the Method of its Transmission. 



10U 



anode in consequence of transmission by the electric field. 

 The remaining 5 per cent, must thus reach the electrode by- 

 other agencies. With such a strong electric field, the effect 

 due to pure diffusion must be very small. It thus seems 

 likely that some of the radioactive carriers have sufficient 

 initial velocity to carry them to the electrode against the 

 electric field. 



§ 8. Velocity of the Carrier. 



Some experiments were made on the velocity of the carrier 

 of excited radioactivity, using the concentric cylinders shown 

 in fig. 2 a. If a and b are the radii of the internal rod and 

 the cylinder, the electric field X at a distance r from the 

 centre, for a P. D. of v volts between the cylinders, is given by 



X = 



V 



Using the same notations and assumptions as in the case of 

 parallel plates, it can be shown that the velocity K of the 

 carrier of excited radioactivity is given by 



{V 1 — a 2 )log e — 



K = 



E+E, 



E (E -E0 T •'; 



The following table shows some of the results obtained for 

 different voltages and periods of alternation : — 



E — E r 



E +E x . 



Alternations 

 per sec. 



P- 



Corrected 

 value of p. 



K. 



1-0 



205 



308 



5-7 



•35 



•32 



205 



308 



11-2 



•24 



•20 



1-2 



205 



308 



17-2 



•19 



•13 



1-2 



205 



308 



34 



•16 



9 





385 



580 



18-3 



•30 



•27 



1-5 



385 



580 



47 



•16 



9 





The values of the velocity of the carrier determined for 

 the uncorrected values of p in the above table vary much 

 among themselves. It will be seen, however, that the value 

 of p increases with the time of alternation and the voltage, 

 as we should expect from the elementary theory. It was not 

 found possible to reduce the observed value of p below about 

 *16, whether the voltage was diminished or the frequency o\ 

 alternation increased. This is to be expected, for we have 



