Note 7 tri — Chapter XXIII · THE PLATINUM METALS

Pigeon (1891) obtained fine yellow crystals of PtH2Cl6,4H2O by adding strong sulphuric acid to a strong solution of PtH2Cl6,6H2O. If crystals of H2PtCl6,6H2O be melted in vacuo (60°) in the presence of anhydrous potash, a red-brown solid hydrate is obtained containing less water and HCl, which parts with the remainder at 200°, leaving anhydrous PtCl4. The latter does not disengage chlorine before 220°, and is perfectly soluble in water.