﻿800 Mr. Gr. Shearer on the 



per unit volume is p/Am. Hence the number of electrons 

 liberated per atom per unit time per unit intensity is 



nAm 

 P 

 or, substituting for n in terms of" n', 



k.Amn ! A\ 

 P 



where k is a constant depending on the exact form of the 

 absorption law chosen. 



If it is assumed that Lenard's law that — is constant holds 



P 

 under the conditions obtaining in these experiments, the 

 result of these calculations is that the number of the electrons 

 liberated per atom per unit time per unit intensity is propor- 

 tional to the product of the number of electrons actually 

 escaping and the atomic weight of the substance from which 

 they are liberated. 



It has been shown that the experimental results led to the 

 conclusion that ri was proportional to (N" — 10). Hence 

 the number of electrons liberated per atom is proportional to 



A.(N-IO). 



In deducing this result several assumptions have been 

 made, some of which are only rough approximations to the 

 truth. Probably the most serious one is that Lenard's 

 law— that /jLz/p is constant — can be applied to this case. 

 Even under the conditions of Lenard's experiments, the 

 result was only an approximate one. A strong argument in 

 favour of its application to these experiments is that it causes 

 the density to disappear from the final correction to be 

 applied to the observed electron emissions. The values for 

 the electron emissions from the elements gold, lead, and 

 bismuth were found to be approximately equal. On the 

 other hand, the densities of these elements are 19*32, 11*37, 

 and 9*80 respectively. If the correction to be applied to 

 deduce the electron emission per atom were a function of the 

 density, all regularity would disappear from the results. If 

 the correction depends only on the atomic weight or atomic 

 number, no such difficulty presents itself. 



When this result is compared with the only other result so 

 far obtained, a serious disagreement presents itself. Moore * 

 found that the electron emission per atom was proportional 



* Loc. cit. 



