The American Practical Brewer and Tanner

by Joseph Coppinger

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.

The aptitude of new hay, malt, and other vegetable matters, to spontaneous combustion, when impacted together by incumbent pressure, and a certain degree of moisture, should be recollected; and that this tendency is not destroyed by excluding the admission of external air, but by quickly cooling and dividing the impacted hay.

The great quantity of oxygen, or vital air, both in the water of dilution, and in the fermentable matter, with which the fluid is more or less saturated, should be also recollected, which is about eighty-five parts in the former, and sixty-four parts of one hundred in the latter.

Though, in an unelastic or fixed state, it is one of the properties of combustion to disengage and render it elastic, great part of which, during the low combustion which it supports, and in which heat is visible or perceptible, and light in an invisible state developed, three parts of this oxygen, with about one third of its weight of carbon, is converted into an elastic state, under the form of fixed air, that separates from the decomposing mass; a circumstance attending also on the combustion of coal and other combustible substances during their decomposition by that process, which supported in them by the external air of the atmosphere, where heat and light are both visible from the intensity and velocity of the combustion; and wholly invisible in the former, not from exclusion of external air, but from the length of time elapsed in low combustion; the one being performed instantaneously, and the other taking several days from its decomposition. Although fixed air is known to extinguish a lighted candle, and destroy animal life, that is, to be equally unfit for the combustion of inflammable bodies, or the support of animal respiration, it is also known to be as successfully employed as atmospheric air, or even dephlogisticated air, to melt glass, &c., when applied to the clear flame of a wax candle, by passing a current of it through a blow-pipe, to direct that flame on the glass to be melted.[4] ]

This will not be so much to be wondered at, when we consider that the proportion of vital air in fixed air is as twenty-seven to nine, and in atmospheric air, the proportion of azotic gas or phlogisticated air, to vital air, is as seventy-three to twenty-seven; therefore, the former contains three fourths of vital air, and the latter little better than one fourth; but the fixed air is in a combined, and the phlogisticated air in an uncombined state. Among the processes made use of by nature for the decomposition of vegetable and animal substances, fermentation, or low combustion, is a principle one. Air, in a fixed or unelastic state, may be as necessary here as air in an elastic state is known to be in the active combustion of inflammable bodies. Chemists and philosophers are no strangers to two sorts of combustion, one in external air, and the other in close vessels.

But this is not the combustion alluded to in fermentation, where all the requisites for complete decomposition is to be found independent of contact with the atmosphere; here one part is oxygenated at the expense of the other, and the other disoxygenated in favour of it.

Nor does the solution, or decomposition of metals by acids, the combustion of inflammable and vital air for the production of water, stand in need of external heat or fire, any more than the low combustion in which fermentation consists for the production of spirit, beer, or wine, than that generated by the self-operation of its own temperature; similar to this is the self-animating principle or power with which nature has endowed the animal body of generating its own heat by respiration.

In fermentation, the caloric, or matter of heat, which is plentifully disengaged by the condensation of oxygen, is prevented from breaking out into flame with the condensing hydrogen, from the presence of affinities in the fermenting mass, ready to absorb and fix them into vinous spirit, ale, beer, &c., with the other component element, carbon; by which they are too instantaneously taken up and fixed, to amount to more than bare ebullition, and pass at once from an incipient state of elasticity, to a fixed and non-elastic one, while the redundant heat, which would otherwise appear, is taken up and carried off by the abundant formation of carbonic acid gas, which requires so great a quantity of caloric to render it permanently elastic, as not only keeps this sort of combustion under ignition, but much below the degree of heat at which the accumulating vinous spirit could be raised to the evaporable or distilling point, though capable, as already observed, of detaching a considerable portion of it with the volatile gas, and of the water of solution, or the water of composition recently formed from the present attractions in its most volatile and incipient state of formation; both which we have seen ascend with the fixed air extricated, partly in a combined, and partly in an uncombined state.