Note 462 — Chapter XII · THE COPPER AND SILVER GROUPS (Continued).—THE THEORY OF COMPLEX IONS

2 Fe2+ + Hg2+ → 2 Fe3+ + Hg ↓. If the treatment with mercuric oxide is carried to completion the final products of the reaction are ferric hydroxide, mercuric cyanide, mercury and potassium hydroxide (Rose, Z. anal. Chem., 1, 300 (1862)):

2 K₄[Fe(CN)₆] + 7 HgO + 7 H₂O → 3 Hg[Hg(CN)₄] + 8 KOH + 2 Fe(OH)₃ ↓ + Hg ↓