Question of the Homogeneity of y-Rays. 



743 





PI. XII.) refer to the uranium X 7-rays for lead and zinc. 

 The fact that the uranium X was in the form of a large 

 surface 5 mm. below the base of the hemisphere somewhat 

 complicates the interpretation of these results. This would 

 have been fatal for the radium y-rays, but for the less 

 penetrating rays of uranium X it is probable that the 

 disturbance so produced is not very great. In addition it 

 was not found practicable to determine the curves over more 

 than the first 2 cm. of the hemisphere, so that the position of 

 the curve with reference to the theoretical is more or less 

 arbitrary. This makes their interpretation rather uncertain. 

 As drawn, both curves agree well over the latter half with 

 the theoretical curve (\pb = 0*66 and Xzn = 0*35), while for 

 the first half the observed values are consistently greater than 

 the theoretical, the departure being greater for zinc than 

 lead. The curves would not at present repay further 

 discussion. All that can be said is that they bear out the 

 view before expressed that if a soft 7-radiation of uranium X 

 exists it must be relatively feeble in comparison with the 

 primary, while at least in the radiation of uranium X there 

 is as yet no sufficient evidence either of its existence or of 

 that of a secondary penetrating radiation. It has been 

 thought advisable to append the observations, from which 

 the 7-ray curves in PI. XII. figs. 4, 5, 10, and 11 have been 

 obtained, in the following two tables. The observations 

 represent divisions of the scale per minute corrected only for 

 the natural leak of the instrument. 



Table I. 



Pb and Zn Complete Hemispheres. 



Ea 7-Rays. See PI. XII. fig. 5. 



Pb. 



8/7/09. 



9/7/09. 



22/6/09. 



! ! z . 



22/6/09. 



1 Zn. 



22/6/09. 



T (cm.)- 



j6'7 mg. Ra. 



6-7 mg. Ra. 



•47 nig. Ra. 



T (cm.). 



"47 mg. Ra. 



T (cm.). 



■47 rag. Ra. 



Ooll 



1147 



1159 



94 



0-185 



188 



4-154 



437 



1009 



807 



774 



59-3 



0-332 



173 



4-448 



39-8 



1495 



567 



537 



400 



0626 



150 



4-742 



37-3 



2-005 



397 



392 



28-8 



920 



134-8 



5-036 



349 



2491 



298 



295 



21-0 



1-214 



119-5 



I 5-330 



33-1 



2-980 



231 



227 



16-2 



1-508 



107-2 



5624 



31-2 



3464 



184-7 



181 



12-6 



1-802 



93 4 



5-918 



30-3 



8-953 



1502 



146-3 



1008 



2096 



835 



! 6-212 



28-3 



4-446 



128-7 



125-3 



8-09 



2-390 



752 



' 6-506 



27-75 



4946 



108-5 



107-5 



7-63 



2-684 



68-2 



i 6-800 



2705 



5-438 



98-2 



975 



6-90 



2978 



61-5 



1 7 094 



26-25 



5-940 



90-7 



90-2 



6-25 



3-272 



556 



7 386 



25 80 



7-44 



824 



82-4 



5-65 



3-566 



520 



1 7-680 



25-25 











3860 



47 7 



8-91 



24-75 



