Sulfur Dioxide: Manganese Dioxide Heated with Sulphur (Thorpe, 1913)

Sulphur dioxide without a flame: manganese dioxide and sulphur heated together give manganese sulphide and sulphur dioxide, MnO2 + S2 = MnS + SO2. Collect the heavy gas by downward displacement, or over mercury if it must be free of air. It is poisonous: 1 part in 2500 of air makes breathing hard and hurts the eyes. Not given: amounts beyond the equation, and the heat. Source: T. E. Thorpe, Dictionary of Applied Chemistry vol. V (1913), p. 302. Picture: the book's text.