Joseph Black (1728-1799) was one of the central figures of the Scottish Enlightenment. His friends and colleagues included David Hume, Adam Smith, Adam Ferguson, William Robertson, William Cullen and James Hutton; together, they formed a celebrated intellectual circle which regularly met, conversed and dined. Black was widely admired for his discovery and characterisation of 'fixed air' (carbon dioxide}, which arose from investigations he undertook at Edinburgh for the dissertation which counted towards his MD degree. His first teaching appointment followed at Glasgow University, where he developed ideas about latent and specific heat, all the more intriguing as there he formed a close friendship with James Watt, whose ambition grew to improve the performance of steam engines. Black's reputation lay largely as a highly talented teacher. From 1766, when he became professor of medicine and chemistry at Edinburgh, his large classes included pupils who were drawn from as far away as America, the West Indies and Russia. Black was also admired for his skill in applying science and economics to the improvement of agriculture and to the developing industrial landscape. According to a contemporary commentator he was, the best judge, perhaps, in Europe of such matters. This publication includes more than eight hundred items of Black's extensive correspondence, most of them published for the first time. It reveals relationships with businessmen, entrepreneurs and former pupils, as well as with prominent scientific and cultural figures of the day, including Antoine-Laurent Lavoisier, James Watt, Benjamin Rush, Josiah Wedgwood and Robert Adam. A number of letters and reports written to and from fellow physicians indicate that Black practised medicine throughout his career, particularly caring for the health of his friends, David Hume among them. There is also a revealing series of letters which point to the financial struggles his Ulster family endured at a period of political unrest in Europe and America, and showing how Black saved them from bankruptcy on various occasions. Documents associated with Black's domestic life and academic work are also included. The letters are preceded by an important introduction, covering Black's life and work, and the context and history of the correspondence, and are provided with extensive annotation. A comprehensive index concludes the work. These volumes therefore comprise an indispensable resource for all those interested in medicine, teaching, the growth of scientific ideas, the social fabric, and the rise of industry in the eighteenth century, and in the Enlightenment itself.