The Alchemical Laboratory

The typical alchemist's laboratory was a dark, cluttered place that stank of smoke and mysterious chemicals. Many alchemists worked at home, in order to save money and avoid outside interference. Some settled in the kitchen, to take advantage of the cooking fire. Others chose the attic or cellar, where late-night activity was less likely to be noticed by inquisitive neighbors. These small, makeshift laboratories were often filled with a exceptional variety of instruments, manuscripts, skulls, animal specimens, and assorted mystical objects. Most alchemists also found room for an altar - an aid they deemed essential to the spiritual aspects of their pursuit. In these surroundings that in fact owed more to mysticism than to science, adepts searching for the Philosophers' Stone inadvertently laid much of the ground work for the later discipline of applied chemistry. 

"A perfect Master ye may call him true, that knoweth his Heates both high and lowe," wrote Thomas Norton, a 15th century British alchemist. Heat was the fundamental requirement of nearly every alchemical process, from distilling dew to smelting lead. To achieve and maintain just the right temperature, alchemists experimented with a number of furnaces, water baths, and other heating apparatus. Some self-regulating furnaces could stay hot without tending by ingenious draft systems, but these were rare. Given an alchemist's limited funds, furnaces could be as crude as the household fire. 

Alchemists were the first to isolate a number of chemicals, from phosphorus to hydrochloric acid, and they also developed new equipment and methods for distilling fluids, assaying metals, and controlling chemical reactions. Some of their devices and techniques are still used at the present day.

Superficially, the chemistry involved in alchemy appears a hopelessly complicated succession of heatings of multiple mixtures of obscurely named materials, but it seems likely that a relative simplicity underlies this complexity. The metals gold, silver, copper, lead, iron, and tin were all known before the rise of alchemy. Mercury, the liquid metal, certainly known before 300 BC, when it appears in both Eastern and Western sources, was crucial to alchemy. Sulfur, "the stone that burns," was also crucial. It was known from prehistoric times in native deposits and was also given off in metallurgic processes (the "roasting" of sulfide ores). Mercury united with most of the other metals, and the amalgam formed coloured powders (the sulfides) when treated with sulfur. Mercury itself occurs in nature in a red sulfide, cinnabar, which can also be made artificially. All of these, except possibly the last, were operations known to the metallurgist and were adopted by the alchemist.

The alchemist added the action on metals of a number of corrosive salts, mainly the vitriols (copper and iron sulfates), alums (the aluminum sulfates of potassium and ammonium), and the chlorides of sodium and ammonium. And he made much of arsenic's property of colouring metals. All of these materials, except the chloride of ammonia, were known in ancient times. Known as sal ammoniac in the West, nao sha in China, nao sadar in India, and nushadir in Persia and Arabic lands, the chloride of ammonia first became known to the West in the Chou-i ts'an t'ung ch'i, a Chinese treatise of the 2nd century AD. It was to be crucial to alchemy, for on sublimation it dissociates into antagonistic corrosive materials, ammonia and hydrochloric acid, both of which readily attack the metals. Until the 9th century it seems to have come from a single source, the Flame Mountain (Huo-yen Shan) near T'u-lu-p'an (Turfan), in Central Asia.

Finally, the manipulation of these materials was to lead to the discovery of the mineral acids, the history of which began in Europe in the 13th century. The first was probably nitric acid, made by distilling together saltpetre (potassium nitrate) and vitriol or alum. More difficult to discover was sulfuric acid, which was distilled from vitriol or alum alone but required apparatus resistant to corrosion and heat. And most difficult was hydrochloric acid, distilled from common salt or sal ammoniac and vitriol or alum, for the vapours of this acid cannot be simply condensed but must be dissolved in water.