HOFMANN, hiWinan. AUGUST WILHELM VON (181S-92). A distinguished German chemist, horn at Giessen. After obtaining the degree of doctor of philosophy, he became assistant to T,iebig in the Giessen laboratory, and in 1843 became professor of chemistry in the University of Bonn. In the same year the Royal College of Chemistry was established in London, and Hofmann was recommended by Liebig as highly qualified for the post of superintendent to the new institution. This college. which subsequently became part of the Royal School of Mines, owes much of its high reputation to Hofmann's ac tivity. On the promotion of Thomas Graham from the post of chemist to the mint to the office of master of that institution. Hofmann was appointed his successor. In Istal he was elected president of the London Chemical Society. In 1863 accepted the chair of eliemistry in the University of Berlin. and in IsliS founded the German Chemical Society. Ile was ennobled in I8ss. Ile served as judge at several industrial expositions, of which he published admirable ac counts, and was a member of many scientific bodies, at home and abroad. Hofmann was one of the greatest chemists of the nineteenth century.
The results of his brilliant researches have formed entire departments in organic chemistry, and have hail an important influence on the de velopment of chemical theory. He investigated the org„anie bases obtained from coal-tar, and dis covered a new and important class of compounds which are deri WI I from ammonia by the substi tution of organic radicals for hydrogen atoms.
Among his most important discoveries is that of aniline among the products of destructive dis tillation of laituminous coal, and the discovery of methods for the artificial preparation of beau tiful coloring substances front aniline. He oh tainaall the colorless base known as rosanilin and its colored salts, such as fuchsin, dahlia (`116f mann's rioter), etc., which are the most impor tant of the colors derived from aniline. These discoveries have contributed greatly to the de velopment of the color industry, and have prac tically revolutionized the art of dyeing. Among his contributions to physical chemistry may be mentioned his method of determining the vapor densities of chemical substances for the purpose of obtaining their molecular weights, and a method of demonstrating the dissociation of gases, such as carbonic-acid gas and water-vapor, by the action of electric sparks. Hofmann was a brilliant teacher, and his Introduction to Mod ern Chemistry (1865, and several later editions) has brought about important reforms in the methods of chemistry. lie also wrote: A Handbook of Organic Analysis (1853) ; The Life Work of Licbig in Experimental and Philo sophic Chemistry (1876) ; Zur Erinncrung en vorangcgangene Kreunde (1889), etc. Consult: Volhard and Fischer, August Wilhelm von Hof mann. Ein Lebensbild, im .4uffrage der Deutsch en Chcmisehen Gesellschaft (Berlin, 1902).