SCHEELE, CARL WILHELM

born Dec. 9, 1742, Stralsund, Pomerania died May 21, 1786, Kping, Swed. Carl also spelled Karl Swedish chemist who anticipated Joseph Priestley's discovery of oxygen and made many other important discoveries. Scheele was first apprenticed for eight years to an apothecary in Gteborg before taking similar positions in Malm (1765) and Stockholm (1768). In 1770 he settled at Uppsala, and in 1775, when he was elected to the Stockholm Royal Academy of Sciences, he moved to Kping, where he became proprietor of a pharmacy. In his only book, Abhandlung von der Luft und dem Feuer (1777; Chemical Observations and Experiments on Air and Fire), Scheele records that the atmosphere is composed of two gasesone that supports combustion and the other that prevents it. The former, fire-air, or oxygen, he prepared from nitric acid, saltpetre (potassium nitrate), manganese dioxide, mercuric oxide, and other substances, and there is little doubt that he obtained the gas about 1772, two years before Priestley. But because of the delay in the publication of his results, he is rarely given credit for this discovery. Scheele's record as a discoverer of new substances is still probably unequaled, in spite of his poverty and lack of ordinary laboratory conveniences. His first scientific paper, published in 1770, dealt with his isolation of tartaric acid from cream of tartar, and in the last years of his life he was the first to isolate arsenic acid (1775), molybdic acid (1778), lactic acid (1780), tungstic acid (1781), and prussic (or hydrocyanic) acid (1783). He also isolated and investigated citric, malic, oxalic, and gallic acids. His analysis of manganese dioxide in 1774 led him to discover chlorine and barium oxide (baryta). Among his other discoveries were glycerine, the pigment Scheele's green (1775; copper arsenite), and the toxic gases hydrogen sulfide, hydrogen cyanide, and hydrogen fluoride.