Carl Wilhelm Scheele (1742-1786)
Carl Wilhelm Scheele (December 9, 1742 - May 21, 1786) was a brilliant German-Swedish chemist credited with discovering numerous chemical substances including oxygen (before Joseph Priestly) and chlorine (before Humphry Davy). Scheele settled in his hometown of Koping in present-day Sweden after the town provided an apothecary for him to engage wholly in scientific research. He went on to do extensive research in toxic chemicals. He prepared compounds of cyanide and arsenic and often tested them on himself. This exposure and the poor ventilation of his apothecary led to a premature death at the age of 43.