Stahl, Georg Ernst

The German Georg Ernst Stahl (1659 - 1734), son to a court secretary, was a chemist, physician, and philosopher.

He was familiar with the theory of phlogiston and worked with metals and various other substances in order separate phlogiston from them. He proposed that metals were made of calx, or ash, and phlogiston, and that once a metal is heated, the phlogiston leaves only the calx within the substance.

The phlogiston theory was later replaced by the theory of oxidation of Antoine-Laurent de Lavoisier.