Joseph Black. Coloured historical engraving of the British chemist, physician and physicist Joseph Black (1728-1799). Black was born in Bordeaux, France, but studied medicine at the Scottish universities of Glasgow and then later Edinburgh. He was later a professor of chemistry at both these universities. Around 1754, Black discovered the gas carbon dioxide. He also proved that this gas did not aid combustion. In 1761, he discovered the phenomenon of latent heat (heat that is present but not evident). James Watt, his pupil, put this discovery to practical use when he made improvements to early steam engines. Engraving by C. Cook.