Or if you are a chemist... C10 H5 Cl N2
A so-called “tear gas” discovered in 1928 and depending on source either named after the its two inventors, Ben Corson and Roger Stoughton, or, unlikely as it sounds, from its chemical name of ortho-chlorobenzylmalononitrile. It was further developed during the 1950s and ‘60s at Porton Down, using volunteer British soldiers. Rather than a gas itself it is a white powder that is dispersed via a secondary agent such as methylene chloride.
CS Gas reacts with moisture on the skin, in the eyes, nose and mouth, and in the lungs, causing a burning sensation. Apart from the pain it causes it also results in tears being shed as the eyes go into an automatic cleaning mode. In severe cases coughing and vomiting can occur, especially if the victim is confined to an area of high concentrations of the gas, such as a room. The effects wear off within a few minutes of reaching clear air.
It is used as a non-lethal riot control agent and training chemical agent. Use in war is prohibited under the 1997 Chemical Weapons Convention. Use in the UK has often proved controversial: It was last used in Northern Ireland in 1972, but has been used by the British mainland police after this time, such as during the Liverpool riots during 1981.
It continues to be used around the world by the military for training, and police forces for riot control or as an aerosol spray against threatening individuals.
In common with many other nations’ forces the British Armed Forces uses CS gas as a CBRN training agent. Soldiers practice eating, drinking and other drills in a CS gas environment, typically a small purpose-built building, resulting in high levels of competence as well as confidence in their equipment and training.
Personnel are routinely exposed to relatively high concentrations of the gas during training. Such exposure serves to illustrate the effectiveness of chemical weapons and the importance of good CBRN drills.