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.
There is also evidence as to the value of hydrochloric acid in scarlatina. Osborne records a prolonged experience in its favor (Lancet, ii., 1862), and more recently Egbert (Pennsylvania) has quoted nearly three hundred cases, all treated by a mixture containing this acid with chlorate of potash (Ranking, i., 1873). He gave about 8 min. of acid with 20 gr. of chlorate every two hours to a child of six, and more or less than this according to age. Occasionally Tinct. camph. co. was added to relieve restlessness; no applications were made to the throat, unless sometimes ice externally; only one death occurred. Of course it may be said that fevers tend to get well, and will do so under any treatment, but yet these results deserve careful attention. I myself constantly use hydrochloric acid internally and locally in cases of scarlet fever where there is marked general asthenia with dark ill-developed rash, and tendency to sloughing in the fauces (v. Chlorate of Potash).