Homogeneous Corpuscular Radiation. 



347 



if the intensity at two distances X\ and .v 2 be I x and I 2 

 respectively we deduce the expression for ft in the form 



logj^looj ^ 



P x 2 — X\ 



In the figure the tangents of the angles which the straight 

 lines make with the horizontal axis were taken as the values 

 of ft in the various cases. The absorption coefficients for 

 the corpuscular radiation from different metals excited by the 

 several homogeneous beams used are given in the following 

 table. 



Table III. 



Tertiary 

 radiators. 



Iron 



Copper .... 



Silver 



Aluminium 



Radiatoi-9 which act as the source of homogeneous 

 secondary radiation. 



Ni. 



Cu. 



Zn. 



As. Se. 



Sr. 



Mo. 



Rl.o. 



Ag. 



Sn. 

 6-41 



38-0 



370 



3.0-8 



302 264 



21-5 



loo 



109 



8-84 







362 



304 



... 



20*8 



152 



10-8 



8-81 



6-67 





... 



354 



30-2 



... 



212 



154 



10-3 



8-78 



663 









296 





200 



15-2 



... 



890 



654 



It should be stated in passing that with aluminium as 

 tertiary radiator the graphs from which the values of ft wore 

 deduced were not quite so regular as in the case of the other 

 tertiary radiators. The means of several determinations were 

 finally adopted for inclusion in the table. In the case of the 

 other tertiary radiators at leasl two determinations for each 

 value of ft were made and the mean taken ; but these values 

 agreed among themselves very closely. 



It will be seen that within the limits of experimental error 

 the absorption coefficients of the corpuscular radiation ex- 

 cited by any particular homogeneous radiation from metals 

 which differ so greatly in atomic weight, density, and other 

 properties as aluminium, iron, copper, and silver, are 

 identical. 

 table. 



This is more clearly brought out in the following 



