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.
Whether sulphuric acid does or does not lower pulse and temperature in the usually employed doses, it certainly is of more service in secondary pyrexial states than in specific fever. In subacute inflammatory conditions of protracted character occurring, e.g., during caseous pneumonia or chronic phthisis, it alleviates the general symptoms, and sometimes the local conditions. It is well suited for phthisical cases with a tendency to undue discharges, for it acts as a grateful tonic and astringent, lessening the night-perspirations, the intestinal flux, the expectoration, and passive haemoptysis; by combination with opium, or belladonna, aromatics, etc., so much relief may be sometimes given as to merit for the remedy its old title of "Elixir Vitriol."
The presence of cough does not contra-indicate its use, but irritation of the fauces must be obviated by mucilage or syrup: acids should, however, be omitted if gastric irritation be excited by them.