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 all forms of ulcerative sore throat, whether scarlatinal or otherwise, but especially when sloughing is present, and when there is marked general asthenia, hydrochloric acid is indicated as well locally as internally. It may be applied with a brush (1 part in 15 of liquid) or in gargle (2 dr. to 8 oz.). In gangrenous or "putrid" sore throat, the nearly pure acid may be carefully and lightly pencilled over the affected part.