The arsines and arsine chlorides are liquids of overpowering smell, and in some cases exert an extremely irritating action on the mucous membrane.
Many organic arsenic compounds are known, analogous to those of nitrogen and phosphorus, but apparently the primary and secondary arsines, AsH2CH3 and AsH(CH3)2, do not exist, although the corresponding chlorine derivatives, AsCl2CH3, methyl arsine chloride, and AsCl(CH3)2, dimethyl arsine chloride, are known.
Chlorine, bromine and iodine decompose arsine readily, the action being most violent in the case of chlorine.
The dimethyl arsine (or cacodyl) compounds have been most studied.
The tri-iodide, AsI3 prepared by subliming arsenic and iodine together in a retort, by leading arsine into an alcoholic iodine solution, or by boiling powdered arsenic and iodine with water, filtering and evaporating, forms brick-red hexagonal tables, of specific gravity 4.39, soluble in alcohol, ether and benzene, and in a large excess of water; in the presence of a small quantity of water, it is decomposed with formation of hydriodic acid and an insoluble basic salt of the composition 4AsOI.