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 most of the later manifestations of this disorder, sulphurous waters have a good reputation, but, in my opinion, without sufficient reason. At Aix-la-Chapelle, for instance, the treatment is conducted mainly by mercurial inunction, and the sulphur-waters used locally and internally, can only be considered adjuvants to this more powerful remedy. I think they serve mainly to cleanse and stimulate the skin, to regulate the action of the bowels and viscera, and to counteract any injurious effects that might arise from the mercury (v. p. 170). They have, perhaps, a further use for diagnostic purposes, since it is said that obscure symptoms really due to old or latent syphilis manifest themselves more fully under a course of the waters, and thus give the necessary indications for treatment by iodides or mercury. Dr. Wetzler gives several instances of this (op. cit.), and I have no doubt of its possibility.
I must say also that I have seen advantage from the use of sulphide of calcium in syphilitic laryngitis, notably when mercury had been previously taken to saturation.