Potassium Platinicyanide, KPt(CN)4, is obtained, combined with three molecules of platinocyanide, namely, as KPt(CN)4.3K2Pt(CN)4. 6H2O, by adding hydrogen peroxide (20-volume solution) to a concentrated solution of potassium platinocyanide, acidulated with sulphuric acid. Bronze, needle-shaped crystals are deposited, displaying a strong metallic reflection. They are readily soluble in water, yielding a colourless solution from which no precipitate is obtained with barium chloride. The solution bleaches cochineal, and liberates iodine from potassium iodide. Thus:
3K2Pt(CN)4.KPt(CN)4 + KI = 4K2Pt(CN)4 + I. |