Potassium Tungsten Bronze, K2W4O12, is obtained by fusing together potassium carbonate and tungstic acid and reducing the mass by coal gas, hydrogen, or tin; or by electrolysis of the fused paraungstate. It yields reddish-violet prisms of density 7.1; a suspension appears blue by transmitted light and green by reflected light. According to von Knorre and Schaefer this is the only potassium bronze which exists; other bronzes, for example K2W3O9 and K2W5O15, have, however, been described.
Two potassium sodium tungsten bronzes have been prepared, 5K2W4O12.2Na4W5O15 and 3K2W4O12.2Na2W3O9. Both are dark red; the former has density 7.117 and when powdered becomes blue. |