This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
With the exception of scabies, acne is the skin disease in which sulphur is most frequently used and gives the best results; the degree of stimulus or irritation supplied by it seems more appropriate than that of any other application, unless it be sometimes mercury. In the simple acne of young people, occurring in the sebaceous glands about the face and shoulders, accompanied by comedo and without much general congestion, a fairly strong preparation may be used, such as the sulphur ointment of the Pharmacopoeia; or potash may be added to it (Lancet, ii., 1878), or a lotion containing 6 dr. of precipitated sulphur and 1 dr. of glycerin, with 6 oz. of rectified spirit (Anderson). When a moderate degree of irritation is present the proportions may be altered; thus, 1 dr. of sublimed sulphur may be rubbed up with a little alcohol, and then 2 dr. of the smoother variety may be added, with water to dilute sufficiently (Morris: Lancet, i., 1855); or a lotion that I commonly use with advantage is made with 2 to 4 dr. of precipitated sulphur, with the same quantity of spirit and glycerin, in 6 oz. of rose-water. Spirits of camphor or ether may be added, to relieve itching or heat, and special indications for internal treatment must be considered. Sometimes dusting with the pure, dry precipitated sulphur answers better than anything (Parsons: British Medical Journal, i., 1879). The local remedies should be lightly or firmly applied, according as they can be borne, left in contact all night, and washed off with mucilaginous decoctions or water in the morning.
For acne rosacea, one of the best applications is an ointment containing 2 dr. of the hypochloride of sulphur in the ounce of rumex ointment (Wilson), or a lotion of 1/2 oz. of sublimed sulphur in 4 oz. of elderflower water. The ointment of iodide of sulphur, which is still stronger, may be carefully used to chronic cases of any form of acne. A certain amount of temporary irritation must be expected from these remedies, and may require their occasional intermission and the use of sedatives; but some compound of sulphur, judiciously employed, will be found the most effective cure. The internal use of calcium sulphide should be conjoined with this treatment.