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[loo-uh-sahyt] /ˈlu əˌsaɪt/
a pale yellow, odorless compound, C 2 H 2 AsCl 3 , used as a blister gas in World War I.
1920-25; named after Winford Lee Lewis (1878-1943), American chemist who developed it; see -ite1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for lewisite
  • Information on lewisite, a potential agent for chemical terrorism.
  • lewisite, a chemical warfare agent containing arsenic, was manufactured in four of the plants.
  • Wastes generated from lewisite manufacturing were disposed in shallow surface impoundments.
  • The non-stockpile section of the agency may be tasked to destroy the lewisite at some point in the future.
British Dictionary definitions for lewisite


a colourless oily poisonous liquid with an odour resembling that of geraniums, having a powerful vesicant action and used as a war gas; 1-chloro-2-dichloroarsinoethene. Formula: ClCH:CHAsCl2
Word Origin
C20: named after W. L. Lewis (1878–1943), US chemist
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Encyclopedia Article for lewisite

in chemical warfare, poison blister gas developed by the United States for use during World War I. Chemically, the substance is dichloro(2-chlorovinyl)arsine, a liquid whose vapour is highly toxic when inhaled or when in direct contact with the skin. It blisters the skin and irritates the lungs. Any part of the body that is contacted by the liquid or vapour suffers inflammation, burns, and tissue destruction. Lewisite was developed in retaliation for German gas attacks during World War I, but was never actually used. It was in the process of manufacture when the armistice was signed.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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