of the Excited Activity of Radium to the Cathode. 529 



making the cylinder V somewhat shorter and fixing the 

 rod BD into a rubber stopper fitting into the end o£ the 

 cylinder. 



In the case o£ vessel I. it was necessary to work with very 

 small quantities of gas in order to get to sufficiently low 

 pressures, and the capillary a was discharged once into Y. 

 With vessels II. and III., a was discharged twice and three 

 times respectively. 



The maximum value to which the activity deposited on 

 AB tends at high pressures is not the same for the three 

 vessels, on account of the difference in their dimensions and of 

 the variation in the quantity of emanation used. 



The results obtained are given in Tables I., II., and III., 

 in which the pressures are given in cm. of mercury and the 

 quantity of activity on the rod in arbitrary units. 



Table I. (Vessel I.) diameter l'l cm. 



Pressure Activity 



in cm. mercury. on rod. 



15-3 180 



8-9 174 



6-35 167 



4-3 161 



2-65 134 



1-7 120 



0-95 93 



Table II. (Vessel II.) diameter 2'6 cm. 



Pressure Activity 



in cm. mercury. on rod. 



9-3 209 



$'7 219 



6-2 224 



5-0 214 



3'3 198-5 



2-7 183 



2-6 198 



22 191 



1-7 177 



1-3 182 



0-95 158 



0-8 150 



0*44 100 



0-32 87 



0-12 50 

 Phil. Mag. S. 6. Vol., 10. No. 59. Nov. 1905. 2 O 



