High Quality Content by WIKIPEDIA articles! 2-chlorobenzalmalononitrile (also called o-chlorobenzylidene malononitrile) (chemical formula: C10H5ClN2) is the defining component of a "tear gas" commonly referred to as CS gas, which is used as a riot control agent. "CS gas" is actually an aerosol of a volatile solvent (a substance that dissolves other active substances and that easily evaporates with it) and 2-chlorobenzalmalononitrile, which is a solid compound at room temperature. CS gas is generally accepted as being non-lethal. It was discovered by two Americans, Ben Corson and Roger Stoughton, at Middlebury College in 1928, and the chemical`s name is derived from the first letters of the scientists` surnames.