Arsenic Subhydride, As₂H

Arsenic Subhydride (or Hydrogen Di-arsenide), As₂H or As₄H₂, was obtained by Moser and Brukl as a red amorphous powder by the oxidation of arsine by means of stannic chloride in the presence of hydrochloric acid. It appears to be more stable than the monarsenide, but in the presence of moist air it gradually decomposes. It is insoluble in water, even when boiling, and is unaffected by hydrochloric acid, but it decomposes yielding arsenic when boiled with concentrated alkali solution or when heated with the fused alkali. When heated alone, it breaks up into arsenic, hydrogen and arsine. It is oxidised to arsenic acid by hydrogen peroxide, bromine or nitric acid.