be an agreeable malt wine, suited to the palate of the district or neighbourhood he lives in, or, ultimately, to the taste of his customers. The time he has allotted himself for attenuation was first founded in error, derived from ignorance of the subject, and slavishly continued by that invincible tyrant, custom. Hurry marks the progress of his fermentation, which can only be corrected by his speedy mode of _cleansing_, and the consequent but necessary perishing of a part. He must begin with more accuracy at the mash tun than the malt distiller, as it is there he must not only regulate the strength, but, partially, the flavour and transparency of his malt wine. His object does not end with the malt distiller's, nor, like his, concentre in one focal point, the solution of the whole of the farina of the plant or grain employed, regardless of milkiness or transparency; he must carefully take the heats of his liquor, so as to solve and combine the qualities he has in view; which, if he misses in the first mash, is partly irremediable in the succeeding ones. His cares do not end here; independent of the minutiæ of fermentation and cleansing, he has the flavour, fining, and bringing forward of his _malt wines_, nearly as much as the strength, to consider and employ his attention.

It will scarcely be supposed that I would make these observations merely with a view of drawing this comparison, though even it might throw some light on the subject, without an attempt at supplying the defects pointed out, and remedying the evils represented.

When the carbonic acid gas, or fixed air, so often mentioned in these papers may be rendered subservient to part of the improvements I have in view, and which is the constant, abundant, and uniform result of low combustion, or vinous fermentation, in proportion of thirty-five pounds weight to every hundred of saccharine or fermentable matter, fermented in a due proportion of liquor, or water; from the decomposition of which last, and the absorption of its oxygen, it is principally obtained.

We have previously seen that one hundred pounds of fermentable matter consists of eight pounds of hydrogen, twenty-eight of carbon, and sixty-four pounds of oxygen; we have also seen that about thirty-five pounds of carbon is extricated and detached from this quantity of fermentable matter, properly diluted in water during fermentation; allowing the usual quantity of spirit at the same time to be formed by the process of this superfluous carbon, (as it now appears) must come principally from that decomposition of the water of dilution, and not from saccharine matter employed, which contains altogether but twenty-eight pounds of carbon, the whole of which must necessarily go to the formation of the fifty-seven pounds of dry alcohol produced.

But not to descend too deeply into particulars that might lead into discussions not absolutely necessary in this place, let us take the produce of ten gallons of ardent spirit, at one to ten over proof. We here find that much more carbon has been generated, and given to the atmosphere, than went to the composition of this quantity of spirit, independent of the large quantity of alcohol dissolved in, and carried off by it, in its flight as before observed.

Allowing the average quantity of fermentable matter in a quarter of malt, barley, or other grain, to be only seventy-five pounds, then four quarters will be equal to three hundred subtile pounds of raw sugar; or eighty quarters of the one will be equal to six thousand pounds of the other, or three tuns weight of unadulterated molasses.

If we estimate the superfluous carbonic acid gas of this quantity of materials at only twenty-eight pounds per hundred, that will be sixteen hundred and eighty pounds dissipated during the fermentation, which is a loss, on every brewing of this quantity of materials, of upwards of forty-one gallons of spirit, of the strength of one to ten.

What is computed here in spirit, may easily be applied to wine, porter, beer, ale, sweets, &c. In barrels allowing three gallons and three quarts of spirit per barrel to the former, and four gallons per barrel to the latter, which gives eleven barrels and three quarters of the one, and ten barrels and a quarter of the other, lost on each brewing of eighty quarters of malt, or the average of that quantity of other materials, by the mismanagement of the fermentation in one point only.

It must appear evident to every person capable of investigating this calculation, that every six or seven pounds of carbon, fixed upon each quarter of malt, or other materials, there will be an augmentation of gravity or strength on this number of quarters, of ten or twelve barrels each brewing; that is, every six or seven pounds of this fugitive carbon that we arrest and fix in the fermenting fluid, as a component part of the subsequent produce, by presenting the requisite portion of oxygen and hydrogen, for the purpose within the sphere of each others attraction, we increase our strength in the before-mentioned _ratio_. It is of little moment whether this redundant gas comes from the water of dilution or from the fermentable matter, as under, if we can by any means turn it to account.

We have presumed the average quantity of fermentable matter at seventy-five pounds per quarter; this must be evidently on the best goods; this will give us a length of three barrels per quarter of malt of eight bushels, of twenty-five pounds per barrel, specific gravity. Suppose the apparent attenuation of these goods to be nineteen pounds, the transparent gravity will be six pounds per barrel, viz.

Gravity of the worts in the cooler just before letting down into the guile-tun, per barrel, 25 lb. Apparent attenuation per barrel, 19 lb. Transparent gravity per barrel, 6 --- 25 lb.

Or take it as it really is, viz. specific gravity per barrel, 25 lb. Real attenuation per barrel, 13 lb. 8 oz. Yest and lees, 5 8 -------- 19 lb. Gravity per barrel, when transparent, 6 --- 25 lb.

It may be said that nineteen pounds is the real attenuation, and the yest and lees produced is part thereof, as the fluid, or beer, in a state of transparency is but six pounds per barrel specific gravity, and it may, in some degree, be allowed to be so, as there is really so much gravity lost during the process of fermentation. If we multiply thirteen pounds eight ounces, which I have called the real attenuation, by four, we shall find the result to be fifty-four pounds, which is nineteen pounds more of superfluous gas upon four barrels of worts, of twenty-five pounds gravity each, than is extricated from an equivalent quantity of saccharine matter; that is, from one hundred pounds of raw sugar or one hundred and twelve pounds of molasses, and their respective waters of dilution, when the yest and lees do not exceed five pounds eight ounces per barrel. This may be truly called an analysis of the fermentable matter, giving the component parts tolerably exact; though much depends on the management of the fermentation, and the subsequent cleansing. By this analysis it appears, that the mucilage of malt, or grain, gives out more gas than the mucilage of sugar; and leaves a doubt on the mind whether to adjudge the superfluous gas to the fermentable matter, or to the water of dilution, or partly to both; but so it is, that these are the products, whatever source we derive them from, and there is no denying facts. The yest first added is not brought into this account.

There is a great similarity of appearance between the two species of low combustion, fermentation and respiration. Fermentation, like respiration, is the spontaneous effort of involuntary motion to decomposition; and in the fermenting mass, as in the animal system, it raises the temperature of both above that of the surrounding atmosphere: that is, it is the cause of heat and involuntary motion, both in the fermenting mass and in the animal system; and, like slow combustion, consumes both, and resolves them into their first principles, from which tendency the latter is constantly withheld by the ingesta, fuel, or food, thrown in. I am well aware I must not carry this reasoning any further.

Deep investigation may be thought not to be the object of our research; but we must always have two things in view in inquiries of this nature; indeed, in every pursuit of useful knowledge, where, like the present, it is connected with the first principles, to pursue the winding path of nature, through all her meanderings, up to the ultimate source of these elements, which are the instruments of her operations; and when we are favoured with a knowledge of these, either as the reward of laboured assiduity and attention, or the result of chance, to copy the original as close as we can.

I know I shall be justly accused with tautology. I must plead guilty to the charge, not having leisure to apply the pruning hook of correction. The misfortune is, that new doctrines must appear in a new dress, by which they wear the garb of novelty, though, with respect to first principles, there is nothing new under the sun; yet the application of these principles might have remained in oblivion for ever if not called into action. The man who in an age calls them into action, and beneficially applies them for the good of that community of which he is a member, may be virtually, though not literally, called the discoverer of a principle. The man that projects, and the man that executes a voyage of discovery, have superior claims to the man at the mast head who first cries out land. The new turn that the discoveries of modern philosophers has given to natural philosophy, requiring a change of names as well as system; unusual words are unavoidably introduced to express new terms of science, which gives a different character and fashion to the whole, that I should have great pleasure in avoiding, were it possible, which it obviously is not, finding it easier to glide down the stream than oppose its torrent.

Notwithstanding that I have calculated upon nineteen pounds only of twenty-five pounds per barrel of fermentable matter being attenuated, and have even in that quantity included five pounds eight ounces of lees and yest, (the least quantity produced,) such calculation must not be admitted to preclude the practicability of attenuating almost every particle of fermentable matter, and replacing it with an equivalent particle of spirit, if that spirit which is now carried off by the avolation of the fixed air, is, agreeably to my proposal, either arrested in its flight, or filtered, after its escape from the guile tun and cleansing vat, by the proper apparatus.

Having in a former part of these papers observed, that attenuation may be carried too far, it may be necessary for me to reconcile these seemingly opposite positions, which should be understood in this way: When the quantity of fermentable matter, suspended in a barrel of worts, intended for beer, or ale, is from five to ten pounds more than twenty-five pounds per barrel, every particle of it may be safely attenuated, as the quantity of spirit generated will be sufficient to preserve the beer, or ale, for any requisite length of time, provided it has been properly hopped, &c., or in lieu thereof, received certain other additions to improve its vinosity, strength, and keeping; when the quantity of fermentable matter in worts is from five to fifteen pounds per barrel less than twenty-five pounds, the height of the attenuation ought to be limited on keeping beer and ale; the spirit generated being insufficient to preserve so much fermented fluid in a drinkable state for any length of time, with the usual additions only, even during the summer heats of our own climate; and if so, it is totally unfit for either exportation to warm latitudes, or for keeping at home.

For the right understanding of these observations, we should consider that the unattenuated fermentable matter is perpetually furnishing a gradual supply of fixed air and spirit, by means of the imperceptible fermentation always going on in vinous liquors.

Weak beers and ales fret and spoil very soon in warm weather, which proceeds from the development and avolation of their fixed air; strong beers and ales have their limits under the same influence of heat, time, change of the atmosphere, &c., and owe their preservation to two things, viz. to a due proportion of fermentable matter unattenuated, or the quantity of spirit they contain; as under these circumstances they are either preserved by the spirit already formed, or that continually supplied by the spontaneous decomposition of the fermentable matter they contain, slowly developing and yielding a fresh supply of air and spirit; hence beer and ales, not too highly attenuated, derive strength and spirituosity from age, when properly stored or cellared, and duly secured from the changes of the atmosphere.

These observations are applicable to sweets, or made wines, and to those which are the produce of the grape, the progress of fermentation and attenuation being (or ought to be) interrupted in them by racking off, which is similar to cleansing in beers and ales: and in Madeiras, and other dry wines, the incipient acidity is corrected and restrained, by proper additions introduced in the early part of the process, and with others of similar effect when the wines are making up, either for use or exportation.

We may gather from these observations, that worts attenuated for beer or ale, to the decomposition of all their fermentable matter, that is, attenuated so high, or so low, that their specific gravity is reduced to the standard of common water, and from that to the degree of levity spirit is known to give to water, in the proportion to the quantity added, and left to the preservation of the spirit formed, they have little or no auxiliary assistance from their original products, already exhausted by the highest or completest attenuation obtainable; an important circumstance, always to be attended to, particularly by those who affect an unnecessarily high attenuation!

The intelligent brewer may, by the assistance of these observations, form a most accurate rule for the regulation of his future conduct in the management of fermentation, according as his beer or ale is to be weak or strong, or for present use or long keeping; for the accomplishment of which, the use of the hydrometer and thermometer claim his peculiar attention, and will undoubtedly answer his expectations, when joined to the certainty he is now at, of knowing when he is, or is not, to expect the development of fixed air and additional spirit, by which he can govern himself accordingly.

These observations lead to a removal of the difficulties that lay in the way, and, at the same time, suggest a mode of applying the present, or of constructing a future _hydrometer_, for ascertaining the strength or the quantity of the vinous spirit in beer, wine, ale, and other fermented fluids, which has long been a desirable object.

The distiller, having none of these niceties to attend to, is governed by the ultimate extent of the attenuation the worts, or wash, is found capable of, and which is both assisted and protracted by its superior density, in its progress from specific gravity to specific levity, if such an expression is admissible.

Fermentation, begun in a fluid more or less saturated with saccharine or fermentable matter, the process is finished sooner or later, and usually in proportion to the degree of saturation, and the being conducted with more or less vigour under a well regulated temperature; for the more a fluid abounds with this matter, the grosser and denser it must necessarily be, and the longer will the attenuation be protracted; the longer it is protracted, in air-tight vessels, and in a healthy and vigourous state of decomposition, the more spiritous and strong will that wash turn out, and the greater the produce of spirit in distillation; hence, it is both protracted and assisted by its density.

A languid may be truly called an unhealthy decomposition, it being productive of diseases common to misconducted fermentation, acidity, putridity, and lack of spirits, with a tendency to precipitate and burn upon the bottom of the still; hence, all the decompositions are confounded together, as in spontaneous fermentation.

The formation of acidity during the process, is not of that injury to the distiller that it is to the brewer, nor is this recent acidity vinegar, as has been supposed by some chemists, but the incipient state of combination of resolving elements, whose particles are in that juxtaposition best suited to absorb developing hydrogen in a nascent state, and intimately to combine with it into vinous spirit, the approximation to which is promoted by time and incumbent pressure: these positions shall be explained as I proceed.

The reason that putridity is so rarely discovered in excited fermentation, is, that it is usually counteracted by the previously evolved acidity, and corrected, but not saturated or neutralized; for, were that the case, the putrid could not immediately succeed the acetous process in the same fluid, nor exist together, as they are known to do in declining beer, vinegar, &c.

The reason that acidity is not more frequently observed and attended to than it is, is because of its being sheathed or covered by the unattenuated sweets, or fermentable matter of the wash that remains undecomposed.

On the other hand, when acidity is very prevalent, it may be mistaken for unattenuated fermentable matter, acidity increasing the density and specific gravity of the fluid.

Putridity, from the avolation of its products, promotes levity, and that in proportion as its increase surpasses that of the general acid; and it is not until the action of the acetous becomes languid, that the putrid process gains the ascendency, when it is then difficult to overcome.

Although these observations may show how the hydrometer, or its use, in unexperienced hands may be baffled, they both distinguish and explain the value of its application; they do more--they elucidate the doctrine of fermentation, and illustrate the goodness of Providence, who has made nothing in vain, but provided nature with its own resources for conducting every operation in the great plan of the universe with uniform and unerring security.

In the decomposition of fermentable matter, either by combustion or fermentation, (which I have defined to be synonimous,) a portion of inflammable air, or hydrogen, is first evolved; secondly, another portion of inflammable air, united with pure air, or oxygen gas, evolves under the form of fixed air; this is the constant and uniform phenomena of these decompositions, and are progressively going on from the beginning to the end of the fermentation, while there is any fermentable matter to attenuate. A due portion of oxygen uniting in a nascent state with a correspondent portion of inflammable or hydrogen, and fixed air, forms the spiritous particles dispersed through the fermenting fluid, which create vinosity, and constitute it wine, beer, or wash.

During which, so great is the avolation of fixed air, (as we have seen,) that much of the ethereal part of the new formed, or, rather, the scarcely-formed spirit, is carried off with it in a gaseous state. This is much assisted by the agency of the atmosphere, which is the solvent and receptacle of ethereal products, whose affinity for them must be as great as it is perfect and immediate--which demonstrates the necessity of having air-tight vats. When we consider the composition of the atmosphere, and that it owes its formation and existence to this cause, and, thereby becomes the menstruum of all created matter, we may be better able to understand the composition and formation of vinous spirits, and, by closely copying the original, more successfully imitate nature. We have seen that the principal phenomena in fermenting fluids is a brisk intestine motion of their parts, excited in all directions with a loss of transparency, or a muddiness, a hissing noise, the generating of gentle heat, and an exhalation of gas. This heat, we must now observe, is always very sensible before the extrication of any gas. We have adverted to the similarity existing between respiration and fermentation, which is remarkably so in the equality of heat produced in both in a healthy state of either, and which seldom exceeds ninety-six degrees of Fahrenheit's thermometer; but there are instances of their being much higher in both, without producing much injury to either. Instances of this could be adduced at home, without referring to warmer climates of the East and West Indies, where the temperature of the atmosphere is so much higher than with us; and that the temperature of the fermenting fluid, when at its height, always exceeds that of the surrounding atmosphere in these latitudes, which makes the similarity still stronger between these two decomposing processes. This is a general and just remark; but, in order to regulate it by practical facts, we must name the medium standard of heat, which rarely exceeds eighty-five degrees with the brewers; this is the medium of seventy-four and ninety-six degrees; but the medium heat is not unfrequently up to ninety-six degrees in the distiller's fermenting backs of Great Britain. Much depends on the degree of temperature the fermentation is pitched at: here, nothing is spoken of but the cleansing heat with the brewers, and the medium heat with the distillers.

For the maintenance of combustion, the free access of air being necessary, an objection may be raised to air-tight vats, as unfit to carry on this process in, to the exclusion of external air; which objection may seem to gather force from the compression it occasions of the fixed air on the decomposing fluid, which is allowed to extinguish active combustion. I must acknowledge these are formidable objections to my definition of low combustion, but I by no means find them unanswerable.