Joseph Black, a Scottish chemist, born in Bordeaux, France, in 1728, died in Edinburgh, Nov. 26, 1799. He was educated at Belfast, Glasgow, and Edinburgh, studied medicine, was a pupil and assistant of Dr. Cullen, and became distinguished by his experiments upon lime. It was supposed that quicklime held in absorption something of an igneous character; but Black discovered that the causticity of the calcareous earths is not derived from any combination, but is their peculiar property, and that they lose this property when they combine with a certain portion of air, to which he gave the name of fixed air, but which is now known as carbonic acid gas. Dr. Black was invited in 1756 to succeed Dr. Cullen at Glasgow, and there made his most important discovery. Ice, he observed, being converted into water, absorbs a large amount of heat, the existence of which is no longer indicated by the thermometer. Water being converted into vapor absorbs another large amount of heat, which is in like manner lost to the senses or the thermometer. Dr. Black, observing these phenomena, said that the heat is concealed (latet) in the water and vapor, and introduced the name and the theory of latent heat. This discovery suggested to Watt, who was a pupil of Black, his improvements in the steam engine.

In-1766 Dr. Black was appointed to the chemical chair of the university of Edinburgh, where his lectures were very successful. His only publications were three dissertations, giving an account of his experiments on magnesia, quicklime, and other alkaline substances; his observations on the more ready freezing of water that has been boiled; and his analysis of some boiling springs in Iceland.