Popular Science Monthly/Volume 37/October 1890/The Evolution of Chemical Truth
By M. LOUIS OLIVIER.
IN his Lectures on Chemical Philosophy, J. B. Dumas has taken notice of the "singular contrast which is to be remarked among ancient peoples between the nourishing condition of industrial chemistry and the entire absence of theoretical chemistry." Empiricism, commanded by the necessities of material life, had, in fact, to precede the disinterested speculations of the reasoning powers. In this way the Phoenicians and Egyptians made discoveries of great significance in the arts of metallurgy, glass-working, and dyeing, without being guided by any scientific light. They interpreted them in a mystical sense, conformable to their religious conceptions of nature. Whatever we may think of their theories, we can not forget the positive bases of them; for the rational science of our century has been derived from their observations, winnowed by the ages. The facts have resisted the assaults of time, while the magic, the theurgic doctrines, found to be sterile, have gradually disappeared to give place at last to the fruitful idea of natural laws. It was a curious metamorphosis, in which astrology, alchemy, and the old medicine predicating the virtues of stones and talismans, mark the transition from the ancient to the modern mind.
It is with great interest that we follow with M. Berthelot the evolution that has thus taken place in chemistry from the ancient Orientals to the Greeks, and from them to us; for it is associated with the development of philosophical ideas, consequently with the history of the human mind. From the time when alchemy in a somewhat sudden fashion made its appearance in the world, till the moment of the fall of the Roman Empire, we know very nearly what it was, but are hardly certain whence it came. The study of which we are about to give an account assigns for it a triple origin: the industrial processes of the ancient Egyptians, the speculative theories of the Greek philosophers, and the mystic reveries of the Alexandrines and Gnostics. This conclusion is derived from the attentive examination of documents that have not been studied before with this point in view; among which are Lepsius's memoir on the metals in antiquity, Egyptian papyruses in Paris and Leyden, and Greek manuscripts in the French National Library and St. Mark's Library in Venice. M. Berthelot has compared with these texts, on one side, the beliefs of the first alchemists concerning the origin of their art; and, on the other, their positive knowledge, as well as the theories accepted in the second and third centuries of the Christian era. The deductions from these different sources are quite concordant.
Zosimus the Panopolitan, "the oldest of authentic chemists," wrote, three hundred years after Christ, that "the Scriptures teach that there is a certain race of demons that have commerce with women. Hermes has spoken of them in his book on nature. The ancient and holy Scriptures relate that certain angels, smitten with love for women, came down upon the earth and taught them the works of nature; on this account, they were driven from heaven and condemned to perpetual exile. From this intercourse sprang the race of giants. The book in which they taught the arts is called Chema, whence the name Chema, which is applied to the most excellent art." This idea of sinning angels who revealed the occult arts and sciences to mortals, is found in several countries. It is "in harmony with the old biblical myth of the tree of knowledge placed in the garden, the fruit of which when eaten brought about the fall of man."
The Theban papyruses at Leipsic attribute the same mystical character—a kind of seal of its Eastern origin—to alchemy. It was Hermes Trismegistes who made known practical metallurgical processes, the hermetic science, the mysterious art of transmutation. The Egyptian priests, who were instructed in it, had to take an oath to keep the secret of it. This custom was preserved among the Neoplatonists and magicians of the fourth century and the alchemists of the middle ages and the Renaissance.
Many of the traditions held in honor among the alchemists seem to have been borrowed from the Theban priests. The number four was sacred with both. The philosopher's stone was called the Egyptian stone in the middle ages. The alchemic sign for water was the hieroglyph for that substance. The sign for tin, which has been transferred to the metal mercury, was also the hieroglyph for the planet Mercury; and a similar identity is observable between the sign for gold and the hieroglyph for the sun. Osiris was the synonym for lead, sulphur, etc.
This mystic relationship of the metals and the planets goes back to the Babylonians, and the idea was perpetuated. Pindar mentioned the relation between gold and the sun; and Proclus, in his commentary on the Timæus, wrote, "The sun produces gold, the moon silver, Saturn lead, and Mars iron."
The symbol for the philosophical egg appears to have originated in Chaldea, and to have been introduced thence into Egypt. So was the idea of the microcosm made in the image of the macrocosm. Thus the Babylonians and the Greeks of Egypt, as well as the Alexandrians and the Chinese, held to these aphorisms, afterward so dear to the alchemists, concerning the generation and transmutation of metals, the panacea, and the elixir of long life.
Traces of Jewish traditions, mingled with Eastern fables, can be found in some of the alchemic beliefs of about the eleventh century. Several papyruses mention important receipts as included in the pretended Secret Book of Moses; a Greek manuscript of St. Mark's represents Mary the Jewess, to whom the invention of the water-bath is attributed, as saying: "Do not touch the philosopher's stone with your hands; you are not of our race, you are not of the race of Abraham." According to Zosimus, the sacred art of the Egyptians and the power of gold that resulted from it were delivered to the Jews by a fraud, and they revealed them to the rest of the world.
This confluence of the Chaldo-Egyptian and Jewish sources of alchemy took effect in the first three centuries of Christianity, or at the time when Gnosticism was flourishing at Alexandria. The first alchemists seem, in fact, to have nearly all fallen under the influence of Neoplatonism and Gnosticism. The symbolical forms of universal life, the allegorical figures in which the philosophical sense of things was hidden, were abundant in their writings; and here and there in them we meet all sorts of Gnostic signs, from the image of the world without beginning or end, represented by the dragon Uraboros, a serpent biting his tail, to the eight-rayed stars and magic circles of Cleopatra's "chrysopaeus." The introduction of Gnostic ideas into the theories of the alchemists undoubtedly accounts for their inclination to explain the hidden properties of nature by signs of double or triple meaning.
The same tendency is evident in the Greek alchemists, whose memory has been preserved by the ancient manuscripts. The St. Mark's manuscripts cite as among the most famous of these, after Hermes, John, Arch-priest of Thutia, and Democritus, the celebrated philosopher of Abdera. But they also introduce to us Zosimus, the experimenter, the historian and biographer of Plato, Olympiadorus, and Stephanus, authors of important memoirs on the art of making gold. For that purpose they employed, according to the manuscripts, a projecting powder endowed with the mysterious power of impregnating bodies. This powder was prepared in the Thebaid, at places which, according to Agatharcides, were centers of metallurgical enterprises.
In the ninth century all the documents are found in the hands of the Arabs, who became the depositories and continuers of Grecian science. Mussulman civilization has handed down to us the history of the mythic alchemists, their mysterious formulas, and the practices which they adopted for blanching and yellowing metals—that is, for changing them into silver and gold. In their conceptions of matter, the Arabs of Spain and Syria followed in part the philosophical systems of pagan Greece; and their authors freely quoted Aristotle, Heraclitus, Xenocrates, Diogenes, and Democritus. The story of their doctrines and brilliant discoveries is told in all histories of chemistry.
M. Berthelot's detailed review of the positive facts which alchemy received from antiquity makes it manifest that Egypt left an inestimable treasure to the world. The priests of Thebes and Memphis made great advances in the knowledge of the art of extracting metals, of forming alloys, and of making vessels and tools out of them. They distinguished crude gold from refined gold, and could work that metal up into a variety of articles. They fed the hope that they might be able to obtain it by coloring asemon, or silver, yellow. Of the latter metal they made money, the value of which was guaranteed by an impressed image. They extracted gold and silver from electrum, a mineral containing both substances, but which presented to their eyes the appearance of a metal like them. This was what led them to the notion of transmutation.
The Egyptians designated as chesbet several kinds of blue or green sapphires colored with cobalt or copper. They made incrustations, amulets, necklaces, and various ornaments of them. They succeeded in compounding an artificial chesbet resembling the natural stone. A fact worthy of remark in the matter is, that this was done by "the assimilation of a colored substance, a precious stone, an enamel, a vitrified color, with metals." This assimilation suggested the new idea of dyeing; "for the imitation of the sapphire rests on the coloring of a large mass, colorless by itself, but constituting the vitrifiable basis, which we dye by the aid of a small quantity of coloring matter. With enamels and colored glasses thus prepared, the natural precious stones were reproduced; they were covered with figures, with objects of earth or stone, and were incrusted with metallic objects."
Among the minerals and metals known to the Egyptians are also mentioned the emerald, malachite, copper in alloys, iron, lead, tin, and mercury, the mobility of which caused it to be regarded as living; whence the name quicksilver. Their tinctorial art included dyeing in yellow, white, and black; and they could also dye purple by means of alkanet and archil. All these changes brought about in the appearance of bodies seemed to be modifications of their properties, and consequently to legitimize the expectation of effecting transmutation. We should, however, recollect that the idea of the fixedness of the properties of bodies is wholly modern. Even Bacon wrote in the seventeenth century: "Observing all the qualities of gold, we find that it is yellow, very heavy, of a certain specific gravity, malleable, and ductile to a certain degree; and whoever is acquainted with the formulas and processes necessary to produce at will the yellow color, the high specific gravity, the ductility, and knows, also, the means of producing these qualities in different degrees, will perceive the means and be able to take the measures necessary to unite these qualities into a definite body; and from this will result its transmutation into gold." This was, in fact, the dream and the mastering passion of the alchemy of the middle ages and the Renaissance.
These conceptions were very ancient, and must be looked for in their original forms in the Greek philosophy. The germ of the doctrine of transmutation is in the Timæus. It rests on the idea of primitive matter, the indifferent supporter of all the qualities that can be heaped upon it. Plato insists upon the idea, which he regards as fundamental, that "the thing which receives all bodies never comes out from its own substance. It is the common basis of all the different substances, and is deprived of all the forms which it would receive otherwise." The primary matter was supposed to be composed of fire, which made it visible, earth, which made it tangible, air, and water, which assured the union of the earth and the fire—these four elements being formed of minute corpuscles, susceptible of changing into one another; for we see, says Plato, "that water, in condensing, becomes stone and earth, and in melting and dividing itself up, becomes wind and air. Air inflamed becomes fire; fire, condensed and extinguished, resumes the form of air; air, thickening, changes into mist, and then flows as water; and from water are formed earth and stones."
All bodies were believed to be the seat of a transformation of this kind. Under the influence of this thought, Proclus wrote, "Things being never able to preserve a nature of their own, who shall dare affirm that one of them is this rather than the other?" It is, therefore, by virtue of a necessary law of nature that bodies are modified, and transformation is possible. This determinist conception was afterward mingled in the minds of the alchemists with Oriental mysticism; but it must be remarked that it presented, in the Greek philosophers Thales, Anaximenes, Heraclitus, Empedocles, Plato, and their immediate heirs, a really scientific character. Michael Psellus was faithful to their doctrine when he wrote to the Patriarch Xiphilin, in a letter which was used as the Preface to the Collection of the Greek Alchemists: "The changes of nature are made naturally, not by virtue of an incantation or a miracle, or of a secret formula. There is an art of transmutation. . . . You want me to teach you the art that resides in fire and furnaces, and which produces the destruction of substances and the transmutation of their natures. Some believe that this is a secret knowledge, gained by initiation, which they have not tried to reduce to a rational form; which seems to me an enormous error. For myself, I try first to learn the causes, and to deduce from them a rational explanation of the facts. I sought it in the nature of the four elements, from which everything comes by combination, and to which everything returns by solution."
From Greece alchemy then received, with the idea of a primary matter and the system of atoms, a whole contingent of rationalistic notions which subsequently modified more or less Christian mysticism and the traditions of the East. The effort of the alchemists of the middle ages to divest the metals of their individual qualities in order to reach the primitive matter, the mercury of the old philosophers, was then in harmony with Plato's metaphysics. But, in the operations they performed for that end, they could only determine the indefinite transformation of the elements, and they represented the mysterious process under the symbolical form of a ring-serpent which has neither beginning nor end. This hopeless picture of chemistry did not cease to be true till the end of the last century. By introducing the balance into laboratories, Lavoisier demonstrated that the weight of metals is invariable, and, in a general way, that the origin of all chemical phenomena lies in the reactions of a small number of undecomposable bodies, the weight and properties of which are constant.
This great discovery sapped the alchemic doctrine of the transmutation at its very foundations. It is, however, still permissible to ask if the present elements, as yet undecomposed, are really simple bodies. If Prout's hypothesis that they are polymers of hydrogen could be demonstrated, the hope of passing from one to the other would be entirely legitimate. But the recently carefully made determinations of the equivalents of simple bodies by Dumas and Stas have weakened that theory. The laws of specific heat, moreover, do not permit us to see in onr present simple bodies polymers of the same substance comparable to known polymers. The specific heat of the last increases, according to Woestyn's law, with the complex structure of their molecule, while the specific heat of simple bodies varies, according to Dulong and Petit's law, inversely as their equivalents.
We may, nevertheless, conceive the unity of matter in another sense. Some chemists oppose to Prout's hypothesis a new and more comprehensive one, which consists in regarding the elements as states of stable equilibrium in which matter exhibits itself. "In this order of thought," says M. Berthelot, "a body reputed simple could be destroyed but not decomposed in the ordinary sense. At the moment of destruction it would at once transform itself into one or several other simple bodies, identical with or resembling the existing elements. But the atomic weights of the new elements could not offer any commensurable relation with the atomic weight of the primary body from which they are produced by metamorphosis. More than this: by working under different conditions we might see appear sometimes one system, sometimes another, of simple bodies, developed by the transformation of another element. Only the absolute weight would remain invariable in the course of the transmutations."
Even under this hypothesis the hope of forming simple bodies need not seem chimerical. Unfortunately, we have no more reasons for encouraging it than for condemning it. All that can be said respecting it is that the present condition of science does not allow us to discern any method that will lead to the end. Would it not be wiser, then, to make our theories more complete rather than venture into this darkness without a guiding thread? It is no mystery to any one that they greatly need improvement. The imponderable fluids have only just passed away; the ether, too, seems to be already withdrawing, taking along with it, perhaps, the atom of the chemists; and does it not seem that everything is about to be explained by motion?
M. Berthelot discusses these questions with his well-known vigor and originality. His work, erudite and pointed, is particularly instructive to the thinker. He in fact restores to our view the affiliation of the systems that were conceived at the birth of chemistry, and which have been revived at our time in the effort to resolve the eternal problem of the constitution of matter. —Translated for The Popular Science Monthly from the Revue Scientifique.