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Show ·/ 54: Additional Notrs. Glass ~~ believed to consist in part of consolidat~d resi.nous etl~er, and thence to attract an electl·ic wtm0sphere round tt, whtch co.nsists 0 f reater proportion of vitreous ether compared to the quantity of ,thea rge sinous, as mentioned m· Proposi·t i·O n No. 4. Th''IS a_tmosp l1 ere may stand off a line fr:om the surface .of the glass, thoug~1 Its attrac.. ti"ve or repulsive power may extend to a much greater distance; and a more equally mixed erectric atmosphere may stand off about the same distance from the surface of a cushion. Now when a ciiShion is forcibly pressed upon the surface of a glass cylinder or plane, the atmosphere of tl~e cushion is f~r~ed within that of the glass, and consequently the v1treous part of It 1s brought within the ~Where of the attraction of the resinous ether combined with the glass, and therefore becomes attracted by it in a-ddition to the vitreous part of the spontaneous atmosphere of the glass; and the resinous part of the atmospl1ere <>f the cushion is at the same time a-epelled by its vicinity to the combined resinous ether of the glass. From both which circumstances a vitreous ether alone surrounds the part of the g-lass on which the cushion is forcibly pressed; which does not, nevertheless, resemble an electrisea coated jar; as this accumulation of vitreous et11er <>n one side of the glass is not so violently con'< lensed, or -so forcibly attracted to the glass by the loose resinous ether '()n the other side of it, as occurs in the charged coated jar. Hence as weak differences of the kinds or quantities of electricity -do not very rapidly change place, if the cushion be sudden~y with. drawn, with or without friction, I suppose an accumulation of vitreous .electric ether will he left on the surface of the glass, which will diffuse itself on an insulated conductor by the assistance of points, or will gradually be dissipated in the air, probably like odours by the repulsion of its own particles, or may be conducted away by the surrounding air as it is repelled from it, or by the moisture or other impurities of the atmosphere. And hence I do not suppose the friction of the glass-~lobe to be necessary, except for the purpose of more easily removing the parts of the surface from the pressure of the cushion to the points of the prime conductor, and to bring them more easily into reciprocal contact. Chemical Theory tif Electricity and JYfagnetism. 55, ~Vhen sealing wax or sulphur is rubbed by a cushion, exactly the aame circumstance occurs, but with the different ethers; as the resinous ether of the spontaneous. atmosphere of the cushion, when it is. pre sed within the spontaneous atmosphere of the sealing wax, is attracted by the solid vitreous ether, which is. combined with it; and at the same time the vitreous ether of the cushion is repelled by j t; and hence an atmosphere of resinous ether alone exists between. the sealing wax and the cushion thus pressed together. lt is.nevertheless. possible, that f1:iction on both sealing wax and g·lass may add some· facility to the accumulations of their opposite ethers by the warmth which it occasions. As most electric machines succeed best after being warmed, I think even in dry frosty seasons. Though when a cushion is applied to a smooth sm.:faced glass, so as to intermi·x their electric atmospheres, the vitreous ether of the cushion is. attracted by the resinous ether combined with the glass; but does not intermix with it, but only adheres to it: and as the glass. turns round,. the vitreous electric atmosphere stands on the solid liesinous electric ether combined with the glass; and is taken a.way by, the metallic points of the prime cond.uct<w. Yet i.f the surface of the glass be ro·ughened by: scratching it with: a diamond or with hard sand, a new event occurs; which is, that the vitreous ether attracted from the· cushion by the 1:esinous. ether com· bined with the glass becomes adhesive to. it; and stands upon the· roughened glass, and wilL not quit the glass t? g.o to. the prime co~ductor · whence the surface of the glass havmg· a v1treous electnc· atmospi1ere unitecJ, as it were, to its inequal!ties, bec~mes· sim~lar to· r-esin· and will now attract resinous electnc ether, hke a sttck of seali~g wax, without combining with it. Whence this curious a~d· Gtherwise unintelligible phenomenon, that smooth surfaced glass ':'111 o·ive vitreous electric ether to an insulated conductor, and glass wtth. ~roughened surface will give r.esinous ethel~ to it. V. Accumulation of electric etlzers by, vicinity. Thou o-Il the contact of a cushion on the whirling glass is th~ eas~s-t method ;et in use for the accumulation. of the vitreous electnc et et. |