Sarin (GB)
Dr. Gerhard Schrader, who had given the German army Tabun, became an employee of the army at the new Elberfeld facility in the Ruhr. In 1938, he developed Sarin, it's name an acronym for the development team's names: Schrader, Ambrose, Rudriger and van der Linde. Tests conducted on laboratory animals in June 1939 showed that Sarin was 10 times more effective than Tabun. During the closing stages of World War II, the Allies were surprised to have captured prototype Sarin munitions. The Soviets dismantled a Sarin plant at Falkenhagen and shipped it back to the USSR. After World War II, Sarin was also produced in Canada, the United States and the United Kingdom. In March 1995, the Japanese doomsday cult, Aum Shinrikyo, attacked Tokyo subway commuters with impure Sarin—resulting in the deaths of 12 individuals and affecting more than 5,000 other passengers. Follow-up investigations revealed that Aum Shinrikyo had sufficient material to manufacture a further 5.6 tons of Sarin. Sarin is both odorless and colorless in its liquid and vapor forms, but is described as smelling similar to rotting fruit in its impure state. Not very persistent, Sarin will linger in the environment for two to 24 hours at 5°C-25°C. When inhaled directly, Sarin causes death within one minute. A dose as small as 100mg · min/m³ will cause death in 50 percent of individuals exposed. If Sarin is absorbed through the skin, death results within ten minutes. Skin exposure of 1.7g on the skin of a man weighing 70 kilograms (roughly 150 pounds) is fatal to 50 percent of exposed individuals. Sarin is five times as heavy as air and represents no fire or explosion hazard. This makes Sarin an ideal agent for delivery by artillery, rockets or aerial spray. Because Sarin is very volatile and non-persistent, it is often thickened with oils or other petroleum products when filled in munitions to leave low-level residues.    

Soman (GD)
Soman was the last of the German nerve agents to be developed. It's name might have been either derived from the Greek verb "to sleep" or the Latin stem for "to bludgeon." Soman combines features of both Sarin and Tabun. In 1945, the archives on Soman research were captured by a Soviet task force. Under the direction of chemical warfare expert Professor Colonel Kargin, the material was shipped to the Karpov Institute in Moscow. A year later, Soman production was under way in the USSR. Soman has a lower evaporation rate than Sarin, remaining effective for about a day, which means that air movement will create a down-wind hazard—a cone-shaped plume of the agent blowing away from the point of delivery. A dose of 50mg · min/m³ of vapor is lethal to 50 percent of those exposed; 350mg of Soman liquid on the skin of a man weighing 70 kilograms (roughly 150 pounds) is fatal to 50 percent of individuals exposed. Though it requires 30 percent more exposure than Sarin to have a lethal effect, it is more readily absorbed into the bloodstream and more readily active with neural tissue—particularly the brain. Soman prevents the formation of cholinesterase in the neural synapses. The peripheral and central nervous systems stimulate themselves to their own destruction in 10 to fifteen minutes. This process includes violent muscle activity and malfunctioning major organs. The brain is the most profoundly affected and ceases to function before the bodily convulsions stop. Soman resembles a clear, heavy solvent or light machine oil and smells initially like over-ripe peaches and changes to a camphor-like odor as the concentration increases. Soman is less of a hazard to exposed skin in the open, but the membranes of the eyes and any open wounds are easy access points that cause rapid death. Soman is 6.5 times as heavy as air, and easily flows into low-lying areas. As a result, it can be used to "flood" subterranean field positions, tunnels and basements, producing long-term contamination. In 1955, the Soviets accidentally created a thickened version of Soman, designated VR-55, in their quest to perfect VX gas. (It was only later discovered that VR-55 compound and VX were different compounds). It was believed that the thickening process involved synthetic polymers and was designed to reduce evaporation and increase the agent's persistency and skin absorption rate.   

Tabun (GA)
Tabun, also known as Trilon-83, was isolated accidentally in January 1937 by German doctor Gerhard Schrader while he was engaged in the search for new pesticides at IG Farben. Controlled tests of the substance in laboratory animals revealed that death could occur within 20 minutes of exposure. Experiments were later conducted on German death camp inmates. Schrader reported his discovery to the Wehrmacht chemical laboratory at Berlin Spandau and within a year, Tabun was adopted as a nerve agent and the first nerve gas went into production at Elberfeld in the Ruhr. Production was relocated to Dyhernfurth-am-Oder in 1940. During World War II, the plant produced 12,000 tons of Tabun, of which 2,000 tons were filled into shells and 10,000 into bombs. At least one Tabun factory was captured by the Soviets, giving them a head start on the CW race. The Western allies considered Tabun production in the 1950s, but it was rejected in favor of the more powerful Sarin nerve agent. Tabun manufacture must be conducted under tightly controlled conditions, with high-speed ventilation and atmospheric filtration. Tabun is a rapidly acting lethal nerve agent that is either absorbed through the skin as a liquid or inhaled as a vapor. It is a pale to dark amber that gives off a colorless vapor. There is very little odor in its pure state, but emits a "rotting fruit" smell as it oxidizes. A vapor dose of approximately 400-mg · min/m³ will kill 50 percent of exposed individuals. A 1.0-gram dose of Tabun on the skin of a man weighing 70 kilograms (roughly 150 pounds) is fatal to 50 percent of exposed individuals. Autopsies of Tabun poisoning victims show massive congestion of body enzymes and fluids in all major organs.   

VX
VX was developed at the ICI Protection Laboratory, when British chemist Dr. R. Ghosh discovered an organophosphate/sulphur compound, which was immediately toxic to mammals as well as insects. The research was originally intended to derive a replacement for the insecticide DDT, but as it was too lethal to employ as a pesticide, the compound was passed to the Chemical and Biological Weapons Facility at Porton Down. The British, however, were already committed to Sarin and Tabun production and passed the compound on to the United States and Canada. Knowledge of VX production somehow leaked, and the Soviets developed their own version of VX in 1955, which they designated VR-55. However it was later discovered that VR-55 was only a thickened version of Soman. It was believed that the thickening process involved synthetic polymers and was designed to reduce evaporation and increase the agent's persistency and skin absorption rate. In 1960, the United States established a small VX plant in Newport, Indiana that was capable of producing 1,300 pounds of VX a year. In 1968, 20 pounds of VX leaked from an aerial spray tank, which was believed empty, and drifted across Skull Valley over the borders of Dugway Proving Ground, Utah, and killed 6,000 sheep. In 1969, it was discovered that canisters of VX stored on the island of Okinawa were leaking and had contaminated U.S. military personnel. As a direct result of these accidents, President Nixon issued an executive order in 1969 to halt U.S. production and development of CW. VX is designed to create casualties through skin absorption or from mist formed by aerial sprays, airburst rockets or artillery munitions. A dose of 10mg· min/m³ of vapor is sufficient to cause death to 50 percent of individuals exposed, while 10mg of VX liquid on the skin of a man weighing 70 kilograms (roughly 150 pounds) is fatal to 50 percent of individuals exposed. Within 15 minutes of exposure to a moderate dose, spasmodic symptoms will present, including twitching and loss of control of the bowels and bladder. Victims of a heavy dose die quickly, their nervous systems and heart, lungs and brain functions shut down, causing the body to cease functioning.