ELECTRODES AND THEIR GENERAL APPLICATION.
Having briefly sketched the nature of the electric currents of use in gynecology, their general applications and the means for measuring and modifying them, it remains to speak of the agents by which these currents may be brought to bear on the pelvic organs. These agents are called electrodes.
The electrodes are internal and external, and it is of prime impor tance that they should be well constructed, else they prove bad' conductors, and, even though we have secured the proper current and have carefully measured the dosage, our therapeutic aim is defeated through the loss of a great portion of the current.
The external electrode in general use consists of a sponge imbedded in rubber sheeting to proteot the clothing of the patient. This sponge electrode has, however, been rejected by the advanced workers in gyneco logical electrotherapy for the reason that it is bulky, dirty, and a source of loss of current, owing to the considerable resistance which it opposes to the passage. In its place have been substituted plates of block tin or of sheet lead, which Engelman!' has had perforated with holes one line in diameter and one inch apart. These plates, being pliable, readily adapt themselves to inequalities of the surface on which they are applied, and they are covered with a thin layer of absorbent cotton, with chamois, with punk (Engelmann), or with rough towelling. The towelling may be cut in sizes to cover the plates, and is held in place by pieces of tape. A further advantage of these plate electrodes is that the material which covers them may be changed for each patient, a much more cleanly method than the use of a sponge. Apostoli covers the abdomen with a layer of potter's clay, but the plates are much more convenient and fully as effective. These plates should vary in size from four to ten inches iii diameter, the general rule as to choice in size being simply that the greater the number of milliamperes used, the larger should be the plate, since the wider the external surface over which the current is disseminated the less the pain. Engelmann uses external electrodes with the following measurements:' 61 by 91 inches; 44 by 61 inches; 34 by 44 inches. The smaller electrode he does not use with currents over 20 milliamperes; the medium with currents over 60 milliamperes; and the larger with currents over this number. Where electrolysis is aimed at, the external electrode
should be large enough to cover as great a surface as is possible, in order to effectively disperse the current at the non-active pole, and this object Apostoli attains through the use of potter's clay.
These plate electrodes are in general applied over the abdomen or the sacrum. Where the object is indirect electrization both these regions are covered; where the aim is direct electrization the abdomen is, in general, the preferable site. They should be moistened in warm water in order to increase their conductivity and to diminish the resistance of the tissues, for a dry surface offers greater resistance than a moist. It is customary to use salt water for moistening the electrodes in order to intensify the superficial revulsive effect of the galvanic current. Engelmann rejects this practice, and says:' " Salt must be avoided; it is not necessary as it was for the poorly conducting sponge electrode, the instrument which I suggest being a much better conductor, and salt is injurious to patient and to instrument. When used upon electrodes by which currents of high intensity are applied, the electrolytic action of the galvanic current decomposes the salt, and chlorine is developed at the positive pole, by which the amount of pain may be increased and the electrode is corroded." Beard and Rockwell,' on the other hand, claim that the use of salt water is an excellent check against the administration of too strong currents, salt water being a much better conductor than simple water, and hence a patient will sensitively feel a current where salt is used which otherwise she would not notice at all. Where, however, a galvanometer is used to gauge the strength of the current, and a large electrode for dispersing it externally, it would seem preferable to dispense with salt, except whore we desire the patient to be conscious of the passage of the current for the moral effect, for otherwise in gynecology it is desirable that our manipula tions should be as painless as is consistent with therapeutic effect.