Ammonium Pyroxyhexathiovanadate, (NH₄)₄V₂S₆O

Ammonium Pyroxyhexathiovanadate, (NH₄)₄V₂S₆O, is deposited in red crystals when hydrogen sulphide is passed into a solution of ammonium metavanadate in ammonium hydroxide of higher specific gravity than 0.898 and the mixture kept for several months at a low temperature. The corresponding potassium salts, K₄V₂S₆O.3H₂O and K₄V₂S₆O.1½H₂O, are prepared in a similar manner. The normal potassium orthothiovanadate, K₃VS₄, has not been separately isolated, although mixtures which most probably contain it, together with the normal ammonium salt, have been prepared.