53» Tixpfrmeists w eleSfric Jtrs stiiJ Batttriet. 



J^xj:{r'i7nintj made wiih a Vii^w to determine in what Degrre the charging Capacity ef coated Jart 

 is increafed by ireathifig into ihcin before ihe charging. 



Experiment I. Prepare the e!e£lrometer in the manner fliewn in the plate, with f!ie jar M 

 annexed, which contains about i68 fqtiare inches of coating*; put into B the pin, marked 

 15 ; take two inches cf watch-pendulum wire, fix to each end a pair of fpring tongs, as is rc- 

 .prefcnted at G m, hook one end to m, and the other to the wire N, communicating with the 

 outfide of the jar ; let the uncoated part of the jar be made very clean and dry ; and let the 

 -prime conductor of an eledtrical machine, or a wire proceeding from it, touch the wire L ; 

 then if the machine be put in motion, the jar and eledtrometer will ^charge, a -, will be feen 

 iy the rifing of the index of k, and when charged high enough, B will be repelled by by and 

 A will dcfcend and difcharge the jar through the wire, which wa« confined in the tongs, 

 and the wire will be fufed and run into balls. 



Experiment 2. Put into the tongs eight inches of the fame fort of wire as before, hang one 

 •pair of tongs to the hook m, and apply the otherto the wire \vhich forms the outfide communis 

 cation : take out the pin in B, and put in its ftcad one marked 30 ; all the other part of the 

 apparatus remaining as before, and the uncoated part of the jar being previoudy cleaned and 

 dried ; the machine being then put in motion, the jar and eleiElrometer will charge, as is 

 ihewn by the rifmg of the ind^ as before ; bet as foon as the jar has received a greater quan- 

 tity of eleftric fluid than before, a fpontaneous explofion will happen without affecting the 

 balls B bf becaufe the difcharge will have pafled along the uncoated part of the jar from the 

 Infide coating to the outfide : ^vhence it follows, that while the jar remains in that clean 

 ftate, it is incapable of receiving a charge high enough to affect the balls, or even a higher 

 charge than Lt had received in the firfl experiment. I^et the uncoated part of the jar be 

 therefore rendered, in a flight degree, damp; which is eafily done, by breathing into the in- 

 fide, through a glafs tube ; put the machine in motion, and no fpontaneous explofion will 

 happen, but the balls B b will repel, as in the firfl; experiment, and the difcharge will happen 

 from A to a, and pafs through the wire placed in the circuit; and though it was eight inches, 

 it will be fufed in the fame degree as two inches in th'e laft experiment, namely, the wire 

 feen red hot the -whole length, and then fall into balls. 



Very different degrees of fufion are caufed by ele(?bric difclvarges, which may caufe grent 

 jmiflakes, if not well attended to. It is proper to adhere to the degree above-mentioned, 

 and particular care ought to be taken to lay the \vire, intended for fufion, ftraight, without 

 any bendings or angles in it. The wire ufed in the two laft experiments, was that which is 

 commonly called watch-pendulum wire, which is flatted ; and as it approaches very near to 

 fucha fliarp edge as might be fuppofed to affcftthe experiment, by permitting a difiipation oi 

 die electric fluid in its paflage, round wires were tried, a-nd the refult was the fame. 



* Tike out the p'n 'u B, ani obfe.vt whether tl.e ball B will remain at reft upon 1/ j if •ot, Mwn the «d- 

 jiifting 'crew atC, till it jull reiiains upoa A. 



By 



