Alchemy

Alchemy, ancient art practiced especially in the Middle Ages, devoted chiefly to discovering a substance that would transmute the more common metals into gold or silver and to finding a means of indefinitely prolonging human life.

Although its purposes and techniques were dubious and often illusory, alchemy was in many ways the predecessor of modern science, especially the science of chemistry. The birthplace of alchemy was ancient Egypt, where, in Alexandria, it began to flourish in the Hellenistic period; simultaneously, a school of alchemy was developing in China. The writings of some of the early Greek philosophers might be considered to contain the first chemical theories; and the theory advanced in the 5th century BC by Empedocles—that all things are composed of air, earth, fire, and water—was influential in alchemy. The Roman emperor Caligula is said to have instituted experiments for producing gold from orpiment, a sulfide of arsenic, and the emperor Diocletian is said to have ordered all Egyptian works concerning the chemistry of gold and silver to be burned in order to stop such experiments. Zosimus the Theban (about AD 250-300) discovered that sulfuric acid is a solvent of metals, and he liberated oxygen from the red oxide of mercury. The fundamental concept of alchemy stemmed from the Aristotelian doctrine that all things tend to reach perfection. Because other metals were thought to be less "perfect" than gold, it was reasonable to assume that nature formed gold out of other metals deep within the earth and that with sufficient skill and diligence an artisan could duplicate this process in the workshop. Efforts toward this goal were empirical and practical at first, but by the 4th century

AD, astrology, magic, and ritual had begun to gain prominence.

A school of pharmacy flourished in Arabia during the caliphates of the Abbasids from 750 to 1258. The earliest known work of this school is the Summa

Perfectionis (Summit of Perfection), attributed to the Arabian scientist and philosopher Geber; the work is consequently the oldest book on chemistry proper in the world and is a collection of all that was then known and believed. The

Arabian alchemists worked with gold and mercury, arsenic and sulfur, and salts and acids, and they became familiar with a wide range of what are now called chemical reagents. They believed that metals are compound bodies, made up of mercury and sulfur in different proportions. Their scientific creed was the potentiality of transmutation, and their methods were mostly blind gropings; yet, in this way, they found many new substances and invented many useful processes. >From the Arabs, alchemy generally found its way through Spain into Europe.