Popular Science Monthly/Volume 43/May 1893/The Discovery of Alcohol and Distillation
|THE DISCOVERY OF ALCOHOL AND DISTILLATION.|
By M. P. E. M. BERTHELOT.
ALCOHOL is an important factor in modern civilizations, the source of great revenues to states, and of immense wealth to those who deal in products containing it. While wine, beer, hydromel, etc., have been in use from prehistoric times, the active principle common to them which produces the pleasant excitement and the disgusting intoxication, and which is concentrated in spirituous liquors, alcohol, has been known for only seven or eight centuries; it was unknown in antiquity. The story of the way the discovery of it was made is one of much interest.
The reservation of the name of alcohol for the product of the distillation of wine is modern. Till the end of the eighteenth century the word, of Arabic origin, signified any principle attenuated by extreme pulverization or by sublimation. It was applied, for example, to the powder of sulphuret of antimony (koheul), which was used for blackening the eyes, and to various other substances, as well as to spirits of wine. No author has been found of the thirteenth century, or even of the fourteenth century and later, who applied the word alcohol to the product of the distillation of wine. The term spirit of wine or ardent spirit, although more ancient, was also not in use in the thirteenth century; for the word spirit was at that time reserved for volatile agents, like mercury, sulphur, the sulphurets of arsenic, and sal ammoniac, which were capable of acting on metals and modifying their color and properties. The term eau-de-vie was given in the thirteenth and fourteenth centuries to the elixir of long/ life. It was Arnaud de Villeneuve who employed it for the first time to designate the product of the distillation of wine. But he used it, not as a specific name, but in order to mark the assimilation which he made of it with the product drawn from wine. The elixir of long life of the ancient alchemists had nothing in common with our alcohol. Confusion of the two has led the historians of science into more than one error.
Our alcohol first appeared under the name of inflammable water, a name which was likewise given to spirits of turpentine. Let us try to determine, from the ancient authors and those of the middle ages, what was the origin of the discovery of alcohol, and to trace the successive steps in the knowledge of that substance. The ancients observed that wine gave out something inflammable. We read in Aristotle's Meteorologica, "Ordinary wine possesses a kind of exhalation, and that is why it gives out a flame." Theophrastus, an immediate disciple of Aristotle's, says, "Wine poured upon the fire, as for libations, throws out a light" —that is, produces a shining flame. Pliny says, still more decidedly, that the Falernian wine, the product of the Faustian field, is the only wine that can be ignited "on contact with a flame"; a thing that happens with some wines very rich in alcohol. These are common phenomena, accidental observations made in the course of sacrifices and festivals which served as the beginning of the discovery. But there had to be many intermediate steps. Among them was this experiment, an amusing trick in physics, doubtless devised by some prestidigitator, which is explained in a Latin manuscript in the Royal Library of Munich: "Wine can be burned in a pot, as follows: Put white or red wine in a pot, the top of the pot being raised and having a cover with a hole in the middle. Having heated the wine till it begins to boil and the vapor comes out through the hole, put a light to it. The vapor will at once take fire and the flame will last as long as it comes out." But alcohol was not isolated by the ancients.
Distillation, or a method of separating the inflammable principle from wine, had to be discovered before a further knowledge of alcohol could be gained-. This process passed through several stages. It also started from common observations. When water is heated in a vessel, its vapor condenses on the walls of surrounding objects, and especially on the cover of the vessel; this can be observed by every one, in domestic economy, on the covers of soup dishes, of kettles, and of tea and coffee pots. Aristotle mentions the fact in his Meteorologica. "Vapor," he says, "condenses under the form of water, if we take pains to collect it." He speaks in another place of a less usual observation, which was probably likewise accidental, and which has been extensively applied in our own time. "Experiment has taught us that sea-water when converted into vapor becomes potable, and the vaporized product, when condensed, no longer resembles sea-water. . . . Wine and all liquids, when vaporized, turn into water." It appeared, then, according to Aristotle, as if evaporation changed the nature of the vaporized liquids and reduced them all to an identical condition—that of water. This change was conformable to the philosophical ideas of the author, wine and sea-water being reduced to the same condition of water, the principle of liquidity, which was regarded by the ancient philosophers as one of the four fundamental elements of things.
Aristotle's remarks on sea-water soon gave the suggestion of a practical process mentioned by Alexander of Aphrodisias, one of his earliest commentators, about the second or third century a. d. According to that author, sea-water was heated in brass kettles, and the water that condensed on the covers was collected for drinking. This was the germ of the industry of the distillation of sea-water, which is practiced now on a large scale on board of vessels. But, before this process could be carried out in a practical form, the modern improvements in the process of distillation had to be discovered.
Similar processes to that mentioned by Alexander of Aphrodisias are described by Dioscorides and Pliny, in the first century a. d., for the preparation of two liquids so different as mercury and spirits of turpentine. These discoveries, also met in accidental observations, began to make more general the ideas of the industrial men and physicists of the time. Cinnabar, or sulphuret of mercury, has been used from remote antiquity as a red coloring matter (vermilion); the Romans got it from Spain, where the principal mines of mercury in Europe are still situated. It was early remarked that, in heating in an iron vessel to purify it, it disengages vapors of mercury, which are condensed on neighboring objects, chiefly on the cover of the vessel. This discovery was the origin of the regular extracting process, described by Dioscorides and Pliny. The cinnabar was placed in a capsule of iron in the middle of an earthenware pot. The cover was sealed on, and heat was applied. After the operation the cover was scraped, in order to detach and collect the globules of mercury which had sublimed from the capsule. Thus was obtained artificial quicksilver, which the ancients supposed to have different properties from natural quicksilver, or that which occurs in Nature in mines. This was an illusion, the mercury being identical, whatever the mode of extraction. At any rate, the process employed for the extraction of mercury by vaporization is the same as that described by Alexander of Aphrodisias for making sea-water potable; and this process, as I shall shortly explain, was the beginning of the alembic.
Another rudimentary process, the first that was applied to the extraction of an essential oil, is described by Dioscorides and by Pliny. It is for the distillation of pine resins, which are now called turpentines. They were heated in vessels over which wool was spread; this condensed the vapor; then the wool was pressed, in order to extract from it the liquefied product, spirits of turpentine, which was then called resin oil or flower of resin. It soon assumed an important function in the composition of the inflammable substances used in the arts and in war. But these terms seem at first to have designated also and at the same time the most liquid part of the resins, as well as the water charged with their soluble principles, which was floating on these resins like whey on milk, at the moment of their extraction; and, lastly, the distilled and odorous water which was vaporized at the same time with the essence. The ancients were in some confusion about these substances, which are distinct in modern chemistry; and this it is which makes the reading and interpretation of the old authors so hard.
The decisive step in the knowledge of distillation was taken in Egypt. There were invented the first real distilling apparatus during the first centuries of the Christian era. They are described precisely in the works of Zosimus, an author of the third century, from the technical treatises of two women chemists named Cleopatra and Mary. In the margin of a Greek text of St. Mark are the drawings of the apparatus, and they agree exactly with the author's descriptions. The apparatus consists of a boiler or balloon-shaped receiver, in which the liquid was put; but the cover was replaced by a large tube topping the balloon, and ending above in a cap shaped like an inverted balloon, to serve as a condenser. The cap was furnished with lateral conical tubes inclined downward, which were intended to collect the condensed liquid and allow it to flow out into small bottles. All the essential parts of a distilling apparatus are here defined. These lateral tubes and their recipients constitute the chief improvement, and are what constitutes the alembic. Among the distinctive characteristics of the primitive alembic described by Zosimus is the multiplicity of the abductor tubes. He distinguishes between two-beaked and three-beaked alembics. The flow of vapor was simultaneous, though there were several beaks, and condensation took place in two or three receivers at once. Another figure represents an alembic with a single beak, to which a large copper tube was attached. An alembic described by Synesius, an author of the fourth century, and figured in less ancient manuscripts, shows the boiler with its cap, furnished with a single tube, the whole apparatus being heated in a marine bath. This form varied but little till the sixteenth century. The alembic passed from the Greco-Egyptian experimenters to the Arabs without any notable change. The Arabs were not, therefore, the inventors of distillation, as has been too often affirmed. In chemistry, as in astronomy and medicine, they merely reproduced the apparatus and processes of the Greeks, their masters, adding a few improvements in details. It is a mistake to trace the discovery of distillation and of alcohol to Rases, or Abulcasis, or other Arabian authors; the verified texts have at least furnished me no indication of that kind. In fact, Rases (tenth century), in the passages cited in support of that opinion, speaks only of vinous liquids or false wines obtained by the fermentation of sugar, honey, and rice; liquids, some of which, like hydromel, were known to the ancients. But there is nothing about distilling them, or extracting a more active principle, in any passage in Rases that I am acquainted with. In the pharmaceutical works attributed to Abulcasis or Abulcasim, a Spanish doctor of Cordova, who died in 1107, we only find a distilling apparatus for preparing rose-water which did not differ in principle from those of the old Grecian alchemists. The Arabs, therefore, were still, in the beginning of the fourteenth century, using the complicated apparatus of the Greco-Egyptians.
Alembics with several beaks were still employed by the Western alchemists in the sixteenth century. In Porta's treatise, entitled Natural Magic, a collection of processes or secret operations, the author mentions the cap of three and four beaks, each furnished with its tube and receiver. It is still the old apparatus of Zosimus. Porta, however, describes two important improvements which have come down to modern industry—graduated condensations during the same operation and the cooling worm. We need not suppose that he invented them, but only that he described the practice of his time. The new feature is as follows: In the alembics described by Zosimus the three pipes are at the same level, and doubtless disengaged an identical vapor; the ideas of the chemists of the time were too vague to allow anything else to be expected. The three tubes of Porta, on the other hand, are at different heights, and the author adds that the highest tube furnishes the purest spirit. We can already discern the ideas that have fructified in our apparatus for fractional rectification, with series of superposed chambers and trays delivering alcohols of higher degrees of concentration from the higher levels. This arrangement, however, was abandoned; at least we find no more trace of it during the following centuries. In this as in many other incidents, the men of the sixteenth century foresaw the most modern advances, but by a kind of intuition, without their having those clear notions and those exact principles of physics which, being wanting, progress is accidental and transient.
Another more durable improvement was that of the worm. The alembics of the ancient Greeks doubtless permitted distilled liquors to be obtained, but on condition of operating slowly and with a very moderate heat. In fact, the vapors were imperfectly condensed on the small surfaces of the tubes and the caps represented in the manuscripts. However little we might try to hasten the distillation, the receivers would become warm and condensation would become almost impossible. Hence the ancient authors prescribed that their apparatus should be heated over very slow fires. They operated by means of sand baths, baths of ashes, or water baths. Sometimes they tried to distill with no other heat than that of fermenting manure or a low fire of dung or sawdust. Their operations were therefore very slow, and often lasted for days and weeks. It required fourteen days, or twenty-one days, a text would say, to perform the operation. Not only did they in this way assure the effect of digestions and cementations, designed to produce gradual permeation with sulphurous and arsenical vapors, into sheets of metal submitted to the tinctorial action of the elixirs, but they also made it practicable to collect the liquids placed in the alembics.
At last, however, the operators of the middle ages perceived that the manipulations could be conducted more rapidly, the distillations, for instance, by cooling the cap and the connected tube that conducted to the last receiver. For that purpose they first fixed around the boiler cap a bucket filled with cold water; this facilitated the condensation, but caused a part of the liquefied vapors to fall back into the boiler. A new improvement—the one described by Porta—consisted in bending the tube between the cap and the receiver and giving it the form of a serpent. This was the origin of the modern still-worm. It was surrounded by cold water in a wooden vessel. But the use of the serpentine arrangement spread very slowly, and was still regarded as recent by the authors of the eighteenth century.
Let us observe here that we are using the word distillation in the modern sense of evaporation followed by a condensation of liquid; but in many authors of the middle ages the sense is more vague. The word means, in its literal sense, a flow drop by drop, and is applied equally to filtration and all refining and purification. The word distill is often employed in the same sense in modern language. It also comprehended from the Greco-Egyptian epoch two fundamentally distinct operations, viz., the condensation of dry vapors into a solid form—such as calamines or metallic oxides, sulphur, metallic sulphurets, arsenious acid and metallic arsenic (which was the second mercury of the Grecian alchemists), and at a later date chlorides of mercury, sal ammoniac, etc.—the process which is now called sublimation. It requires special apparatus, which the ancients devised and used, and which gave rise to the Arabian aludel. We mention this here on account of its connection with many modern industries, although it has no relation to the discovery of alcohol.
I proceed now to describe distilled liquids and the successive steps made in their study. "Celestial things above, terrestrial things below," was the phrase by which the Grecian alchemists designated the products of all distillation and sublimation. They declared that "the sublimed vapor emitted from below up is called divine. . . . White mercury is likewise called divine, because it, too, is emitted from below up. . . . The drops which affix themselves to the covers of boilers are likewise called divine." In this expression we find the marks of Aristotle, Dioscorides, and Alexander of Aphrodisias. The alchemists, according to their usage, interpreted these purely physical ideas by symbols and a curious mysticism. Democritus (or the alchemic author who took that name) called the spherical apparatus in which the distillation of water was carried on "celestial natures." The separation which is effected in these between volatile water and fixed matter is expressed as follows in the text of Olympiodorus, who lived at the beginning of the fifth century: "Earth is taken in the early morning, still impregnated with the dew which the rising sun lifts with its rays. It is then like a widow and deprived of its spouse, according to the oracles of Apollo. . . . By divine water I mean my dew, aërial water." In the same style Comarius, a writer of the seventh century, drew the allegorical picture of evaporation and the condensation that accompanies it, condensed liquids reacting on the solid products exposed to their action: "Tell us. . . how the blessed waters descend from above to visit the dead, stretched out, chained, and loaded down in darkness and shadow, in the interior of hades; . . . how new waters enter in, . . . come by the action of the fire; the cloud holds them up; it rises from the sea, sustaining the waters."
This singular language, this enthusiasm borrowing the most exalted religious formulas, need not surprise us. The men of that time, excepting a few superior geniuses, had not reached that state of calm and abstraction that permits the contemplation of scientific verities with a serene coolness. Their education, the symbolical traditions of ancient Egypt, and the gnostic ideas with which the first alchemists were all impregnated, did not allow them to preserve their even balance. They were transported and intoxicated, as it were, by the revelation of that hidden world of chemical transformations which appeared to the human mind for the first time.
In the first Greek treatises, all the active liquids of chemistry are confounded under the common name of divine water or waters. "Divine water is one in kind," they said; "but it is multiplied as to species, and admits of an infinite number of varieties and methods of treatment." They designated those varieties by the most various symbolical names, such as aërial water, fluvial water, dew, virginal milk, water of native sulphur, silver water, Attic honey, sea-foam, etc. Confusion was systematically engendered by this variety of denominations, for the avowed purpose of concealing the secrets of the alchemical fabrications from the vulgar and uninitiated. Although it is occasionally possible to discern something precise in the deliberate vagueness of the descriptions, there does not exist among them, so far as I know, any text that is applicable to the distillation of wine. It is barely possible that the principle of fractional distillation and the diversity of its successive products are indicated in one or two passages, but those passages appear to apply to the treatment of alkaline polysulphides or of organic sulphureted substances, which have nothing in common with alcohol.
I have not, moreover, met in the Arabic treatises on medicine and materia medica as yet printed, or in the manuscript Arabic works of Geber and other alchemic authors which I possess and am preparing for publication, with any precise text relative to alcohol or to any definite distilled liquid. I have already explained the passages of Rases that have been wrongly cited as bearing on this point, which relate only to fermented liquids without reference to their distillation or to the extraction of alcohol. So Abulcasim, who has been cited, after describing some distilling apparatus modeled after the dibicos and tribicos of the Greeks, adds simply, "According to this method, whoever wants distilled wine can distill it." He gives directions for distilling rosewater and vinegar in the same way. He speaks only of distillation in a mass. Still, the idea of the preparation of a distilled fragrant water, like rose-water, appears here clearly for the first time; but there is nothing in it that applies to an essence proper, or especially to alcohol.
I repeat that simply a distillation of wine, without any distinction between the successive products of a fractional distillation, is meant in these texts. But it was perceived from that time, contrary to the opinion of Aristotle, that distilled wine was not identical with water; still, our authors do not speak of alcohol, although the knowledge of that substance would result almost immediately from the study of the distilled liquids yielded by wine.
The most ancient manuscript containing a precise reference to this product is in the Clef de la peinture, which was written in the twelfth century. It is a receipt in cipher, which when deciphered and translated reads: "By mixing pure and very strong wine with three parts of salt and heating it in vessels designed for the purpose, we obtain an inflammable water, which is consumed without burning the matter on which it is placed." This meant alcohol. The property of burning on the surface of bodies without burning them greatly struck the first observers of it. A more explicit mention is contained in the Treatise on Fires of Marcus Græcus, a Latin work drawn from Arabian and Grecian sources, no manuscripts of which, however, are of earlier date than the year 1500. It is a compilation of technical receipts, mostly relating to the art of war. The receipt for the burning water was added later to the original text; for it is not a part of another manuscript that exists in Munich, but is inserted in it outside of and after the Treatise on Fires. It contains some new hints and characteristics, and is as follows: "Preparation of Inflammable Water.—Take wine, black, thick, and old. For a quarter of a pound add two scruples of very finely powdered sulphur, one or two of tartar, extract of a good white wine, and two scruples of common salt in coarse fragments. Place the whole in a good leaden alembic; put on the cap, and you will distill the burning water. It should be kept in a glass vessel tightly closed." The Munich manuscript adds: "These are the virtue and propererties of the inflammable water: A rag moistened with it and set on fire will burn with a great flame. When the fire is extinguished the cloth will be found unharmed. If you dip your finger in this water and then put fire to it, it will burn like a candle and not suffer any wounding." This was in fact a prestidigitator's trick; and the part those people played is manifest in the beginnings of a large number of inventions in antiquity and the middle ages. In any case the facts pointed to in this description are exact, and show how first observers are often struck by real or apparent properties of bodies, even though they be insignificant. Frequently, too, they complicate operations by superfluous if not annoying details, to which, according to the theories by which they are guided, they attach the same importance as to the rest. For instance, in the first receipt of Marcus Græcus is a direction to add sulphur previous to the distillation, which occurs likewise in a book by Al Farabi, transcribed into another manuscript of the same period, as well as in Porta's Natural Magic, which was composed in the sixteenth century. It is therefore not accidental. It is the product of a theory which is expounded at length in several texts, held by the chemists of the time, that the great moisture of wine is opposed to its inflammability. To counteract this they added salts or sulphur, the dryness of which, they said, augmented the combustible properties. One of these old authors refers, in support of his theory, to dry wood and green wood, unequally combustible, according to the season when they were cut and the proportion of moisture they contain.
We should recollect also that volatility and combustibility were then confounded and called sulphurity, a term which was still applied in this sense in the time of Stahl, at the beginning of the eighteenth century. These ideas go back to the Grecian alchemists, who called every volatile liquid and every sublimate sulphurous (or divine) water. In this we can see the origin of those complicated preparations, so hard to understand now, which were employed by the old alchemists. They tried to communicate to bodies the qualities in which they were lacking by adding to them substances in which those qualities were supposed to be concentrated. Hence sulphur was added to wine in the belief that it would render the manifestation of its inflammable principle easier.
The first man of science known by name who spoke of alcohol is Arnaud de Villeneuve, who was of a date posterior to the composition of these writings. He is commonly spoken of as the author of the discovery, though he never himself presented such a claim. He only spoke of alcohol as a preparation known in his time, which he admired very much. He recorded of it in his work Concerning the Preservation of Youth: "We extract, bydistillation of wine or its lees, burning wine, called also eau-de-vie. It is the most subtile portion of the wine."
He then exalts its virtues: "Discourse on Eau-de-vie.—Some call it water of life; some of the moderns say it is permanent water, or rather golden water, on account of the sublime nature of its preparation. Its virtues are well known." He next enumerates the maladies for which it is a cure: "It prolongs life, and therefore deserves to be called water of life. It should be kept in a golden vessel; all other kinds of ware, except glass, are liable to be acted upon by it." Then he speaks of alcoholates: "On account of its simplicity, it receives every impression of taste, odor, and other properties. When the virtues of rosemary and sage are imparted to it, it exercises a favorable influence on the nerves," etc. The pretended Raymond Lulle, a more modern author than Arnaud de Villeneuve, speaks of alcohol with equal enthusiasm. He describes the distillation of the inflammable water, derived from wine, and of its rectifications, repeated seven times if necessary, till the product burns without leaving a trace of water, and adds, "It is called vegetable mercury." So it appears that the alchemists in the beginning of the fourteenth century were taken with such admiration for the discovery of alcohol that they likened it to the elixir of long life and the mercury of the philosophers. Yet we have to be cautious against taking every text concerning the mercury of the philosophers or the elixir of long life as applicable to alcohol.
The elixir of long life is a fancy of ancient Egypt. Diodorus Siculus calls it "the remedy of immortality." Its invention is attributed to Isis, and the composition of it may be found in the works of Galen. The formulas for it in the middle ages were various. It was also reputed to be capable of changing silver into gold, or, in other words, was credited with the same chimerical properties as the philosopher's stone.
Although the discovery of alcohol did not give realization to these illusions, it has nevertheless had the gravest consequences in the history of the world. Alcohol is an eminently active agent, and thereby at once useful and harmful. It may prolong human life or shorten its term, according to the use that is made of it. It is also a source of inexhaustible wealth for individuals and states—a more fruitful source than the pretended philosopher's stone of the alchemists could have been. Their long and patient labors were therefore not lost; and their dreams have been realized beyond their hopes by the discoveries of modern chemistry.—Translated for The Popular Science Monthly from the Revue des Deux Mondes.