Overview

Until the late eighteenth century, the accepted theory of chemical reaction was the "phlogiston theory." This theory, whose name was coined by German chemist Georg Stahl (1660-1734) in the early 1700s, stated that a substance "phlogiston," which is Greek for "burned," was liberated when any material underwent combustion or when a metal was oxidized. By the late 1700s chemists, especially Antoine Lavoisier (1743-1794), had applied quantitative measurements and demonstrated that oxidized metals, or metals that had rusted, weighed more than nonoxidized ones, thus proving that phlogiston did not exist. Proponents of the phlogiston theory then countered that phlogiston was a negative quantity. Finally by 1800, after several new gases had been discovered and their role in combustion and oxidation identified, the phlogiston...