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From Alchemy to Chemistry
By John Read
Dover Publications, Inc.Copyright © 1995 Dover Publications, Inc.
All rights reserved.
Concerning the Nature of Things
CHEMISTRY, in a rudimentary form, must have been coeval with civilisation. At a very early stage in the evolution of man as an observant and thinking being he must have formed some kind of misty idea respecting the nature of the material world around him. He planted his feet upon the solid earth, waded through the running streams, and breasted the strong winds of his environment. Also he discovered how to produce fire. So he became conscious of earth, air, fire and water, and also of many different kinds of matter, or 'stuff,' with which he came into contact. He discovered many uses to which they could be put, either in their native state or after treating them in various ways. He found that fire, which at first he had regarded with superstitious dread, could be brought under control and used with advantage by reason of certain changes that it could bring about in the nature of material things, as well as acting as an agreeable source of warmth.
Man has been described as a thinking animal. He is also possessed of an insatiable curiosity. In the intervals of his struggle for existence, which consisted largely in this primitive state in securing food, shelter, and protection from the many dangers that threatened him, he brought his rudimentary reasoning powers to bear upon the character of everyday things and phenomena. Then he sought to bring his observations into some kind of order and to establish a general framework into which he could fit them. In the fullness of time his dim ideas blossomed into what we may regard as primitive theories.
Probably the earliest integration of this kind which is of interest in the remote ancestry of science arose from a primitive mode of human thinking based upon a distinction between pairs of opposites: this has been called the 'Doctrine of the Two Contraries.' Thus it is significant that in the first chapter of the Book of Genesis chaos is depicted as being reduced to order by the separation of opposites, of day from night, of light from darkness, and of the waters from the land. Moreover, the universe of the ancient religion of Mesopotamia was conceived as being under the control of Baal, the Father God, and Astaroth, the Mother Goddess. Baal, the Sun-god, was a hot, active, light, immaterial and positive principle; Astaroth, the Moon-goddess, was cold, passive, heavy, material and negative. Osiris and Isis took similar positions in the cosmology and religion of ancient Egypt.
The Doctrine of the Two Contraries found a much later and more elaborate expression in the earliest fundamental theory of physical science, known usually as the 'Theory of the Four Elements.' Although often ascribed to the great Greek philosopher Aristotle (c. 350 B.C.), this theory goes back much farther in time: its essentials had been recognised in Egypt and India more than a thousand years earlier. In the Orient, the related Chinese conception of the Five Elements (Wu-hsing), based also upon the Doctrine of the Two Contraries (Yin-Yang), likewise claims a great antiquity.
Aristotle's theory rested upon the supposed existence of four elementary properties or qualities. These formed two pairs of opposites: hot and cold, wet and dry. When combined pairwise, as represented in the appended diagram (Fig. 1), they gave rise to the four fundamental simple bodies, or elements: earth, air, fire and water. All kinds of matter were held to be composed of these four elements, associated in different proportions. Further, according to Aristotle, the four elements were also incorporated with a prima materia: this had no material existence until it became allied with 'form,' after which it could enable one element to pass into another, by a process of transmutation.
Hovering behind these four elements was a shadowy and ill-defined fifth. Aristotle called it ether, the element of the stars; the neo-Platonists called it Logos, otherwise the Word, God, or Reason; and among the medieval philosophers it was known as the quinta essencia, fifth being, or quintessence, sometime confused in alchemy with the Philosopher's Stone.
The Aristotelian theory dominated scientific thought until the time of Robert Boyle in the middle of the seventeenth century. Its implication of the possibility of changing, or transmuting, one element into another was particularly important. As an example of this conception, it appeared that water, the cold-wet element, could be transmuted by the application of heat into air, the hot-wet element, through the displacement of the cold quality by the hot one. In modern terms, of course, this process of vaporisation is considered as a purely physical one. Solid water (ice), liquid water, and gaseous or vaporised water (steam) are different physical forms of the same substance, and there is no question of transmutation of one kind of matter into another being concerned in interconversions of these three forms.
It would be unjustifiable, in the light of present knowledge, to dismiss the theory of the Four Elements as ill-conceived or useless. Clearly this theory summarised in a compact form the result of long ages of observation and thought. In one sense, the 'elements' Earth, Water and Air represent the three states of aggregation of matter—the solid, the liquid, and the gaseous. Again, the 'element' Fire may represent energy, a constant agent in bringing about material changes. Transmutation, in turn, belonged to the wider conception of metamorphosis, a universal and essential part of folklore. The possibility of transmuting one element or one metal into another would be ranged in the imagination alongside the observed and spectacular changes of seeds into flowers, of caterpillars into butterflies, or of tadpoles into frogs. The turning of tin into silver, or of copper into gold, would seem to be trifling changes in comparison with such metamorphoses as these, or with the turning of Lot's wife into a pillar of salt, or the petrifaction of the Witch of Wookey Hole by a 'lerned wight of Glaston,' when—in one of 'Mendip's sunless caves'—
The ghastly hag he sprinkled o'er;
When lo! where stood a hag before,
Now stood a ghastly stone.
The philosophers of ancient Greece were much concerned with the problem of the ultimate constitution of matter, upon which they held divided opinions. There is little doubt that their ideas were inherited to a large extent from the earlier civilisations of Egypt, Syria and Asia Minor. According to Aristotle (c. 350 B.C.), matter is continuous and therefore capable of infinite subdivision; but Epicurus (c. 300 B.C.), elaborating the pre-Aristotelian views of Democritus of Abdera (c. 400 B.C.) and Leucippus (sixth century B.C.), held it to have a grained or discontinuous structure, consisting of atoms of the same primordial material which differed in their size, shape and form. The Roman poet Lucretius, in the first century B.C., expounded this conception of an atomistic structure of matter with great fervour and eloquence in his famous work, De Rerum Natura ('Concerning the Nature of Things').
Since the Greek philosophers had little inclination for experiment, and reached their conclusions by processes of abstract thought, their ideas were merely speculative and remained unresolved for more than two thousand years. Nevertheless, this early interest in the nature of the 'stuff' of which the material world around us is composed was sustained throughout succeeding ages, and led eventually to a rudimentary form of experimental science known as alchemy. For more than a thousand years alchemy remained essentially static, until, during the seventeenth and eighteenth centuries of our era it blossomed slowly into the modern science of chemistry.
Modern chemistry deals with the study of the 'stuff' of the material universe. It is obvious at a glance that 'stuff' of many different kinds lies around us, or, in other words, that matter is heterogeneous and not homogeneous or of uniform composition. A lump of granite, for example, is distinct in its appearance and also in its properties from a pool of sea-water.
Chemistry goes beyond superficial observation of this kind, and shows that granite and sea-water themselves are heterogeneous materials. One of the leading tasks of chemistry is to devise processes for separating from such mixed materials their various homogeneous constituents. Thus, when the heterogeneous material, sea-water, is distilled it yields a homogeneous liquid material known as water. This distinctive kind of matter is called a 'substance.' The residual sea-salt is still heterogeneous. It consists of a mixture of several other substances, among them being common salt. These solid substances can be separated from each other by using further processes which take advantage of their different properties. Such separative processes play so important a part in chemistry that this science used to be known in German as Die Scheidekunst, that is, 'the art of separating.'
Chemistry does not stop at this point. It proceeds far beyond the preparation of pure individual substances from naturally occurring materials. Each individual substance has to be characterised by a study of its properties. Also chemistry is concerned with the composition of each distinct substance and with the possible ways of breaking it down into simpler substances and of building it up from other substances.
The kind of information thus acquired is all of a 'qualitative' nature, concerned with the kinds of constituents; but of equal importance is the 'quantitative' aspect, which depends upon weight and measurement and takes cognisance of quantity or proportion.
All such studies are fundamental; but they constitute only a fraction of the functions of modern chemistry. Historically, they did not begin to come into effective action until the second half of the eighteenth century.
Concerning the Application of Things
In the pre-history of man, knowledge must have been acquired slowly and laboriously, by trial and error, of the different properties of the many materials that came to his hand. The manipulation of things and their application to everyday uses, particularly in the provision of food, fuel, clothing and shelter, brought a familiarity with their properties and paved the way for later speculations concerning their fundamental nature.
Such a sequence ran through the whole history of chemistry until the present age. The rule-of-thumb applications of things, bringing a growing acquaintance with their properties, led to an increasing knowledge of their intimate structure. In other words, application preceded theory. In recent times the close knowledge now gained of the fine structure of matter has tended to reverse this sequence; so that theory may now often dictate methods of adapting natural materials, or even of elaborating purely artificial ones designed for specific purposes.
It may therefore be argued that the primitive beginnings of chemistry are to be sought in man's adaptation of natural materials to his needs. Perhaps the most spectacular, although by no means the most common, of these materials is gold. This gleaming yellow metal, malleable and untarnishable, lent itself readily to use in the decorative arts of early man. In the Euphrates valley there were expert workers in gold so long ago as 3500 B.C., and the washing, fusion, and weighing of gold were depicted in drawings on the walls of Egyptian tombs a thousand years later (Fig. 2). This beautiful metal, which remains unaffected by any ordinary agency, has always held a high place in man's esteem. There is indeed little doubt that the development of alchemy was largely bound up with attempts to solve the problem of the occurrence of gold in the earth's crust and to produce it artificially. The oldest map in existence is one of a gold-mining region in ancient Egypt; it dates from about the time of Tutankhamûn (c. 1350 B.C.), whose solid gold coffin was found to weigh more than two hundredweight.
Throughout the many civilisations of man, his primary motive has been the provision of food. It is thought that the primitive communities of the Tigris and Euphrates valleys owed their formation and development, possibly some nine thousand years ago, to the prevalence of wild barley in that region. Now barley, with the help of water and yeast, gives rise to both bread and beer; and these fundamental sustainers of the human organism have maintained their primeval importance through the later civilisations of Babylon and Egypt, down to the present day. It is clear therefore that a practical knowledge of fermentation, a typical biochemical process, has been applied from prehistoric times.
Beer finds mention also in the Papyrus Ebers, dating from about 1550 B.C. This 68-foot roll, discovered in the Theban necropolis, has been called 'the oldest book in the world.' It is essentially a primitive pharmacopoeia, containing more than eight hundred prescriptions and remedies. One of these, described as 'a delightful remedy against death,' consisted of half an onion mingled with the froth of beer. The Papyrus states also that garments may be protected from the depredations of mice by smearing them (i.e. the garments) with cat's fat. Mention is made of many mineral ingredients, such as stibnite, sulphur, soda, lead, common salt and saltpetre. The Papyrus Ebers provides the earliest written example of the close connection between chemistry and medicine, an association that was destined to become of the first importance to chemistry some three thousand years later, in the so-called period of iatrochemistry. Thus, in the search for remedies to cure human ills and to prolong life can be traced another far-reaching root of chemistry.
Among such remedies, plant products took a prominent place. There was a great demand for the spices, incenses and perfumes of southern Asia and its adjacent islands for these and other purposes. This demand constituted indeed a main factor in the rise of traffic and commerce among the early civilisations. Trade flowed along the caravan routes extending from China, India and Arabia to Egypt and the Black Sea. Later, Phoenicia, by virtue of its geographical situation, became a distributive centre of commerce between Orient and Occident; and Sidon and Tyre, in particular, acquired much wealth and fame thereby.
The use of medicinal remedies has been closely associated all down the ages with attention also to the outward appearance of the human body, yet it is somewhat surprising to find that the application of beautifying materials, which we now call cosmetics, stretches back into a remote antiquity. In the British Museum, for example, there is a substantially built toilet box, made of wood and mounted on four legs, which may be described as the ancient Theban counterpart of the modern 'vanity bag.' It belonged to Tutu, the wife of a scribe named Ani, who lived about 1400 B.C. It was used as a receptacle for various aids to beauty, including unguent vases of terra-cotta and alabaster, and a double stibium tube with pencils for applying the contained powder and medicinal paste. Stibium, a name given to various black powders and specifically to native antimony sulphide, was in common use among the lovely ladies of long ago for darkening their eyebrows and eyelashes and also as a protective paint in hot and dusty weather.
It was some five hundred years after the days of Tutu that the Sidonian princess, Jezebel, 'painted her face, tired her head, and looked out at a window,' upon the rapid approach of Jehu the son of Nimshi. Her action has been partly misrepresented by unduly severe critics of later generations, seeing that she 'put her eyes in painting' [a more accurate translation] at least partly as a routine protective measure against dust and insects.
The Assyrians had a word guhlu, meaning 'eye-paint,' and this was later rendered into Arabic as kuhl. The 'kohl pots,' or 'kohl tubes' used as containers for these black stibium powders were often exquisitely designed and ornamented. Among specimens still extant is one in faience inscribed with the name of Tutankhamûn's queen. Others, still older, are delicately carved in ivory with designs modelled on papyrus-buds and stems of lilies. Later, among the Romans, the perfume bottles, scent boxes and other containers for cosmetics, were characterised by their delicate workmanship and elegant designs.
In many ways the ancient civilisations had a keen sense of beauty. This they applied in modelling, shaping and decorating the materials which they found to suit their purposes. Constant practice of this kind led them to gain an ever-increasing knowledge of the properties and adaptabilities of the things they handled. They acquired a practical knowledge of a surprising range of processes, such as brewing, soapmaking, glassmaking and dyeing, which are now included in the operations of chemical technology.
Indigo-dyed wrappings of mummies found in the tombs of ancient Egypt have kept their colour to the present day: they testify to the skill of the dyers of those far-off days. Most of the ancient dyes were of plant origin. There is little doubt, for example, that both indigo (from the indigo plant) and alizarin (from madder) found application in dyeing Joseph's coat of many colours. The most costly dye known to the ancient world was, however, of animal origin. This was the famous Tyrian Purple, the imperial colour, the use of which was denied to ordinary mortals. It was extracted with meticulous care from the glands of certain shellfish (Murex) found in the waters of the Eastern Mediterranean. There were large factories for this purpose at Tyre and Sidon, and others are known to have existed at Athens and Pompeii.
It was of this Purple of the Ancients that Browning wrote:
Who has not heard how Tyrian shells
Enclosed the blue, that dye of dyes,
Whereof one drop worked miracles,
And coloured like Astarte's eyes
Raw silk the merchant sells?
It is one thing to discover a coloured substance; but its attachment, in a fast or permanent condition, to a fabric is a different and often difficult matter. That the ancient dyers had attained a complete mastery of the art of dyeing with Tyrian Purple is clear from the assertion of Lucretius in De Rerum Natura: 'The purple dye of the shellfish so unites with the body of wool alone, that it cannot in any case be severed, not were you to take pains to undo what is done with Neptune's wave, not if the whole sea were willed to wash it out with all its waters.'
Excerpted from From Alchemy to Chemistry by John Read. Copyright © 1995 Dover Publications, Inc.. Excerpted by permission of Dover Publications, Inc..
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