Carl Wilhelm Scheele (1742-1786), Swedish chemist, aged about 25. In 1774 he became the first to isolate chlorine, although he did not identify it as an element. In the book Experiments on Air and Fire (1777), he argued that the atmosphere was comp- osed of two gases. One, which supported combustion (oxygen), he called 'fire air', and the other, which inhibited combustion (nitrogen), he called 'vitiated air'. His discovery of oxygen was made two years before Priestley, but it was the latter who published first. Scheele was not averse to tasting the new compounds he produced (such as hydrocyanic acid), and this was undoubtedly a factor in his early death.