Bismuth Arsenides

When bismuth and arsenic are melted together there is no evidence of chemical combination. The two elements are only slightly miscible in the molten state and separate completely on solidification if an open vessel is used, but according to Heike they are perfectly miscible if melted in a sealed tube. Descamps melted a mixture of bismuth and excess of arsenic under fused boric oxide, keeping the temperature as low as possible, and obtained a product of density 8.45 and approximate composition Bi₃As₄, but it is doubtful whether this was a definite compound.

Bismuth Monarsenide, BiAs, may be obtained by passing arsine through a solution of bismuth trichloride containing a minimum quantity of hydrochloric acid. It is a black substance unattacked by water, dilute acids or alkalis, but decomposed by concentrated hydrochloric acid with formation of arsine.