of the Active Deposit of Actinium, 
739 
negative pole of a battery o£ 320 volts, the brass tube being 
connected to the mid-point. 
The exit-tube E could be connected to a Fleuss pump and 
a set of tubes containing calcium chloride and cotton-wool, 
thus ensuring a supply of dry and dust-free air. 
The wires were exposed usually for about two hours, when 
they were removed and their activities compared by measuring 
the saturation currents, which they separately produced in a 
cylinder connected to an electrometer. 
Observations were made for pressures between 2 mms. and 
76 cms. of mercury. The numerical results are collected in 
Table I. and shown graphically in fig. 2. 
Tip:. 2. 
20 30 4-0 
T^ffEssuft^ /m Cms 
Table I. 
6c 
To 
Pressure 
in cms. 
Activity in Arbitrary 
Units. 
Ratio of 
Activities. 
— ve 
Cathode. Anode. 
-f ve 
76 
15 7-fi 
2 
4 
12 
24 
36 
60 
22 
51 
35 
62 
137 
200 
270 
83 
8-7 
5-2 
5-7 
55 
4-5 
4-0 
26 
12 
6 
5 
.0 
It will be observed that the ratio of the activities of the 
two wires increases steadily as the pressure is diminished, 
