S22 



ELECTRICITY. 



exhibit no sign of electricity, because the operation 

 of the one is just the reverse of that of the other, and 

 their power is neutralized and inoperative. If com- 

 pletely separated, however, each will manifest a 

 strong electrical power, the one attracting those 

 bodies which the other repels. The causes that 

 determine the species of electricity excited in the 

 respective bodies, of which the surfaces are made to 

 rub against each other, have not been satisfactorily 

 ascertained. The meclianical configuration of the 

 surfaces appears to liave more influence in the result, 

 than the nature of the substances themselves. Thus 

 smooth glass acquires vitreous electricity by friction 

 with alinost every substance, except the back of a 

 cat, which induces the resinous electricity ; but 

 oughened glass, if rubbed with the same substances, 

 becomes charged with resinous electricity, while the 

 rubbing bodies acquire the vitreous. Silk, rubbed 

 by resin, takes the vitreous, but with polished glass, 

 the resinous electricity. The following is a fist of 

 several substances, which acquire vitreous electricity, 

 when rubbed with any of those which follow it, in 

 the order in which they are set down ; and resinous 

 electricity, if rubbed with any of those which pre- 

 cede : 



The back of a cat Paper. 



Polished glasn. Silk. 



Woollen cloth. Gum-lac. 



Featbern. Roughened glass. 



Wood. 



Iii the experiment above mentioned of the silk rib- 

 bons, the black ribbon exhibited the vitreous, and 

 the white one the resinous electricity. But when the 

 ribbons are differently excited, as the one being 

 drawn lengthwise and at right angles over a part of 

 the other, the one which has suffered friction in its 

 whole length acquires vitreous, and the other resin- 

 cms electricity. Indeed, the slightest difference in 

 the conditions of these and similar experiments, or 

 the species of electricity arising from friction, will be 

 often sufficient to produce opposite results. Another 

 important observation, with regard to electrical phe- 

 nomena, requires to be stated previous to our con- 

 clusion of the present head. Whenever a body is 

 charged with electricity, although it be perfectly 

 insulated, it tends to produce an opposite electrical 

 state in all the bodies in its vicinity, and this with 

 greater energy in proportion as the distance is smaller. 

 This effect is termed the induction of electricity. In 

 consequence of this law, if an electrified body, charged 

 with either species of electricity, be presented to an 

 unelectrified or neutral body, the electrical condition 

 of the different parts of the neutral body is disturbed. 

 The electrified body induces a state of 'electricity con- 

 trary to its own, in that part of the neutral body which 

 is nearest to it, and consequently a state of electricity 

 similar to its own in the remote part. Hence the 

 neutrality of the second body is destroyed by the 

 action of the first ; and the adjacent parts of the two 

 bodies, having now opposite electricities, will attract 

 each other. It thus appeal's, that the attraction which 

 is observed to take place between electrified bodies 

 and those that are unelectrified, is merely a conse- 

 quence of the altered state of those bodies, resulting 

 directly from the law of induction. 



II. The hypothesis which naturally suggests itsell 

 for the explanation of the phenomena above stated, 

 is that of a very subtile, imponderable, and highly 

 elastic fluid, pervading all material bodies, and capa- 

 ble of moving with various degrees of facility through 

 the pores or actual substance of different kinds o 

 matter. In some, as in those we call conductors or 

 non-electrics, it moves without any apparent obstruc 

 tion ; while in others, as in those we call non-con 

 doctors or electrics, it moves with difficulty. More 

 over, as the phenomena appear to indicate the 



agency of two kinds of fluid, we shall, for the pre- 

 sent, assume the existence of two species, and 

 shall speak of these under the names of the vit- 

 reous and the resinous electricities. They must 

 each have, when separate, the same general proper- 

 .ies as have already been enumerated above ; while, 

 in relation to each other, there must be a complete 

 contrariety in their nature, so that, when combined 

 together, t heir action on the bodies in their imme- 

 diate vicinity shall cease. And it is when existing 

 n this state of union or neutrality, that bodies are 

 said to be in their natural state as respects electricity. 

 We shall now proceed to compare the suppositions 

 we have made with the facts, as presented to us by 

 mture, and developed by experiment. a. Facts 

 connected with excitation. From various causes (of 

 which the friction of surfaces is one), the state of 

 union in which the two electricities naturally exist in 

 aodies is disturbed: the vitreous electricity is impelled 

 n one direction, while the resinous is transferred to 

 the opposite ; and each manifests its peculiar powers. 

 When accumulated in anybody, each fluid acts in pro- 

 portion to its relative quantity, i. e., to the quantity 

 which is in excess above that which is still retained, in a 

 state of inactivity, by its union with electricity of the 

 opposite kind. Thus, when glass is rubbed with a me- 

 tallic amalgam, a portion only of the electricities at the 

 two surfaces is decomposed ; the vitreous electricity 

 resulting from this decomposition attaches itself to 

 the glass ; the resinous to the amalgam. What re- 

 mains in each surface undecomposed, continues to 

 be quite inert. 6. Facts connected with distribution. 

 Both of these fluids, being highly elastic, their par- 

 ticles repel one another with a force which increases 

 in proportion as their distance is less ; and this 

 force acts at all distances, and is not impeded by the 

 interposition of bodies of any kind, provided thoy are 

 not themselves in an active electrical state. It has 

 been deduced, from the most careful analysis, tnat 

 this force follows the same law with that of gravita- 

 tion : viz. that its intensity is inversely as the square 

 of the distance. The mode in which the electricity 

 imparted to a conducting body, or to a system of 

 conductors, is distributed among their different parts, 

 is in exact conformity with the results of this law, as 

 deduced by mathematical investigation. While the 

 particles of each fluid repel those of the same kind, 

 they exert an equally strong attraction for the par- 

 ticles of the other species of electric fluid. This at- 

 traction, in like manner, increases with a diminution 

 of distance, and follows the same law as to its inten- 

 sity : viz. that of the inverse ratio of the square 

 of the distance. This force, also, is not affected by 

 the presence of any intervening body. c. Facts 

 connected with transference. Since the two electri- 

 cities have this powerful attraction for each other, they 

 would always flow towards one another, and coalesce, 

 were it not for the obstacles thrown in their way by 

 non-conductors. When, instead of these, conducting 

 substances are interposed, they enter into union 

 with great velocity, producing, in their transit and 

 confluence, several remarkable effects. When once 

 united, their powers remain dormant, until again 

 called into action by the renewed separation of the 

 fluids. d. Facts relating to attraction and repulsion. 

 The repulsion which is observed to take place be- 

 tween bodies that are insulated, and charged with 

 any one species of electricity, and other bodies simi- 

 larly charged, is derived from the repulsive power 

 which the particles of this fluid exert towards those 

 of their own species ; and the attractions between 

 bodies differently electrified, is derived from the at- 

 tractive power of the vitreous particles for those of 

 the opposite kind. In all cases, the movements of 

 electrified bodies represent the forces themselves 





