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 ]

n. [ Ferro- + cyanide. ] (Chem.) One of a series of complex double cyanides of ferrous iron and some other base. [ 1913 Webster ]

Potassium ferrocyanide (Chem.), yellow prussiate of potash; a tough, yellow, crystalline salt, K4(CN)6Fe, the starting point in the manufacture of almost all cyanogen compounds, and the basis of the ferric ferrocyanate, prussian blue. It is obtained by strongly heating together potash, scrap iron, and animal matter containing nitrogen, as horn, leather, blood, etc., in iron pots. [ 1913 Webster ]