Osmium Sulphite, OsSO₃

Osmium Sulphite, OsSO₃, is prepared by reduction of a solution of osmium tetroxide with sulphur dioxide. The solution at first becomes yellow, and finally assumes an indigo-blue colour. On evaporating to dryness and drying at 100° C. in vacuo the salt is obtained as a black, insoluble powder, which, however, dissolves in acid.