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.
Velpeau was the great advocate for a thorough mercurial treatment of this inflammation, and by enormous doses of calomel used concurrently with inunctions, he expected so to alter the blood in a few hours as "to prevent its furnishing the elements of a severe inflammation." Trousseau adopted for some time a similar method, for which he substituted later that of Dr. Law, giving minute doses frequently. Without accepting Velpeau's theory, it may be said that mercurial treatment - or rather calomel with opium - has been less completely abandoned in this inflammation than in many others. Watson certainly says "he is doubtful if it has ever done good, while if it purge it must do harm," but I believe that small doses of calomel or of sublimate (1/100 to 1/50 gr.) have conduced to the recovery of some of my cases of acute and "idiopathic" peritonitis. I have generally given them every one to three hours alternately with aconite, and used opium as required for relief of pain. In localized forms of peritonitis, occurring, for instance, after perforation, or from peri-typhlitis, opium is the most important remedy.