Electro-therapeutics: a condensed manual of medical electricity / By D. F. Lincoln.

  • Lincoln, David F. (David Francis), 1841-1916.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Electro-therapeutics: a condensed manual of medical electricity / By D. F. Lincoln. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    and the shock has commonly a duration of at least a second, while the faradic current occupies but the mi- nutest fraction of a second. When the galvanic current has been traversing a nerve or a muscle in a certain direction for some time, the organ appears to become fatigued, and reacts less briskly to the closure-shock. While in this condi- tion, a current applied in the opposite direction will act with greater vigor than if no current at all had been applied. If we desire to take advantage of these facts, and pro- duce a very powerful reaction, we employ an instrument for instant reversal of the direction of the current. The poles of the battery are kept constantly applied to the body, but by turning the handle of the instrument the direction of the current is changed, so that what was the positive pole becomes negative, and vice versa. This procedure is called the Voltaic Alternation. The explanation of the process is as follows: At the positive pole the nerve or muscle is in a state of de- pressed susceptibility (anelectrotonus); instant suspen- sion of the current produces a rapid disappearance of the depression, which has the effect of a stimulation; a simultaneous introduction of the negative pole j)roduces a second stimulation, which is added to the former, pro- ducing a contraction of double vigor. At the other point of application, stimulation occurs under similar laws, but is less vigorous. By repeating the reversals at intervals of a few seconds the ,organ is brought into a state of high excitability. The effect upon nerves of sense is less thoroughly understood, but is doubtless similar to that, upon the motor nerves ; in particular, the