Lewisite
When pure, a colorless oily liquid solidifying at -13 °C. Impurities cause colors ranging from brown to violet. Faint odor of geranium. Irritating to the eyes and mucous membranes at concentrations below the threshold of odor. Very toxic; used as a war gas. Produces severe vesication (blistering) even through rubber (Merck); absorbed through the skin to produce seven systemic effects. Antidote: dimercaprol (British Anti-Lewisite). Prolonged exposure of container to fire or intense heat may result in violent rupturing and rocketing of container.