Alchemists employed both physical procedures and magic to convert base metals, such as lead, into gold, and to create elixirs of eternal life. While alchemy is commonly defined as a field of knowledge developed in Europe from the Middle Ages until the eighteenth century, its roots reach into the distant past. The term alchemy is derived from the Arabic definite article al and chymia, a term which may have been used to indicate the practice of manipulating substances. Indeed, the practice of manipulating substances, exemplified by the art of cosmetics, was known to the ancient Egyptians, and predates alchemy itself.
Before the practice of alchemy was established in Alexandria, Egypt, at around 300 b.c., humankind had been changing substances and developing techniques that would be used by alchemists and later by chemists. Heat was used to cook and dry foods to make them more readily digestible and/or preserve them. Heat along with making specific combinations of materials was used in making pottery. Parts of specific plants, as well as seashells and some types of rock were treated with fermented liquids, slat and other materials to make pigments and dyes. Glass was first made from sand and sodium carbonate, found in dry lake beds around Alexandria, and later improved greatly by the addition of lime, calcium oxide. Techniques such as extraction, crystallization and fermentation were used to produce medicinals.
A number of techniques were also developed to obtain and purify metals. Copper, silver, gold and a combination of gold, and silver known as electrum can all be found as the metals in nature. Iron was probably also first known in its metallic state from meteors (in Arabic it was called the metal of heaven). Around 3000 b.c, the Sumerians found that they could obtain copper from certain earths, or ores, by heating the earths with a source of carbon such as straw. The processing of using heat and a reducing agent to obtain a metal is called smelting. Iron was produced at about the same time by smelting. Until it was discovered that carbon was necessary to produce a strong material, iron was not as useful as bronze, which is a combination of copper and tin. Artisans learned to distinguish ores by their characteristics such as color, texture, color produced in a flame, smell and so forth so that they could eventually produce a number of different metals. By 300 b.c., seven metals were widely known in the region at the eastern end of the Mediterranean Sea: gold, silver, electrum (thought to be a separate metal), copper, iron, tin, and lead. Iron and some high quality steel was also known in sub-Saharan Africa, India, where steel was used for surgical instruments, China, and Japan, where it was used for swords and knives, and in what is now Turkey, where it was used for weapons.
Artisans fabricated apparatus to carry out techniques that are still important today. "Maria the Jewess" is known as the inventor of several types of apparatus, including a distillation still, the hot-ash bath and water bath (the double boiler is referred to in France as the bain-marie for this reason). Others developed extraction apparatus much like a percolator, and numerous types of vessels for extraction, distillation and sublimation.
The period of the practice of alchemy is generally accepted to be from about 300 b.c. to the eighteenth century. The beginning is marked by the effort to determine the nature of matter in a fundamental way using physical processes to manipulate matter and observe the results. This period marked the initial attempts to understand transformations of matter rather than develop and repeat recipes. The beginning of alchemy is attributed to the spread of ideas of the Greek philosophers to what is now Egypt as a result of the conquests of Alexander the Great (356-323 b.c.. Several of the Greek philosophers developed concepts of the material world based on observations of natural phenomena rather than on myths. Among the most important of these concepts was the extension of the four-element idea of Empedocles (fifth century b.c. by Aristotle (384-323 b.c.. Empedocles postulated that all matter is composed of various proportions of the elements (which he called roots): earth, water, air and fire. Aristotle associated qualities to each of these four elements: cold and dry were associated with earth, cold and moist with water, hot and moist with air and hot and dry with fire. Aristotle justified his idea with the observations that wood when burned produces smoke (air), a gummy residue (water), ash (earth) and fire, so all four elements are present in wood. The approach of the Greek philosophers such as Aristotle that led to alchemy and eventually chemistry was the use of observation to develop a theory that was then tested for logical consistency with other observations. Alchemists went beyond the philosophers by using experiments, transforming matter themselves, to test their ideas.
Alchemists struggled to find ways that qualities, such as inherent hotness or moisture or purity (gold representing the purity of metals) could be extracted from materials and recombined to make valuable products such as precious metals or medicines. The Arab world expanded greatly during the time of the founder of Islam, Mohammed (c. 570-632), and a few decades after his death. From the mid-seventh century to the mid-eighth century, Moslems conquered the region from Persia (now Iran, Iraq and Turkey) to Spain. Alchemy spread with the Moslem conquest, bringing into Europe the techniques developed by artisans over many centuries, as well as Greek ideas, absorbed by Moslem scholars, about the nature of matter.
Alchemists in Europe were especially intrigued, as many Arab alchemists were, with mercury and sulfur. They could quite readily convert mercury from brightly colored solids (actually oxides or sulfur compounds of mercury) to shiny, metallic liquid metal and reverse the process. They also readily converted sulfur from a bright yellow solid to solids of other colors and to a gas and to the very reactive acid, sulfuric acid (called vitriol or vitriolic acid for its destructive action). Attempts to transform matter into gold were often based on the idea that gold could be achieved by transforming a material so that its properties became more and more like those of gold; properties such as yellowness, heaviness and softness. Alchemists found many ways to make yellow solids, heavy alloys, and malleable alloys but, of course, never gold itself.
Another objective of many alchemists was an elixir that would prolong life. A Swiss alchemist who called himself Paracelsus, or "better than Celsus," the influential Roman medical writer who lived in the first century a.d., assembled the most extensive compendium of chemical treatments. Paracelsus (1493-1541) undertook a systematic study of chemical reactions to develop medicines and recorded his results early in the sixteenth century. He found that solutions of a variety of materials in alcohol (tinctures) were effective in treating several skin disorders and that mercury was effective against syphilis. Several dramatic cures that he effected led others to adopt his approach.
Alchemy in other parts of the world, in particular India and China, has been associated mainly with the development of medicinals. As early as the third century, Chinese alchemists used formulations of mercury as elixirs and attempted to transmute other substances into gold to use the gold as an elixir to prolong life. Gold colored powders and liquids were a mainstay of the Chinese alchemist's practice. From the second century, Indian alchemists recorded their procedures for producing medicines as well as metals and other practical substances such as alcohol, acids, alkalis and useful salts of the common metals.
Alchemy is often associated with secrecy and unscrupulousness, and with good reason: some alchemists were charlatans. A typical trick was to coat a gold object with a metal that could be dissolved by an acid. The object would be dipped into the acid, most likely with appropriate fanfare and perhaps incantations and ceremony, to reveal the transmuted gold. Others purported to have transmuted metals or concocted elixirs and sold their recipes to others.
Several alchemists and others interested in the nature of matter wrote extensive accounts of what was known at the time that were not shrouded in secrecy. The thirteenth-century scholar, Bartholomew the Englishman, who taught at the University of Paris, wrote a nineteen- volume treatise entitled Book of the Properties of Things that included Aristotle's ideas as well as ideas of the Arab alchemists concerning the importance of mercury and sulfur. A French Dominican priest named Vincent de Beauvais compiled an 80-volume encyclopedia titled Mirror of Nature, meant to summarize all known science and natural history. Vannoccio Biringuccio (1480-1539) wrote the first printed book on metallurgical chemistry, Concerning Pyrotechnics in 1540. Georgius Agricola (1494-1555) wrote On Metals. His descriptions of assaying, smelting procedures, refining, production of glass and other processes in metallurgy and geological chemistry were used for over two centuries. Even those writings of alchemists who did not hide their procedures in secret codes are often hard for modern scientists to decipher, however. The materials alchemists used were typically impure mixtures whose composition varied according the site from which they originated. This also made it hard for the procedures developed by one alchemist to be repeated reproducibly by others even when the procedures were revealed.
The transition from alchemy to chemistry occurred in the eightheenth century. The establishment of chemistry as the science we know it today required several critical changes in approach. The scientific method of testing hypotheses by experimentation, using only information that could be observed, not the pronouncement of an authority figure, was the first step. The idea of basing judgements about nature only on observation has been attributed to Roger Bacon (c.1214-1294), who espoused this basic concept of empirical science at a time when theology was the dominant intellectual discipline. It took another five hundred years, however, for Bacon's ideas to become relevant to changes in the nature of matter, because many of the most common chemical processes (such as combustion, oxidation of metals, and reduction of metal ores to metals) involve invisible gases, and early scientists, including alchemists, alchemists did not appreciate the importance of weighing materials before and after chemical changes occur.
It was not until the latter half of the seventeenth century that experimenters such as Robert Boyle (1627-1691) determined properties of gases and even later that gases were identified as specific, distinct substance. The first gas to be so characterized was carbon dioxide, discovered by the physician Joseph Black (1728-1790), who termed it "fixed air" and determined that it was a product of combustion and respiration as well as a component on calcium carbonate. Nitrogen was discovered by Daniel Rutherford (1749-1819) as the unreactive component of the atmosphere, the gas that remained after oxygen and carbon dioxide were removed. Joseph Priestley (1733-1804), who also prepared hydrogen chloride, ammonia, nitrous oxide, and other gases, discovered oxygen. Priestley also invented soda water (for which he received his greatest award, the Copley Medal of the Royal Society), by forcing carbon dioxide produced by fermentation into water.
Perhaps the most crucial step in the development of chemistry as a science was the careful experimentation of Antoine Lavoisier (1743-1794) in the latter half of the eighteenth century, culminating in his postulation of the existence of a relatively small number of distinct and immutable chemical elements that could be combined in fixed ratios to produce chemical compounds with their own distinct properties. Tragically, Lavoisier's own work was terminated when he was beheaded, principally for his role as a tax collector, in the French revolution, but his ideas were widely accepted, leading to a fundamental change in the way that chemical changes were examined and explained.
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