A Short History of Hydrogen Sulfide
From the sewers of Paris to physiological messenger
Around 1750, a humble young Swede beginning his career as an apothecary was fortunate to have a series of very understanding mentors who allowed him considerable free time for reading and experimentation. His name was Carl Wilhelm Scheele, and he turned out to be a gifted chemist. Like many chemists before and after him, Scheele seems to have given little thought to the biological effects of the materials with which he worked. One day while distilling potassium ferrocyanide with sulfuric acid, he noted a “strong, peculiar and not unpleasant odor.” He brought himself to taste this gas and described it as “slightly on sweet [sic] and somewhat heating on the mouth.” Today we describe the odor as that of bitter almonds and call the gas hydrogen cyanide. Scheele may have been fortunate to have escaped with his life.
Perhaps a guardian angel was with him again on the day that he treated ferrous sulfide (pyrite, or fool’s gold) with a mineral acid. He called the rank odor that resulted Schwefelluft (sulfur air) and referred to it as stinkende (stinking or fetid). Today we refer to the odor as that of rotten eggs. His patron, the Swedish chemist and mineralogist Torbern Olof Bergman, also demonstrated its presence in some mineral springs. The publication date for these original observations was 1777—around the time of the Paris accidents. The fact that the same man discovered both hydrogen sulfide and hydrogen cyanide was the start of a long series of coincidences and discoveries about the two chemicals that would uncover their similarities.