1911 Encyclopædia Britannica/Williamson, Alexander William
WILLIAMSON, ALEXANDER WILLIAM (1824–1904), English chemist, was born at Wandsworth, London, on the 1st of May 1824. After working under Leopold Gmelin at Heidelberg, and Justus von Liebig at Giessen, he spent three years in Paris studying the higher mathematics under Comte. In 1849, he was appointed professor of practical chemistry at University College, London, and from 1855 until his retirement in 1887 he also held the professorship of chemistry. He had the credit of being the first to explain the process of etherification and to elucidate the formation of ether by the interaction of sulphuric acid and alcohol. Ether and alcohol he regarded as substances analogous to and built up on the same type as water, and he further introduced the water-type as a widely applicable basis for the classification of chemical compounds. The method of stating the rational constitution of bodies by comparison with water he believed capable of wide extension, and that one type, he thought, would suffice for all inorganic compounds, as well as for the best-known organic ones, the formula of water being taken in certain cases as doubled or tripled. So far back as 1850 he also suggested a view which, in a modified form, is of fundamental importance in the modern theory of ionic dissociation, for, in a paper on the theory of the formation of ether, he urged that in an aggregate of molecules of any compound there is an exchange constantly going on between the elements which are contained in it; for instance, in hydrochloric acid each atom of hydrogen does not remain quietly in juxtaposition with the atom of chlorine with which it first united, but changes places with other atoms of hydrogen. A somewhat similar hypothesis was put forward by R. J. E. Clausius about the same time. For his work on etherification, Williamson in 1862 received a Royal medal from the Royal Society, of which he became a fellow in 1855, and which he served as foreign secretary from 1873 to 1889. He was twice president of the London Chemical Society, from 1863–1865, and again in from 1869–1871. His death occurred on the 6th of May 1904, at Hindhead, Surrey, England.