1896-97.] Experiments on Electric Properties of Uranium. 423 
This cardboard cylinder could be moved backwards and forwards 
in the aluminium cylinder, so that the distance between the 
insulated disc in the latter and the aluminium end of the former 
could be varied. The uranium influence thus acted through the 
aluminium end of the cardboard box, and made the air between 
the end and the insulated aluminium disc conductive. The leak- 
age was in this way made slow enough to be easily observed on 
the electrometer. The rate of leak was not perceptibly increased 
when the piece of uranium was heated or when the sunlight fell 
on it. The aluminium end of the cardboard box and the outside 
coating of the aluminium cylinder were connected to sheaths. 
4 
The insulated aluminium disc was connected to the inside coating 
of B. The inside coatings were charged to a known potential, 
and then left to themselves. 
The air space between the insulated aluminium disc and the 
aluminium end' of the cardboard box was 2 centimetres. The volt- 
ages used were therefore voltages per two centimetres of air space. 
With this arrangement the leakage per minute at different voltages 
was : — 
Voltage. 
6 
10 
44 
38 
176 
750 
1250 
2000 
3000 
Leakage per minute 
in scale divisions. 
56 
65-5 
113 
128 
156 
219 
229 
260 
276 
[Sensibility of electrometer 24 sc. divs. per volt of subsidence of 
difference of potential between coatings of A.] 
