Black, JOSEPH, an eminent chemist, was born in 1728, at Bordeaux, where his father was engaged in the wine-trade. Both his parents were of Scotch descent, but natives of Belfast, to which city their son was sent for his education in 1740. In 1746 he entered the university of Glasgow, and studied chemistry under Dr Cullen. In 1751 he went to Edinburgh to complete his medical course, and in 1754 took his degree. In his famous graduation thesis (1756) he showed that the causticity of lime and the alkalies is due to the absence of the carbonic acid present in limestone and in what are now called the carbonates of the alkalies. To this he gave the name 'fixed air,' which gave way before that of 'carbonic acid,' first used by Lavoisier in 1784. The book was a distinct contribution to chemical science, and by Brougham and Robison is placed second only to Newton's Optics as a model for scientific investigation. Black pointed out the path afterwards followed by Cavendish, Priestley, and Lavoisier. On the removal of Cullen in 1756 to Edinburgh, Black succeeded him as professor of Anatomy and Chemistry in Glasgow, but soon after exchanged duties with the professor of the Institutes of Medicine, and lectured on the subject for ten years, practising the while as a busy physician, yet finding time for original investigation.
Between 1756 and 1761 he evolved that theory of 'latent heat' on which his scientific fame chiefly rests, and which formed the immediate preliminary to the next great stride in discovery by his pupil and assistant, James Watt. In 1766 he succeeded Cullen in the chair of Medicine and Chemistry in Edinburgh, and henceforward he devoted himself chiefly to the elaboration of his lectures, in which he aimed at the utmost degree of perspicuity, and with perfect success. His class became one of the most popular in the university; it occasioned, however, some disappointment that one so capable of enlarging its territory made no further contributions to chemistry. Though of an extremely delicate constitution, he prolonged his life, by care and temperance, to the age of seventy-one. He died on December 6, 1799. His lectures were published in 1803 (2 vols. Edin.), edited by Professor Robison.