550 Lucian — Distribution of the Active Deposit of 



All the values given in the present paper refer to distribu- 

 tions for which the proper correction has been made. 



The curve for volts in fig. 2 would be expected to remain 

 horizontal for all amounts of the emanation employed. The 

 upward slope of the curve for very small amounts may be due 

 to residual electric iields as well as to molecular agitation and 

 initial diffusion from the recoil-column which are of no effect 

 for larger amounts. 



Some experiments of not a very high degree of precision 

 were tried with a negative potential applied to the case, the 

 central electrode being earthed. A typical set of equilibrium 

 values with added capacity for —600 volts on the case is as 

 follows : 



nr • • i tit mms. 



Maximum activity on the central electrode . . = -08 — 



J sec. 



Maximum activity on the case ._ = 10*7 " 



Total activity _. __. = 10-78 " 



Cathode percentage .._ = 99-36 <f 



Corrected for diffusion __ = 94*6 " 



The corrected value for the cathode percentage is quite in 

 accordance with the values for +600 volts when the central 

 electrode was made the cathode. 



It is now evident that if we followed Walmsley's procedure 

 and obtained the distribution of the active deposit by measur- 

 ing the activity of the central rod, first as cathode and then as 

 anode, neglecting* the deposit on the case, we would obtain for 

 large potentials a cathode activity apparently very nearly 100 

 per cent of the total amount. 



The experiments with a negative applied potential show 

 further that the activity deposited on the anode is due entirely 

 to neutral particles ; for, if negative particles existed in the 

 vessel, the activity when the central electrode is made the 

 anode should be larger than the amount which settles there by 

 diffusion alone ; whereas by a simple calculation, from the 

 value of diffusion on the case, we find that for +600 volts on 

 the case and a total amount corresponding to 10*78 mms./sec. the 

 activity diffusing to the central electrode is -113, which is 

 larger than the value obtained here (/08i for —600 volts on the 

 case. This shows conclusively that no negative particles exist, 

 or at least, take part in the transfer of activity considered. 



The above difference between the values of the active deposit 

 that diffuses to the central electrode as anode and cathode can 



* A close examination of the figures given by Walmsley in Table I (loc. 

 cit.) seem to warrant the statement here made that he did neglect considera- 

 tion of the activity which diffused to the case (anode) at high potentials. 



