Bis(2-Chloroethyl)sulfide

Sulfur mustards are rapidly corrosive to brass and steel at 149 deg F (65 deg C); they are destroyed by strong oxidizing agents.

... Vigorous reaction with oxidizing materials. Incompatible with bleaching powder. ... When ... on contact with acid or acid fumes, it emits highly toxic fumes of oxides of /sulfur oxides and hydrogen chloride/; it will react with water or steam to produce toxic and corrosive fumes