Arsenic Tricarbide, AsC₃

Arsenic Tricarbide, AsC₃, is formed as a brown amorphous precipitate when a solution of arsenic trichloride reacts with the double compound of magnesium carbide and iodide:

2AsCl₃ + 3Mg₂C₂I₂ = 2AsC₃ + 3MgI₂ + 3MgCl₂

The product resembles the corresponding phosphorus carbide. It is insoluble in acids and alkalis, and when heated or rubbed it explodes with liberation of carbon and arsenic.

Arsenic carbonate has not been prepared, but arsenic salts of several organic acids, including arsenic cyanide, thiocyanate, acetate and tartrate, are known. Arsenic chromithiocyanate, As[Cr(SCN)₆], has also been described.