Electricity (ANIMAL the branch of electric)

Collier's New Encyclopedia (1921)

ANIMAL, the branch of electric science to which an experiment by Galvani gave birth. His wife, who was making soup from frogs, happened to put them, after being skinned, in proximity to a charged electrical machine 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 dead frog with its crural muscles by a metallic circuit. He came to the erroneous conclusion that animal electricity existed in the nerves and muscles of frogs, etc. In this explanation Galvani ignored the metallic connecting wire. His contemporary, Volta, gave attention to this, and found that the contraction of the limbs is more energetic when the connecting arc is made of two metals instead of one. He therefore inferred 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' electroscope. In 1793 he published these views, and in 1800 first described and constructed what has since been called after him the voltaic pile. Febroni observing that the disks of zinc in the pile became oxidized in contact with the acidulated water, considered, as did Wollaston and Davy, that the oxidation was the chief cause why electricity was disengaged. Now voltaic piles have nearly given place to voltaic or galvanic batteries 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 Franklin electricity were so applied. Fra 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 considerable length in the writings of Tiberius 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 treatment than was possible of a gentler trea by means of the Leyden jars. For a long time static electricity was not in ase, but more recently there has been a return to that method because of modern methods of application. The application of electricity to the human body for curative purposes may be divided into three forms; static, galvanic, and faradic. The first form is produced from the ordinary frictional machine, in which glass plates are revolved against chamois, rubber or horsehair 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 machines. The first form, static electricity, produces 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 rise It sets free the potential activity. energy cells, causes contraction of protoplasm, excites nerve fibers, nerve cells and nerve centers, and stimulates nutrition. It is, therefore, effective in the treatment of lumbago, spastic paralysis, locomotor ataxia, chronic and muscular rheumatism, neuritis, progressive muscular atrophy, insomnia, congestion of the liver, and sciatica. It also serves to nervous headaches, hysteria, control neurasthenia, and is valuable also as a general tonic. It has also been effectively 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 reason 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 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 contraction, of the muscular system, succeeded with a distinct interval by a momentary sensation or flow of heat due to the electric current. During the continued passage of the current, slight tingling sensations and a raising of the temperature are felt, especially ly in those parts in contact with the electrodes, which become painful and congested. On opening 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 proportion to the intensity, rather than to the amount of the electricity which flows through the body. The use of this 32-Vol. III-Cyc method of application is to exercise atrophied muscles and secure their nutrition. In surgery the electrolytic action of the galvanic current destroys tumors and abnormal growths in the nasal cavity. The galvanic current is also used in heating a cautery for searing a surface to secure a cicatrix. The use of faradic electricity is usually for its tonic effect. The continued passage of the interrupted currents acts chiefly as a mechanical stimulant, first exciting, and after a time depressing the vitality of the parts in the circuit. Vibrations produced by purely mechanical means, without the use of electricity, may be made to cause very similar effects. Faradization is especially applicable to those diseases in which a deficiency of functional energy is involved, as in mild cases of spinal and peripheral paralysis. Changes of circulation or of the molecular state may be excited in the central organs by reflex irritation. It has also been used with good effect in the treatment of gout, rheumatism, widespread ecezma, and constipation, when due to indigestion. Galvanic electricity, however, will also produce all the effects due to the faradic current, but to a very much higher degree. ELECTRIC LAMP. See ELECTRIC LIGHT.