Page:Collier's New Encyclopedia v. 03.djvu/567

LEFT ELECTRICITY, ANIMAL 493 ELECTRICITY IN MEDICINE Electric Heater, Electric Railways, etc. ELECTRICITY, ANIMAL, the branch of electric science to which an experi- ment by Galvani gave birth. His wife, who was making soup from frogs, hap- pened to put them, after being skinned, in proximity to a charged electrical ma- chine belonging to her husband. On touching them with a scalpel their legs became greatly convulsed, Galvani on his return was told what had occurred, and repeated the experiment on several occasions. He united the lumbar nerves of a dead frog with its crural muscles by a metallic circuit. He came to the erroneous conclusion that animal elec- tricity existed in the nerves and muscles of frogs, etc. In this explanation Gal- vani ignored the metallic connecting wire. His contemporary, Volta, gave attention to this, and found that the con- traction of the limbs is more energetic when the connecting arc is made of two metals instead of one. He therefore in- ferred that the metals took the active part in producing the contraction, and the disengagement of electricity was due to their contact, and that the animal parts constituted only a conductor, and at the same time a very sensitive elec- troscope. In 1793 he published these views, and in 1800 first described and constructed what has since been called after him the voltaic pile. Febroni ob- serving that the disks of zinc in the pile became oxidized in contact with the acidulated water, considered, as did Wol- laston and Davy, that the oxidation was the chief cause why electricity was dis- engaged. Now voltaic piles have nearly given place to voltaic or galvanic batter- ies of which there are many varieties. ELECTRICITY IN MEDICINE. The use of electricity in treatment of human diseases dates back to the 18th century, when the electric spark and frictional electricity were so applied. Franklin was the first to use shocks from Leyden jars for the treatment of paralysis. As far back as 1775 the effect of static electricity on the human system was well known, and was dealt with to con- siderable length in the writings of Ti- berius Cavallo in 1777. The discovery of voltaic, or galvanic, electricity in 1800, and of faradic electricity during the past century were further steps in electro-therapeutics, since they allowed of a gentler treatment than was possible by means of the Leyden jars. For a long time static electricity was not in use, but more recently there has been a return to that method because of mod- ern methods of application. The application of electricity to the human body for curative purposes may be divided into three forms; static, gal- vanic, and faradic. The first form is produced from the ordinary frictional machine, in which glass plates are re- volved against chamois, rubber or horse- hair brushes, the current being received in Leyden jars. Galvanic electricity is set in motion by the voltaic battery. And faradism, or faradic electricity, is produced by induced, or interrupted, currents, generated by magneto-electric or electro-magnetic induction coil ma- chines. The first form, static electricity, pro- duces many effects on the human body. It has been long known that the body loses weight through its application, and that it causes the temperature either to rise or fall, due to increased functional activity. It sets free the potential energy cells, causes contraction of proto- plasm, excites nerve fibers, nerve cells and nerve centers, and stimulates nutri- tion. It is, therefore, effective in the treatment of lumbago, spastic paralysis, locomotor ataxia, chronic and muscular rheumatism, neuritis, progressive mus- cular atrophy, insomnia, congestion of the liver, and sciatica. It also serves to control nervous headaches, hysteria, neurasthenia, and is valuable also as a general tonic. It has also been effec- tively used in reducing sprains. The only danger of its use, in unpracticed hands, lies in the liability of a reduction of the blood pressure, which in certain cases may produce bad effects. For this rea- son care should be taken to avoid the numerous quacks and charlatans who advertise widely the use of electricity for curative purposes. For this reason it is advocated that the use of electricity be restricted to the legitimate medical profession. Galvanic treatment is produced by passing a voltaic current from a battery of many elements through the living body, which causes a shock, or contrac- tion, of the muscular system, succeeded with a distinct interval by a momentary sensation or flow of heat due to the eiectric current. During the continued passage of the current, slight tingling sensations and a raising of the tempera- ture are felt, especially in those parts in contact with the electrodes, which be- come painful and congested. On open- ing the circuit, the depolarization of the tissues which follows is accompanied by a second shock and a glow of heat, which are powerful in proportion to the length of time the circuit has been closed. The contraction of the muscles is in pro- portion to the intensity, rather than to the amount of the electricity which , flows through the body. The use of this / 32— Vol IU— CyT