German chemist responsible for proving that organic compounds do not need a vital force supplied by a living tissue in order to be made. In 1828 Wöhler heated the inorganic compound ammonium cyanate and found that it was converted into urea. Urea is a nitrogen-containing compound that is produced by the metabolism of proteins in mammals and found in the urine. Wöhler proved that metabolic processes are chemical in nature by showing that benzoic acid was converted to hippuric acid. Another significant contribution was the discovery of calcium carbide, which reacts with water to produce acetylene. See long biography on p. 180.