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(lo͞o`əsīt'), liquid chemical compound used as a poison gaspoison gas,
any of various gases sometimes used in warfare or riot control because of their poisonous or corrosive nature. These gases may be roughly grouped according to the portal of entry into the body and their physiological effects.
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. Like mustard gas and nitrogen mustard, it is a blistering agent; when inhaled, it is a powerful respiratory irritant. The absorption of lewisite, which penetrates ordinary clothing and even rubber, through the skin may be fatal. Chemically, lewisite is dichloro-2-chlorovinyl arsine, ClCHCHAsCl2. It boils with decomposition at 190°C;, and its vapor has a faint odor of geraniums. Lewisite is neutralized by reaction with British antilewisite (2, 3-dimercapto-1-propanol). It is named after its developer, the American chemist Winford Lee Lewis.



(after the American chemist W. L. Lewis, 1878-1943), ClCH=CHAsCl2, β-dichloro(2-chlorpvinyl) arsine (αlewisite), a war gas with a toxic (systemic), irritating, vesicant effect. The commercial product contains admixtures of bis (β-chlorovinyl) chloroarsine (ClCH = CH)2AsCl (βMewisite) and tris (β-chlorovinyl) arsine (ClCH=CH)3As (γ-lewisite).

A mixture of cis and trans isomers, a-lewisite is characterized by boiling points of 170° and 196°C (melting points, —44 and -1.2°C; density, 1.6092 g/cm3 at 23.5°C). All of these compounds are colorless liquids, insoluble in water but readily soluble in organic solvents.

In water, α-lewisite undergoes rapid hydrolysis to form toxic β-chlorovinylarsenic oxide C1CH—CHAsO. With oxidants (H2O2, HNO3), it is converted to β-chlorovinyl arsenic acid C1CH = CHAsO(OH)2. In the presence of alkalis, a-lewisite readily dissociates to yield acetylene, and c/s-α-lewisite dissociates to yield vinyl chloride.

Lewisite is formed by the reaction of acetylene and AsCl3 in the presence of AlCl3, HgCl2, and other catalysts.

The human body cannot tolerate lewisite concentrations greater than 2.10-2mg per l, which irritate the upper respiratory passages. The lethal doses are 0.25 mg/per l (15 min) when inhaled and 25 mg per kg when absorbed through the skin. Dimercaptopropanol and its derivatives are effective in the treatment of lewisite-induced affections.

Lewisite was first obtained at the end of World War I (1914-18), but it was never used for military purposes.


Rukovodstvo po toksikologii otravliaiushchikh veshchestv. Kiev, 1964.
Stepanov, A. A. “Otravliaiushchie veshchestva.” Zhurnal Vsesoiuznogo khimicheskogo obshchestva imeni D. I. Mendeleeva, 1968, vol. 13, no. 6.



(Ca,Fe,Na)2 A titanian romeite mineral.
(organic chemistry)
C2H2 AsCl3 An oily liquid, colorless to brown or violet; forms a toxic gas, used in World War I.