MISCELLANEOUS EXPERIMENTS. 53 



The results in parts I and II are not satisfactory. Thus the separate 

 determination of a for each tube added together are much larger than the 

 corresponding datum for the tubes abreast: 



I, II, V: 



Separately = 42,000 ions per second. 



Together 37,ooo 



I, II, III, IV, V: 



Separately 57, 600 



Together 37,000 



With the tubes together, a certain number of ions apparently failed of 

 capture, but this is not the case, as is shown in table 1 6, where all ions are 

 caught for dp/p = o.2%, much below the present datum. 



The third part of the table, however, shows accordant results, giving 

 14,000 ions per second separately and 14,300 when the tubes are acting 

 together, but the ionization is lower (D = 22 cm.). 



In part IV the drop in pressure is larger. The agreement is satis- 

 factory, = 65,000 ions per second when the tubes act together and 

 = 65,000 when their separate effects are added, but in other similar 

 cases the results were not so good. Thus in the last series V, the separate 

 and joint effects are 460,000 and 340,000; here, however, the high nucle- 

 ation is due to the presence of radium within the chamber in sealed 

 aluminum tubelets, and the diffuse coronas are hard to measure. 



The method of graduation depending on the use of sealed batches of 

 radium, together and separately, has not, therefore, given trustworthy 

 results. The chief reason for this is that the rate of production a is as the 

 sixth power of the aperture 5 



/R 



a/a' = S*/S 



If the tubelets were equally strong their sum would be ^$a = i.3\/a, 

 which is about the relation of aperture for contiguous crimson and green- 

 yellow coronas. Hence small subjective differences play a large part in 

 such experiments. 



