hydro-ferricyanic acid

from The Collaborative International Dictionary of English v.0.48

Ferricyanic \Fer`ri*cy*an"ic\, a. [Ferri- + cyanic.] (Chem.)
   Pertaining to, or derived from, a ferricyanide.
   [1913 Webster]

   {Ferricyanic acid} (Chem.), a brown crystalline substance,
      {H6(CN)12Fe2}, obtained from potassium ferricyanide, and
      regarded as the type of the ferricyanides; -- called also
      {hydro-ferricyanic acid}, {hydrogen ferricyanide}, etc.
      [1913 Webster]