38 
Proceedings of Royal Society of Edinburgh. 
Leakage from Electrified Metal Plates and Points placed 
above and below Uninsulated Flames. By The Right 
Hon. Lord Kelvin, G.C.V.O., F.R.S., and Dr Magnus 
Maclean. 
(Read July 5, 1897.) 
§ 1. In § 10 of our paper “ On Electrical Properties of Fumes 
proceeding from Flames and Burning Charcoal,” communicated to 
this Society on 5 th April, results of observations on the leakage 
between two parallel metal plates with an initial difference of 
electric potential of 6 '2 volts between them, when the fumes from 
flames and burnings were allowed to pass between them and round 
them, were given. The first part (§§ 1-4) of the present short 
paper gives results of observations on the leakage between two 
copper plates 1 centimetre apart, when one of them is kept at a 
constant high positive or negative potential ; and the other, after 
being metallically connected with the electrometer-sheath, is dis- 
connected, and left to receive electricity through fumes between 
the two. 
The method of observation (see fig. 1) was as follows : — Two 
copper plates were fixed in a block of paraffin at the top of a round 
tinned iron funnel 96 centimetres long and 15*6 centimetres internal 
diameter. A spirit-lamp or a Bunsen burner, the only two flames 
used in these experiments, was placed at the bottom of the funnel, 86 
centimetres below the two copper plates. One terminal of a voltaic 
battery was connected to one plate, B, and the other terminal w^as 
connected to the sheath of a Kelvin quadrant electrometer. The 
other copper plate was connected to one of the pair of quadrants of 
the electrometer in such a way that by pulling a silk cord with a 
hinged platinum wire at its end, this copper plate and this pair of 
quadrants could be insulated from the sheath of the electrometer 
and the rest of the apparatus. On doing so with no flame at the 
bottom of the funnel, no deflection from metallic zero was observed, 
even when the other plate was kept at the potential of 94 volts by 
the voltaic battery ; this being the highest we have as yet tried. 
