Johann Joachim BecherBorn 6 May 1635; died Oct 1682 . German chemist, physician and adventurer who gave an early theory of combustion (1669) in which all flammable objects were supposed to contain a substance which was released when the object burned. Becher called it terra pinguis (L. fatty or combustible earth). Thus, the conversion of wood to ashes by burning was explained on the assumption that the original wood consisted of ash and terra pinguis, which was released on burning. In the early 18th century Georg Stahl renamed the substance phlogiston. Becher also made practical suggestions, for example, that sugar was necessary for fermentation and that coal could be distilled to yield tar, though he also experimented to obtain gold from sea sand. |