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Electricity (Powerful physical agent)
a powerful physical agent which makes its resistance manichemical decompositions and other pheproducing light and heat, commotions, chemical decompositions and other phenomena. when amber was rubbed with silk it became capable of attracting light bodies. when amber was rubbed with silk it bemore than this regarding electricity; The ancients seem to have known no nor for the first 16 centuries of the Christian era was much addition made to the solitary known fact in electricity.
He Queen Elizabeth and to James I., pub- Queen Elizabeth and to James I., pubfor the first time the word "electric" was for the first time the word "electric" was used in connection with science. and electricity as two emanations of one fundamental force. He showed that not died in 1603. fundamental force. He showed that not merely amber, but sulphur, glass, etc., are electrics. Otto Guericke, of Magdeburg, discovered that there was a repulsive as well as an attractive force in electricity, and about 1647 constructed the first electrical machine.
He regarded magnetism Newton, in 1675, observed signs of electrical excitement in a rubbed plate of glass. Hawkesbee, who wrote in 1709, also observed similar phenomena; and Dufay, in the "Memoirs of the French Academy," between 1733 and 1737, generalized so far as to lay down the principle that electrified bodies attract all those which are not so, as soon as they have become electric by the vicinity or contact of the electric body. and repel them Dufay also discovered that a body elec- Dufay also discovered that a body elecstance repelled another electrified in a similar way, and attracted one which had been electrified by contact with glass.
He thence concluded that the electricity derived from those two sources was of different kinds, and applied the names vitreous and resinous to them.
Franklin attributed this difference to an the former condition existing in electrified glass and the latter in resins. Otto Guericke had discovered that his sulphur globe, when rubbed in a dark ELECTRICITY place, emitted faint flashes of light, and shortly afterward it was noticed that a similar phenomenon occurred at the surface of the mercury when the barometer was shaken a fact which one of the celebrated mathematicians, Bernouilli, attempted to explain on the Cartesian system, but which was afterward correctly attributed by Hawkesbee to electric charges. Wall, in 1708, observed the sparks produced from amber, and Hawkesbee noticed the sparks and "snapping" under various modifications. Dufay and Abbé Nollet were the first to draw sparks from the human body, an experiment which attracted great attention, and became a species of fashionable diversion at the time.
The discovery of the Leyden jar is attributed to Cunæus of Leyden, in 1746, who, while handling a vessel containing water in communication with an electrical machine, was surprised at receiving a severe shock. A similar event had happened the year previous to Von Kleinst, a German prelate.
In the 18th century the names of the principal contributors to the advancement of electrical science are Newton, Hawkesbee, Dufay, Guericke, Cunæus of Leyden (to whom we owe the Leyden jar), and Franklin, who, 1747, pointed out the circumstances on which the action of the Leyden jar depends. Monnier the younger discovered that the electricity which bodies can receive depends on their surface rather than their mass, and Franklin soon found that "the whole force of the bottle and power of giving a shock is in the glass itself"; he further, in 1750, suggested that electricity and lightning were identical in their nature, and in 1752 demonstrated this fact by means of his kite and key. About the same time D'Alibard and others in France erected a pointed rod 40 feet high at Marli, for the purpose of verifying Franklin's theory, which was found to give sparks on the passage of a thunder cloud. Similar experiments were repeated throughout Europe, and in 1753 Richman was instantly killed at St.
Petersburg by a discharge from a rod of this kind.
The more important discoveries since those days relate rather to electricity produced by voltaic or magnetic action.
In the later history of electricity no name is greater than that of Michael Faraday, who was born in London in 1794, was appointed by Sir Humphry Davy assistant in the laboratory of the Royal Institution in March, 1813, and in 1831 commenced the publication of a series of splendid discoveries in electricity.
The past history of electricity centers ELECTRICITY round the frictional machine and the voltaic battery. The first-named is now only of experimental interest, and the second, if we except its use in signaling (telegraphy and telephony), is quickly being supplanted by the more economical and vastly more powerful dynamomachine. To this contrivance, in its various forms, as designed by different makers, and in less degree to the secondary battery (now quite in its infancy), electricians look for the advancement of their science. The fact that the Gramme and similar machines are reversible is considered to be one of the most important discoveries of the century. By reversible is meant its power to act as a motor when coupled up with a distant machine, under which circumstances its armature rapidly revolves in the reverse direction to what it would do if used directly-as in the production of the electric light. By such means the electrical transmission of power from place to place has become possible.
Important advances in the knowledge of the connection between electricity and matter have in recent years been made through the observation of the ionization of gases. The principal researches along this line were made by Professor J. J.
Thomson, at the Cavendish Laboratory, at Cambridge, England.
All gases can be made conductors of electricity when the molecules of the gas have been broken into parts, that is, ionized. Among the methods for ionizing gas are (1) application of high temperature; ature; (2) the passage of a spark in the neighborhood; (3) exposure to Röntgen rays or to rays from a radioactive substance such as uranium; (4) exposure to "cathod" rays; (5) exposure to "ultraviolet" light. It has been established that the negative ions of all gases, however they may be produced, are identical. The practical application of electricity to industry and to domestic uses has been one of the great developments of the last generation. The development of the automobile has called for storage batteries of high power and electricity and has also been employed as a motor power for motor vehicles. See MOTOR VEHICLE. In transportation, the use of electricity has come to be common, especially in suburban lines of railroad where a long haul is not required. For domestic use electricity is employed not only for lighting and heating but for devices including vacuum cleaners, electric irons, washing machines, and countless other devices.
For a discussion of the different phases of electricity and its use, see STORAGE BATTERIES, ELECTRICAL MACHINE, TRANS- MISSION OF ELECTRIC POWER, DYNAMO, became greatly convulsed. Galvani on touching them with a scalpel their legs chine belonging to her husband. On in proximity to a charged electrical mapened to put them, after being skinned, who was making soup from frogs, hapetc. of electric science to which an experi-