ash3

from The Collaborative International Dictionary of English v.0.48

Arsine \Ar"sine\ ([aum]r"s[i^]n or -s[=e]n), n. [From
   {Arsenic}.] (Chem.)
   A compound of arsenic and hydrogen, {AsH3}, a colorless and
   exceedingly poisonous gas, having an odor like garlic;
   arseniureted hydrogen.
   [1913 Webster]