E L K C T R I C I T V. 



" '>"- In order to perform thce experiments with less 

 ~~" trouble. Mr Sy miner made his sul>M-quait experiments 

 by drawir through the hand. The fol- 



lowing at Hl.ick silk is highly 



susceptible, of electricity, being excited alnm-t in-' 

 taneouslv, and with very little friction. White silk 

 is greatly inferior to it, exhibiting neither sp irks, nor 

 emitting a crackling noise, but affecting the electrome- 

 ter very slightly. A black and a white silk stocking 

 drawn through the hand together, exhibit no electri- 

 city till they are separated. Mr Symmer wi nt 

 as to charge the I.evden phial by means of excited 

 stocking-! ; and with four silk stocking! he even kind- 

 led spirits of wine. The electrical cohesion b. 

 white and black silk stockings attracted Mr S\ ni- 

 mer's particular notice. A weight of from one to 

 twelve ounces was required to separate them. At ano- 

 ther time they required 17 ounces, including the scale 

 and the black stocking, which was- 20 times the v, 

 of the white stocking that supported them ; the weight 

 acting in a direction parallel to the cohering surfaces. 

 \\ hen one of the stockings was turned inside out. and 

 put within the other, the separation required 80 ounces, 

 whereas 10 was sufficient when they were applied to 

 one another externally. With stockings of a more 

 substantial make, one of them being put within the 

 other, without being turned inside out, the separating 

 weight was nine pounds, wanting a few penny- weights, 

 which is 55 times the weight of the supporting stock- 

 ing. When the white was turned inside out, and put 

 within the black, so that their interior or rough sides 

 were together, the separating weight was no less than 1 .3 

 Ibs 1 I dwt. which is M times tlie weight of the support- 

 ing stocking. When the application of the stockings 

 was merely external, as before, they lifted only 1J of a 

 pound, or 10 or II times the weight of the whole stock- 

 ing. MrSymmerfoundlikewi.se, that excited stock- 

 ings adhered also to unelectrified bodies, with broad 

 and polished surfaces. Having thrown a stocking ac- 

 cidentally out of his hands, he was astonished to find it, 

 some time afterwards, sticking to the paper hangings 

 of the apartment They adhered also to the painted 

 bo srds of the room, and to the looking glass, and often 

 remained suspended for a whole hour upon the hang- 

 ings. 



Sjrmmer' Mr Symmer concludes, from his experiments, that 

 theory. there are two distinct electric fluids ; that electricity 

 consists in the possession of a larger portion of one or 

 the other power than is necessary to maintain an even 

 balance with the body ; and that the electricity is ne- 

 gative or positive, according as the one or other power 

 prevails. 



S'gniorAlessandroAmadcoVaudonia, who constantly 

 wore a Ix-avcr shirt between two others, in cold weather, 

 found that the upper shirt always adhered to the bea- 

 ver shirt wlien it was taken off, and emitted electric 

 sparks. This experiment was repeated by his friend 

 Beccaria. 



Liboonof The experiments of Mr Symmer attracted the notice 



('una, f M. Cigna, who published an account of several inte- 



1765. resting results, in the .W/-/HOJ/JS uf the Aca>!rm:i of Turin 



Born 173V. for I7<>5. Having extended two dry white or black 



I 1799. gjik ribbons above each other, upon any smooth plain 



surface, he drew over them the sharp edge of an ivory 



ruler. Both the ribbons adhered to the plain, and when 



taken from it together they attracted each other, the 



un lei 01 n- having been electrified positively, and the 



upper cue negatively. When they -were lifted separate- 



ly. they repelled one another, having both acquired the K 

 negative clvctricitv. In removing both the ribbons ~*~~Y~~* 

 '.e plain, and in their subsequent separation, i 



ere ;;1\\ ;iys \ isible bet 



T having acquired, by the preceding ope- 

 ration, the same electricity, wen placed upon any rough 

 conducting body, such a* cotton or hemp, not \er\ <l:-\ . 

 they exhibited, on separation, tw o contr.-.ry eleetri. 

 which disappeared upon joining them together. When 

 the tv.o ribbons were rubbed on that rough su: 

 they alw-iys were electrified in an opposite 111.1:1111 i 

 upper one having the negative electricity. 



of a nnur'i surface was produced by a ) 

 tor. When the two riblxms, hanging parallel, and re- 

 pelling each other, had the point of a needle drawn op- 

 jm-ite to one of them, along its whole lei 

 instantly rushed together, the ribbon nean.-t the r. 

 having its electricity changed. An uneleetrifi.il ribbon 

 acquired electricity by placing it upon a rough surface, 

 and laying an electrified ribl>oi> nl)ve it. or by holding 

 it parallel to an electrified riblxin, and drawing a point- 

 ed conductor opposite to it. as before. If the rib' 

 were rubbed with any skin, or n piece of smooth glass. HI 

 place of the ivory rider, the same results were obtained ; 

 but when a stick of sulphur was employed, the electri- 

 cities were always the reverse of what they were before, 

 the rubl>ed ribbon being always negative. It'one of the 

 ribbons was black and the other white, then whichever 

 of the two was the uppermost, and in whatever way 

 they were rubbed, the white one was generally posi- 

 tive, and the black one negative. Whenever the upper 

 piece of silk, however, was loose, yielding, and like a 

 net, or of the same structure as a stocking, so that it 

 could be rubbed against the lower one, and whenever 

 the rubber was of such a nature as to impart but little 

 electricity to glass ; under these circumstances, the elec- 

 tricity imparted to the upper piece of silk did not de- 

 pend upon the rubber, but upon the surface which sup- 

 ported it, the black being always negative, and the 

 white positive. When the structure of the silk was 

 hard, stiff, and close, and when the rubber had the cha- 

 racter of communicating much electricity to glass, then 

 the upper piece of silk derived the character of its elec- 

 tricity from the rubber, and not from tl>e supporting 

 surface. 



In another set of experiments, he brought an electri- 

 fied ribbon near an insulated plate of lead, and observed 

 a feeble attraction. When his (inner was brought to 

 the lead, a spark was emitted, after which the ribbon 

 was vigorously attracted, and both together exhibited 

 no marks of l>emg electrified. I'pon taking away the 

 ribbon, appearances of electricity were exhibited in 

 both, and a spark was seen between the plate and the 

 finger When two glass plates were placed upon a 

 smooth conducting body, communicating with the 

 ground, and excited in the same manner as the ribbons. 

 they likewise acquired electricity, and stuck firmly both 

 to the conductor and to one another. When the con- 

 ductor was a plate of lad, not very thick, it was sup- 

 ported by the attraction. No signs of electricity v en- 

 exhibited when they were all together. I'pon remo- 

 ving from the conductor the two plate -s to- 

 gether, their electricity was positive on both sides, while 

 the conductor if it had been insulated, seemed to be 

 negatively electrified. When the two plates of glass 

 were separated, the upper one was positively electrified, 

 and the lower one negatively. With a rough conduc- 

 tor they scarcely contracted any electricity, though. 



