Chemical properties of bismuth

Elemental bismuth is inert in dry air at room temperature, but oxidizes slowly to become covered with a thin film of the oxide, which gives it a beautiful multi-colored luster. Above its melting point, it oxidizes rapidly to form an oxide film. At red heat in air, it bums with a bluish flame to give a yellow fume of bismuth oxide (BiiOj). It can also be attacked by super-heated water vapor to form the yellow oxide. Heating with sulfur produces bismuth sulfide Bi2S3 as a dark brown to grayish black solid. 

Treatment of a solution of bismuth chloride in hydrochloric acid with hypophosphorous acid gives free bismuth as a dull gray powder with a 

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