Charcot, as has been stated, supposed that the effects produced by the application of metals were due to electrical action. This theory does not suffice to explain all of the effects. By Dr. Tuke, "expectant attention" was invoked to explain the phenomena, but this theory is not tenable. Vigouroux holds that the difference in electrical tension of some point of the organism is the real explanation of the phenomena resulting from the application of metals to the surface.

According to Burq, the order of susceptibility to the impression of metals is as follows, each individual, as a rule, being susceptible to one metal only: iron, copper, gold, silver, tin, platinum (only rarely). These metals are applied in the form of disks, or large coins, and sometimes disks of wood coated with the metals. Some other substances, as mentioned above, have exhibited the same phenomena, but the metals are unquestionably the most important. The metallic disks or coins are placed as a bracelet around the limb to be acted on, or individual disks are held in position by a bandage. The effects follow in a few minutes. The skin, previously pallid, cold, and without sensibility, becomes flushed, warm, and acutely sensitive, and in a short time the special senses are restored to their normal functional activity. As has been described, corresponding losses occur on the other side.

Metallotherapy has been employed chiefly for the restoration of sensibility in cases of the hemianaesthesia of hysteria, of paralysis of sensibility, in some instances of hemiplegia, and of certain functional paralyses of motility. It is not possible to formulate a set of rules for distinguishing the cases which will be benefited by these applications. Sometimes remarkable results are reached in a few applications; then, again, unaccountable failures occur.

Cases of writer's cramp, and of chorea, among the spasmodic affections, and neuralgia, have been suddenly cured by the use of the esthesiogenic metal; but failures are greatly more frequent than the successes. When the metal to which the patient is sensitive has been ascertained, the further treatment may be conducted by the internal use of the same.

Authorities referred to:

[The literature of this subject is now so extensive, that its enumeration would occupy space entirely out of proportion to its utility here. A few of the more important contributions are given.]

Burq, M. Thése de Paris, quoted in Bull. Gén. de Thérap., vol. xcvii, p. 33.

Perkins, Benjamin Douglas, M. A., son of Dr. Perkins the discoverer. The Efficacy of Perkins's Patent Metallic Tractors in Topical Diseases, etc., London, 1800.

Petit, Dr. L. H. Sur la Metallothérapie. Bull. Gen. de Thérap., vols, xcvii, xcviii. A series of papers.

Tike, Dr. Hack. Metalloscopy and Expectant Attention. Journal of Mental Science, January, 1879, p. 598.

Vigouroux, Dr. Le Progrés Medical, December 7, 1878, p. 944.

Westphal, Prof. Dr. Berliner klinische Wochenschrift, July 29, 1878.