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.
In superficial burns the strong solution has been applied, and to deeper injuries, when the true skin is affected, the solid stick has been used with the object both of forming a covering from air, and of lessening the degree of cicatrization (Fricke). This method has not met with general support, but a modified plan was recommended by Mr. Skey, who used a lotion containing about 6 gr. in 1 oz. for infants, and twice that strength for adults, covering the part immediately afterward with cotton wool (Lancet, ii., 1861). A mixture with linseed oil has been commended (Wernher), and the solid stick is always useful in later stages when ulcerations are slow to heal. Hebra applies it once or twice daily, especially where there is liability to adhesions.
3. Counter-irritant. - The action of the remedy when applied locally in superficial inflammations, has earned for it the title of "caustique antiphlogistique," but we cannot recognize in it any distinctly caustic action, any more than we can verify the production of a "substitutive inflammation," which replaces for a time the original malady, and then itself subsides (v. p. 11). The main factor in the result is an astringent effect on the vessels and nutritive processes, but there are cases in which, when the nitrate is applied to some other than the affected part, it will relieve by an action which may properly be called counter-irritant or derivative, the "medication irritante transpositive" of Trousseau. Thus, Liston and Elliotson treated erysipelas by its application to the neighboring sound skin, and Lubanski, Egan, and others treated amenorrhoea by pencilling the os uteri (Dublin Journal, 1848).