Sulphammonium, S(NH₃)_x

When sulphur reacts with liquid ammonia at temperatures varying between -38° C. and -11.5° C., the solution obtained is blue in colour and from it red, fern-like leaflets are obtainable, to which the name sulphammonium has been given. Sulphammonium is formed also by the action of hydrogen sulphide on nitrogen sulphide, N₄S₄, dissolved in ammonia at -35° C., and by the action of ammonia and a limited amount of hydrogen sulphide on lead or mercury dithiodi-imide. Red, fern-like leaflets of solid sulphammonium are also produced by submitting a mixture of nitrogen and ammonia at -12° C. to a pressure of 45 atmospheres in the presence of sulphur.

Examination of the absorption of light of various wave-lengths by solutions of hydrogen sulphide and nitrogen sulphide in liquid ammonia shows that several compounds must exist.

Sulphammonium decomposes into ammonia and sulphur under ordinary pressures. With liquid ammonia in sealed tubes at temperatures between 0° C. and 20° C. it gives the compound (NH₃)₂S.2NH₃, and at -23° C. it forms (NH₃)₂S.NH₃. With iodine in solution in liquid ammonia, sulphammonium forms an ammoniacal compound of sulphur iodide. The blue colour of a solution of sulphammonium may possibly be due to the presence of colloidal sulphur.