produced by the Action of Thorium Compounds. 183 



curve B, the variation of the amount of induced radioactivity 

 on inside cylinder ; and curve 0, the variation of the amount 

 of radioactivity on the sides and ends. The ordinates of 

 curves B and C are increased three times in order to show 

 them on about the same scale as A. It will be observed that 

 the shapes of the curves A and B are similar. The u knee " 

 of both curves occurs for about the same voltage. The 



Fiff.10. 



curve C shows that as the voltage diminishes, the amount of 

 radioactivity on the sides and ends increases, reaching a 

 maximum when the voltage is zero. The currents due to the 

 radioactivity of B, given in the third column of the table, are 

 for 50 volts between the cylinders. The value given for 310 

 volts is probably too large, as it was measured for 310 volts 

 between plates, instead of 50 as in the other experiments. 



In the fifth column is given the total current due to the 

 radioactivity on ends and sides plus the action of cylinder B. 

 It will be observed that the resulting values are not very 

 different, except the value for 310 volts, which, for reasons 

 above explained, is probably too large. 



It looks as if a certain number of radio-active particles were 

 given out from the thorium and that these were carried to 

 various parts of the vessel, the effect due to the whole number 

 being about the same as if they were all concentrated on the 

 negative electrode. 



