# 1911 Encyclopædia Britannica/Spirits

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​SPIRITS. The original meaning of the word spirit (Lat. spiritus, from spirare) was wind in motion, breath, the soul, and hence it came to denote that which gives life or vigour to the human body and other objects, and it is, therefore, synonymous with everything eminently pure, ethereal, refined or distilled. In popular chemical nomenclature the term “spirit” in its former sense is still occasionally encountered, for instance, "spirits of salts" for hydrochloric acid. The spirits of the British Pharmacopoeia (e.g. sp. aetheris nitrosi; sp. chloroformi; sp. camphorae) are solutions of various substances obtained either by distilling these with, or dissolving them in, the rectified spirit of the Pharmacopoeia, which latter is pure alcohol with 16% by weight of water.
In the modern sense, spirits may be broadly defined as the products resulting from the distillation of saccharine liquids which have undergone alcoholic fermentation. Spirits of wine means rectified spirit of a strength of 43 degrees over proof and upwards. By rectified spirit is meant spirit rectified at a licensed rectifier's premises. Proof spirit, which is the standard spirit of the United Kingdom, is legally defined (58 Geo. III. c. 28) as a spirit which at 51° F. weighs exactly twelve-thirteenths of the weight of an equal volume of distilled water. The strength of proof spirit at 60° F.—the temperature now generally employed for official calculations—is now officially regarded as being equal to a spirit containing 57.06% by volume, or 49.24% by weight, of absolute alcohol. Spirit which possesses a greater or smaller alcoholic strength than proof is described as being so many degrees over or under proof, as the case may be. The strength is legally estimated by Sykes’s hydrometer, which was legalized in 1816 by 56 Geo. III. c. 40. The degrees “over” or “under” proof as ascertained by Sykes’s hydrometer are arbitrary percentages by volume of a standard spirit contained in the spirit under examination. This standard spirit is proof spirit. For example, by a spirit of strength 75.25 degrees over proof (absolute alcohol) is meant a spirit of such a strength that 100 volumes of the same contain an amount of spirit equal to 175.25 volumes of the standard (proof) spirit. A spirit of 25 degrees under proof is one of which 100 volumes contain only as much alcohol as do 75 (i.e. 100−25) volumes of proof spirit. According to Nettleton, “proof spirit” would appear to be the outcome of an attempt to produce a mixture of pure alcohol and water, containing equal weights of the constituents. The term “proof” probably originated from a rough test for spirituous strength formerly employed, which consisted in moistening gunpowder with the spirit and applying a light. If the gunpowder did not ignite, but the spirit merely burned away, the spirit was regarded as being under proof, i.e. it contained so much water that the gunpowder became moist and refused to deflagrate. The basis of the standard of other countries is almost invariably the unit volume of absolute alcohol, the hydrometers, or rather" alcoholometers—such as those of Gay-Lussac and of J. G. Tralles—employed indicating the exact quantity of alcohol in a mixture at a standard temperature, in percentages by volume. In the United States the term “proof” is also employed, American proof spirit being a spirit which contains 50% of alcohol by volume at 60° F. American “proof” spirit is, therefore, considerably weaker than British "proof." Allowing for this difference and also for the fact that the American standard gallon (which is really the old English wine-gallon) is equal to 0.833 of an imperial gallon, the American “proof” gallon roughly equals 0.73 of a British proof gallon.
| Fig. 1.—Ancient form of Still, used in China. | Fig. 2.—Ancient form of Still, used in Central India. |
Historical.—The art of distillation, more particularly the preparation of distilled alcoholic fluids for beverage and medicinal purposes, is of very ancient origin. It is probable that the art of making spirits was well known many centuries before the advent of the Christian era. According to T. Fairley, the Chinese distilled liquor “sautchoo” was known long before the Christian era, and "arrack" was made in India at a date as remote as 800 B.C. Aristotle in his Meteorology (lib. ii. ch. ii.) says “Sea-water can be rendered potable by distillation: wine and other liquids can be submittedto the same process. After they have been converted into humid vapours they return to liquids.” There is, on the whole, little doubt that spirits were manufactured in Egypt, India, China, and the Far East generally, as far back as 2000 B.C. Figs. 1–4 (from Morewood’s Inebriating Liquors, published in 1838) show very ancient forms of stills in use in China, India, Tibet and Tahiti.
Fig. 3.—Ancient form of Still, used in Tibet.
As far as can be ascertained the oldest reference to the preparation of a distilled spirituous liquor in the British Isles is contained in the “Mead Song” written by the Welsh bard, Taliesin, in the 6th century.He said “Mead distilled I praise, its eulogy is everywhere,” &c. (Fairley, The Analyst, 1905, p. 300). The same authority points out that the knowledge of distillation in the
Fig. 4.—Ancient form of Still, used in Tahiti.
British Isles was independent of the art of distillation from wine, seeing that distillation from grain was known in Ireland before the art of making wine came to Europe. An Irish legend states that St Patrick first taught the Irish the art of distillation; but, however that may be, it is certain that at the time of the first English invasion of Ireland (1170–72) the manufacture of a spirit distilled from grain {i.e. whisky) was known to the inhabitants of that country. It is probable that grain spirit was first prepared in the Far East, inasmuch as a spirit distilled from rice and other grains was made in India before the Christian era. The establishment of regular distilleries in England appears to date back to the reign of Henry VIII., and they are said to have been founded by Irish settlers who came over at that time. It is difficult to obtain exact data
regarding the origin of the distilling industry in Scotland, but, as Fairley says, it is probable that distilling was carried on there almost as early as in Ireland. At the time of the Tudors Scotch whisky was held in great repute in England. The production of a spirit from wine (i.e. brandy) appears to have been known in the 9th century; but, according to Morewood, the first attempt at the distillation of wine in France is attributed to Arnaldus de Villa Nova, in the 13th century. As a manufacturing industry the distillation of brandy in France began in the 14th century. The history of the spirit industry in the United Kingdom is, as Nettleton has well pointed out, inseparably connected with questions of taxation. According to one writer, it was not until 1660 that an excise duty was first imposed on the consumption of spirit (" aqua vitae ") in the United Kingdom, but it appears probable that the industry generally was taxed in one form or another in the reign of Elizabeth, when it first began to assume considerable importance. No record, however, of the quantity of spirit on which duty was charged was kept until 1684. In that year duty was paid on 527,492 gallons. At the end of the century the consumption reached 1,000,000 gallons, and in 1745 it had risen to a quantity equivalent to about 5,000,000 gallons at proof. Cromwell imposed a tax of 8d. per gallon, but this was soon lowered to 2d. In 1751 a tax equivalent to is. per proof gallon was imposed, and in 1766 this was further increased to 2s. After this various changes and complex methods of assessing the duty were introduced (see Nettleton, The Manufacture of Spirit, Marcus Ward, 1893) until, in more modern times, a more rational and uniform system was introduced.
Conditions of Manufacture.—The principal act now governing and regulating the manufacture of spirits and the working of distilleries in Great Britain is the Spirits Act of 1880. The provisions of this and of the other acts bearing on the subject are exceedingly numerous and complicated, and, therefore, only a few of the chief points can be set forth here, so that an adequate appreciation may be gained of the arduous and rigid conditions under which the spirit manufacturer is, in order to ensure the safeguarding of the revenue, constrained to carry out his operations. A distillery must not, without permission, be carried on at a greater distance than half a mile from a market town, nor may it be situated within a quarter of a mile from a rectifying establishment. A distiller must give notice of the erection of new plant or apparatus, of the time of brewing, of the removing of sugar from store or of yeast from wort or wash, of the making of " bub," of the locking of the spirit receiver supply pipe, &c. He may use any material he pleases, provided that the gravity of the wort can be ascertained by the saccharometer, but he may not brew beer nor make cider, wine nor sweet wines. When the worts are collected in the wash-back (fermenting vessel) a declaration must be made at once, specifying the original gravity and the number of dry inches remaining in the back. At the end of every distilling period a return must be delivered showing (a) the quantity of brewing materials used, (b) the quantity of wort or wash attenuated and distilled, (c) the quantity of spirits produced at proof -strength, and (d) the quantity of “feints” remaining. Regulations also exist with regard to the amount of " bub " (see below) that may be added to the worts, or the quantity of yeast that may be removed from the wash, concerning the time permissible for drawing over spirit at the various stages, as to placing in and taking spirit out of store, the number and size of vessels, the locking of the latter, and the painting of the pipes carrying various liquids in certain colours. The methods of assessing the duty are three- fold, and whichever of these methods gives the highest return is the one adopted. The first is the " attenuation charge." This consists of levying the charge due on one gallon of proof spirit for every hundred gallons of worts collected and for every five degrees of attenuation observed, the latter being calculated by taking the difference between the highest specific gravity of the worts and the lowest gravity of the wash after complete fermentation. Secondly, there is the " low-wines charge," calculated upon the bulk-quantity at proof-strength of the low wines produced by the distillation of the wash; and lastly, the " feints and spirits charge." This is the method usually adopted, as it generally gives the highest results; it is assessed on the number of bulk gallons at proof of the feints and spirits produced by the final distilling operations. The duty, which was fixed at 10s. per proof gallon in i860, remained at that rate until 1890, when an addition of 6d. was made, but a further increase to the like amount made in 1894 was remitted in the next year owing to the unsatisfactory results obtained. The rate remained at 10s. 6d. until 1900 when it was raised to us., a further increase being made in 1909–1910.
Legally, the word “spirit” implies spirit of any description, and all liquors, mixtures and compounds made with the same. In the same way plain spirit is any British spirit which has not been artificially flavoured, and to which no ingredient has been added subsequent to distillation.
The extremely severe and inelastic provisions of the acts governing the manufacture of spirit in the United Kingdom have proved to be a very serious impediment to the development of the spirit industry on modern lines, and have placed the British manufacturer at a considerable disadvantage as compared with his foreign competitors. There is little doubt that the enormous revenue derived from the spirit industry could be adequately safeguarded in a manner more consistent with the development of the industry on sound commercial and technological lines than it is at present.
Production and Consumption.—The production of spirit in the United Kingdom amounted in 1907 to roughly 50,000,000 proof gallons, the consumption to a gallon per head of population. In the decade 1880–1890 the quantity of spirits distilled remained practi- cally stationary at about 40,000,000 gallons, but during the ten years 1890–1900 there was a rapid increase, the maximum being attained in 1898, when nearly 64,000,000 gallons were produced. A point had then been reached at which the production had considerably outstripped the consumption, due in part to the desire of the spirit trade to meet the increased demand for “matured” spirits, and in part to the fact that an excessive amount of capital had, owing to the increased popularity of Scotch whisky, been attracted to the distilling industry. This over-production led to a vast increase in the quantity of spirit remaining in warehouse. In 1906 production and consumption were about equal, and the quantity of spirit in warehouse represented roughly a five years' supply.
The following figures regarding production, consumption, duty, &c, need no explanation:—
United Kingdom
1. Statistics regarding Home-made Spirits.
The importation of foreign potable spirits into the United Kingdom has fallen off materially since 1870–1875, during which period it stood at 16,000,000 to 17,000,000 gallons. This is chiefly due to the decreased consumption of brandy, and, to a smaller extent, to the diminishing importance of rum and other foreign spirits. The most remarkable change in this connexion is in the case of foreign methylated spirit. At onetime (1891) the quantity of this article imported ​
2. Statistics regarding Imported Spirits.
was almost equal to the amount manufactured in the United Kingdom, the figures being 1,995,782 gallons for the home produce and 1,456,108 for the foreign. For various reasons—chiefly owing to the surtax of 4d. per gallon on all foreign spirit—the quantity imported has gradually dwindled away, and at the present time is practically negligible. The principal spirit-producing countries are Russia and Germany, the United States coming next, and then France, Austria and the United Kingdom in succession, followed by Hungary, Holland and Belgium. The following are the figures for 1905:—
| | Proof gallons. |
| Russian Empire | 161,366,000 (1904) |
| Germany | 146,014,000 |
| United States | 125,042,000 |
| France | 160,584,000 |
| Austria | 55,682,000 |
| United Kingdom | 48,520,000 |
| Hungary | 40,216,000 |
| Holland | 13.552,000 |
| Belgium | 11,924,000 |
If we except Canada and the Cape (which make roughly 6,000,000 and 1,500,000 gallons respectively), the production of the British Empire, apart from the United Kingdom, is very small. British Guiana exports 3,000,000 to 4,000,000 and Jamaica about 1,500,000 gallons of rum.
With regard to the consumption in gallons per head, Denmark stands first with 2.4, then follows the Austro-Hungarian Empire, with 1-98, Germany with 1.43, Holland with the same figure, France with 1-37, Sweden with 1.36, the United States with 1.26, Belgium with I -10, and last the United Kingdom with 0.91. The consumption in Russia is about equal to that of the United Kingdom. The figures given are for the year 1905. In the British colonies Western Australia comes first with a consumption per head of 1.33 gallons; and then in order Queensland 1.32 gallons; Canada 0.94 gallon; New South Wales 0.77 gallon; New Zealand 0.73 gallon; Victoria 0.64 gallon; the Cape 0.68 gallon, and South Australia 0.47 gallon. Of the spirits distilled in the United Kingdom, Scotland produces roughly one half, England and Ireland about one quarter each. Although the number of distilleries in England and Ireland has varied but little of recent years, the number in Scotland increased from 120 in 1880 to 161 in 1899. In 1906 the actual numbers were—Scotland 150; Ireland 28; England 8. The apparent anomaly between the number of distilleries and the quantity of spirit produced in different parts of the kingdom is explained by the fact that the great majority of the distilleries in Scotland and Ireland are small, pot-still distilleries, whereas the English works are all of considerable capacity. It is difficult to arrive at any satisfactory figure with regard to the amount of capital invested in British and Irish distilleries, but it probably exceeds twenty millions.
Illicit distillation has almost ceased to exist in Great Britain, but in Ireland the number of annual seizures under this heading is still considerable. In 1906-1907, out of a total of 974 detections and seizures, 968 were in Ireland.
The spirit produced in the United Kingdom is made almost exclusively from malt, unmalted grain (chiefly maize, rye, barley, wheat and oats) and molasses. The relative proportion of malt to unmalted grain has shown a slight tendency to increase during the past twenty years, but the quantity of molasses employed has increased very largely in the same period, owing mainly to the fact that home-made spirit has largely displaced the foreign article for several industrial purposes and particularly for methylation. The estimated quantities of the various materials employed in 1883 and 1906 respectively were as under:—
| Year. | Malt (quarters). | Unmalted grain (quarters). | Molasses and sugar (cwt.). |
| 1883 | 859,363 | 1,054,081 | 165,529 |
| 1906 | 1,151,199 | 1,090,286 | 985,808 |
With regard to the materials employed in the manufacture of spirits in France, roughly 80-90% now consist of maize (and other starchy substances), beetroot and molasses, whereas in 1840 nine- tenths of the alcohol produced was derived from the grape and other fruits. This change is due in part to the ravages of the oïdium disease (1850–1857) and the phylloxera (1876–1890), which destroyed an immense number of vines, but chiefly to the increased demand for commercial spirit in the arts and manufactures, and also to the improved methods for obtaining a high-class spirit from practically any starchy or saccharine material. In 1905 the number of alcohol units (the unit = 1000 hectorlitres of pure alcohol) distilled from maize and other starchy materials was 589, from molasses 516, from beetroot 1002, from wine, cider, lees and fruits 499. In Germany roughly 75% of the spirit manufactured is derived from potatoes. In 1905 the total spirit distilled amounted to 3786 units (of 1000 hectolitres of pure alcohol), of which 2877 units were obtained from potatoes, 765 units from grain and 1 44 units from molasses and other material. In Russia spirits are distilled chiefly from potatoes and rye, in the United States from maize.
Manufacture.—The manufacture of spirits consists broadly in converting starchy or saccharine matter into alcohol, the latter product being subsequently separated, concentrated and rectified. When spirits are made from a purely saccharine material the process of conversion into alcohol is a relatively simple one, but where farinaceous raw products are employed it is primarily necessary to transform the starch contained in them into sugar. The main varieties of spirits manufactured from sugar, or from sugar-containing materials, are:—
Sugar-derived Spirits :
| Raw Material. | Product. |
| Wine. | Brandy. |
| Sugar-cane and cane molasses. | Rum. |
| Beetroot; beet molasses. | Industrial alcohol. |
Occasionally wine, cider, perry and cane molasses are also employed for making either plain potable spirit or industrial alcohol, and at times cane molasses (chiefly obtained from Cuba and the West Indies) are used somewhat extensively in England for the manufacture of plain spirit. Occasionally, also, plain potable spirit is derived from beets, but rarely from beet molasses, the spirit derived from the latter being somewhat difficult of rectification.
The chief spirits derived from starchy materials, and their corresponding raw materials, are as follows:—
Starch-derived Spirits :
| Raw Material. | Product. |
| Cereal grains: chiefly barley, rye,   oats, wheat and maize. | Whisky, “corn brandy,” “vodka,”  plain spirit; industrial alcohol. |
| Potatoes | Industrial alcohol. |
A. Spirits Derived from Saccharine Materials.—The manufacture of the finer brandies, such as those of Cognac, is, as far as the processes involved are concerned, by no means a complex matter. The excellence of this class of spirit is due mainly to the character of the wine employed Brandy. and to the great experience of the distillers in selecting and blending the raw materials and finished products. The character of the wine is, of course, chiefly due to the peculiar soil and climatic conditions, and in some degree to the methods of cultivation. The latter, it may be added, have since the reconstitution of the Charente vineyards subsequent to their partial destruction by the phylloxera (see Brandy) been much improved. In the pre-phylloxera days the vineyards were planted and cultivated in a very rough and ready fashion, without any attempt at regularity of planting. The result was that the vines spread practically unrestrained in every and any direction. In consequence there was a great irregularity of growth, feeble and hardy plants being found side by side, and the yield was poor. In vineyards constructed in the modern style the vines are planted in regular rows, and the bushes are, with a view to obtaining regular and rapid ​ripening, methodically supported by wire. The wines produced by the Charente vineyards are of a light(white) character and possess no marked "bouquet," but they nevertheless produce a spirit of a peculiarly fine and delicate character. It is remarkable that the fuller and more aromatic wines of the Gironde and of Burgundy, for instance, are not so suitable for the manufacture of brandy as the relatively poor growths of the Charente. The apparatus employed for the distillation of the fine Cognac brandies is generally of a very simple pot-still type. Fig. 5 depicts the still-room of a Charente distillery
Fig. 5.—Old Cognac Pot-still.
Fig. 6.—Modern Cognac Pot-still. (Martell & Co.)
of former times, and fig. 6 shows one of Messrs Martel's distilleries in Cognac, equipped on modern lines. It will be seen that, in principle, there is very little difference between the two sets of plant, the reason being that experience has shown that for wines producing the finest brandies, the simplest form of still is also the best. For the distillation of wines not of the highest quality (from the brandy distillers' point of view) more complicated apparatus is employed, as the spirit from these wines must be more highly rectified than is the case with the finest brandies. Broadly speaking, it may be said that the type of still is suited to the production in the most economical manner of the best spirit to be obtained from the wine of a particular district. In Cognac, brandy is generally, but not universally, made by the "brouillis et repasse" system, this being a double distillation in a simple pot-still. The stills are (compared with whisky pot-stills) very small, holding roughly one hundred gallons, and the distillation is conducted very slowly and carefully, lasting about eight hours. Sometimes the whole of the spirit is collected in one receiver (corresponding to the low wines of Scotch whisky), but frequently the "brouillis," as the results of the first distillation are termed, are divided into several fractions. The "brouillis" which contain about 25 to 35% of alcohol are redistilled, this second distillation being called the "bonne chauffe" or "repasse." The first runnings—which vary in quality according to the quality of the wine, the manner of heating, &c.—are termed "produit de tete" or "tetes," and are separately collected and mixed with the "brouillis" of the following operation. The spirit which next comes over (starting at a strength of about 80% and running down to about 55%) is the "cœur," and as a whole, marks roughly 66 to 70% of absolute alcohol by volume. The residue in the still is then run down to water, and the spirit so obtained, which shows 20 to 25%, is called "seconde," and is either mixed with a fresh charge of wine cr rectified separately, the stronger portion being mixed with the "brouillis," the weaker with a charge of wine (see Brandy).
There are two main kinds of rum, namely, Jamaica rum and rum of the type prepared principally in Demerara and Trinidad (see Rum). There are two varieties of Jamaica rum (a) the common clear rum, and (b) flavoured, or "German" rum. (a) "Common clear" rum is prepared Rum. from a mixture of sugar-cane molasses, "skimmings" (the scum from the boiling cane juice) and "dunder," this last name being given to the spent lees from previous distillations. Previous to use the "skimmings" are subjected to acid fermentation either alone or in conjunction with "trash" (crushed cane). The wort, which on the average contains about 10 to 15% of sugar, ferments very slowly, owing to the fact that very little yeast—the latter being derived from the cane rind—is present. Roughly five to ten days are occupied by this operation. At first the fermentation is mainly alcoholic, but it rapidly assumes an acid character, owing to the presence of a great number of acidifying bacteria derived from the "dunder" and "skimmings." The, distillation of the fermented wort is carried out in pot stills heated by fire or steam, either of a simple type or provided with rectifiers. In the former case two distillations are necessary, the first resulting in the production of a weak alcoholic liquid termed "low wines," the second, which consists in a rectification of the low wines, producing "high wines" or strong rum. The other type of still is provided with two rectifiers, which are interposed between the still and the condensing worm. These are charged with low and high wines respectively. The first runnings of the still (25 to 40 o.p.) constitute the rum proper, the next fraction the high wines, and the final distillate the low wines. (b) Flavoured or "German" rum is prepared from the same materials as the "common clear" variety, with the addition of "acid" and "flavour." "Acid" is obtained by acidifying fermented cane juice by means of cane "trash" and refuse from the wash backs. "Flavour" is prepared in much the same way as "acid," except that "dunder" sediment is also added. The fermentation, which is to a very great extent bacterial, results in the formation of large quantities of acid, including much butyric acid and compound esters. The distillation of "flavoured" rum is carried out in much the same manner as that of the "common clear." The manufacture of "Demerara rum" is differentiated from that of the Jamaica varieties mainly by the fact that the fermentation in the former case is practically purely saccharomycetic (i.e. yeast), whereas the latter is largely schizomycetic (i.e. bacterial). For the distillation of the Demerara rums, which are much lighter in flavour than the Jamaica varieties, stills of the "patent" (see below) or rectifying type are frequently employed (see Rum and Arrack).
For the manufacture of industrial spirit from saccharine materials see below, under Industrial Alcohol.
B. Spirits Derived from Starchy Materials.—The manufacture of spirit from saccharine materials is, as we have seen, a relatively simple operation, the sugar being transformed into alcohol by fermentation, and the latter then distilled off. To convert starchy matter into alcohol is a much more complicated matter. To the operations necessary for the transformation of sugar into spirit, must, in the case of starchy materials, be added that of converting the starch into sugar. This is accomplished either by the action of a diastatic ferment, such ​ as that present in malted grain (see Brewing) or secreted by certain living organisms, or by an acid such as sulphuric acid. The latter process is little employed at the present time. The materials employed by the distiller, and the methods of preparation and treatment to which they are subjected before and after entering the distillery, are in some respects similar, in others materially different, from those employed by the brewer. The materials most frequently employed are maize, rye, barley malt, raw barley, oats, wheat and potatoes. Comparing the main operations (apart from the actual process of distillation) of the brewer with those of the distiller, it is true that these are identical in the sense that they consist in the conversion of starch into sugar and of the latter into alcohol; but whereas the object of the brewer is to produce beer, of which alcohol forms only a relatively small proportion, the distiller, broadly speaking, desires to produce alcohol, and it is this fact which is responsible for the differences alluded to above.
Distillery Malting.—Where malt is employed as the main raw material, as, for instance, in the case of Scotch pot-still whiskies, and also, but to a minor degree, in Irish pot-still whiskies and patent-still whiskies, the process of preparation does not, except in some specific particulars, differ very widely from that used in making brewer's malt (see Malt). With regard to the barley employed for this purpose, certain qualities which are of the greatest importance to the brewer, such as the nature of the husk, colour, and friability of the starch, are of little interest to the distiller, and providing that the grain is sound and that it contains a high percentage of starch and malts as well, it will pass muster as an average distillery material. It is usual to give barley intended for patent-still work a rather longer period in the steep and on the floors than in brewery malting, and it is well to treat the steep-water with some antiseptic, preferably lime, as the distiller has not the opportunity of lessening the dangers of bacterial infection at subsequent stages which is afforded to the brewer by the boiling and hopping of the wort. In distilleries where barley malt is not used as the main raw material, but mainly or chiefly as a diastatic agent (for instance, in potato and maize distilleries on the continent of Europe), the so-called “long” malt process is widely employed. This consists essentially in subjecting the grain first to a somewhat lengthy steep (until the increase in weight due to the absorbed water is about 40 to 45%), and secondly to a very prolonged “flooring” at a moderate temperature, great attention being paid to the conditions of ventilation and humidity. It was formerly believed that the germinating barley grain attains its maximum of diastatic power after a very short period, and that when the acrospire is three-quarters “up” and the rootlets say one and a half times the length of the grain, the malt is ready for removal from the floor. M. Delbruck, Hayduck and others have, however, shown that this is not the case, and the practical results obtained by adopting the twenty days’ “flooring” period (and its attendant conditions) have amply confirmed the scientific researches on this subject.
Hayduck has shown that the relative diastatic strengths of " short " (seven to ten days) and " long " (twenty days) malt are, (1) for heavy barleys as 100: 128-5 (average), (2) for light barleys as 100: 160-5 (average). In contradistinction to the brewer (who can only use it on exceptional occasions and for special purposes), the distiller prefers, whenever this is feasible, to use green malt rather than kilned malt. One of the principal objects of kilning brewing malt is to restrict the diastatic power; but this is the very factor which the distiller desires to preserve, as the green malt possesses roughly twice the diastatic activity of high kilned malt. It is obvious that the distiller, who regards his malt merely as a starch-converting agent, will, ceteris paribus, use as little kilned malt as possible. The malt whisky distiller cannot, however, use green malt, as he relies to a great extent on the kilning process for the development of the peculiar flavour characteristic of the article he produces. Moreover, it is frequently difficult during hot weather to obtain a satisfactory green malt supply, especially as the latter will not bear carriage for any distance, and distillers who make pressed yeast (commonly called “German” yeast) find that a proportion of kilned malt is necessary for the satisfactory manufacture of this article. When the distiller is unable to use green malt he will, by preference, use a malt which has been kilned at as low a temperature as possible. Under these conditions the kilning is little more than a drying operation, and the temperature is rarely raised above 130 F.
Although green or low-dried barley malt is the saccharifying agent usually employed both in the United Kingdom and on the continent of Europe, malts prepared from other cereals are not infrequently employed for this purpose. According to Glaser and Moransky the relative starch-transforming capacities of the various malted grains, taking barley as the unit, are as follows:—
| Barley malt | 1.00 |
| Rye malt | 0.93 |
| Wheat malt | 1.08 |
| Oat malt | 0.30 |
| Maize malt | 0.28 |
Oat malt, notwithstanding its low transforming power, possesses certain advantages, inasmuch as it is easily and rapidly prepared, it acts very quickly in the mash tun, and its diastatic power is well maintained during fermentation. Rye is best malted in conjunction with a little barley or oats, as it otherwise tends to superheat and to grow together in a tangled mass.
Distillery Mashing.—Distillery mashing, although outwardly very similar to the process employed in brewing, differs very widely in some important particulars. In brewing all the necessary fermentable matter is formed from the starch by the mashing operation. The wort so obtained is then hopped and sterilized. This method of working, however, cannot be adopted by the distiller. The brewer must have a certain proportion of dextrinous, non-fermentable carbohydrate matter in his wort; the distiller, on the contrary, desires to convert the starch as completely as possible into fermentable, that is, alcohol-yielding, material. This result is obtained in two ways: first, by mashing at low temperatures, thus restricting the action of the diastase less than is the case in the brewer's mash; and, secondly, by permitting the diastatic action to continue during the fermentation period. Low temperature mashing alone will not have the desired effect, for part of the dextrinous bodies resulting from diastatic starch-transformation are not further degraded by diastase alone, but are rendered completely fermentable by the combined action of diastase and yeast. Hence the distiller is unable to boil, that is, to sterilize his wort, as he would thereby destroy the diastase entirely. In this he is at a serious disadvantage compared with the brewer, as an unsterilized wort is very liable to bacterial infection. The latter danger prevents the distiller from taking full advantage of the benefits of low-temperature mashing, and he is obliged to heat his mash to a temperature which will, at any rate, be a partial safeguard against the bacterial evil. The method employed varies according to the nature of the mash and the quality of the spirit that it is desired to obtain, but in principle it consists, or should consist, in bringing the mash as rapidly as possible to the temperature of maximum saccharification, keeping the whole at this point for some little time, then heating to the temperature of maximum liquefaction, and subsequently to as high a temperature as is consistent with the thickness of the mash and the preservation of sufficient . diastase for the fermenting period.
The Fermenting Operations.—The conditions and methods of distillery fermentation vary considerably, and in some respects radically, from those employed in the brewery. In order to obtain the maximum alcohol yield the distiller is obliged to work with unsterilized wort, and at relatively high temperatures. The necessity for the former condition has already been explained, but the latter is due to the fact that the optimum working capacity of distillery yeast is reached at a temperature markedly above that most favourable to brewing types. Apart from this, if the distiller worked at brewing temperatures the ​ brewing yeasts would predominate, and these produce less alcohol than the distillery types. Thus at 75° F. (and above) distillery yeasts tend to predominate. The conditions of fer- mentation which are more or less forced upon the distiller are unfortunately also very favourable to the development of bacteria, and if special methods are not adopted to check their development, the result would seriously affect not only the quantity but also the quality of alcohol produced. The micro- organisms chiefly to be feared are those belonging to the class of fission fungi (schizomycetes), such as the butyric, the lactic, the mannitic, and mucic ferments.
Souring.—It has long been known to practical distillers that in order to avoid irregular (bacterial) fermentations it is necessary either to let the wort " sour " naturally, or to add a small quantity of acid (formerly sulphuric acid was frequently employed) to it before pitching with yeast. The reason for this necessity was until recent times by no means clear. It has, however, now been demonstrated that a slightly acid wort is a favourable medium for the free development of the desirable types of distillery yeasts, but that the growth of brewery yeasts, and especially of bacteria, is very much restricted, if not entirely suppressed, in a " soured " liquid. The acid which is the result of a properly conducted souring is lactic acid, formed by the decomposition of the sugar in the wort, by bacterial action, and according to the equation C$_6$H$_{12}$0$_6$ = 2C$_3$H$_6$O$_3$.
For various reasons (one being that in order to restrict the lactic fermentation when sufficient acid has formed it is necessary to heat the soured liquid to a higher temperature than is desirable in the case of the main wort) it is inexpedient to allow the souring process to take place in the main wort. It is usual to make a small mash, prepared on special lines, for the production of the "bub" (German Hefegut), as the soured wort is termed. This is allowed either to "sour" spontaneously, or, better, is inoculated with a pure culture of B. acidificans longissimus, which for this purpose is undoubtedly the best variety of the lactic acid bacteria. The optimum developing temperature of this organism is about 104° F., but it is better to keep the wort at 122 F., for at the latter temperature practically no other bacteria are capable of development. When the lactification is completed the wort is raised to 165° F. in order to cripple the lactifying bacteria—otherwise souring would go on in the main fermentation—and after cooling to the proper point it is pitched with yeast. When a good crop of the latter is formed the whole is added to the main wort. The beneficial effects of souring are not due to any specific action of the lactifying bacteria, but purely to the lactic acid formed. It has been found that excellent—and in some respects better—results can be obtained by the use of lactic acid as such in place of the old souring process. Some success has also attended the introduction of hydrofluoric acid and its salts as a substitute for lactic acid. Hydrofluoric acid is poisonous to bacteria in doses which do not affect distillery yeasts, and the latter can be cultivated in such a manner as to render them capable of withstanding as much as 0.2% of this acid. Bacteria, apparently, cannot be “acclimatized” in this fashion. Worts treated with hydrofluoric acid produce practically no side fermentation, and it seems a fact that this substance stimulates diastatic action, and thus permits of the use of relatively low mashing temperatures. The yeast employed in British and Irish pot-still and in some patent-still distilleries is still generally obtained from breweries, but it is now generally recognized that—at any rate for the production of industrial alcohol and for " plain " spirit—a special type of yeast such as the so-called " German " yeast, a good deal of which comes from Holland, but which is now also produced in the United Kingdom on a considerable scale, is desirable in the distillery. This variety of yeast, although closely allied botanically to that used in brewing (belonging as it does to the same class, namely Saccharomyces cerevisiae), is capable of effecting a far more rapid and far more complete fermentation than the latter. Probably the most widely known and best "pure-culture" distillery yeast is the one called " Species II," first produced in the laboratories of the Berlin Distillers' Association. The optimum working temperature of distillery yeast is at about 81.5° F.; but it would be inexpedient to start the main fermentation at this temperature, as the subsequent rise may be as much as 36°. It is, therefore, usual to pitch at about 80° F., and then, by means of the attemperator, to cool down very slowly until the temperature reaches 60° F. The temperature subsequently rises as fermentation goes on, but should not exceed 85° F. Pot-still malt whisky distillers frequently work at somewhat higher temperatures. Fermentation is carried on until practically all the saccharine matter is converted into alcohol; and when this is the case, the gravity of the mash is about equal to, or even a little below, that of water. In malt whisky distilleries the original gravity of the wort is usually from 1.050 to 1.060, occasionally lower, but in grain and potato distilleries the worts are often made up to a higher gravity. In Germany gravities as high as 1.11 are employed; but in that country "thick" mashes, owing to the method employed to raise the duty, are a matter of necessity rather than of choice.
It will be seen from the above that the employment of malt for the purpose of rendering starch soluble and fermentable leaves a good deal to be desired in regard to both the mashing and fermenting operations in the production of spirit. The use of acid for this purpose is also attended by serious drawbacks inasmuch as a considerable proportion of the starch is converted into " reversion " products which are practically unfermentable and thus considerable caramelization is brought about by the action of the acid. In the case of the production of potable spirits such as whisky, where the alcohol yield is not the only object, and the conservation of a specific flavour is desired, it is doubtful whether any material improvement can be made in this connexion, as it seems probable that part of the flavour may be due to some of the circumstances which from the point of view of alcoholic yield alone are most undesirable. For the production of industrial alcohol, however, and for the preparation of spirit intended to be used in compound potable spirits and liqueurs, these difficulties have now been surmounted. The older methods at the disposal of the distiller have of late years been enriched by the discovery that certain micro-organisms (or rather the enzymes contained in them) possess the power of converting starch into sugar, and also of splitting up saccharine materials into the ordinary products of alcoholic fermentation. It is possible to inoculate a sterilized wort with a pure culture of a micro-organism of this description and subsequently with a pure culture of yeast, and so to avoid all undesirable features of the older processes.
Details concerning the practical application of this discovery will be found below under Industrial Alcohol.
Distillation.—The primary object of the distillation of all fermented liquids is that of separating, as far as possible, alcohol from the non-volatile constituents of the wash. In the second place the object of the distiller is to rectify and concentrate the dilute alcoholic liquid obtained by simple distillation. The degree and manner of rectification and concentration vary in accordance with the type of spirit to be produced, and it will be better therefore to discuss methods of distillation under the headings of the different types of spirit concerned.
1. Scotch Pot-still Whisky.—The raw material employed in the manufacture of Scotch pot-still whisky is practically without exception malted barley only. The malt is prepared in much the same way as brewery malt, except that it is generally cured (dried) with a peat, or mixed peat and coke,Whisky. fire. It is to this peat drying that the so-called smoky flavour of most Scotch pot-still whisky is due. The malt is mashed in a mash-tun on lines similar to those obtaining in the brewery, except that the mashing heats are somewhat different. They should be so regulated as to obtain the maximum yield consistent with the preservation of the proper flavour. In order to obtain as high a yield as possible four separate mashes are as a rule made with the same lot of grist, the temperature of each successive mash being somewhat higher than that preceding it. The worts obtained from the first three mashes are united prior to ​fermentation. The liquor from the last mash is used as mashing liquor for the next lot of malt. The general scheme of operations subsequent to mashing is illustrated by fig. 7, which depicts the process at one of Messrs Buchanan’s distilleries.
After the wort has been drawn off it is run through a refrigerator, and then passes to the wash backs. The latter are large wooden vessels corresponding to the fermenting backs of the brewer. Here the wort is pitched with yeast, the fermentation starting as a rule
Fig. 7.—Diagram of Malt-whisky Pot-still Plant. (Messrs J. Buchanan’s Glentaucher’s Distillery, Speyside, N.B.)
at something over 70° F. The maximum temperature attained at some distilleries frequently exceeds 90° F., but in the opinion of the author this is excessive. Fermentation proceeds until the whole of the saccharine matter is converted into alcohol, and when this is the case the gravity of the fermented wort—now termed wash—should be equal to, or a little lower than that of water. The wash from the various wash backs is now collected in the wash charger, which is an intermediary vessel serving for the mixing of the contents of the different wash backs, and also for the purpose of enabling the revenue officer to ascertain the total volume and strength of the wash. In this way he obtains a check on the quantity and gravity of the wort as taken prior to fermentation. From the wash charger the wash passes to the wash still, which is a copper vessel varying in size in Scotland from about 3000 to 8000 gallons. The usual size is about 5000 to 6000 gallons. This still is heated either by direct fire (as shown in the illustration), or frequently by means of a steam jacket or steam coil. The wash still is provided with rakes or chains actuated from outside for the purpose of preventing the solid contents of the wash from being charred. The whole of the spirit is drawn off in one fraction from this still, and is condensed by means of a copper coil cooled by running water. The distillate so obtained is termed "low wines," and the strength is generally about 50 u.p. The next stage in the process is the redistillation of the low wines. This takes place in the low wines still, which is a vessel similar to the wash still, except that it is rather smaller. The distillate from the low wines still is collected in three separate fractions termed respectively and in the order of their collection, (a) foreshots, (b) clean spirit or whisky, (c) feints. The quantity of each of these three fractions collected will vary somewhat according to the nature of the spirit being made, the quality of the material employed, and to other circumstances into which it is not necessary to enter. As a rule the foreshots will be run from the starting of the still down to 25 to 30 o.p. Whisky will be collected from about 25 to 30 o.p. to proof, the remainder, namely the residual fraction, from proof down to water, being feints. In collecting the various fractions the distiller is mainly guided by the alcoholic strength of the spirit coming over, by its flavour, and by its behaviour on mixing with water. It is the object of the distiller to obtain a clean spirit or whisky which gives as little "blueing," that is opalescence, when mixed with water as possible. The foreshots and feints are run into the feints receiver, the whisky to the spirit receiver. The distiller is able to divert the spirit coming over into either of these receivers at will by means of a movable arm contained in the spirit safe. The spirit safe is a closed vessel containing two or more broad funnels each of which is connected with a pipe leading to a feints or spirit receiver as the case may be. The movable arm fixed on to the pipe leading from the condensing coil can be actuated from without by the distiller. In this way the distiller is able to regulate the distillation at will without having access to the spirit. The quality of the spirit coming over is judged by means of the apparatus contained in the sampling safe. This is another closed vessel containing hydrometer jars fitted with hydrometers, and with a water supply. A small part of the spirit coming from the coil passes through this box into the hydrometer jars, where its strength is taken by means of the hydrometers and its behaviour towards water ascertained by mixing with a known volume of the same. The strength of the whisky collected varies at different distilleries, but it is generally from 25 to 30 o.p. The quantity and strength of the spirit are gauged in the spirit receiver by the revenue officer, and the spirit is then run into casks and placed in store. The residue jn the wash still is termed "pot ale" or "spent wash," the residue in the low wines still is termed "spent lees." Both these liquors are run to waste, or where local circumstances make it necessary are destroyed, or modified by means of a purification process. In some cases the solid matter contained is converted into manure. The mixed feints and foreshots contained in the feints receiver are worked up in the subsequent operation, being mixed with the next lot of low wines in the proportion of roughly one third mixed feints and foreshots, and two-thirds low wines. The object of the double distillation as described is in the first place to concentrate the alcohol contained in the wash, and secondly to rectify it. Part of the volatile by-products pass out in the spent wash and spent lees; another part is eliminated by the modification which some of these products undergo during storage in the feints receiver.
2. Irish Pot-still Whisky.—Both as regards the raw material employed and the manner of manufacture, Irish pot-still whisky differs very appreciably from the Scotch variety. There are a few distillers who work with malted barley only, but the great majority employ a mixture of from (generally) 25 to 50% of malted barley and 50 to 75% of a mixed grist of "raw" (i.e. unmalted) rye, wheat, barley and oats. The malt is not peat cured. The distillation is carried out in a type of still radically different from the Scotch pot-still. The stills (of which there are generally three as against two in the Scotch process) are very large, ranging up to 20,000 gallons. A characteristic feature of the Irish pot-still is the great length and height of the "lyne-arm," i.e. the pipe connecting the still with the condensing coil. This lyne-arm generally runs up vertically from the still for a distance of 10 to 20 ft., then horizontally for another 30 or 40 ft., again vertically for 10 to 20 ft., and is then connected to the condenser. The horizontal portion of the lyne-arm lies in a shallow trough fitted with a water supply, and the temperature of the spirit vapours prior to their passing to the condenser may thus be regulated at will. According to the length and height of the lyne-arm and the temperature of the water jacket, more or less of the vapours condense and are carried back to the still by means of a pipe running back from the horizontal portion
Fig. 8.—Diagram of single type of Irish Pot-still Plant. (Messrs John Jameson’s Distillery, Dublin.)
of the lyne-arm to the still. The return pipe is fitted with a cock, which enables the distiller to regulate the return flow. Occasionally there is a further return pipe for the condensing coil, but this is not usual. The result of this form of plant is that it is possible to work up far greater quantities of wash and ​ to obtain a much higher rectification in a single operation than is possible in the case of the Scotch pot-still.
A single type of Irish pot-still plant as employed at Messrs J. Jameson's, Dublin, is shown in fig. 8. It will be noticed that in this case there is no return pipe from the lyne-arm. The method of collection and of working the Irish pot-stills is a great deal more complicated than that described under the Scotch variety. Three stills are employed and strong low wines and weak low wines, strong feints and weak feints are collected, and mixed in varying proportions according to the discretion of the distiller.
3. American Pot-still Whisky.—There are two main varieties of American pot-still whisky, namely, rye whisky, in which rye is the predominant raw material, and Bourbon whisky, in which maize or Indian corn is the chief substance employed. There are different varieties of these whiskies.
“Sour mash” whisky is made by scalding the raw material with pot ale (i.e. the residue left in the stills from the previous operation), then cooling down to mashing temperature and saccharifying by means of malt. The distillation is sometimes carried out with naked fire, but more generally by means of steam which is passed into the wash (termed “beer” in America), either in a free state or by means of a coil, and then collecting the spirit, after condensing and subsequently rectifying by means of a second distillation (termed "doubling"). “Sweet mash” whisky is made by mashing the raw material in the ordinary way by means of malt. The stills generally employed for making whisky by this process contain three compartments situated above one another and connected by means of a curve pipe. Live steam blown into the lower compartment causes the wash to boil. The vapours go up through the curved pipe into the next compartment and so cause the contents of the latter to boil. The vapour from the second compartment then passes up to the third in the same manner. The vapour from the third compartment passes into a vessel charged with low wines, and the vapours so obtained are finally condensed, forming whisky, or “high wines.”
4. Patent-still Whisky.—Scotch and Irish patent-still or "grain" whiskies are manufactured usually with a mixed grist of raw and malted grain, and by means of an apparatus usually termed the “patent,” but more properly called Coffey's still. For the manufacture of patent-still whisky a grist containing generally 25% or more of malted barley is employed. The balance consists of maize together with malted and unmalted rye, oats and wheat, and the mixture of grains employed varies at different distilleries. The mashing takes place as a general rule in an ordinary mash-tun, and calls for no special mention. The fermentation is conducted in much the same way as at pot-still distilleries, except that at some patent-still distilleries where bakers' yeast is made it is conducted on somewhat different lines, the conditions being adjusted so as to suit the propagation of a healthy type of yeast of a particular type. For fermentation of this description it is well recognized that the use of selected or pure yeast is necessary. The fermenting vessels, wash chargers, &c., are much the same as in the pot-still distillery except that they are of much larger size. The "patent" still was invented by Aeneas Coffey in the early part of the 19th century with a view of accomplishing in one operation that which necessitates several operations in the pot-still, of economizing time, fuel, and material, and also of obtaining at will a spirit of a higher purity than that which can be got by the pot-still. It is sometimes stated that the patent still does not produce whisky, but merely plain spirit or alcohol, but as a matter of fact this is not the case. It can be so worked by selecting the proper materials and by running the still in a particular way as to produce an article which is most distinctly a potable spirit of the character of whisky. It can also be employed by altering the proportion of the materials and by running the still differently to produce a spirit which may be used for purposes of methylation, or which may pass through the hands of the rectifier and emerge as plain spirit or alcohol pure and simple. It is, however, quite impossible to obtain from the Coffey still a really plain or silent spirit such as that produced by some of the stills on the continent of Europe; in order to obtain this type of spirit, the product of the patent still is treated by the rectifier in a special rectifying still with charcoal and potash. In certain details the Coffey still has been modified since it was devised by the inventor, but in principle it has been very little altered. Although it does not in some respects compare with some of the modern continental rectifying stills, it must be remembered that it is not made for the purpose of obtaining pure alcohol, and from this point of view it is a remarkable tribute to the ingenuity of Coffey that he should at so early a date have designed so perfect an apparatus.
The still shown in fig. 9 is one of the type designed by Messrs Robert Willison of Alloa for Scotch grain whisky distilleries. The Coffey still is a double still consisting of two adjacent columns, termed respectively the rectifier and analyser. Both columns are subdivided into a number of chambers by perforated copper plates. The main structure is of wood firmly braced with iron. Each compartment communicates with the next by means of a drop pipe standing slightly above the level of the plate and passing downwards into a cup, which forms a water seal or joint. Each compartment is also fitted with a safety valve in case of the plates choking or of the pressure rising unduly. At the beginning of the operation both columns are filled with steam at a pressure of about 5 ℔. The steam at the base of the analyser passes upwards through it, and then to the bottom of the rectifier by means of the pipe B (termed the low-wines vapour pipe), and then up through the rectifier. When both columns are filled with steam the wash is pumped up from the wash charger through the copper pipe A to near the top of the rectifier, which it enters at the point A'. The pipe A runs from the top to the bottom of the rectifier forming a double bend in each compartment, and the wash (contained in the pipe) travels down in a zigzag course until it reaches the base of the rectifier at the point C. From here (still remaining in pipe A) it is pumped to the top of the analyser, where it emerges from the pipe and covers the plate of the top compartment. As there is an upward pressure of steam the wash is not able to pass through the perforations of the copper plate forming the base of the compartment, but collects until its level reaches the top of the first drop pipe. Through this it passes into the cup on the plate below and so out on to the next plate. The drop pipes being trapped by the cups the steam cannot pass upwards through the former. In this way the wash passes through compartment to compartment of the analyser until it reaches the bottom, and then passes out by means of the spent wash siphon. The steam on its passage up through the analyser carried with it the alcoholic vapours and other volatile matters contained in the wash. The alcoholic vapours pass from the top of the analyser to the bottom of the rectifier, and then upwards through the latter from compartment to compartment. In so doing they are gradually cooled by the wash flowing down through the pipe A. This gradual cooling causes the less volatile constituents to condense and so to flow downwards through the column until they reach the base of the rectifier. At a certain point in the upper part of the rectifier (marked S in the illustration) the bottom of the compartment in question is formed not of a perforated plate, but of a stout copper sheet, pierced by a fairly wide pipe, which stands up about two inches above the level of the former. This is termed the spirit plate. It is so placed that the alcoholic vapours condense either on or immediately above it. The alcohol passes out from the spirit plate chamber from one of the two pipes shown in the illustration (either to the spirits or to the feints receiver as the case may be), and is then further cooled, in order to complete the condensation, by means of coils immersed in flowing water, as shown in the illustration. In order to render the condensation still more perfect the upper chambers of the rectifier are fitted with coils through which cold water is passed. The vapours condensed by this fall upon the spirit plate. The vapours which have an appreciably lower boiling-point than ethylic alcohol, such as the aldehydes, together with a large volume of carbonic acid gas derived from the wash, pass out of the top of the rectifier by means of the “incondensible gas” pipe E, and thence to a separate condensing coil. The spirit obtained is of high strength, generally about 64 o.p. The less volatile constituents of the wash, generally termed “fusel oil,” which pass out of the base of the rectifier, are cooled and then passed to the oil vessel. After the apparatus has been worked for some time the fusel oil which floats in a layer on the top of the contents of the oil vessel is skimmed off. The watery layer from the oil vessel, which still contains a little alcohol, is again passed through the apparatus to remove the last trace of the latter. By employing the cold wash to cool the alcoholic vapours much condensing water is saved as compared with the ordinary pot-still apparatus. Conversely, as the hot alcohol vapours heat the cold wash to boiling-point, there is a great economy of coal as compared with the older process.
The distillation is controlled by an operator standing on the platform P. The operator is able by means of the sampling apparatus X to determine the quality and strength of the spirit and of the wash. He is able, by regulating the quantity of steam admitted to the apparatus, by modifying the rate of pumping, and by running ​the spirit either to the spirit or to the feints receiver, as the case may be, to control the strength and quality of the product in much the same manner as does the pot-still distiller.
Fig. 9.—Diagram of a Coffey Still. (Messrs R. Willison & Co., Alloa.)
Industrial Alcohol.—By industrial alcohol is understood spirit which is employed for other than potable purposes. Alcohol is largely employed in the industries and arts, and for domestic purposes. It is chiefly used for the manufacture of varnish, fine chemicals and dye-stuffs, for pharmaceutical purposes, and in the form of ordinary methylated spirit for lighting and heating. Ordinary methylated spirit for domestic purposes is prepared in the United Kingdom by adding 10 parts of wood naphtha and a small quantity of mineral naphtha to 90 parts of strong spirit. This spirit may be employed duty free for any purpose, except that it may not be purified in such a manner as to produce pure alcohol or a potable spirit. Up to the year 1906 British manufacturers were forced either to use this spirit or to pay the full duty if they wished to use any other variety. As a result of the recommendations of the industrial alcohol committee of 1904-1905 the Revenue Act of 1906 contained provisions modifying this undesirable state of affairs. Manufacturers may now use a special "industrial methylated spirit," which consists of alcohol 95 parts and wood naphtha 5 parts, and they may also, under certain conditions and restrictions, employ pure alcohol. It is generally considered that the most satisfactory way of methylating or "denaturing" spirit intended for technical purposes is that which consists in adding one of the ingredients which would ordinarily be used in the course of manufacture, or some other ingredient which does not interfere with the manufacture of the specific article in question. In the year 1906 the total quantity of "industrial methylated spirit" employed in the United Kingdom was 2,041,373 proof gallons. The quantity of pure alcohol employed in the same year was 435,915 gallons; for the same period the total quantity of ordinary methylated spirit produced was 6,055,285 gallons. On the continent of Europe and in America alcohol is used in the industries to a greater extent than is the case in the United Kingdom.
The raw materials generally employed in making industrial alcohol are the sugar beet, and beet or cane molasses, potatoes, maize, rice and similar starchy materials. The manufacture of spirit for industrial purposes in many respects resembles the process for manufacturing potable spirit, but, broadly speaking, it may be said that the raw materials employed need not be of so high a class, and that the main object of the distiller in this case is to produce as high a yield of alcohol as possible. Taste and flavour are secondary considerations, although in the case of industrial alcohol employed for some purposes—for instance, for pharmaceutical preparations—a very fine spirit is required. When beets or molasses are employed for making alcohol, the process is a comparatively simple one. If beets are used the sugar is extracted from them in much the same way as is the case in the manufacture of sugar itself (see Sugar), although in recent years a process for steaming the beets under pressure in much the same way as in the preparation of potato mashes has been employed. The sugar present in the beet and in molasses is not directly fermentable. It is generally rendered so by the addition of a small quantity of mineral acid. The saccharine solution is then pitched with yeast and fermented in the ordinary way. Potatoes, maize, rice and other starchy materials are generally treated under pressure with steam in a close vessel termed a converter. This method entirely disrupts the starch cells, and so renders the starch very readily convertible. When the pressure "cooking" is completed the mash is run out of the converter into the mash tun proper, where it is treated with a minimum quantity of malt at the most suitable temperature. The wort obtained is, after (as a rule) removing a part of the husks and skins by means of special machinery, pitched with yeast and fermented.
We have seen above in the paragraphs dealing with the general features of distillery operations that the method of converting starch into sugar by means of malt possesses very serious ​drawbacks. Of late years a process has been discovered whereby these disadvantages, as far as industrial spirit is concerned, are entirely overcome. It has been known for some time that certain micro-organisms (or rather the enzymes contained in them) possess the power of converting the starch directly into fermentable sugar, and further of splitting up the latter into the usual products of alcoholic fermentation. Among the organisms of this description first known may be mentioned the moulds, Aspergillus Oryzae and Eurotium Oryzae. Later A. L. C. Calmette discovered a mould to which he gave the name Amylomyces Rouxii, which was employed by A. Collette and A. Boidin for producing alcohol on an industrial scale. Since then Boidin has discovered another mould to which he gave the name of Mucor β, which possesses advantages over the other micro-organisms named inasmuch as it works more rapidly and in a more concentrated wort. The amylo process, as this method of producing alcohol is termed, is now worked on a very large scale in many countries. The process consists in inoculating a sterile (mostly maize or rice) mash in a closed vessel with a very small quantity of the spores of the mould, passing filtered air through the liquid for a certain time, thus causing the material to develop very rapidly, and subsequently inducing fermentation by the addition of a pure yeast culture. The mould is of itself capable of fermenting the sugar produced, but it is found that the yeast acts more quickly, and will stand a greater percentage of alcohol, than the former. The whole process occupies about five days. The advantages accruing from operating, as is the case in the amylo process, with sterile worts are enormous, inasmuch as undesirable bacterial and side fermentations are impossible. The quality and yield of the alcohol is, owing to this fact, considerably improved. The fact that no malt is employed leads to a further very considerable economy. The general course of operations in the amylo process may be gathered from fig. 10. The maize or other raw
Fig. 10.—Diagram of the Amylo Process.
material is steeped in the vessels AA with a sufficient quantity of dilute acid to convert the secondary into primary phosphates. When the steeping operations are complete the material passes into the converters BB. After conversion is completed the disintegrated material passes into the vessel C, and thence by means of the pipe D to the fermenting vessels EEE. After fermentation is completed the wash passes to the still F.
It is impossible at present to employ the amylo process in its most satisfactory form in the United Kingdom owing to the fact that it is necessary in order to take full advantage of the process to employ a thick wort, i.e. one from which the husks have not been removed. The gravity of a wort of this description cannot be taken by the saccharimeter prescribed by the spirit Acts, but no doubt this difficulty will in time be overcome. The average yield by the amylo process is from one to one and a half gallons a cwt. of raw material more than is the case with the processes orclinarily employed in the United Kingdom.
Distillation of Industrial Alcohol.—A still intended for the distillation of industrial alcohol should be so devised as to yield a spirit of the greatest strength and purity in the most economical manner. Stills are now constructed which yield in one operation a spirit containing up to 98% of absolute alcohol, and free from all but the merest traces of aldehyde, fusel oil, &c. (foreshots and tailings). An excellent still of this kind is that of R. Uges. He takes advantage of the fact that if a liquid containing 15% of alcohol is boiled, the quantity of fusel oil in the vapour is equal to the amount in the remanent fluid, and that if the percentage of alcohol is less than 15% the amount of fusel oil in the vapour is greater than that in the liquid. It is therefore possible, by working on proper lines, to remove the whole of the fusel from the mash by a single operation. By subjecting the vapours so obtained to a carefully regulated dephlegmation, the fusel oil condenses, together with the steam and a certain proportion of alcohol â€" in practice 15%. By further cooling the liquid so obtained the fusel separates out, and, being specifically lighter, rises to the surface of the watery spirit, and is then easily removed. This form of still is so arranged that any change from the correct temperature necessary for the adequate separation of the concentrated " feints " into two layers is automatically corrected by the admission of more or less cooling liquor to the refrigerating pipe coiled round the dephlegmating column. The " foreshots " (aldehyde, &c.) are removed by submitting the alcoholic vapour passing through the main dephlegmator to further purification. The Ilges apparatus yields three continuous streams of fine spirit, fusel oil, and foreshots respectively.
By-products of Fermentation and Distillation. —The main constituent of spirits is, of course, ethyl alcohol â€" spirit of wine—but all spirits contain small but varying quantities of by-products and it is by these that the character of a spirit is determined. The by-products are mainly formed during fermentation, but are also to a certain extent pre-existent in the raw materials, or may be formed during the operations preceding and succeeding fermentation. The nature of the by-products is complex, and varies sensibly according to the raw materials employed and the methods of malting, mashing, fermentation and distillation.
The by-products may be classified as follows: (a) higher alcohols—usually going under the name of fusel oil; lb) esters; (c) fatty acids; (d) fatty aldehydes and acetals; (e) furfuryl aldehyde; (/) terpene, terpene hydrate and ethereal oils; and (g) volatile bases. The higher alcohols consist of mixtures of fatty alcohols (C n H2â€ž-)-iOH), containing three or more atoms of carbon in which, as a rule, amyl alcohol (C 5 H n OH) predominates. The fusel oil of British pot-still spirits is chiefly composed of amyl and butyl alcohols, whereas in patent spirits propyl alcohol preponderates, that is, in the finished or fine spirit, since the fusel oil separated from patent spirit in the course of distillation consists mainly of amyl and butyl alcohols. Broadly speaking, the higher alcohols present in pot are of higher molecular weight than those in patent spirits. Potato fusel contains a high proportion of isobutyl alcohol, grain fusel of n-butyl alcohol. The acid present in spirits is chiefly acetic acid, but small quantities of other acids are also found. The esters, formed by the interaction of alcohols and acids chiefly during the fermenting and distilling operations, consist almost entirely of fatty acid radicles in combination with ethyl and, to a minor extent, amyl alcohol. Ethyl acetate (acetic ester) is the main constituent of the esters, the others being mainly ethyl valerate, butyrate and propionate. Oenanthic ether (ethyl pelargonate) is one of the characteristic esters of brandy. Furfuryl aldehyde (furfurol) is a characteristic product in pot-still spirits, although it occurs to a greater or less extent in patent spirits according to the degree of rectification. It is probable that the furfural is formed by the splitting up of a part of the pentoses contained in the wort. It was formerly thought that its occurrence in relatively large quantities in pot-still spirits was due to the charring effect of the action of the fire gases on the carbonaceous matter adhering to the bottom and sides of the still, but the author has shown that this is not the case, inasmuch as he has found that spirits distilled by means of a steam jacket instead of direct fire contain quite as much furfurol as those distilled in the old way. Terpene and terpene hydrate are characteristic constituents of grain fusel. Although the ethereal oils appear to play an important part in determining the character of a spirit, too little is at present known of these substances to warrant any closer description.
Effect of Maturing on the By-products.—That potable spirits (excepting, of course, pure alcohol) and wine are greatly improved by age is an undeniable fact, and one that has been recognized for many hundreds, and even thousands, of years. Thus in the gospel of St Luke we have the statement "that no man having drunk old wine, straightway desireth new: for he saith, ​ The old is better.” And again in the Apocrypha, " New friends are like new wine: when it is old, thou shalt drink it with pleasure." There is little doubt that the beneficial effect of age on the character of spirits is due to the changes effected in the character and quantity of the by-products, but the exact nature of these changes is by no means clear. Such improvement as takes place is apparently connected in some way with the free access of air to, or rather the satisfactory ventilation of, the containing vessel ; for spirits preserved entirely in glass undergo relatively little change, either in taste or in chemical composition, whereas cask storage materially affects both these factors.
Concerning the changes which take place during maturation, it was formerly believed that the higher alcohols decreased with age, and that the main reason of the improvement noticeable in mature spirits was due to this fact. The author has, however, shown conclusively that this is not the case, but that on the con- trary the higher alcohols generally increase during maturation. This decrease is not absolute, but only relative, and may be due to the fact that the higher alcohols are less volatile than ethyl alcohol. There is a decided increase during maturation of both the volatile and non-volatile acids. On the whole also the esters and aldehydes generally tend to increase, but not to so great an extent as was formerly believed to be the case. There is, however, a marked decrease in regard to furfurol. The type of cask exercises a marked influence on the course of maturation; and, as regards whisky, spirit stored in a sherry cask undoubtedly matures more quickly than that contained in a plain wood cask. The relative humidity of the cellar in which spirit is stored has a very great effect on the course of maturation. In a very damp cellar the spirit will lose alcohol very rapidly and as a resiilt all those changes which are favoured by these conditions will take place with relative rapidity. On the other hand, in a very dry cellar the loss of alcohol is relatively smaller than that of water (cf. Schidrowitz and Kaye, Joum. Soc. Chem. Ind., June 1905).
Physiological Effects of Spirit By-products.—The nature of the physiological effects produced by the ingestion of spirits varies considerably, not only according to the class of spirit (i.e. whether whisky, brandy, rum, &c.) consumed, but also with its condition (i.e. whether new or old, and so on) ; and there is no doubt that the causation of these phenomena is intimately connected with the nature and quantity of the by-products, to which, as has been already said, the character of the spirit is due. Commenting on a statement in Bailey's Book of Sports to the effect that wine and brandy had a tendency to make a man fall on his side, whisky to make him fall forward, and cider and perry to make him fall on his back, Sir T. Lauder Brunton (Evidence, Spirits Committee, 1891) suggests that these state- ments—if correct—might indicate definite injury to various parts of the cerebellum. Thus, if the anterior part of the middle lobe of the cerebellum is injured, the animal tends to fall forward; when the posterior part is affected, the head is drawn backwards, &c. Brunton is inclined to believe that the varying action of different spirits may be due to the specific action of specific products on the separate nerve centres. Thus the cause of the epileptic convulsions produced by the injection of absinthe has been traced to the specific action of the chief flavouring agent of this liqueur.
In view of the doubt which modern research has thrown on the older theories, to the effect that the improved character of a mature, as compared with a new, spirit is due to the decrease in the quantity of the higher alcohols (i.e. the fusel oil), a discussion of the specific action and relative toxicity of these bodies may seem superfluous, more especially as they occur in quantities which are apparently incapable of producing serious effects. As, however, there is considerable reason for believing that the higher alcohols do influence, at any rate, the flavour of the spirit a brief reference to their physiological action seems to the author not out of place. Broadly speaking, the toxicity of the fatty alcohols increases with their molecular weight. Dujar-din-Beaumetz and Audige found that the lethal dose for dogs was 5–6 grammes per kilo-body-weight for ethyl (ordinary) alcohol; 3·75 grammes for propyl alcohol; 1·8 grammes for butyl; and 1·5 grammes for n-amyl alcohol. It is interesting to note that the experiments of these investigators were conducted chiefly with the pig, as the digestive organs of the latter animal are very similar to those of man, and also because the pig is apparently the only animal which willingly takes alcohol with its food. With regard to the action of spirits generally, the investigators named above found that the digestive organs of pigs fed for thirty months with pure alcohol alone were not affected, whereas the animals treated with similar quantities of imperfectly purified spirit (whether derived from the beet, the potato or from grain) suffered considerably.
Of late years the attention of pharmacologists has been directed to furfurol especially, and the aldehydes generally, as being, at any rate in part, the cause of the unpleasant after or by-effects of certain spirits. Curci and others showed that furfurol in certain doses is poisonous to animals. Brunton and F. W. Tunnicliffe demonstrated a poisonous action of this substance upon man, and, comparing the after-effects upon animals of spirits containing, and freed from, aldehydes, found certain important physiological differences between them. I. Guareschi and A. Mosso first drew attention to the fact that numerous samples of reputedly pure spirits contained small quantities of certain volatile bases of an alkaloidal nature. They apparently belong to the pyridine series, and have effects similar to those of strychnine. E. Bamberger and Einhorn discovered the presence of pyridine, dimethylpyridine and other bodies belonging to the same series, in commercial fusel oil. It is possible that the existence of these volatile bases in spirit may have given rise to the—on the face of it absurd—suggestion that tar bases have been used as adulterants of whisky. It appears likely that the formation of the bases in question is connected with the use of inferior or decaying grain or maize. Thus the spirit produced in Sweden in 1879 was particularly bad and had very curious effects, and it was found, on investigation by M. Husz, that it had actually been largely prepared from decomposing grain. Moreover, C. Lombroso discovered an alkaloidal body in decayed maize, the action of which was not unlike that of strychnine. The quantities of these bases which have been found in spirits are very small, but it must be remembered that substances are known—such as abrine, for instance—which have marked effects in practically unweighable quantities. It is possible that these volatile bases may be responsible for some of the effects—very similar to alkaloidal poisoning—produced by crude spirits such as Cape “smoke” and the cheap Portuguese liqueurs.
Having described the nature and effects of spirit by-products, and the changes occurring in them during storage, the question that arises is: How is the knowledge gained by scientific research in this direction applied in practice? It may be said that the old adage " prevention is better than cure " holds good in the spirit industry as elsewhere, and the distiller, therefore, tries as far as possible to avoid the formation of those by-products which are objectionable, or at any rate to remove them during the course of manufacture. These methods for obtaining a satisfactory potable spirit are so far, however, only successful up to a certain point, and the distiller is therefore bound to have recourse to prolonged storage or to one of the many artificial processes of purification and maturing, the majority of which have been devised—with varying success—during recent years. Referring, in the first place, to what may be called the natural or “preventive” methods for the production of a well-flavoured spirit, it is necessary (a) that the water supply (for steeping, mashing, &c.) be a good one; (b) that no mouldy or inferior material be used; (c) that mashing heats be kept within reasonable limits; (d) that refrigerators be constructed so as to avoid bacterial infection; (e) that the “souring” of the wort be conducted on proper lines; (f) that a favourable and vigorous type of yeast be used; and (g) that stills, &c, be kept perfectly clean. Coming next to the methods ordinarily or frequently employed by distillers for eliminating the undesirable by-products, which, despite all care, are formed in the course of manufacture, the most important undoubtedly is purification by rational fractional distillation. By properly regulating the distilling heats, by ​using a well-devised still, both in the first instance and also for rectifying, a product very free from fusel oil, and especially from fatty aldehydes and volatile ethers, may be obtained. The removal of acids—objectionable chiefly on account of the unpleasant decomposition products which they form in still—is carried out by neutralizing the still contents with an alkaline medium. The alkali so used also decomposes undesirable esters, and retains some of the aldehydes. For the elimination of fusel oil, treatment with charcoal is the most common method. Luck has suggested for this purpose the passing of the alcoholic vapours through petroleum, which is said to absorb the higher alcohols much more easily than it does ordinary spirit; and some distillers have successfully tried the method of V. Traube, which consists in treating the spirit with a saturated aqueous solution of various inorganic salts. This causes the formation of a supernatant layer, which is said to contain practically all the fusel oil as well as the greater part of the foreshot by-products, i.e. fatty aldehydes, &c.
Finally, there remain for consideration the artificial maturing processes. These are exceedingly numerous, but it may be said at once that the great majority of them are hardly to be taken seriously. Thus one inventor, acting on the alleged fact that spirits are improved by lengthy journeys, suggests that a miniature railway, with numerous obstacles to augment the rolling and shaking action, be laid down in the distiller’s warehouse. Of the methods worthy of consideration may be mentioned, first, those depending solely on the action of currents of air, oxygen and ozone. They exist in numerous modifications, but the principle involved, broadly speaking, is to pass a current of hot or cold air or oxygen, or alternate currents of hot and cold air, or a current of ozonized air, through the liquid, with or without pressure, as the case may be. According to the patents of E. Mills and J. Barr, new whisky rapidly acquires the character of the mature sherry-cask stored spirit if the action of alternate hot and cold air currents be assisted by the addition of a little sherry and a minute trace of sulphuric acid, the latter being subsequently neutralized by lime. Secondly, there are the processes which make direct or indirect use of the electric current. Of the indirect methods in this class may be mentioned that of Hermite, which consists essentially in adding an electrolysed solution of common salt to the spirit, and subsequently redistilling. Thirdly, the processes which rely on accelerating natural cask action by artificially reproducing the conditions attendant on the latter in a purposely exaggerated or heightened form. One method strives to obtain this object by heating the spirit under pressure in an atmosphere of oxygen in a vessel containing a quantity of oak shavings. This process certainly seems calculated to remove a portion of the by-products, for the “grog” obtained in A. H. Allen’s experiments by steaming the staves of an old whisky cask contained appreciably more fusel oil and esters than commercial whisky. Fourthly, we have the methods chiefly dependent on the action of cold. R. P. Pictet, by cooling a new brandy to −80° C., is said to have obtained a liquid which had apparently acquired the properties of a twelve-year-old spirit. R. C. Scott’s process consists in energetically treating spirit which has been cooled down to 0° C. with dry filtered air, and the operations are so conducted, it is said, that there is no loss of alcohol or of the important aromatic esters. According to the published data, the quantity of the fusel oil is materially reduced by this method, and the quality of the spirit much improved. None of the above processes has apparently (although in practice they may give satisfactory results) been devised with a view to effecting the direct removal of those specific substances (furfurol, other aldehydes and volatile bases) which later research has shown to be present to a greater extent in new or inferior spirits than in the matured or superior article, and to some of which, at any rate, owing to their acknowledged toxicity in very small quantities, it is more than reasonable (as Lauder Brunton and Tunnicliffe have pointed out) to suppose that at least a part of the evil effects by drinking new or inferior spirit may be ascribed. In this connexion a patent taken out by J. T. Hewitt is of interest, inasmuch as it deals with the problem of spirit purification on seemingly rational scientific lines. This patent takes advantage of the fact that furfurol and similar aldehydes can be removed from spirits by distillation with phenyl-hydrazine-sulphonate of soda, which salt forms non-volatile products with the substance in question.  (P. S.)
* ↑ For the sense of disembodied persons, see Spiritualism.
* ↑ The above chiefly applies to industrial spirit, in the manufacture of which a product which is practically pure alcohol is desired. These methods can only be used to a limited extent by whisky and brandy distillers, for a complete removal of by-products also entails destruction of the spirit’s character.