ELECTRICAL BATTERY. 



ELECTRICAL EQO. 



794 



account for the effect of the wire* on a magnetised needle, that mag- 

 netic current* revolve about every particle or rather every physical 

 point of a magnetised body, u it were in the plane of an equator to an 

 infinitely small sphere ; and ha assumed that the fluid in the conducting 

 wire of a battery exert* action* upon these revolving currents, by 

 which the plane* of the revolutions are brought into such ] 

 that, if produced, they would pan through the axis of the conducting 

 wire. It u evident however that the effect thus produced on the 

 needle is the same a* that which was before described ; for, as the 

 planes of the revolving currents are supposed to be perpendicular to 

 the axis of the magnetised body, that axis must tend to place it.-.-lf in 

 the direction of a tangent to a circle supposed to be perpendicular to 

 the axis of the conducting wire of the battery. 



It has been ascertained that the current of electricity produced by 

 the electrical machine causes deviations in a magnetised needle ; and it 

 is now generally believed that the electric, galvanic, and magnetic fluids, 

 if such there be, are identical. [ELECTRICITY.] An experiment made 

 by Mr. Faraday, in which a magnetised needle caused to float on water 

 was found to enter a glass tube having its axis on a level with the 

 surface and about which a galvanic conducting wire was spirally 

 wound ; while such magnetised needle would not enter the bore of a 

 hollow magnet placed in the same situation as the glass tube seemed 

 however to show that the nature of the galvanic and magnetic fluids 

 was not absolutely the same. But H. Ampere, in explanation, h;w 

 observed that the result of the experiment is not inconsistent with the 

 hypothesis of identity ; since, when the wire is coiled about the glass 

 tube, the needle is within the electric current, whereas it is outside of 

 the currents about the particles of the magnetic tube. 



ELECTRICAL BATTERY, a number of cylindrical vessels of 

 glass, each precisely similar to the usual Lcydoi jar [ELECTRICITY, 

 COMMON], the open top being covered by a plate of wood, into 

 which is screwed the foot of a brass pillar which terminates at the top 

 with a ball of the same metal, and at the bottom with a chain, which 

 descends to the lower part of the jar inside ; or, as in the annexed 

 figure, the rod may be solid throughout its length, or only branch out 

 a little at the bottom to serve as a support, in which case the jars do 

 not require wooden covers. Both the inside and outside of each jar 

 are lined with tin-foil to within about two inches of the top. These 

 are contained within a wooden box, the interior of which is lined 

 with tm-foil ; a piece of wire passes through the foil and the side of 

 the box, and carries on the exterior of the latter a ring, to which 

 should be affixed a chain descending to the table or to the ground ; 

 or the chain may be put iuaide the box, as at c, in contact with the 

 coating of one of the jars. 



The ball or knob at the top of every jar is perforated, in order that 

 it may receive one of the brass rods of a system of bars by which the 

 tops of all the jars are connected together ; the rods are terminated 

 with brass balls, and one of these, or a ball at the upper extremity of a 

 pillar forming part of the system, or a wire leading therefrom, is pre- 

 sented to the conductor of the electrical machine when the battery is 

 to be charged. This kind of battery was first proposed by Gralath, a 

 German, in 1747 ; and the manner of charging and of discharging it 

 differs in no respect from the manner of performing the like operations 

 with a single jar. 



The quantity of electricity in a jar or battery is directly proportional 

 to the superficies of the coating and to the degree of intensity ; and 

 the latter is in the inverse ratio of the thickness of the glass. The 

 particles of vitreous or of positive electricity which, by the machine, are 

 excited in the conductor, and with that on the interior surfaces of the 

 jars, exert, through the glass, attractive powers upon the resinous or 

 negative electricity, which by that attraction ore brought from the 

 earth tn the exterior surfaces of the jars : this accumulation within the 

 jars continues till the repulsive powers of the particles are great enough 

 to counteract the power of the machine to supply fluid through the 

 conductor : the charge of the battery is then a maximum. The battery 

 is usually furnished with a pith-ball or quadrant electrometer [ELEC- 

 TROMETER], shown in the figure, which indicates by the amount of its 

 divergence the progress of the charge. The discharge is made by 

 means of a bent wire called a ditcharging rod, or by a more convenient 

 form of apparatus known as the unirerial discharger. The power of a 

 battery is estimated by the quantity of metallic wire which it will 

 ignite or melt. The battery, consisting of 100 jars, which was mode by 

 Cuthbertaon for the museum at Haarlem, and which contained 550 

 square feet of coating, ignited 65S inches of iron wire yfe inch diameter. 



The engraving represents the battery arranged for the deflagration 

 of metallic wires. A conductor is led from the inner coatings of;the 

 jars to an insulated arm (/) of a discharging apparatus (A), while a 

 second conductor passes from the insulated boll (6) to one of the insu- 

 lated rods of the muvtml ditcharger If). The wire to be burnt (w) is 

 attached to a card supported by an insulated stand, and this wire is 

 connected with the other rod of the universal discharger, which con- 

 nect* it by means of a wire with the outer coating of the battery. 

 When the battery is sufficiently charged the lever is withdrawn, 

 when the ball a falls down through a hole in the metal arm / upon the 

 ball b, whereby the circuit is completed, and the charge, passing 

 through the whole conducting arrangement thus formed, restores the 

 equilibrium in an instant ; but the wire (w) being thinner than any 

 other part of the discharging wire, there U a very slight delay in the 



of the charge, the consequence of which is that the enormous 

 power of the electric fluid has time to act, and the wire (w) is 



so completely fused as to be dissipated in vapour, a portion of which 

 leaves on the card a stain more or less characteristic of the metal. 



The batteries in which electricity is excited by the chemical action 

 of a fluid upon a metal, or of two metals upon one another, ore called 

 Galvanic or Vuliaii- : they are of various kinds, and will be more con- 

 veniently described under GALVANISM. 



ELECTRICAL CLOCK. [HOROLOGY.] 



ELECTRICAL CONDENSER, a term applied chiefly to such 

 instruments as are employed to collect and render sensible very small 

 quantities of electricity. The principle upon which a comU-n.-iT of 

 electricity acts may be thus stated : When the electricity of any Imdy 

 is decomposed by being brought near another body which has received 

 from an object in contact with it more than its natural quantity of 

 either kind (vitreous or resinous), the fluid of that kind is rejiolli.l 

 from the first body, and that of the opposite kind then disposer the 

 second body to receive a new supply of the former kind frmn the 

 object with which it is connected. For example, if a tliin circular 

 plate of metal, having attached to its circumference a glass handle, by 

 which it may be insulated when held in the hand, be made to receive a 

 small quantity of fluid (suppose it to be vitreous) from the conductor 

 of an electrical machine with which it may be put in connection by a 

 wire ; and then a similar piece of metal, connected with the earth by 

 being held in the hand or supported on a pillar of metal, be brought 

 directly under it and so near as almost to touch it, the nearest surfaces 

 of both having been covered with a thin coat of resinous varnish ; the 

 electricity of the latter plate will be decomposed, the vitreous portion 

 (in the case supposed) flowing to the earth and the resinous portion 

 being attracted by the fluid in the plate which is connected with tlio 

 conductor to the upper surface of the other plate. This resinous fluid 

 now attracts more of the vitreous fluid from the conductor to the 

 under surface of the plate in connection with it, and the latter fluid 

 further decomposes the free electricity in the former plate, thus causing 

 in it a new repulsion of the vitreous fluid, and a new attraction of the 

 resinous fluid to its upper surface. The like process continues till an 

 equilibrium is produced between the vitreous fluid supplied by the 

 conductor and the resinous fluid which is drawn from the earth. 



If the plate which is connected with the conductor be now removed 

 from thence by means of the glass handle, the fluid in it, having no 

 means of escape, will, on the plate being presented to an electrometer, 

 make its condensed state manifest by producing a greater effect than if 

 the plate, while attached to the conductor, had been unaccompanied by 

 the other plate. 



Many different kinds of condensers of electricity have been con- 

 structed, and one is represented under ELECTRICITY, COMMON. The 

 condensers of Volta and Cavallo are best known ; but, except for some 

 particular purposes. Coulomb's Electrical Torsion Balance [ELECTRO- 

 METER] may be advantageously used when it is required to determine 

 the intensity of the fluid in any body. 



ELECTRICAL EGO. A glass vessel, ellipsoidal in shape, arranged 

 so that the included air may be exhausted at the air-pump. On 

 sending a stream of electricity through this apparatus various effects 

 are produced, depending on the amount of exhaustion, the force of the 

 electrical current, and the nature of the included gas. When the glass 

 is filled with air the discharge has a white appearance ; but as the air 

 is withdrawn, the whiteness diminishes, and at length becomes violet. 

 On increasing the intensity of the discharge, the light increases in 

 brilliancy. When the vessel is partially exhausted, and a cm-rout 

 produced by Rhumkorff's apparatus sent through it, the negative boll 

 and the stem which supports the glass, become enveloped in a lumi- 

 nous aureola, formed apparently of several distinct beds of different 

 shades of blue : the positive bail and a portion of its stem are also 

 enveloped in a thin and flocculent aureola of a pinkish hue, while 

 the space between the balls or poles, is filled with a cloud of con- 

 tinuous diffused reddish light. This supposed Gratification, as it 

 is called, of the electric light, has lately attracted a great deal of 

 attention. It is found to be more decided if, previous to the ex- 

 haustion of the air, some vapour of turpentine or pyroligneoua acid, 



