Ethyldichloroarsine, sometimes abbreviated `ED`, is an organoarsenic compound with the formula CH3CH2AsCl2. This colourless volatile liquid is a highly toxic obsolete vesicant or blister agent that was used during World War I in chemical warfare. The molecule is pyramidal with the Cl-As-Cl and C-As-Cl angles approaching 90° (see image). Its tox.....
C2H5AsCl2;a blister agent used in World War I; irritating to the respiratory tract. ... (05 Mar 2000) ... 
(ED) Type: Term Pronunciation: eth′il-dī-klōr′ō-ar′sēn Definitions: 1. Blistering agent first used in World War I; irritating to the respiratory tract.
a colorless, volatile, poisonous liquid, CHAsCl, having an irritating, fruitlike odor: formerly used as a blister gas.