DISTILLATION

(Eng. and Fr.; Branntweinbrennerei , Germ.) means, in the commercial language of this country, the manufacture of intoxicating spirits; under which are comprehended the four proce es, of mashing the vegetable materials, cooling the worts, exciting the vinous fermentation , and separating by a peculiar ve el called a still , the alcohol combined with more or le water. This art of evoking the fiery demon of drunkenne from his attempered state in wine and beer, was unknown to the ancient Greeks and Romans. It seems to have been invented by the barbarians of the north of Europe, as a solace to their cold and humid clime; and was first made known to the southern nations in the writings of Arnold us de Villa Nova, and his pupil, Raymond Lully of Majorca, who declares this admirable e ence of wine to be an emanation of the Divinity, an element newly revealed to man, but hid from antiquity, because the human race were then too young to need this beverage, destined to revive the energies of modern decrepitude. He further imagined that the discovery of this aqua vitæ , as it was called, indicated the approaching consummation of all things—the end of this world. However much he erred as to the value of this remarkable e ence, he truly predicted its vast influence upon humanity, since to both civilized and savage nations it has realized greater ills than were threatened in the fabled box of Pandora. I shall consider in this place the first three of these subjects, reserving for the article Still an account of the construction and use of that apparatus. Whiskey, from the Irish word Usquebaugh, is the British name of the spirituous liquor manufactured by our distillers, and corresponds to the Eau de vie of the French, and the Branntwein of the Germans. It is generated by that intestine change which grape juice and other glutino-saccharine liquids spontaneously undergo when exposed to the atmosphere at common temperatures; the theory of which will be expounded under the article Fermentation . The production of whiskey depends upon the simple fact, that when any vinous fluid is boiled, the alcohol being very volatile, evaporates first, and may thereby be separated from the aqueous vegetable infusion in which it took its birth. Sugar is the only substance which can be transformed into alcohol. Whatsoever fruits, seeds, or roots afford juices or extracts capable of conversion into vinous liquor, either contain sugar ready formed, or starch susceptible of acquiring the saccharine state by proper treatment. In common language, the intoxicating liquor obtained from the sweet juices of fruits is called wine; and that from the infusions of farinaceous seeds, beer; though there is no real difference between them in chemical constitution. A similar beverage, though probably le palatable, is procurable from the juices and infusions of many roots, by the proce of fermentation. Wine, cyder, beer, and fermented wash of every kind, when distilled, yields an identical intoxicating spirit, which differs in these different cases merely in flavour, in consequence of the presence of a minute quantity of volatile oils of different odours. I. The juices of sweet fruits contain a glutinous ingredient which acts as a ferment in causing their spontaneous change into a vinous condition; but the infusions of seeds, even in their germinated or malted state, require the addition of a glutinous substance called yeast, to excite the best fermentation. In the fabrication of wine or beer for drinking, the fermentative action should be arrested before all the fruity saccharum is decomposed; nor should it on any account be suffered to pa into the acetous stage; whereas for making distillery wash, that action should be promoted as long as the proportion of alcohol is increased, because the formation of a little acetic acid is not injurious to the quality of the distilled spirit, but rather improves its flavour by the addition of acetic ether, while all the undecomposed sugar is lost. Distillers operate upon the saccharine matter from corn of various kinds in two methods; in the first they draw off a pure watery extract from the grain, and subject this species of wort to fermentation; in the second they ferment and distil the infused ma of grains. The former is the practice of the distillers in the United Kingdom, and is preferable on many accounts; the latter, which is adopted in Germany, Holland, and the north of Europe, is le economical, more uncertain in the product, and affords a cruder spirit, in consequence of the fetid volatile oil evolved from the husks in the still. The substances employed by the distillers may be distributed into the following cla es :— 1. Saccharine juices. At the head of these stands cane-juice, which fresh from the mill contains from 12 to 16 per cent. of raw sugar, and like the must of the grape enters into the vinous fermentation without the addition of yeast, affording the species of spirit called Rum, which is po e ed of a peculiar aroma derived from an e ential oil in the cane. An inferior sort of rum is fabricated from mola es, mixed with the skimmings and washings of the sugar pans. When mola es or treacle is diluted with twenty times its weight of warm water, and when the mixture has cooled to 78° F., if one twelfth of its weight of yeast be added, fermentation will speedily ensue, and an ardent spirit will be generated, which when distilled has none of the aroma of rum; proving this to reside in the immediate juice or substance of the cane, and to be di ipated at the high temperature employed in the production of mola es. Though the cane juice will spontaneously undergo the vinous fermentation, it does so more slowly and irregularly than the routine of busine requires, and therefore is quickened by the addition of the lees of a preceding distillation. So sensible are the rum distillers of the advantage of such a plan, that they soak woollen cloths in the yeast of the fermenting vats, in order to preserve a ferment from one sugar season to another. In Jamaica and some other of our colonies, 50 gallons of spent wash or lees are mixed with 6 gallons of mola es, 36 gallons of sugar-pan skimmings (a substance rich in aroma), and 8 gallons of water; in which mixture there is about one twelfth part of solid saccharum. Those who attend more to the quality than the quantity of their rum, will use a smaller proportion of the spent wash, which is always empyreumatic, and imparts more or le of its odour to the spirit distilled from it. The fermentation is seldom complete in le than 9 days, and most commonly it requires from 12 to 15; the period being dependent upon the capacity of the fermenting tun, and the quality of its contents. The liquid now becomes clear, the froth having fallen to the bottom, and few bubbles of gas are extricated from it, while its specific gravity is reduced from 1·050 down to 0·992. The sooner it is subjected to distillation after this period the better, to prevent the lo of alcohol by the supervention of the acetous stage of fermentation, an accident very liable to happen in the sugar colonies. The crude spirit obtained from the large single still at the first operation, is rectified in a smaller still. About 114 gallons of rum, proof strength, specific gravity 0·920, are obtained from 1200 gallons of wash. Now these 1200 gallons weigh 12,600 libs., and contain nearly one eighth of their weight of sugar = 1575 libs.; which should yield nearly its own weight of proof spirit, whose bulk is = 1575 0·92 = 1712 pound measures = 171·2 gallons; whereas only 114 are obtained; proving the proce es to be conducted in a manner far from economical, even with every reasonable allowance. Mr Edwards gives the following estimate: “The total amount of sweets from an estate in Jamaica which makes 200 hogsheads of sugar, is 16,666 gallons. The wash set at the rate of 12 per cent. sweets, should return 34,720 gallons of low wines, which should give 14,412 gallons of rum, or 131 puncheons of 110 gallons each.” By my own experiments on the quantity of proof spirit obtainable from mola es by fermentation (afterwards to be detailed), one gallon of sweets should yield one gallon of spirit; and hence the above 16,666 gallons should have afforded the same bulk of rum. But here we are left somewhat in the dark, by not knowing the specific gravity of the rum spoken of by Mr. Edwards. The only light let in upon us is when he mentions rum oil-proof, that is, a spirit in which olive oil will sink; indicating a density nearly the same with our actual excise proof, for olive oil at 60° F. has the specific gravity 0·919. When a solution of sugar of the proper strength is mixed with wine lees, and fermented, it affords a spirit by distillation not of the rum, but of the brandy flavour. The sweet juices of palm trees and cocoa nuts, as also of the maple, and ash, birch, ., when treated like cane juice, afford vinous liquors from which ardent spirits, under various names, are obtained; as arrack , .; the quantity being about 50 pounds of alcohol of 0·825 for every 100 pounds of solid saccharine extract present. Honey similarly treated affords the metheglin so much prized by our ancestors. Good whey, freed from curd by boiling, will yield 4 per cent. of spirit of wine, when fermented with the addition of a little yeast. 2. The juices of apples, pears, currants, and such fruits, afford by fermentation quantities of alcohol proportional to the sugar they contain. But the quality of the spirit is much better when it is distilled from vinous liquids of a certain age, than from recently fermented must. Cherries are employed in Germany, and other parts of the Continent, for making a high-flavoured spirit called Kirsch-wa er , or cherry water. The fully ripe fruit is crushed by a roller pre , or an edge-stone mill, along with the kernels; the pulp is fermented in a ma , the liquid part is then drawn off, and distilled. More or le pru ic acid enters from the kernels into this spirit, which renders it very injurious, as a liquor, to many constitutions. I was once nearly poisoned by swallowing a wine gla of it in the valley of Chamouni. The ripened red fruit of the mountain ash constitutes a good material for vinous fermentation. The juice being mixed with some water and a little yeast, affords when well fermented, according to Hermstaedt, 12 pounds, or 1 1 ⁄ 2 gallons, of alcohol from 2 bushels of the ripe berries. 3. Many roots contain sugar, particularly beet, from which no le than 7 per cent. of it may be extracted by judicious means. Hermstaedt recommends to mash the steam boiled clean roots, and add to the paste two-thirds of its weight of boiling water, and a thirtieth of its weight of ground malt, mixing the materials well, and then leaving them three hours in a covered ve el. The mixture must now be pa ed through a wire sieve, with meshes of one-third of an inch square each; the residuum is washed with a little cold water, and, when the temperature has fallen to 77° F., the proper quantity of yeast must be added, and the fermentation suffered to proceed in a covered tun. In 5 or 6 days it will be complete, and will afford by distillation, from 100 pounds of beet root, about 10 or 12 pounds of proof spirits. Carrots and parsnips, when similarly treated, yield a considerable quantity of alcohol. II. Ardent spirits or whiskey from fecula or starchy materials. I have already pointed out, in the article Beer , how the starch is transformed into a saccharine condition, by malting and mashing; and how a fermentable wort may be obtained from starchy meal. By like operations may all vegetable substances, which consist chiefly of starch, become materials for a whiskey distillery. To this cla belong all the farinaceous grains, potatos, and the pods of shell fruits, as beans, vetches, horse-chesnuts, acorns, . 1. Whiskey from corn. All those species of corn which are employed in breweries answer for distilleries; as wheat, rye, barley, and oats; as well as buckwheat, and maize or Indian corn. The product of spirits which these different grains afford, depends upon the proportion of starch they contain, including the small quantity of uncrystallizable sugar present in them. Hermstaedt, who has made exact experiments upon the subject, reckons a quart (Pru ian or British) spirits, containing 30 per cent. of the absolute alcohol of Richter, for 2 pounds of starch. Hence 100 pounds of starch should yield 35 pounds of alcohol; or 4·375 gallons imperial, equal to 7·8 gallons of spirits, excise proof. 100 pounds of the following grains afford in spirits of specific gravity 0·9427, containing 45 per cent. of absolute alcohol (= 9 ⁄ 11 of British proof,) the following quantities :— Wheat, 40 to 45 pounds of spirits; rye, 36 to 42; barley, 40; oats, 36; buckwheat, 40; maize, 40. The mean of the whole may be taken at 40 pounds, equal to 4 1 ⁄ 4 gallons imperial, of 0·9427 specific gravity = 3·47 gallons, at excise proof. The chief difference in these several kinds of corn consists in their different bulks under the same weight; a matter of considerable importance; for since a bushel of oats weighs little more than the half of a bushel of wheat, the former becomes for some purposes le convenient in use than the latter, though it affords a good spirit. Barley and rye are the species of grain most commonly employed in the European distilleries for making whiskey. Barley is mostly taken either partly or altogether in the malted state; while the other corns are not malted, but merely mixed with a certain proportion of barley malt to favour the saccharine fermentation in the mashing. It is deemed preferable to use a mixture of several sorts of grain, instead of a single one; for example, wheat with barley and oats; or barley with rye and wheat; for the husks of the oats diffused through the wheat flour and rye meal keep it open or porous when mashed, and thus favour the abstraction of the wort; while the gluten of the wheat tends to convert the starch of the barley and oats into sugar. When the whole of the grain, however, is malted, a much more limpid wort is obtained than from a mixture of malt with raw grain; hence the pure malt is preferable for the ale and porter brewer, while the mixture affords a larger product, at the same cost of materials, to the distiller. When barley is the only grain employed, from one-third to one-sixth of malt is usually mixed with it; but when wheat and rye are also taken, the addition of from one-eighth to one-sixteenth of barley malt is sufficient. Oats are peculiarly proper to be mixed with wheat, to keep the meal open in the mashing. The following are the proportions used by some experienced Scotch distillers. | 250 | bolls, containing 6 bushels each, being used for a mashing, consist of, | | 25 | bolls of | oats, | weighing | 284 | lbs. per boll, or | 47 | 1⁄3 | lbs. per bushel; | | 42 | | malt | | 240 | | 40 | | | 25 | | rye | | 320 | | 53 | 1⁄3 | | | 158 | | barley | | 320 | | 53 | 1⁄3 | | | 250 | mean | 48 | 1⁄2 | | From each boll, weighing 291 lbs., 14 imperial gallons of proof whiskey are obtained on an average; equivalent to 11·2 gallons at 25 over proof. The malting for the distilleries is to be conducted on the same principles as for the breweries, but the malt ought to be lightly kiln-dried, and that preferably at a steam heat, instead of a fire, which is apt to give an empyreumatic smell to the grain that pa es into the spirits. For such persons, indeed, as relish the smell of burned turf, called peat-reek in Scotland, the malt should be dried by a turf fire, whereby the whiskey will acquire that peculiar odour. But this smell, which was originally prized as a criterion of whiskey made from pure malt, moderately fermented and distilled with peculiar care, has of late years lost its value, since the artifice of impregnating bad raw grain whiskey with peat-smoke has been extensively practised. Dr. Kolle, in his treatise on making spirits, describes a malting kiln with a copper plate heated with steam, 18 feet long, and 12 feet broad, on which a quantity of malt being spread thin, is changed every 3 or 4 hours, so that in 24 hours he turns out upwards of 28 cwt. of an excellent and well-kilned article. The malt of the distiller should be as pale as po ible, because with the deepening of the colour an empyreumatic principle is generated. When Indian corn is the subject of distillation, it must be malted in the same way as described in the article Beer . According to Hermstaedt, its flour may be advantageously mixed with the crushed malt in the mash tun. But its more complete di olution may be accomplished by Siemen’s mode of operating upon potatos, presently to be described. 1. Mashing. Barley and raw grain are ground to meal by millstones, but malt is merely crushed between rollers. If only one-tenth or one-eighth of malt be used with nine-tenths or seven-eighths of barley, some husks of oats are added, to render the mash mixture more drainable. When 40 bushels of barley and 20 of malt form one mashing, from 600 to 700 gallons of water, heated to 150° F., are mixed with these 60 bushels in the mash tun, and carefully incorporated by much manual labour with wooden oars, or in great concerns by the mechanical apparatus used in the breweries. This agitation must be continued for 2 or 3 hours, with the admi ion from time to time of about 400 additional gallons of water, at a temperature of 190°, to counteract the cooling of the materials. But since the discovery of diastase , as the best heat for saccharifying starch is shewn to be not higher than 160° F., it would be far better to mash in a tun, partially, at least, steam encased, whereby we could preserve the temperature at the appropriate degree for generating the greatest quantity of sugar. If the wort be examined every half-hour of the mashing period, it will be found to become progre ively sweeter to the taste, thinner in appearance, but denser in reality. The wort must be drawn off from the grains whenever it has attained its maximum density, which seldom exceeds 150 lbs. per barrel; that is, 360 + 150 360 = 1·42, or 42 per cent. As the corn of the distiller of raw grain has not the same porosity as the brewer’s, the wort cannot be drawn off from the bottom of the tun, but through a series of holes at the level of the liquor, bored in a pipe stuck in at the corner of the ve el. About one-third only of the water of infusion can thus be drawn off from the pasty ma . More water is therefore poured on at the temperature of 190°, well mixed by agitation for half an hour, then quietly infused for an hour and a half, and finally drawn off as before. Fully 400 gallons of water are used upon this occasion, and nearly as much liquor may be drawn off. Lastly, to extract from the grains every thing soluble, about 700 gallons of boiling hot water are turned in upon them, thoroughly incorporated, then left quietly to infuse, and drawn off as above. This weak wort is commonly reserved for the first liquor of the next mashing operation upon a fresh quantity of meal and malt. The English distiller is bound by law to make his mixed worts to be let down into the fermenting tun of a specific gravity not le than 1·050, nor more than 1·090; the Scotch and Irish distillers not le than 1·030, nor more than 1·080; which numbers are called, gravity 50, 90, 30, and 80, respectively. With the proportion of malt, raw grain, and water, above prescribed, the infusion first drawn off may have a strength = 20 per cent. = spec. grav. 1·082, or 73 lbs. per barrel; the second of 50 lbs. per barrel, or 14 per cent.; and the two together would have a strength of 61·2 lbs. per barrel = 17 per cent., or spec. grav. 1·070. From experiments carefully made upon a considerable scale, it appears that no more than four-fifths of the soluble saccharo-starchy matter of the worts is decomposed in the best regulated fermentations of the distiller from raw grain. For every 2 lbs. so decomposed, 1 lb. of alcohol, spec. grav. 0·825 is generated; and as every gallon of spirits of the spec. grav. 0·909 contains 4·6 lbs. of such alcohol, it will take twice 4·6 or 9·2 lbs. of saccharine matter to produce the said gallon. To these 9·2 lbs., truly transmuted in the proce , we must add one-fifth, or 1·84 lbs., which will raise to 11·04 the amount of solid matter employed in producing a gallon of the above spirits. Some distillers mash a fourth time; and always use the feeble wort so obtained in mashing fresh grain. 2. As the imperfect saccharine infusion obtained from raw grain is much more acescent than the rich sugary solution got from malt in the breweries, the distiller must use every precaution to cool his worts as quietly as po ible, and to keep them clear from any acetous taint. The different schemes of cooling worts are considered under Beer and Refrigeration . As the worts cool, a quantity of starchy matter is precipitated, but it is all carefully swept along into the fermenting tun, and undoubtedly contributes to increase the production of alcohol. During the winter and temperate months, when the distilleries are most actively at work, the temperature at which the worts are set is usually about 70° F. When much farinaceous deposit is present, the heat may be only 65°, because, in this case, a slow fermentation seems to favour the conversion of that starch into sugar. In some German distilleries a little chalk is mixed with the worts, to check acidity. 3. The fermentation. The yeast added to the worts as a ferment, ought to be the best top barm of the London porter breweries. About 1 gallon of it is requisite for every 2 bushels of meal and malt worked up in the mashing proce ; and of this quantity only a certain proportion is introduced at the beginning; the remainder being added by degrees, on the second and third day. Should the fermentation flag, a little more may be added on the fourth or fifth day, and the contents of the tun may be roused by an agitator. About 8 or 9 gallons may be introduced four days in succe ion to the quantity of worts extracted from 60 bushels of the farinaceous materials; or the third day’s dose may be intermitted, and joined to the fourth on the subsequent day. Great diversity, and no little caprice prevail among distillers in respect of the periods of administering the yeast; but they should be governed very much by the appearance of the fermentation. This proce continues from nine to twelve or even fourteen days, according to circumstances; the tuns being left quite open during the first five days, but being covered moderately close afterwards to favour the full impregnation of the liquor with carbonic acid, as a fermenting agent. In consequence of the great attenuation of the wort by the generation of so much alcohol, no good body of yeast continues to float on the surface, and what is formed is beat down into the liquor on purpose to promote the fermentation. The temperature of the wash gradually increases till towards the end of the fourth day, when it attains its maximum height of about 25° above the pitch of 55° or 60° at which it may have been set. The time of the greatest elevation of temperature, as well as its amount, depends conjointly upon the quality of the yeast, the nature of the saccharo-starchy matter, and the state of the weather. It is highly probable that the electrical condition of the atmosphere exercises a considerable influence upon fermentation. We know the power of a thunderstorm to sour vinous fluids. An experimental inquiry into the relation between electricity and fermentation, could not fail to prove both curious and profitable. The diminution of the density of the wort is carefully watched by the distiller, as the true criterion of the succe of his proce . This attenuation , as he calls it, is owing partly to the decomposition of the sugar, which communicated its gravity to the solution, and partly to the introduction of the lighter alcoholic particles. Were all the saccharo-starchy matter resolved into gaseous compounds, the wort would become water; but since a part of it remains undecomposed, and a portion of alcohol is produced at the expense of the decomposed part, the degree of attenuation becomes a somewhat complicated problem in a theoretical point of view; the density due to the residuary sugar being masked and counteracted by the spirit evolved. Could the alcohol be drawn off as it is formed, the attenuation would probably become greater, because the alcohol checks the fermentative action, and eventually stops it, before all the saccharum is decomposed. After the wash has taken its highest degree of temperature, not much more spirit is found to be generated; were this therefore removed by proper means, the remaining vegetable matter would undoubtedly yield a further product of alcohol. In the attenuation of raw-grain wash, the specific gravity seldom arrives at 1·000; but most commonly stops short at 1·002 or 1·004. When the vinous fermentation comes to an end, the acetous is apt to commence, and to convert a portion of the alcohol into vinegar; a result which is easily ascertained by the increasing specific gravity, sour smell, and acidulous reaction of the wash upon litmus paper, which remains after the paper is heated, showing that the red colour is not caused by carbonic acid. Fermentation proceeds with more uniformity and succe in the large tuns of the distiller, than in the experimental apparatus of the chemist; because the body of heat generated in the former case maintains the action. But I have succeeded in obviating this inconvenience in operating upon 80 or 90 gallons, by keeping up the temperature, when it begins to flag, by transmitting hot water through a recurved pipe plunged into the tun. We have already mentioned that one gallon of spirits, one in ten over-proof, is upon the average generated from 11·04 libs. of starch sugar; hence we conclude that one pound water-measure of spirits at proof (= 1 ⁄ 10 imperial gallon) is produced from one pound of the saccharum.