H4CN6Fe

Ferrocyanic Fer`ro*cy*an"ic, a. [Ferro- + cyanic: cf. F. ferrocyanique.] (Chem.) Pertaining to, derived from, or designating, a ferrocyanide. [1913 Webster]

{ferrocyanic acid} (Chem.), a white crystalline substance, {H4(CN)6Fe}, of strong acid properties, obtained from potassium ferrocyanide, and regarded as the type of the ferrocyanides; -- called also {hydro-ferrocyanic acid}, {hydrogen ferrocyanide}. etc. [1913 Webster]