A Practical Treatise on Brewing/Appendix/Observations on Electricity

by William Black

For the following remarks on Electricity, as connected with brewing, I am indebted to my friend Dr. Cumming, of 34, Lowndes-street, Pimlico, who has been some time engaged in investigating the effects of electricity on various substances:—

It has long been observed, that fermented liquors are soured after thunder storms, and it has not only been observed that fermented liquors are so affected, but also that butter, milk, animal food, and all organised matters, having a disposition to chemical change, are sometimes most rapidly decomposed after thunder. These changes we are induced to ascribe to electrical agency, from the well known fact, that animals killed by lightning almost immediately become putrid. Dr. Franklin relates a remarkable instance of the rapid decomposition of a "flock of sheep, assembled under a tree which were killed by a flash of lightning. The proprietor, desirous of saving something, sent persons next morning to flay them; but the putrefaction was such, and the stench so abominable, that they could not execute his orders. The sheep were consequently buried in their skins." We might adduce many well-attested instances of similar effects produced on animals struck by lightning; and it can be proved by the evidence of many butchers in this city, that serious losses are often sustained by the rapid putrefaction of meat after thunder: a fact with which philosophers have long been acquainted. Dr. Franklin^[1] suggested (no doubt from his knowledge of these effects of electricity) that animals might be rendered tender for the table by being killed by lightning. We are prepared experimentally to prove, that such chemical changes in fermented liquors are promoted by electricity, and not only in fermented liquors, but in all matters subject to decomposition; and the popular belief in the influence of this wonderful agent, which has so long been entertained, being thus corroborated by experiment, we may, I think, look upon it as an established truth, that such chemical effects are produced by electrical changes, at least by those which take place during thunder.

There are, however, variations observable in fermentations and other chemical processes, when no thunder-storms occur. For instance, it has been noticed by many intelligent brewers, that their fermentations are more brisk during frost than they are during soft and warm weather, though in the latter case we might expect them to be rendered more active by the concurrence of a higher temperature. Bakers have observed similarly active states of the fermentation of their dough during frosty weather, while in soft and warm weather their fermentations are sometimes dull, and their bread apt to become sour.

It has been noticed both by bakers and brewers, that their fermentations are brisk during high winds, and more especially during high winds from the east and north, when no change of temperature appears to be concerned. Many variations in chemical actions obviously take place, when no alteration of the temperature or other sensible qualities of the surrounding atmosphere can be observed, by which they might be produced. We are consequently inclined to think, that changes take place in the electrical states of the earth and air, not manifested to us by the phenomena of thunder and lightning, by which variations may be produced in chemical actions, and probably, chemical affinities brought into play, which might remain quiescent without their agency.

We learn from the researches of Beckerel^[2], by what feeble electrical forces great chemical results may be produced. Slight electrical polarity, produced by the temperature of a piece of metal being higher at one end than at the other, is sufficient to excite certain chemical actions.^[3] From these facts, we may imagine the great power those alterations in the electrical states of the earth and air, which are constantly occurring in connection with meteorological changes, must have on chemical processes.

Mr. Weekes, of Sandwich, has kept a register of the electrical changes of the atmosphere for the last three years, which may be seen in the Transactions of the London Electrical Society. The instrument he uses for ascertaining these changes, is a wire for collecting the atmospherical electricity, extended between two elevated points, and connected with them by non-conductors. From the centre of this atmospherical wire, another wire extends to the electroscope, by which the power and appearance of the electricity collected by the former are manifested. To give an idea of the quantity thus collected, I shall simply give Mr. Weekes' report for 9th May 1841, as per the register for that month:—"During a rain-and-hail shower, splendid and nearly incessant torrent of sparks for nearly an hour. The electric current exhibits singular intensity, rapidly decomposing fluids, igniting combustible substances, &c. The lateral discharge partially consumed an iron nail three and a-half inches long, with the brilliancy of an ordinary fire-work." We have here given one of the more decided instances of electrical changes occurring without thunder; but by a perusal of the register for three years, it will be seen, that changes are constantly observed in connection with changes of weather; and even without any decided change of weather, we find this influence, though to a much less extent, ever fluctuating and unsteady. We may consequently presume, if chemical actions are affected by electrical influence, that from the highest intensity of those electrical movements to the most feeble, chemical effects, varying in degree and kind, are produced in matters prone to decomposition. By observing the phenomena which pass around us, we may soon become convinced of the truth of these remarks. For instance; from ponds, the bottoms of which are composed of earthy and vegetable matters, we have, prior to changes of weather, and especially prior to and during rain, quantities of gas escaping in bubbles. Our sense of smell affords evidence of the emanation of effluvia from putrescent matters, being more abundant at one time than another; and this is so generally observed in London, and its connection with changes of weather so obvious, that many consider an increase of stench from drains to be a sure premonition of rain.^[4]

Some imagine, from the frequent occurrence of stench from sewers and drains, during easterly winds, that currents of air from that direction enter the drains, and force the stench back into the houses. But we know, that electrical movements are much more powerful than usual during easterly wind, and previous to and during rain, and consequently the more abundant extrication of gases and effluvia under such circumstances, may more properly be looked upon as an evidence of the chemical effects of electricity.

It has been noticed by many of our army medical officers at Gibraltar, that it is extremely difficult to keep armour clean during the north-east winds, which they call the black Levanters. These winds are certainly said to be moist, and this may probably be considered sufficient to account for their oxidating effects; but in order to ascertain that such processes of oxidation are affected by some less manifest influence, we have made comparative observations as to the time required, to oxidate or rust bright but unpolished plates of iron. When these plates are slightly sponged over with distilled water, the moisture will at one time evaporate without leaving a speck of rust, while at another, a covering of rust forms upon it almost immediately. We have found this more rapid tendency to oxidation, coincident with a high state of the electrical tension of the earth, upon which variations in other processes of oxidation also appear to depend. For instance, it is a matter of general observation, that our fires burn more brightly than usual, during frosty weather. A similar activity of combustion is also observed during high winds, especially when from the east or north. We have noticed the more obvious changes of the process of combustion, and also of the oxidation of iron, for two years, at the same time keeping a register of the electrical tension of the earth; and during this period we have found the more evidently bright states of combustion corresponding so uniformly with high electrical tension, that they may probably be considered as cause and effect.

From these facts we may, I think, conclude that fermentations must be greatly affected by electrical agency, and that many variations in those processes commonly ascribed to variations in the quantity or quality of the yeast employed, to temperature, &c. &c. really depend upon the changes of this more powerful and extensive influence. The very remarkable instance given by Mr. Black, page 35. of the suspension of fermentation before a thunder-storm, and its immediate recommencement when the wort was pumped out of the vat embedded in the earth, into casks placed on wooden stands, affords a strong proof of the power of electricity over these processes. We cannot doubt but the cessation of the process was in this instance the effect of the negatively electric state of the earth which is generally observed before thunder. Whether the isolation produced by transferring the liquor from the vat into casks supported by wooden stands, was anywise effective in its recommencement, we cannot say. Negative surfaces do not appear to promote the chemical changes to which such liquors are disposed, at least we think this a fair inference from the results of the following experiments.

Into three pots of similar size and shape, two of them made of copper, and one of wood, we put equal quantities of wort. We kept them precisely in the same circumstances; but one of the copper pots was rendered negative by having a disk of zinc in its bottom. In the course of three weeks the worts in the other two pots underwent spontaneous fermentation, became sour, and ultimately putrid, whereas that in the negative pot, continued free from every appearance of fermentation and chemical change, and as sweet to the taste for months as it was at the beginning.^[5] These experiements have been frequently repeated with the same results; and if it be proved by further investigation, that chemical changes in worts are retarded by negative surfaces, coolers may be constructed on this principle, and reservoirs for preserving beer, in which a second fermentation or fret (as it is technically termed) will be less apt to occur: an accident, which is so often a cause of great loss to practical brewers. Vessels composed of zinc and copper are, of course, objectionable on account of their poisonous qualities. We find, however, from the investigations of M. Martens, member of the Royal Academy at Brussels, that iron may be rendered passive or negative, by a dull red heat, insomuch that it is not affected by the unfuming nitric acid of commerce, which powerfully affects common iron. The immersion of iron in highly concentrated nitric acid has the same effect, and so has also the crystallisable, or highly concentrated acetic acid. Passive vessels may, consequently, be made of this metal which is, I believe, already used for these purposes, without this important preparation.

It is not our intention to enter into any theoretical consideration of these phenomena; we merely point them out to practical men, in order to induce them to avail themselves of the opportunities they enjoy, in conducting their great processes, by their observations and experiments, to aid us in tracing the effects of an agent, which we have reason to consider, not only influential in producing variations in the operations of the brewery, but, what is still more important, variations in the constitution of our atmosphere, and probably effects on the functions of life, the comprehension of which may aid us, both in the prevention, and better treatment of epidemic and contagious diseases.

We may observe, that brewers cannot too carefully avoid the circumstances calculated to produce electro-chemical action, pointed out by Mr. Black; for it cannot be doubted, from the proofs he adduces, that local galvanic action is produced by the use of metallic cocks and chains of pipes, which, being acted upon by the wort, cause unsoundness.

Although the subject of electricity, as connected with brewing, has already been pretty fully treated of in the former part of this work, yet as electricity and electro-chemical action, as connected with fermentation, are at last beginning to attract a little more attention than they have hitherto done, a few additional remarks upon the subject may not be deemed superfluous. They will tend further to show the extraordinary influence exercised by that still incomprehensible fluid or body, not only upon fermentation but upon everything connected with the manufacture of beer, and also, as it is now thought, upon every process, both natural and artificial. My former remarks were principally confined to the injurious effects of galvanism, as producing an electro-chemical action in the process of fermentation. These injurious effects I considered to have been caused by chains of pipes, consisting of various metals, having been connected with the fermenting tuns, and other departments of the brewery; and many facts and cases in point were mentioned, showing that this was the true cause. Many people, however, were led to suppose that, as this action was not so hurtful at some times as at others, its injurious effects had no foundation in reality; but every one, more or less acquainted with the principles of electrical science, must admit the fact, that different oxidizable metals in contact cannot be immersed even in water, without the excitation of galvanic currents. When, however, such combinations of metals are immersed in acidulated liquors, such as worts undergoing fermentation, currents, more or less powerful in proportion to the quantity of acid contained in those liquors, must be produced.

Acids increase the conducting power of liquors, and upon this property depend their effects of increasing the power of galvanic currents. From causes already stated and explained in my Treatise on Brewing, acids are sometimes formed in the worts, even in the coolers. Hence it may be easily comprehended that electro-chemical action must, in such circumstances, be more powerful, and, consequently, more hurtful. When the worts are sound and sweet, the currents are proportionately feeble; but they never can be absent so long as metallic combinations are used in the brewery: even when most feeble, they constitute a force^[6] superadded to, or giving direction to the chemical affinities engaged in the fermenting process, and they must constantly operate as disturbing causes, increasing or modifying a process, the success and perfection of which depends on its being permitted to go on to its completion, uninfluenced by any force save its own intestine affinities. It is now an established law, incontestibly proved by the experiments of Faraday, Daniell, and other philosophers, that the electro-chemical action of a current of electricity is always definite, and directly proportionate to the absolute quantity of electricity which circulates; and however feeble such a current may be, it must, if it at all exists, act electro-chemically.

We have already shown how impossible it is to avoid galvanic currents, if metals are used; but common electricity, circulating in currents, acts electro-chemically, as well as galvanism; and we may conceive, when electro-currents are slowly descending to the earth from superincumbent clouds, that they must, by the extent and conducting power of chains of pipes, be powerfully concentrated and directed to the worts with which such pipes are connected, and that thus an agent is rendered deleterious by being so collected, which would, under ordinary circumstances, have little effect.

From these observations it is evident that the great want of uniformity in the process of brewing, now so much objected to, and the consequent injury to the beer, can never be fully got the better of until these causes of failure are in some way or other removed. I shall, in the mean time, beg leave to refer to what has been previously said upon this subject in a former part of this work, and shall now proceed to state some curious effects which have also come under my notice, with regard to the influence of atmospheric electricity upon fermentation.

Dr. Cumming’s observations as to the preservative qualities of negative vessels for worts or beer, are well worthy of attention; if negative utensils tend to prevent acidity in worts, which they no doubt do, they must have the same effect on beer, with this further advantage, that, as it retards fermentation, it must prevent fret, which is a spurious or second fermentation, proceeding from an increase of temperature, or other atmospherical changes. It has been always found, that the more isolated vats, or casks in which beer has to be kept, can be rendered, the better chance has the beer of not being injuriously affected by electricity. If vats, therefore, can be constantly kept in a negative state, the beer will be much less liable to suffer from fret, than when subjected to every electrical change which may occur.

Atmospheric EIectricity

From Dr. Cumming’s remarks, it will be seen, that when worts or beer were placed in a state of positive electricity, they very rapidly went to decay, and got sour; but when placed in a negative vessel, they would keep for an indefinite length of time without undergoing any change. It was also found that when yeast was applied, the worts under positive electricity very rapidly got into a state of fermentation, and soon became acid; while in the other, or negative state, little or no fermentation took place, and that which did occur did not produce any acidity, a little frothy matter appeared upon the surface, unaccompanied by any other change. This accounts for the anomalies which take place in fermentation when the appearance of the atmosphere indicates thunder. It is a common observation that any man can brew in winter, and no doubt before the introduction of these metallic mains, &c., now in such common use in the brewery, much less difficulty was experienced in the process of fermentation in the winter months, because fewer electrical, changes take place at that season (having seldom thunder-storms to dread) than in warmer weather or summer. Galvanism, however, now neutralizes these advantages, and the process of brewing has become about as uncertain during winter as in the heat of summer, thereby causing the great want of success and uniformity already mentioned.

Let us now revert to the fluctuations which take place in the fermenting tuns, when the appearance of the atmosphere indicates thunder.

It is generally supposed, that before thunder the atmosphere is positively, and the earth negatively, electrified; but suppose it the reverse, the same anomalies would take place in fermentation, and similar effects be produced,—viz., that positive electricity would cause fermentation to go on too rapidly, while negative electricity would altogether prevent it: thus showing, that, whenever the equilibrium is unduly disturbed during that process, fermentation becomes irregular, and of course uncertain.

When fermentation is going on as regularly and prosperously as possible, should the process suddenly cease or become inactive, it indicates an approaching thunder-storm, and during this inactivity no addition of yeast will have any effect in causing it to go on. It may be remarked, however, that no additional acidity takes place, nor does any other harm happen to the worts during this cessation than merely the delay. Very soon after the thunder begins, the fermentation will resume its activity, and with a very little additional yeast, will get on, perhaps, more vigorously than before, and should any acidity be produced, it will be at this time, and not during the state of inactivity I have already mentioned as occurring before the commencement of the storm. I have observed these anomalies to take place more than once during the progress of the same fermentation, and could, if necessary, mention day and date for them. We at present know no means of totally preventing the influence of electricity on fermentation, but its occurrence may be often ameliorated, and sometimes even averted, by a judicious arrangement of the fermenting tuns, but not by the admixture of metals already adverted to, which at all times prevents either regularity or uniformity in the process. The fermenting vessels should be in every way as perfectly insulated as possible, and not in any way exposed to the steam arising from other parts of the brewery, the influence of which will immediately destroy the fermentation by throwing down the head. They should be placed upon brick pillars, and if supported by baked wooden bearers, so much the better, and each one should be placed separately by itself. These precautions will at all times be found serviceable. Other means may be afterwards discovered which may be more effectual, but these would require careful investigation. It cannot now be doubted that failure in the success of the process of fermentation is greatly influenced by electro-chemical agency. It also appears that if the electrical equilibrium be disturbed or destroyed during any part of the process of fermentation by the intervention of atmospheric electricity, an entire stop is for a time put to the process in some instances, while in others it is accelerated to such a degree as to produce acidity. The equilibrium being in both cases destroyed, no uniformity of action can go on, and more or less free acid will be produced in the beer according to circumstances, as a comparison of different beers by means of the litmus test will distinctly show, for in some cases where the electro-chemical action has been strong, instead of a brownish-red colour, a pretty bright red will appear, showing that a considerable excess of free acid has been generated.

Let our great brewers then, instead of being led away by vague assertions, unauthorised by practical experience, and unattended with any real benefit,—but too often the contrary,—devote a little more attention to chemistry, by means of which most other arts have been so greatly benefited. We shall thus, it is to be hoped, do away with the imputation of our being at present excelled by other countries, in the production of a beverage which has been so long considered as peculiarly our own.

1. Vide Franklin's works, vol. vi. p. 231.
2. Scientific Memoirs, vol. i., Beckerel on the Chemical Effects of Electric Currents.
3. Vide Transactions of the London Electrical Society, part v. p. 281., M. Martens on the Passivity of Metals.
4. Vide Sir Gilbert Blane on the Diseases of Seamen, page 267.
5. This the Author had the opportunity of witnessing.
6. See "Faraday’s Experimental Researches on Electricity," vol. i. p. 148., par. 518.