ELECTRICITY 



414 



ELECTRODE 



See Coulomb. Microfarad. See Farad. Micro- 

 volt, one millionth part of a volt. Milliampere. 

 See Ampere. Ohm, the unit of resistance. Practi- 

 tically, it is the resistance of a pure silver wire one 

 meter in length and one millimeter in diameter. The 

 theoretic or absalute unit is -nnroWffTT P art OI " ^ e 

 unit practically used. Volt, the unit of electro-mo- 

 tive force, or the force sufficient to cause a current of 

 one ampere to flow against a resistance of one ohm. 

 The following is the voltage of several popular cells : 

 Smee, 0.65; Bunsen, 1.90; Daniell, 1.05; Callaud, 

 0.60; Leclanche, 1.50. Volt-ampere, the unit of 

 electric work. It is the amount of pressure developed 

 by a current of one ampere having an electromotive 

 force of one volt. Its mechanical equivalent is about 

 44.2 foot-pounds per minute. It is sometimes called 

 a Watt. Volt-coulomb, the unit of electric work. 

 Watt. See Volt-ampere. Weber, an ampere. Unit 

 of Work, the erg ; it is equal to the work required 

 to move a body through one centimeter against a force 

 .of one dyne. The reciprocal relations of these elec- 

 tric units may be expressed thus: — 



1 volt X 1 coulomb = 1 joule 



1 volt X 1 ampere = 1 watt 



1 volt X 1 ohm = 1 ampere 



1 ampere X t ohm = 1 volt 



1 volt X 1 ampere X 1 ohm = 1 watt 



1 volt X 1 ampere X 1 ohm X 1 second = 1 joule 



1 ampere X 1 second = 1 coulomb 



Electricity (e-lek-tris'-it-e) \jfktKTpov, amber]. One of 

 the forces of nature developed or generated by chem- 

 ism, magnetism, or friction, and probably a mode of 

 ethereal vibration, closely analogous to and converti- 

 ble into heat and light. It has been largely employed 

 in its various forms for therapeutic purposes. Most 

 animal and vegetable fibers (living) contract when an 

 electric current is passed through them, and, in fact, 

 no substance is known that does not offer some resist- 

 ance to the passage of an electric current. By the 

 Conducting Power of a substance is meant the ability 

 of a given length and area of a cross-section of that 

 substance to conduct electricity, as compared with an 

 equal length and area of a cross-section of some other 

 substance, such as pure silver or copper. This power 

 may, in various substances, be pronounced, partial, or 

 absent. Good conductors are silver, copper, other 

 metals, charcoal ; partial conductors are water, the 

 human body, cotton, wood, marble, paper; non-con- 

 ductors, oils, porcelain, dry wood, silk, resins, dry air, 

 shellac, gutta-percha, ebonite, paraffin, glass. E., 

 Animal, free electricity in the body. E., Chemic. 

 See E., Galvanic. E., Faradic, that produced by 

 induction. E., Franklinic, frictional or static elec- 

 tricity. E., Frictional, that produced by friction. E., 

 Galvanic, that which is generated by chemic action 

 in a galvanic cell. E., Inductive, that produced in 

 a body by proximity to an electrified body without 

 contact. E., Magnetic, that developed by bringing a 

 conductor near the poles of a magnet. See Current. 

 E., Medical, that used for therapeutic purposes. E., 

 Static, frictional electricity. E., Voltaic, same as 

 galvanic or chemic electricity. 



Electrization (e-Lk-triz-a' -shun) \rfkmTpov, amber]. 

 The application of electricity to the body. E., General, 

 the therapeutic application of electricity to all parts of 

 the surface of the body. 



Electrize (e-lck' '-trlz) [ijAearpov, amber]. To treat by 

 means of electricity. 



Electrizer (e-leh'-tri-zer) [ffAEKrpov, amber]. A metal 

 disc of copper and zinc, or silver and zinc applied to the 

 surface of the body, and connected with copper wirt, 

 exciting, through the perspiration, a feeble galvanic 

 current. 



Electro- (e-lek' '-tro-) [r/AEKTpov, amber]. A Greek word 

 used as a prefix to denote connection with or relation 

 to electricity. E. -anesthesia, inability to perceive 

 the sensation made by electricity upon the skin. 

 E. -biology, the science of the electric relations and 

 laws of organic beings. E.-bioscopy. See Bioscopy. 

 E.-centesis, the use of electrolysis to cause absorp- 

 tion of effusions, as in pleurisy. E. -chemistry, the 

 science of the inter-relations and laws of electricity 

 and chemistry. E. -cystoscopy, examination of the 

 bladder by means of electric illumination. E. -diag- 

 nosis, diagnosis by means of the exaggeration or 

 diminution of the reaction of the excitable tissues of 

 the body when subjected to the varying influences of 

 electric currents. E.-esthesia, ability to perceive the 

 sensation made by the reception of an electric dis- 

 charge ; it may co-exist with local anesthesia, or 

 with loss of the power to perceive other sensations. 

 E.-magnet, a mass of soft iron surrounded by a 

 coil of wire. E. -magnetic Inertia, a term some- 

 times employed instead of inductance or the self- 

 induction of a current. E. -magnetism, magnetism 

 induced within iron, steel, or nickel, by introducing 

 it within a coil through which a current is passing. 

 E. -massage, the transmission of a current of elec- 

 tricity through a kneading instrument ; the use of 

 labile currents applied by means of a rolling or wheel 

 electrode, or by a sponge or brush. E. -motive, 

 pertaining to the mechanic or motor effects of elec- 

 tricity. E. -motor Force, that which sets electricity 

 in motion ; the difference of potential between two 

 points. It is estimated in volts. E. -muscular, per- 

 taining to the action of electricity upon muscles. 

 E. -muscular Contractility, the contractile response 

 of a muscle to an electric current. E. -muscular Sen- 

 sibility, the impression upon a sensory nerve by 

 electric irritation. E.-otiatria, electricity applied to the 

 treatment of diseases of the ear. E. -pathology, the 

 study of morbid conditions by the aid of electric irrita- 

 tion. E. -physiology, the study of electric reactions, 

 properties, and relations of organs and organic tissues. 

 E.-puncturation, or E. -puncture, the use of needles 

 as electrodes, which are thrust into an organ, or tumor, 

 e . g. , into the cavity of an aneurysm, with the object 

 of coagulating the contained blood. E. -sensibility, 

 an effect produced on a sensory nerve by its electriza- 

 tion. E. -statics, the science of static electricity, or 

 that developed by friction and induction. E.-thanasis, 

 a word proposed for death by electricity. E. -thera- 

 peutic Bath. See Bath. E. -therapeutics, the 

 science and art of the application of electricity for 

 therapeutic purposes. E. -therapy. See E.-tJura- 

 peutics. E. -thermometry, the determination of the 

 radiation of body-heat by means of an electric ther- 

 moscope. E. -vital, pertaining both to electricity and 

 to the phenomena of life. E. -vitalism, the theoretic 

 identification of the vital forces with electricity. 



Electrode (e-lek' -trod) [///le/crpov, amber; 666c, a way]. 

 The instruments, fastened to the conducting cords of a 

 battery, that are used in the application of electricity 

 to the body. The standard sizes of electrodes tun 

 erally adopted in therapy are, according to Erb, as 

 follows : — 



1. Fine electrode, % cm diameter. 



2. Small " 2 " 



3. Medium " 7.5 " 



4. Large " 6X2 " 



5. Very large 8 X16 " 



E., Brush, one end fitted with a camel's-hair pencil. 

 E., Clay, a therapeutic electrode of clay shaped to tit 

 the part of the body to be treated. E., Electro- 

 therapeutic, the therapeutic electrode is generally 



