﻿58 Mr. Norman Campbell on Delta Rays. 



is when the magnetic field acts and the electrons cannot pass 

 from one electrode to the other. An anomaly which has 

 hitherto been left unnoticed is thus readily explained. 

 According to the original theory the number in the third 

 row of the " — "•column of Table II. should represent the 

 quantity of the incident radiation. This number is different 

 for each of the materials, although, since the incident radiation 

 is excited at the soot electrode in each case, it would be 

 expected that it should be the same. However, if we 

 estimate the incident and emergent radiations by (1), this 

 anomaly disappears. .We obtain the following figures : — 



Aluminium— soot ... E = 0'258 ; I = 0'250 *. 



Copper— soot E = 0*216 ; 1 = 0249. 



Silver— soot E = 0*177 ; 1 = 0*248. 



Gold— soot E = 0*199; 1 = 0*244. 



It will be seen that the incident radiation, which proceeds 

 from the soot, is the same in each case approximately ; while 

 the emergent radiation, which proceeds from the metal, is 

 different. It appears then that in this case it is more 

 satisfactory to estimate the emergent and incident radiations 



by (l).. 



Turning now to the results when both electrodes are of the 

 same material we get the following results according as the 

 quantities are calculated by (1) or (2) : — 



By (2) Aluminium.. E = 0*261 1 = 0*264 



Copper E = 0*257 1 = 0*205 



Silver E = 0253 1 = 0189 



Gold E = 0-264 1 = 0-214 



Soot E = 0-263 1 = 0-268 



By(l) Aluminium.. E = 0*291 1 = 0*234 



Copper E = 0-240 1 = 0*222 



Silver E = 0-220 1 = 0*222 



Gold E = 0-239 1 = 0-239 



Soot E = 0-262 1 = 0-269. 



These results are not entirely satisfactory, for in some cases 

 one method of calculation and in other cases the other makes 

 the incident and emergent radiations equal. The only case 

 in which both methods make the radiations equal is that of 

 soot. But at any rate there is no evidence that the incident 



* It has been noted that the curves for soot are not completely 

 saturated until a potential difference of 80 volts is employed. The 

 numbers used for calculating the total quantity of radiation from soot are 

 those for 80 volts and not those given in Table II. in the row " V=40." 



