Question of the Homogeneity ofy-Rayi 



731 



prolonged attempt to interpret the curves obtained led to no 

 very definite conclusion, partly perhaps on this account. I£ 

 the ionizations shown by the dotted curves are subtracted 

 from the observed values one would expect to obtain a curve 



having the relation 



y^-Bf-^ + Ce-^ 



(3) 



where C and X 3 refer to the soft primary 7-radiation, if such 

 exists. The zinc curve and to lesser extent the lead and iron 

 curves so obtained are nearly straight lines. Either k, and 

 hence B, must be very small (which cannot be true at least 

 for iron as the dotted-line curve shows) or X 2 must be 

 relatively very large. In other words the secondary radiations 

 are wholly /3-rays and secondary y-rays play no appreciable 

 part. The zinc curve can be approximately represented by 

 the equation 





= Ae- x i T + Ce-^ T 



where \, is 037, \ 2 5'15, A 0'3 and C 0*7. The following 

 table shows that the agreement between the observed and 

 calculated values is fairly close. The deviations are not large 

 but they are greater than the errors of measurement. 





I T 



I 



T cm. 



— observed. 



icalc). 









u 



•1065 



1-84 (jrf-javsi 



•692 



•142 



■627 



•622 



"1775 



•541 



•560 



■213 



•500 



•510 



•2485 



•446 



•468 



•2840 



•413 



•432 



•355 



(•375) 



C375) 



•4-26 



•342 



•334 



•4S>7 



•314 



•303 



•508 



•284 



•281 



•639 



•269 



•263 



•745 



•255 



■243 



•852 



•238 



•227 



The ratio \ 2 /\i is 14, and if the energies of the two types 

 of rays are proportional to the ionizations divided by the 

 absorption coefficients it follows that the energy of the soft 

 type initially is only one-sixth of that of the hard type. 

 Even if such a soft type exists, therefore, in the 7-radiation of 



