Alexander Crum Brown was a pioneer in the study of the relationship between chemical constitution and physiological activity. An Edinburgh man descended from a line of distinguished theologians, he attended the Royal High School and then spent a year at Mill Hill School. He studied Arts and Medicine at Edinburgh University, graduating MA and MD at the same time as reading for a science degree at London University. He became a lecturer in Chemistry at Edinburgh in 1863, succeeding to the Chair of Chemistry in 1869, which he occupied until his retiral in 1908. Crum Brown developed a system of graphic representation for the formulae of organic substances which, with minor modifications, is still used. With Thomas Fraser he did pioneer work on the correlation of molecular structure with pharmacological effect and with Sir James Walker he 'effected an elegant and novel electrosynthesis of organic acids'.