The Collaborative International Dictionary of English v.0.48:

Hydroferricyanic \Hy`dro*fer`ri*cy*an"ic\, n. [Hydro-, 2 +
   ferricyanic.] (Chem.)
   Pertaining to, or containing, or obtained from, hydrogen,
   ferric iron, and cyanogen; as, hydroferricyanic acid. See
   Ferricyanic.
   [1913 Webster]