Georg Ernst Stahl

Georg Ernst Stahl (1660-1734), German chemist and physician, who is best known as the main developer of the phlogiston theory, which offered an explanation for combustion. Although many of Stahl's theories have been replaced by more modern ideas, his work was important in the development of chemistry. Stahl was born in Ansbach, Bavaria, and served as court physician at Weimar. He lectured on medicine at the University of Halle and in 1716 became physician to Prussia's King Frederick William I. Basing his work on that of his teacher, Johann Joachim Becher, another German chemist, Stahl proposed that a substance called phlogiston is the basis for both combustion and oxidation. He was the first chemist to recognize that these processes are analogous. The phlogiston theory was later disproved by the French chemist Antoine Lavoisier, who demonstrated the role of oxygen in combustion. In medicine, Stahl supported the vitalist viewpoint that life processes are different from physical or chemical ones, but his work helped advance a rational approach to mental illness.