Tungsten Subphosphide, W₄P₂

By strongly heating a mixture of phosphoric acid and tungstic anhydride in a carbon crucible, lustrous steel-coloured crystals of this phosphide are obtained. The crystals are six-sided prisms of density 5.21. It conducts electricity well, is very stable in air even at higher temperatures, and is very resistant to acids. When heated in a current of oxygen it burns brilliantly. It dissolves in a fused mixture of alkali carbonate and nitrate.