1635-1682

German chemist remembered primarily for his influence on Georg Stahl. Becher's Physicae subterraneae (1669) attempted to adapt traditional alchemical ideas to the growing body of chemical knowledge. He divided solids into three kinds of earth—terra vitrescible, terra fluida, and terra pinguis. Becher treated the latter substance, known as "fatty earth," as the principle of inflammability similar to the alchemical sulfur. Stahl later developed the terra pinguis concept into the phlogiston theory.