Sodium Bromosmate, Na₂OsBr₆

Sodium Bromosmate, Na₂OsBr₆.4H₂O, may be prepared by the action of dry hydrogen bromide on sodium osmisulphite, 3Na₂O.OsO₃.4SO₂.5H₂O, or better by decomposition of the same with aqueous hydrogen bromide, of density 1.45. A deep purple-red solution is obtained from which long, dark brown prisms crystallise out, possessed of a metallic appearance.