new "Eledlrical Injlrumcnt . 25 g 
If you touch any part of the tin plate or tin tubes with your 
finger, the eleCtricity is thereby intirely removed, and that 
will be the cafe whether the lateral frames are up or down. 
Exp. 11. Take an extended piece of tinfoil, about four yards 
fquare, and, holding it by a filk thread, electrify it lo weakly 
as not to be capable of affeCting an electrometer ; then bring it 
in contaCt with the tin plate of the collector, whilft the late- 
ral frames are up. This done, remove the tin-foil, let down 
the lateral frames one after the other, and on doing this, the 
electrometer W will immediately manifeft a confiderable degree 
of eleCtricity. But if the electrometer were to fhew no fenfi- 
ble degree of eleCtricity, a fmaller collector, viz. one having a 
tin plate of about four fquare inches, muft be brought into 
contaCt with the tin plate of the large collector, whillf the 
lateral frames of the latter only are down ; and then the 
fmall collector being removed from the large one, its lateral 
frames are opened, and its tin plate is prefented to an electro- 
meter, which will thereby be eleCtrified to a much greater de- 
gree than the electrometer W was by the large collector. 
Exp. hi. Let a common cork-ball electrometer be fattened to an 
infulated conductor, having about two or three fquare feet of 
furface, and communicate to it fuch a quantity of eleCtricity as 
may be lufficient to let the balls of the electrometer ftand at 
about one inch afunder. In this ftate bring the conductor in 
contaCt with the tin plate of the collector for a very Ihort time, 
and it will be found, that the balls of its electrometer will im- 
mediately approach and touch each other, Ihewing that the 
eleCtricity of the conductor is gone to the plate ot the col- 
lector; and, in faCt, if you let down the lateral frames, the 
balls of the electrometer W will immediately repel each other 
to a very great degree. 
Vol. L XXVIII. N n 
It 
