and its Products of Transformation. 

 Table III. 



831 



1 



1 Time in Days. 



Activities in Arbitrary Units. 











Activities 

 observed. 



Activities minus 

 final constant 6 '5. 



Activities minus 



constant, reduced 



to 100. 







17-6 



11-1 



100 



0-2 



17-4 



109 



98-2 



05 



171 



10 6 



9.r2 



11 



161 



96 



86-r» 



1-4 



156 



91 



819 



16 



154 



8-9 



80-1 



22 



14-5 



8-0 



720 



32 



13-5 



7-0 



630 



35 



13-2 



67 



602 



45 



123 



5-8 



524 



52 



11-9 



5-4 



48-6 



62 



112 



4-7 



422 



72 



106 



41 



36-8 



8-2 



101 



36 



324 



9 4 



97 



3-2 



28-8 



10-6 



93 



26 



234 



142 



7-8 



1-3 



117 



32 



(V7 



0-2 



1-8 



62 



65 











122 



65 











radium E was also investigated. According to Hatm and 

 Meitner* the rays from a single radioactive product are 

 absorbed according to an exponential law. The rays from 

 radium E in radio-lead were examined by Hahn. who found 

 that the absorption curve departed from the exponential long 

 before the y-ray effect could influence it, since this latter has 

 been found by Meyer and v. Schweidler to be '03 per cent., 

 and by Schmidt *016 per cent, of the total activity. Hahn 

 showed that this deviation was due to some radium emanation 

 remaining in radio-lead, which could be got rid of by heating. 

 Meyer and v. Schweidler found that the /3 rays from radium 

 E 2 are absorbed approximately according to an exponential 

 law, the coefficient \ for aluminium being 44 cm., and that 

 some soft j3 rays also come from the long period products, 

 which are half absorbed by l*o x 10 -4 cm. of aluminium. 

 The absorption of the ft rays from radium E was also 

 measured in the present case and found to be exponential, 

 and the absorption coefficient for aluminium found to be 

 43 cm. -1 and for copper 164 cm. -1 



* P%. Zeit. ix. p. 321 (1908). 



