Abu-Bakr Muhammed ibn Zakariya al-Razi (also transliterated as ar-Razi) was born around 854 in Ray, near the city of Teheran (the Persian Empire, now Iran). Al-Razi (in the Latinized West, Rhazes) achieved mastery in a number of fields, including philosophy, logic, poetry, and music. Around the age of thirty he left Ray for Baghdad (now in Iraq), where he was active in the reconstruction of the city hospital. Al-Razi became famous as the most prominent physician in the Islamic world, his fame comparable only to that of another Persian physician, Ibn Sina (who became known in the West as Avicenna). Al-Razi’s written works in medicine have been widely studied, Latin editions of which remained in use as late as the seventeenth century in Europe. From him we have the earliest distinction between smallpox and measles, and the understanding that smallpox occurs only once in a person’s life. As a skilled chemist he recognized the toxicity of arsenic (arsenic oxide), but prescribed small doses of this compound in the treatment of many skin diseases and anemia.

Like his predecessor, the Arabian alchemist Jabir ibn Hayyan (sometimes known as Jabir), al-Razi was influenced in his alchemical views by Aristotle’s theory of the four elements. Jabir ibn Hayyan was the first of many well-known alchemists from the Islamic world. Born in Iran to parents of Arab descent, his life took place against a backdrop of political turmoil. His father was executed for conspiring to overthrow the Umayyad caliphate. Jabir often found himself on the run as his patrons rose to and fell from power.

Far from an ivory-tower academic, Jabir came to alchemy through his practical work as an apothecary. He was influenced by the Neo-Platonists and other ancient Greek writers whose works were then being translated into Arabic. He added to classical alchemical thought and practice in several ways. In alchemical practice, he added plant and animal substances to the metals and earths that dominated ancient classical alchemy. This could possibly reflect his background in preparing medicines, and no doubt reflects his concern with the practical aspects of material transformations. On the theoretical side, he built on the ideas of Aristotle, the Greek philosopher, who had formalized the idea that all matter was made of four elements: earth, air, water, and fire. To these, Jabir added the concept of “natures,” which he listed as hotness, coldness, dryness, and wetness. Natures paired to make elements, in Jabir’s system. For example, hotness and dryness combined to make fire. Jabir professed that metals were formed from mercury and sulfur in varying combinations, and that achieving the right combination would produce gold. In this regard he was the founder of the mercurialist school of alchemy, a long tradition whose adherents would one day include Robert Boyle and Isaac Newton.

The ancient Greek philosopher Leucippus taught his students to notice that while sand is made of fine particles, from a distance the beach looks continuous like the sea. Thinking along these lines, one of his students, Democritus, came to the conclusion that all matter is ultimately made of indivisible particles. He gave them the name atomon. Remember that when a doctor removes your appendix we call it an appendectomy, and when the tonsils are removed we call the affair a tonsillectomy, the suffix tomy coming from the ancient Greek word for cutting or dividing. Thus atomon means “it can’t be divided,” and in time became our word atom.

Little is known about the life of Democritus, who hailed from the city of Abdera in Thrace. We do know that his ideas did not catch on. Rather, Aristotle’s view that matter is continuous and infinitely divisible held sway for more than 2,000 years, until the early 1800s, when John Dalton demonstrated that atoms did a very good job of explaining what was observed in chemical transformations. Even so, not all scientists were convinced that matter was made of atoms until the early 1900s, when The Svedberg’s studies of Brownian motion gave unequivocal proof of their existence.

Arabic alchemists had modified the Aristotelian system with respect to the composition of minerals, whereby two elements, mercury and sulfur, were responsible for “the mercurial and sulfurous principles” of a given substance. Later called “philosophical” Mercury and Sulfur, these elements (or principles) were thought to be the substances from which all metals were formed. This Sulfur-Mercury theory later became highly influential among European thinkers, for example, Isaac Newton. To this Sulfur and Mercury, al-Razi added a third constituent, a salty principle (which was later reproposed by Paracelsus). In al-Razi’s opinion metals were comprised of particles of these elemental constituents, while the identity of the metal depended on the relationships between these indivisible particles and the empty spaces between them.

In contrast to Jabir, who inclined toward numerical mysticism, al-Razi became practiced in experimental work. This is apparent from his two most influential works, Kitab al-Asrar (The Book of Secrets), and Kitab sirr al-Asrar (The Book of the Secret of Secrets). In these works he gave several recipes for the alleged transmutation of common metals into precious ones, and crystal or glass into precious stones. Perhaps al-Razi’s main contribution to chemistry was his attempt to systematize laboratory practices, to which end he listed contemporary laboratory equipment and techniques used in chemical experiments. Another influential contribution to chemistry was his classification of all the chemical substances he knew, for this is the earliest attempt of which we are aware. Al-Razi divided these substances into four main groups: vegetable, animal, derivative, and mineral. The last group consisted of six subgroups: (1) spirits ( volatile substances, such as mercury, sulfur, and arsenic sulfide); (2) metals (gold, silver, copper, tin, iron, lead, and “karesin,” probably a bronze composed of copper, zinc, and nickel); (3) stones (ores and minerals of iron, copper, zinc, but also glass); (4) atraments (metallic sulfates and their derivatives); (5) boraces (borax, but also sodium carbonate [confused with borax]); and (6) salts (in which categorization sodium chloride appears under four different terms, other salts being sodium carbonate, potassium carbonate, and others).

In later life al-Razi became blind, which, according to some sources, was a result of his indefatigable activity—for he is said to have written approximately 200 works. According to other sources his blindness was a result of torture, the punishment he was given when he failed to produce precious metals via alchemical transmutation. Al-Razi died in 925 or 935 in Ray.