| Ferrous hydrogen ferrocyanide, H2Fe[Fe(CN)6], results when hydrogen ferrocyanide solution is heated to 110°-120° C. with exclusion of air. It readily oxidises to ferric hydrogen ferrocyanide, Fe•••H[Fe••(CN)6].H2O, which is a blue compound, insoluble in water, oxalic acid, and ammonium oxalate solutions. |