612 Mr. S. Russ on Distribution in Electric Fields of 
thorium oxide, or of a preparation of actinium kindly lent 
me by Professor Rutherford. 
The wire A was connected to the positive, B to the negative 
pole of a battery giving 320 volts, the brass tube being- 
connected to the middle point. 
The exit-tube E was 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. 
When experimenting with thorium the wires were exposed 
to the emanation for 24 hours, after which they were removed 
and their activities tested with an electrometer in the manner 
already described. 
The ratio of the activities of the cathode and anode at 
atmospheric pressure was found to be about 200 : 1; on 
reducing the pressure to 2 mms. the ratio was diminished to 
25 : 1, this reduction being mainly due to the decrease in 
activity of the cathode already observed by Rutherford 
(loc. cit.). No certain increase in the very small activity of 
the anode was observed. 
In the experiments with actinium the wires were exposed 
usually for about 2 hours. 
At atmospheric pressures the ratio of the activities of the 
cathode and anode was about 2 to 1, while at 2 mm. pressure 
it was 22 to 1, the increase in the ratio being mostly due 
to an increase in the activity of the cathode. The active 
deposit on the two wires decayed at the same rate, namely, 
that of actinium A. 
These results show that while the greater part of the 
active deposit from actinium emanation has a positive 
charge, yet at amospheric pressure a very considerable 
fraction has a negative charge, and is therefore directed to 
the anode. 
For purposes of comparison the activities obtained on a 
wire when exposed to the emanations of Ra, Th, and Ac at 
atmospheric pressure are tabulated. 
Wire charged Wire charged 
negatively. positively. 
Thorium 200 1 
Radium 200 10 
Actinium 200 100 
Conclusion, 
In view of the different distributions in an electric field of 
the active deposits of thorium, radium, and actinium, it is 
difficult to think of the whole series of events between the 
