The effects of a mere accumulation of electricity in the system have not been satisfactorily determined. We feel often very differently before and after a thunder-storm. Many persons imagine they can detect by their sensations the approach of certain changes in the weather, before any evidence of such changes is presented by ordinary signs. I know neuralgic persons who suffer much more in certain kinds of weather than in others, though completely protected against any influence of cold or instances, the ends of the excitors should be covered with buckskin or other similar material, which will imbibe and retain moisture. A sort of hollow cylinder containing a wet sponge (Fig. 1) should be used, when it is desirable to cover some extent of surface. M. Duchenne uses sometimes a bunch of fine wires, in the form of a brush or broom (Fig. 3), the wires being fixed at one end in a hollow cylinder, from which they project at the other, and the cylinder being screwed upon an insulating handle.

Silent Conduction. When the body, by contact with an excited prime conductor, becomes the route through which the electric current passes, however powerful may be the machine, and however rapid the current, no observable effect is produced either upon the sensations, or any of the functions.

The Aura. This is said to operate as a mild stimulant to the portion of surface upon which it is made to act; and has sometimes been employed for this purpose in affections of very delicate organs, as the eye. But the influence, if any, must be extremely slight.

The Electric Bath. Very different statements have been made as to the effects of electricity accumulated in the system, in a state of insulation. Some have found it to increase the frequency of the pulse, and promote the secretions, especially those of the skin, kidneys, and salivary glands, and have obtained great supposed advantages from it in rheumatic neuralgia, and paralytic diseases. Giacomini, while admitting that the positive electric bath produces no impression on any one of the interior functions, imagined the negative to be powerfully depressing, and capable of advantageous use as a contra-stimulant agent It is not impossible that, in certain very susceptible individuals, the bath may have some influence; but I have found no effect from it in my own person, and the same I believe to be the experience of most who have tried it; and, without calling into question the accuracy or trustworthiness of those who have made opposite statements, we are, I think, justified in at least suspecting, that the phenomena observed were really ascribable to the mental state of the persons acted on, and in no degree to the electricity. As to the supposed cures of rheumatism, neuralgia, and palsy, we know well how powerful mental influence is in many cases of those affections, and bow often the favourable changes which have taken place spontaneously with time, have been ascribed to the last remedy used. But, though we may doubt the remedial influence of simple electrical accumulation, yet the bath may be made a means of gentle stimulation to the surface, by the sensation produced when the electricity is drawn from the body, under these circumstances, by sparks.

Sparks. The spark, whether drawn from an excited prime conductor by the body, or from the excited and insulated body by other substances, is attended with more or less sensation, of a sharp, pungent character, very slight when the spark is small, but painful when the electric tension is very great, though seldom so severe that it cannot be readily borne. The electricity scarcely penetrates beyond the surface; yet it in some degree excites the skin, and, if the operation is continued, produces rubefacient swelling, and some tenderness to the touch. It may therefore, be occasionally used with advantage in this method, as a gentle excitant in inactive states of the surface, and as a revulsive in internal diseases of no great severity. It may be concentrated in one spot, or applied extensively over the surface; and, for the latter purpose, the bath probably affords the most convenient means. By the interposition of flannel, which may cover the ball of the director, or be applied to the surface of the body, a great number of minute sparks may be drawn rapidly, with less discomfort to the patient.

Leyden Jar. When the body is made the connecting medium between the two surfaces of a Leyden jar, a quick painful sensation is experienced, denominated the shock, which is always disagreeable, and may be so violent as to be quite insupportable. This is attended with a quick, jerking, muscular contraction, and even the deep-lying muscles may be brought into energetic action. If applied to the hands, the sensation is felt chiefly in the wrists, elbows, and breast. If directed so as to reach the nervous centres, the shock radiates through the whole system. When severe, its first observable effect, independently of the sensation and spasm produced, is to depress function by overwhelming it. Thus, the skin for a short distance around the point of entrance is whitened, and its temperature lessened, while the follicles project in consequence of the shrinking of the tissue. The part is also more or less benumbed. If the shock is passed through a nerve of sensation, numbness is apt to be felt in the parts supplied by it; and a severe shock through the brain or spinal marrow, produces, in the former case, mental confusion, forget fulness, dimness of vision, etc., in the latter, feebleness approaching to paralysis of the lower limbs. The violence of the effect is proportionate both to the electric intensity and quantity. A small jar, highly charged, will produce a greater effect than a larger one feebly charged; but, the intensity being equal, the degree of effect is then proportionate to the quantity, or to the magnitude of the apparatus. The shock from an electric battery is capable of producing temporary insensibility, and probably death. After fatal effects from lightning, streaks of redness are said to be sometimes observed along the surface; and the blood is, in general, fluid, and the muscles flaccid, as if universal death had taken place immediately. The depression occasioned by the shock from the jar speedily passes off, and is followed by more or less reaction. In this method of application, electricity may sometimes be usefully employed for exciting parts which lie deeply, and are extremely insusceptible, or in rousing a torpid system by the shock, or for depressing nervous excitement by its first overwhelming effects; but it is impossible to limit its action precisely to any one muscle or part; and there may be hazard, in cases of great depression, of dangerously adding the prostration of the shock to that already existing. Allusion has been before made (see pages b.502-3) to a mode of regulating the remedy which will obviate this latter danger. In some instances,the subcutaneous adipose tissue is so thick, or the cellular tissue so edematous, that the dynamic currents will not penetrate them. In such cases recourse may be had to the jar.