MURRAY, John, an eminent chemist, was born in Edinburgh in 1778, and became a pupil of the celebrated Dr Joseph Black. Murray commenced his career as an apothecary in his native city; but soon began to give chemical lectures, which were remarkable for clearness of diction and a happy mode of illustration; so that he was justly considered one of the ablest and most popular teachers of chemistry in the present century. His System of Chemistry, in 4 vols. 8vo, went through four large editions, and was regarded as one of the very best works on the subject of that period. The first volume contains a very admirable statement of the doctrines of heat in relation to chemistry, as promulgated by Black and later philosophers. His smaller work, entitled Elements of Chemistry, in 2 vols., was also very popular. Dr Murray afterwards gave annual courses of materia medica and pharmacy, which were numerously attended; and he published a good System of those branches of medicine, which went through two editions. The publication of Playfair's admirable Illustrations of the Huttonian Theory of the Earth, in 1802, quickly called forth Murray's Comparative View of the Huttonian and Neptunian Theories. He was a zealous defender of the latter; and although the igneous origin of mineral bodies is now generally received, Murray has given us by far the best and most ingenious defence of the Neptunian doctrines ever given to the world. Dr Murray was the author of several papers in the Transactions of the Edinburgh Royal Society; one of the most interesting of which is "The Analyses of several Mineral Waters," in which he showed how salts obtained by their evaporation may be different from those actually dissolved in the waters. Dr Murray was much respected and esteemed by those who best knew him. He died prematurely, of disease of the heart, on 22d June 1820. (r. s. r.)