Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

If we but coil a fine bit of platinum wire into a small spiral, it may be heated, even instantly, to a white beat, by making con- tact with a galvanic battery of large-sized cups, of quick action, and few in number. Thus it can serve the most perfect office of a cautery that is known in surgery. For this purpose, as we have elsewhere explained, it takes some half dozen half-gallon jars of a Bunsen or Grove's battery. It must be borne in mind that when using a compound gal- vanic battery of high series for remedial purposes, that the law of this current is heat, in proportion to the power of the current and the obstacle opposed. This capability of such a current is aroused, then, not only by a small or poor conducting wire, but also by passing through a portion of the human body, as in or- dinary treatments. Therefore the operator must know that if the electrodes are retained for some time on the same spot, while a large current is flowing, there will be danger of producing a slough, simply from cooking the flesh by electric heat. Let the same current pass through a small quantity of water, as in a glass tube, and it is seen to be not only rapidly decomposed, but it also boils, and that instantly and furiously. But there need be no kind of danger of this accident occurring, except from sheer ignorance or carelessness. Magnetism versus Electricity. — M. Becquerel contends that all bodies are more or less magnetic. The action of the mag- net, it is known, was for a long time regarded as a special action exercised only upon certain bodies. Now, it is acknowl- edged to be all but universal, and perhaps quite so; for most bodies are found to be susceptible of experiencing its influence, although not endowed with magnetic properties. The action of the magnet is identical with the action exercised by closed elec- tric currents, exterior to the circuit which they are traversing. This law is now admitted by all, for the identity rests at once upon experimental and mathematical proofs. It is also proved, says De la Kive, by the fact that these two species of action — i. e., certain extra-polar electric working and magnetic action — may in all cases be substituted for each other to produce, in varied degrees, the same effects under the same circumstances. 12