Sodium Potassium Platinocyanide, NaKPt(CN)₄

Sodium Potassium Platinocyanide, NaKPt(CN)₄.3H₂O, results when the copper salt is decomposed with a mixed solution of sodium and potassium carbonates. It crystallises in beautiful orange-coloured monoclinic prisms, and closely resembles the barium potassium salt. Its crystallographic elements are:

а: b: с = 0.85694: 1: 0.47296. β = 95° 5'.

It differs from the potassium salt in that it does not effloresce in the air. At 120° C. it becomes anhydrous, turning pale yellow in colour, but developing a reddish brown hue upon exposure to sunlight.