Joseph Black

Joseph Black 1728-99, Scottish chemist and physician, b. France. He was professor of chemistry at Glasgow (1756-66) and from 1766 at Edinburgh. He is best known for his theories of latent heat and specific heat. He also laid the foundations of chemistry as an exact science in his investigations on magnesium carbonate, during which he discovered carbon dioxide, which he called "fixed air."

Black, Joseph (1728–99). Chemist who showed that gases enter into chemical reactions. Black studied medicine at Glasgow University with William Cullen, and then migrated to Edinburgh where in 1754 he submitted his MD dissertation on magnesia alba, a remedy for stomach aches. This he extended into a paper in 1756. He followed a cycle of reactions, in which ‘fixed air’ (carbon dioxide) is driven off from the stone on heating, leaving a powder akin to quicklime. With water it is slaked; and then slowly absorbs or fixes air or gas again to turn back into the starting substance. In 1756 he succeeded Cullen as professor of chemistry (within the medical school) at Glasgow, and in 1766 in Edinburgh. He also noted how much heat was needed to turn ice into cold water, or boiling water into steam: the phenomenon of latent heat. He was an early convert to Lavoisier's new chemistry.

David Knight

Black, Joseph (1728–99) Scottish chemist and physicist. Rediscovering ‘fixed air’ (carbon dioxide), Black found that this gas is produced by respiration, burning of charcoal and fermentation, that it behaves as an acid, and that it is probably found in the atmosphere. He also discovered hydrogen carbonates (bicarbonates). He investigated latent heat and specific heat but was unable to reconcile it with the phlogiston theory.