Vanadium Trisulphide, V₂S₃

The most convenient method for the preparation of vanadium trisulphide in quantity consists in drawing the vapour of carbon disulphide for several hours over vanadium pentoxide heated to redness. It also results from the action of hydrogen sulphide gas on vanadous oxide, V₂O₃, or on the higher oxides of vanadium, or from the action of hydrogen sulphide at a red heat on any chloride or oxychloride of vanadium. Vanadium trisulphide has been obtained in black, glistening scales, of density 3-7, or as a black, amorphous powder, of density 4.0, according to the initial material. On being heated in air this sulphide evolves sulphur dioxide and forms vanadium pentoxide, but the reaction proceeds much less readily than in the case of the lower sulphide. The behaviour towards acids, colourless ammonium sulphide, yellow ammonium sulphide, caustic soda, and ammonium hydroxide is like that with the lower sulphide.