According to the phlogiston theory, propounded in the 17th century, every combustible substance consisted of a hypothetical principle of fire known as phlogiston, which was liberated through burning, and a residue. The word phlogiston was first used early in the 18th century by the German chemist Georg Ernst Stahl. Stahl declared that the rusting of iron was also a form of burning in which phlogiston was freed and the metal reduced to an ash or calx. The theory was superseded between 1770 and 1790 when the French chemist Antoine Lavoisier showed that burning and rusting both involved oxygen and concluded that both ash and rust were compounds of oxygen. Lavoisier's oxidization theory has been accepted by scientists from about 1800 to the present day.
Bibliography: Conant, James B., ed., Overthrow of the Phlogiston Theory: The Chemical Revolution of 1775-1789 (1950); Partington, J.R., and McKie, D., Historical Studies on the Phlogiston Theory (1981).
Last modified on: Friday, October 17, 1997.