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.
Weak solutions of potash salts or liquor po-tassae relieve the itching and irritation of these disorders, also of pruritus, and to some extent of pruritus vulvae. A lotion made by boiling 1/2 oz. of potassa sulphurata in 1 pint of water, is very useful.