Electro therapeutics

Fig . 2857. ELECTRO-THERAPEUTIC BATTERY. over this there fits a secondary coil of fine wire. In the best instruments the strength of the current can be regulated in two ways, one being the sliding of the iron bundle in and out of the primary, and the other the sliding of the secondary coil on or off from the primary. Some form of simple magnetic interrupter of the primary current is nece ary, with a suitable means of regulating the rate of interruption. At each action of the interrupter two currents are induced (in opposite directions) in the secondary coil. In the primary there is a current induced in the reverse direction on the making, and in the same direction on the breaking of the circuit. The currents from a faradic machine thus alternate in direction, and also differ in strength, the breaking current, being reinforced by the "extra stream" of the primary, being considerably the stronger. -Physiological Effects . When a direct current is employed of from 10 to 15 mill i-amperes, with electrodes of 1 to 2 inches diameter, a pricking sensation is felt in the skin, followed by a burning. On breaking the circuit the skin will be found bright red in color, thus showing increased vascularity. On a gradual diminution of the current, the sensation first vanishes under the positive pole; and on slow increase, first appears under the negative, showing that the latter is the more vigorous in action. The effect of such a current on the muscles is to produce contraction. By applying a large sponge electrode to the spine in the dorsal region and a smaller conical one to some such muscle as the biceps of the arm, a current of sufficient strength will cause this muscle to contract at the moment of making and breaking circuit. To yield electrolytic effects it is nece ary to apply to the surface a broad electrode connected with one pole, and to use a platinum or steel needle at the extremity of the other conductor. If this needle be inserted into the tumor which it is desired to remove, or applied to any mucous surface, and a current of from 15 to 250 mill i-amperes pa ed, the ti ue touched by the needle will be decomposed. The effect at the external electrode will be inappreciable, owing to its broad surface and small density, but at the pointed one, whose current density is large, the result will be marked. If this electrode be positive, the products of decomposition will be strongly acid, as shown by their reddening litmus paper, and the ti ue will contract around the electrode. If it be negative, the ti ue will decompose rapidly and the products of decomposition will manifest a strong alkaline reaction, a frothy material pa ing from the electrode, which will have free movement in a sinus caused by its action. The negative pole has thus a much more considerable disintegrating effect than the positive. - Effect of Induced Currents. When a weak induced current is applied to the skin, a sensation of gentle pricking or tingling is felt, which grows painful as the current strength is increased, but never harms as in the case of the direct current. If applied to a muscle, a muscular contraction follows; and if the shocks be repeated with sufficient slowne a series of such contractions will take place. But if the shocks follow rapidly, the muscle will be thrown into a state of tetanus or continued contraction, each shock occurring before the muscle has relaxed from the preceding. -Electrical Diagnosis. Electrical currents serve a useful purpose in the diagnosis of certain affections of the nerves and muscles. Thus, in some diseases of the spinal cord and the cerebro-spinal nerves the normal phenomena of muscular contraction are found to be much altered. In some cases a muscle may fail to respond to a faradic current of any strength, and yet contract when interrupted primary currents are employed. In other cases the response to voltaic current stimuli may vary in character from that shown under normal conditions of health. These phenomena are termed the "reactions of degeneration."- Applica tions to Disease. Static electricity is found of value in the treatment of various nervous affections, such as neuralgia of old standing, chorea, hem i-anæsthesia, hysteria, and hystero-epilepsy. The voltaic current is employed in acute neuralgias, such as sciatica, tic-douloureux, .; in atrophy of muscle following hemiplegia, diabetes, .; in spinal irritation and chronic myelitis; in the stiffened joints from chronic rheumatism and in lumbago; in chronic pharyngitis; glandular laryngitis, and chronic tonsilitis; and in other diseases a ociated with chronic inflammation and defective nutrition. Faradization is of use in nervous exhaustion attended with insomnia, in functional disorders of the generative organs, in acute articular rheumatism, in which it gives great relief to the inflamed and painful joints, and in various other disorders of the nervous and muscular system. Electrolysis. The employment of electricity in the removal of abnormal conditions of ti ue is of much usefulne . Nævi and aneurisms are frequently cured by electrolysis, needles which are insulated to within a quarter of an inch of their points being plunged into the tumor and the current sent through them. The contents coagulate around the needles, forming a nucleus around which further clotting takes place, the result being the obliteration of the nævus or the strengthening of the walls and filling of the sac in in an aneurism. For uterine hemorrhage a current of 100 to 250 mill i-amperes is used, the positive current being carried by a thick platinum wire to the mucous membrane of the uterus, a large surface electrode lying on the abdomen. The positive current acts as a powerful hæmostatic, and this proce , in skillful hands, checks most cases of hemorrhage. Fibroid tumors of the uterus are treated by currents of similar strength applied in the same way. In this case the disintegrating effect of the negative current is preferred, it either lying in the uterine cavity or being applied to the substance of the tumor. Similar treatment is employed in various inflammatory conditions of the uterus, both internal and external. All these effects depend on certain conditions, as the strength of the current, the reduction of the resistance of the skin by the use of a large surface electrode, and the density of the current at the part to be acted on, obtained by the use of the needle electrode. As regards the use of "galvanic" or "magnetic" belts, from which such benefits are claimed, it cannot be said that these benefits are discernable. is po ible in this way to produce a more or le constant current of electricity, and it may be that in some cases benefit has resulted. But the action is irregular, the current cannot be directed or controlled, and troublesome ulcerations have been produced in the skin from prolonged contact with the negative pole. As regards the so-called "magnetic belts," there is nothing to show that they have any influence whatever on the ti ues or functions of the body. Powerful magnets have no apparent influence upon the body, and none can be expected from these pieces of magnetized watch spring or wire. If any relief from pain follows their application, it is most probably due to the heat-preserving effects of the flannel in which they are sewn. Electrotint, n. An art by which drawings are made with any substance insoluble in the solution of sulphate of copper. When the design is completed, the plate is immersed in the solution, and a reverse made by the electro-coppering proce ready for the printer. It is the application of the electrotype to the art of engraving. It was invented in 1840 by E. Palmer, who gave it afterward the name of glyphography. It