227666-A is referenced by 9 patents.
Barium and strontium hydrates are obtained by treating a solution of the sulphide with ammonia. Half of the barium or strontium separates as hydrate and may be washed free from sulphide with water containing ammonia. The rest of the barium or strontium is converted into hydrosulphide, which, after expulsion of the ammonia may be treated with carbon dioxide to recover sulphuretted hydrogen. To obtain practically all the barium or strontium as hydrate the sulphide is treated with ammonia and caustic alkali.