EXPERIMENTS.
The most striking and the most corn , mon experiments are those which consist in the galvanic energy upon the organs of .animals. If two metallic rods, or, what is equally convenient, two silver spoons, be grasped, one in each hand, the skin of the part being previously moistened with a solution of salt, and one of the spoons be brought in contact with one end of the • battery, the moment the other comes in contact with the other end of the battery is felt in the elbows. One of a hundred will be felt in the shoulders. A greater number of plates give so forcible a shock to the muscles, as to be dreaded a second time.
The shock appears to depend upon the number of plates. The stun, or first pression, is much the same, whatever may be the size of the plates ; at least, from the size of two inches square to that of ten ; the surfaces being as four to one hundred. The effect upon the muscles, as well as upon the cuticle itself, is very different from large plates, when the se ries is the same. It appears that the shock, or first impression, is as the series, which is also as the intensity of th elec tricity. If the shock be received from the same number of large plates, the same species of commotion is produced, in the first instance, as with the small plates ; but if the contact be still kept up, a continua tion of the effect is perceived, which is felt through the whole arms, producing a vast tremor, attended with a sensation of warmth. If the plates be from eight to twelve inches square, this effect may be perpetually kept, while the acid in the cells is expended.
Though small plates have been recom mended for medical purposes, we think large ones will be found more likely to have a good effect. If the medical advan tage is to be derived from the stimulus of galvanism, the effect of a perpetual and regular current of that stimulus must cer tainly be preferable to the rapid transmis sion of a small quantity.
The galvanic shock may also be conve niently given, by immersing the hands or the feet into vessels containing a solution of salt, and bringing wires from each end of the battery into the liquid. If any other part of the body is intended to be ope rated upon, a sponge, moistened with salt water, fastened to a metal plate connect ed with one end of the battery, may be applied to the part, and the hand or foot put into a vessel of the same liquid, con nected by a wire with the other end of the battery. Small bits of sponge or bits of leather may be fastened to the end of the connecting wires, and made more or less moist, as the delicacy of the part may require. This contrivance is very useful in operating upon the eyes or ears.
When galvanism is used medically, it should first be very feebly, and the effect gradually increased, as the sus ceptibility of the part will admit. if the part has, from disease, become so languid and insusceptible, as not to be sensible of the effect, it should be scarified, or by other means have the cuticle removed. This is sometimes the case with languid tumours, and some cases of paralysis.— Though we had no great opinion of the medical agency of galvanism, we have lately heard of several very successful cases, one of which in particular was the cure of perfect loss of speech. if the naked metal of the wire from a powerful battery be applied to the skin, it becomes cauterized and blistered.
If the plate, covered with a moistened sponge, connected with one end of the battery, be applied to back of the head, at the same time that the moist tened fingers of one hand are slightly applied to the other end, a smarting sensation will be felt in the part, and a taste at the same time will be felt in the mouth, similar, but in a greater degree, to that occasioned by the piece of zinc and the shilling when laid upon die tongue. This experiment succeeds the best with a small number of large plates, as much as ten inches square.