Chemically generated aerosols, used primarily for military purposes. They are of four types: (1) FS, a mixture of sulfuric anhydride and chlorosulfonic acid, used in shells and bombs and sprayed from airplanes; (2) FM, titantium tetrachloride, the same as FS but brilliant white and will drop like a curtain when sprayed; (3) HC, a mixture of hexachloroethane, aluminum, and zinc oxide, burns to yield a white cloud; (4) WP, a white phosphorus, burns to form a white cloud of phosphoric acid, an excellent smoke producer.See Fog; Smoke; Chemical Warfare.