44 Proceedings of Royal Society of Edinburgh. [sess. 
In place of the metal point, a round disc of zinc, 8 centimetres 
in diameter, was fixed, as shown in fig. 3, to the end of another 
steel wire of the same length ; and leakage from it to the flame 
above it, observed. For the same distance between the flame and 
either the point or the metal disc, the rate of leakage through the 
same difference of potential, was less for the point than for the disc. 
Thus with the flame 25 centimetres above the point the time of 
drop from 3000 volts to 2000 volts was 1 min. 53 secs., and with 
the flame the same distance above the disc the time of drop from 
3000 volts to 2000 volts was 1 min. 14 secs. This is a very 
important result. 
§ 8. Experiments were next made to find if ; and if so, how 
much ; the leakage is diminished by putting non-conducting plates 
of glass, paraffin, mica, between the point or disc and the flame. 
At a corner of each plate was pasted a little square of tinfoil, so as 
to prevent any electrification of the non-conducting substance by 
handling. These pieces of tinfoil were always kept metallically 
connected with the sheath of the electrometer. Each plate was 
fixed with its under surface 1 cm. above the steel point. In 
preliminary experiments (of which a continuation is deferred until 
