Medical Electricity, Or Elertro-Therapentics, the therapeutical application of the various kinds of electricity. The attempt to employ electricity in medicine dates as far back as the knowledge of the phenomena of electricity itself. The history of electro-therapeutics may be divided into four periods: 1, the period before the invention of the electrical machine and Leyden jar; 2, from the invention of this machine to the discovery of galvanism; 3, from the discovery of galvanism to that of magneto-electricity; 4, from this last discovery to the present time. Of the first period little is known. The ancients occasionally ate of the raja torpedo on account of its supposed curative 'properties, and 1,000 years ago the women of western Africa are said to have placed their sick children in pools of water containing these fish. Scribonius Largus, a physician of the time of the emperor Tiberius, employed electric fishes for the cure of gout, and Pliny and Dioscorides speak of electricity as a therapeutical agent in several diseases. It was not till about the middle of the 18th century, or a century and a half after the observations of Dr. Gilbert of Colchester in England, that much was done in the way of applying frictional electricity in electro-therapeutics. About this time a German named Kratzenstein is said to have restored the use of a paralyzed finger by electricity, and experiments were made in the Vienna hospital under the direction of De Hacn with considerable success.

In France Jallabert, Sigaud-Lafond, Bertholon, and others became enthusiastic advocates of its application; and especially Mau-duyt, who made a favorable report to the royal society of medicine in 1773. The agent was employed in every form then attainable - in baths, in electric jets and streams, and in shocks. Cavallo, in his "Essay on the Theory and Practice of Medical Electricity" (London, 1780), collected all the various ideas of his day on the subject, by which it was credited with being of service in paralysis of the muscles, impaired vision and hearing, chorea, epilepsy, chronic rheumatism, scrofulous enlargement of the glands, and in reanimating the apparently dead. The natural magnet had been used by Paracelsus, and its mysterious properties were greatly extolled by him; and the use of artificial magnets by Maximilian Hell of Vienna drew considerable attention to this form of electricity as a curative agent. But the magnet, unless employed to induce electric currents, is almost inert for this purpose, and consequently practical men could never from this, or from frictional electricity alone, derive that degree of benefit commensurate with the inseparable disadvantages from delay, exposure of person, etc, attending their use.

The discoveries of Galvani and Volta gave a new electric force, and the controversy between their followers revived the interest of the medical profession and physicians generally in electro-therapeutics. In 1797 Humboldt published his celebrated work, Ue-ler die gereizte Muskel- und Nervenfaser, in which the power of galvanism to change the secretions was shown, as also the dependence of nervous sensibility upon external circumstances, such as muscular exertion and diseased condition. The book exerted a profound influence, not only upon the development of the science of medical electricity, but upon the progress of physiology. The resuscitation of persons inanimate from suffocation or nervous derangement attracted about this time much attention, and Hufeland and Sommering made a series of experiments with special reference to this subject, arriving at the conclusion that the phrenic nerve offered the best pathway to the galvanic current for restoring suspended animation. Pfaff, Reil, Humboldt, and others also recommended galvanism as an efficacious agent in cases of paralysis of certain organs, and Valli proposed it as a test in cases of apparent death.

The introduction of Volta's pile in 1799, by which the intensity of the L'alvanie current was greatly augmented, gave an additional advantage, as by it penetration into deeper parts of the body was possible. Loder, Bischoff, Lichtenstein, Hers, and others directed their attention to its application in cases of paralysis of the extremities andnerves of special sense. At the same time Prof. Schaub in Cassel, and Eschke, director of the institution for the deaf and dumb in Berlin employed it in cases of impaired hearing and of deaf mutes. But owing to the frequent failures of electricity to realize the hopes of its friends, the great body of scientific physicians were slow to recognize it as a trustworthy therapeutical agent, and it fell into the hands of charlatans, who offered the voltaic pile for sale as a panacea. The circumstance that mesmerism, which had made its appearance some time before, was connected in the public mind with electricity and magnetism, had the effect of discouraging practitioners from making investigations in that direction. Faraday's discovery of inductive electricity in 1831 was the commencement of a new era in the history of medical electricity.

The construction of magneto-electric machines by Saxton, Keil, Et-tinghausen, and Stdhrer offered facilities for the use of electricity in medicine not before known; but these machines were costly, and Wagner, Rauch, Duchenne, and Du Bois-Rey-mond made cheaper voltaic apparatus of considerable intensity; and jmysicians and scientific men generally employed much of their time in making experiments. Among the English who engaged in this pursuit were Marshall Hall, Golding Bird, Stokes, Phillips, Graves, and Donovan; among the French, Poiseuille, Petrequin, Masson, Duchenne, and A. Becque-rel; and among the Germans, Weber, Ileiden-reich, Richter, Moritz Meyer, Schultz, Erd-mann, Baierlacher, Eckhardt, Remak, Althaus, and Rosenthal. Pravaz was the first to conceive the idea of curing aneurism by galvano-puncture; the English surgeon Liston was the first to apply the method to the human subject; the Italian Cinisilli was the first to make a successful operation. - The manner of applying electricity in therapeutics has been various, and at present differs in different cases.

The earliest method of using the frictional electricity of the ordinary machine was to take the sparks from the prime conductor, soon after which it was the practice to take sparks from the patient, who was placed upon an insulated stool. On the introduction of the Ley-den jar, shocks were taken from this apparatus, but no great degree of system in its application was ever attained. The most remarkable and practical successes of electricity have perhaps been in the domain of surgery, by the employment of electric currents of sufficient quantity to raise platinum wire to a white heat. This mode of employment cannot be strictly called therapeutic, as the action is simply one of heat, and possesses no intrinsic properties beyond those of the actual cautery. But it is applied in situations where it would be impossible to apply the same degree of heat produced in any other manner. Galvano-caus-ty, as this operation is called, is employed for extirpating and abolishing tumors and diseased growths. A battery of from 16 to 24 of Grove's cells, or an equivalent battery of any form, is all that is required to produce the current. (See Galvanism.) Electrodes of platinum wire of different thicknesses, and of various forms and lengths, to meet the requirements of different cases, are connected with portable conducting wires in such a manner as to admit of the most convenient application.

In electro-therapeutics two forms of current are used: the direct battery current, and the induced, electro-magnetic, magneto-electric, or faradic currents. (See Electro-magnetism, and Magneto-electricity.) When the direct current is employed, the operation is called simply galvanization; when the induced or interrupted current is used, the process is called faradization. The direct current may be used of such strength and so applied as to produce decomposition of the fluids and solids of the parts to which it is applied, an operation which has received the name of electrolysis. Needles of various forms and sizes are employed as electrodes. They are inserted into the diseased parts, and the therapeutical results are dependent in a great measure upon the fact that diseased parts are more readily destroyed by electrolytic action than sound parts. Batteries for electrolytic purposes should be coupled for intensity, as quantity arrangement produces too much heat, and has not sufficient intensity to overcome resistance.

The general effects of electricity upon the various parts of the body are as follows: "When a current from 12 or 16 Grove's elements is passed through the brain, by placing one electrode upon some part of the cranium, which should be slightly moistened, and the other upon some other part of the body, as along the spinal column, or in the hands or under the feet, flashes of light appear on breaking the current, and a metallic taste is perceived. M. Erb has demonstrated that the skull' offers no obstruction to the passage of the current. Galvanization of particular parts of the brain will excite contractions of the muscles. Matteucci showed that electric stimulation of the crura cerebri is followed by muscular contractions; but the most marked effects of electricity are upon the special senses. If a metallic plate connected with one electrode is placed upon the forehead and the other over the infra-orbital nerve, it will cause the sensation of a vivid flash of light. Galvanic stimulation of that part of the sympathetic system supplying the iris will produce dilatation of the pupil. The sense of hearing is also intensified, and favorable results have been obtained by repeated applications of the continuous current through the parts containing the different portions of the ear.

The olfactory nerve is not affected by the induced or faradic current, but a moderately strong continuous current will produce a peculiar odor, which is not to be confounded with that of ozone, afforded by the friction machine. The sense of taste is easily affected by the galvanic current. A simple experiment consists in placing a plate of zinc beneath the tongue and a plate of a more negative metal, as copper or silver, above it, and bringing the edges of the two together, when a flash of light and a metallic taste will be perceived. Electrization of the motor nerves results in a contraction of the muscles which are supplied by them, which occurs upon the closing of the circuit, ceasing when the current is broken. The effect is greatest when the negative electrode is applied to the nerve and the positive to the muscle. Hitter found that when the current was applied in the direction of the nerve it's excitability was diminished, but in the other direction the irritability was increased. If the electrodes are applied to the surface of the body, a sense of warmth will be felt in the part. A strong current will produce a sense of prickling or tingling, which may increase to a state of extreme pain.

With the interrupted or faradic current, if the breaks are made slowly, the sensation will differ from that which occurs when they are very rapid; and this will vary with the part operated upon, and with the variety of electrode employed. A moist sponge may occasion only a slight disturbance; but a bundle of pointed wires may create an intense sensation. The amount and distributions of the nerves beneath the skin will also be followed by a difference of sensation. Remak holds that the nearer the nerves are to the brain the greater will be the excitability. The application of the continuous current for any great length of time will diminish sensibility. Faradization and static electricity have but little influence upon the sympathetic system of nerves; but the continuous current from a battery of many couples may be passed through many parts of it. When the cervical portion is electrically insulated, dilatation followed by contraction of the pupils occurs, the pulsations of the heart are less frequent, and the tension of the arterial walls is diminished. That the vaso-motor system of nerves may he decidedly affected appears from the fact that galvanization excites the peristaltic action of the intestines, and greatly affects the calibre of the capillaries and larger blood vessels.

The stomach and intestines and other abdominal organs are readily influenced by applying the electrodes at either side of the abdomen, or by applying one electrode over the abdomen and the other along the spinal column. The continuous current sent through the splanchnic nerves increases the peristaltic movements of the intestines, while faradization diminishes them. The details of the practice of electro - therapeutics, especially from the fact that changes are liable to bo made, are purposely omitted in this work. - See "Electricity in its Relations to Practical Medicine," by Dr. Moritz Mever, translated and edited by W. A. Hammond', M. D. (New York, 1869); "A practical Treatise on the Medical and Surgical Uses of Electricity," by George M. Beard, M. D., and A. D. Rockwell, M. D. (New York, 1871); "Clinical Electro-Therapeutics," by Al Ian McLane Hamilton, M. D. (New York, 1873); and "A Treatise on Medical Electricity," by Julius Althans, M. D. (Philadelphia, 1873).