Mustard gas, though technically not a gas and often called sulfur mustard by scholarly sources, is the prototypical substance of the sulfur-based family of cytotoxic and vesicant chemical warfare agents, which can form large blisters on exposed skin and in the lungs. It has a history of use as a blister-agent in warfare and, along with organoarsenic compounds such as Lewisite, is the most well-studied of such agents. Related chemical compounds with similar chemical structure and similar properties form a class of compounds known collectively as sulfur mustards or mustard agents. Pure sulfur mustards are colorless, viscous liquids at room temperature. When used in impure form, such as warfare agents, they are usually yellow-brown and have an odor resembling mustard plants, garlic, or horseradish, hence the name. The common name of "mustard gas" is inaccurate because the sulfur mustard is not actually vaporized, but dispersed as a fine mist of liquid droplets. Mustard gas was originally assigned the name LOST, after the scientists Wilhelm Lommel and Wilhelm Steinkopf, who developed a method of large-scale production for the Imperial German Army in 1916.