Preparation of Hydrogen Sulphide
In the present work this gas was always prepared from potassium hydrosulphide which was made from barium sulphide (commercial). Barium sulphide was treated with dilute hydrochloric acid and the resulting hydrogen sulphide washed thoroughly with a solution of potassium hydrosulphide and then with pure water. It was then passed into a strong solution of potassium hydroxide until the later was saturated. When it was required, it was set free from this solution by adding dilute sulphuric acid and again washing the resulting gas with a strong solution of potassium hydrosulphide.