GERHARDT, CHARLES (-FRDRIC)

born Aug. 21, 1816, Strasbourg, Fr. died Aug. 19, 1856, Strasbourg French chemist who, with Auguste Laurent, developed a classification of organic compounds. His idea that all organic compounds were based on four main types (i.e., hydrogen, hydrogen chloride, ammonia, and water) was opposed by his contemporaries and was later abandoned, but it proved important in the subsequent rationalization of structural organic chemistry. Gerhardt was one of the first to make a systematic and methodical use of equations in expressing chemical reactions. He also promoted Jean Dumas's concept of homology as an aid in organizing the reactions of series of compounds, and he favoured the definition of acids as substances containing replaceable hydrogen atoms. Among his noteworthy experimental efforts was the preparation of anhydrides of carboxylic acids (1852). He became professor at the Universit de Montpellier (1844), and at Strasbourg (1855).