It becomes more and more apparent that arsenic is generally applicable to neuroses of the vagus. In asthma, I have long held it to be the most powerful prophylactic tonic that we possess. It is also an excellent remedy in gastralgia; although I have rather dwelt (in the text of this work) on the action of strychnia in this disease, I would not omit my testimony to arsenic. Dr. Leared has related some exceedingly interesting cases bearing on this point. (See _British Medical Journal_, November 23 and 30, 1867.) NOTE IV. INFLUENCE OF GALVANISM ON CUTANEOUS PIGMENT. Dr. Reynolds pointed out to me the exceedingly curious fact, which I have several times verified, that the constant current, in relieving facial neuralgia, not unfrequently disperses, almost instantaneously, the brown skin-pigment that has collected in the painful region; _e. g._, near the orbit. NOTE V. THE ACTUAL CAUTERY. A remedy for inveterate neuralgia which of late years I had almost discarded--the actual cautery--has quite recently yielded me very good palliative results in two cases. Its omission from the text of the chapter on Treatment was an accident due to the effect of habit in making one, half unconsciously, reckon this remedy as a "counter-irritant." The longer I practise, however, the more decidedly I am convinced that the actual cautery, if properly applied, does not act as an irritant at all; and this fact was sufficiently in my mind, when writing of irritant remedies, to make me omit the cautery from that section. I should have inserted it under the heading of remedies that interrupt the conductivity of nerves, and thus give the centres temporary rest. The only useful way to apply it is, to make an iron white hot, and very lightly brush the skin over so as to make an eschar not followed by suppuration. The galvano-cautery (Stohrer's Bunsen) is the best for the purpose, but I have made the flat-iron cautery serve very well. FOOTNOTES: [35] Art. "Neuralgia" ("Reynolds's System of Medicine," vol. ii. 1868.) [36] Practitioner, vol. iv., 1870. [37] Berlin. klin. Wochensch., 1865. [38] In a paper on the "Hypodermic Use of Remedies," in the _Practitioner_ of July, 1868, I gave the reasons for this opinion in full; and I see no reason to alter any thing I then said. [39] Practitioner, vol. iv. [40] Berlin. klin. Wochensch., 17, 1868. [41] "System of Medicine," vol. ii. [42] The English reader may consult Althaus ("A Treatise on Medical Electricity," second edition, Longmans), or Meyer ("Medical Electricity," translated by Hammond: Trubner & Co.) [43] "A Treatise on Medical Electricity," second edition, Longmans. [44] _Op. cit._ [45] Berlin. klin. Wochensch., 22, 1865. [46] _Op. cit._ [47] "Les Paraplegies et l'Ataxie du Mouvement." Par S. Jaccoud. Paris, 1864. PART II. DISEASES THAT RESEMBLE NEURALGIA. CHAPTER I. MYALGIA.