1897-98.] Leakage from Electrified Metal Plates. 
43 
steel wire 43 centimetres long was fixed to the insulated terminal 
of the multicellular electrometer, with its point vertically below an 
ordinary gas-burner, as shown in fig. 2. 
§ 6. By means of a small carrier metal plate (a Coulomb’s proof 
plane) a positive or negative charge was given to this wire and the 
quadrants of the multicellular till the reading on the scale w r as 240 
volts. The leakage was then observed (a) with gas not lit, (b) with 
gas lit at different vertical distances above the point of the wire. 
We found that there was rapid leakage when the flame was one 
centimetre above the wire ; and the times of leakage from 240 volts 
to about 100 volts increased as the flame was raised to greater 
distances above the point ; or, otherwise, the rate of fall of 
potential in one minute from 240 volts diminished as the distance 
of the flame above the point was increased. When the vertical 
distance of the flame above the point was 15 centimetres, or more, 
the time of leakage from 240 volts was practically the same as if 
the flame was not lit at all. A plate of metal, glass, paraffin, or 
mica, put between the point and the flame, diminished the rate of 
leakage. The leakage from 200 volts during the first minute is 
given in the following table, for different distances of the flame, 
with no intervening plate. 
Distance of flame 
above point 
Leakage during 
one minute 
Remarks. 
Centimetre 
1-0 
1-5 
3 0 
6-0 
Yolts 
200 to 60 = 140 
200 to 92 = 108 
200 to 179= 21 
200 to 196= 4 
200 to 197= 3 
No gas lit, hut wire on the electro- 
meter as in the other tests. * 
§ 7. Similar experiments were made with higher voltages 
measured by the vertical electrostatic voltmeter, and we found 
that when the flame was three or four centimetres above the point, 
there was very rapid discharge; but when the flame was 60 
centimetres or more above the point, the leakage from 3500 volts 
was practically the same as if the flame was not lit. 
* We sometimes found the multicellular electrometer to insulate so well 
that in five minutes there was no readable leakage from 240 volts. 
