The last formula is suitable for many cases of acne when sulphur would not be well borne; but the pustules of this disorder may often be aborted with still more satisfactory results by means of the acid nitrate of mercury. The apex of the pustules should be lightly touched with this, on a glass brush, or a match point, and the drop of liquid should be soon removed by blotting paper or sponge: some temporary irritation may be expected.