Barium Hydroxyhydrosulphide

Barium Hydroxyhydrosulphide. - By extracting barium sulphide with water a solution containing equal molecular quantities of the hydroxide and hydrosulphide is obtained. This is probably a solution of a double compound, Ba(OH)₂.Ba(SH)₂, or a hydroxyhydrosulphide, Ba(OH)(SH). By mixing concentrated solutions of the two constituents a compound is precipitated of composition Ba(OH)₂.Ba(SH)₂.10H₂O, or, regarded as a hydroxyhydrosulphide, Ba(OH)(SH).5H₂O. The maximum yield is obtained when about thirty molecules of the hydrosulphide are present to one of the hydroxide. The pressure of sulphuretted hydrogen over this compound is very small compared with that over the hydrosulphide.

The hydroxyhydrosulphide may also be formed by the incomplete saturation of barium hydroxide with sulphuretted hydrogen, by passing hydrogen through a solution of the hydrosulphide, or by the action of sodium hydroxide on barium hydrosulphide or sulphide. It is evident that the latter cannot be used as a method for the preparation of barium hydroxide. Pure barium hydroxide can never be crystallised from solutions obtained by the action of water on barium sulphide.

The composition of solutions in equilibrium with the hydroxyhydrosulphide at different temperatures has been determined.