﻿Transformation of Radium A. B, and C. 

 Table II. 



81 



Time in 



minutes. 



Long Exposure. 



Short Exposure. 



Obs. 



Calc. 



Obs. 



Calc. 







80-3 

 669 



557 



49 : 6 



44 : i* 



41-2 



38 : 6 

 362 



312 

 26-4 

 217 

 177 

 14-4 

 9-32 

 591 

 3-84 

 2-23 

 1-35 

 •812 

 •4S1 

 •2-0 



1000 



70 -ii 

 66-8 



55 : 6 



49 : 6 



44 : 5 

 41 4 



:;s : s 



36-4 

 31-3 



263 

 21-9 



17 9 

 14-5 

 930 

 5-85 

 3-63 

 2"22 

 1-34 

 •812 

 •480 

 •290 



040 

 39-9 

 259 



13 : 8 



"> : 44 

 573 

 460 



412 



3-1)2 



392 



391 



3-65 



327 



2-81 



2-36 



1-60 



103 



•66 



•41 



•25 



15 



1000 

 632 



40-2 

 2.59 



140 



'8-35 

 572 



456 



i'-i'i 



391 

 393 



391 

 365 

 326 

 284 

 2-40 

 1-64 

 107 



•43 



•20 

 •16 



2 



4 



(j 





9 



10 



12... 



15 



IS 



20 



21 



25 



30 



40 



50 



tin 



70 



80 



100 



120 



140 



160 



180 



2oo 



220 



240 





radium A. In the above experiments the radius of the testing 



vessel was about 25 cms. and its length about 10 cms. There- 

 fore a large pari of the a particles from both radium A and C 

 had an ionizing path of less than -k cms. Now Bragg and 

 Kleeman (Phil. Mag. Sept. 1905) have clearly shown that an 

 a particle from radium A produces a considerably larger 

 number of ions per cm. during the first 4 cms. of its path 

 than is produced by an a, particle from radium C during the 

 same distance. This fact accounts satisfactorily for the mean 

 value, 1*25, obtained for the ratio in the present experiments. 



The remarkable agreement between the experimental and 

 theoretical curves over so long a period of time would seem 

 to be conclusive proof that the products A, B, and C are 

 successive, and that the periods, which were obtained by direct 

 experiments and used in these calculations, are very nearly 

 correct. It would not seem probable that any one of the 

 above periods was incorrect by more than two or three tenths 

 of a minute, inasmuch as a change of three tenths of a minute 

 in the period of radium B would make a 6 per cent, change 

 in the calculated value of the ionization current at the time 

 210 minutes. 



Phil. Mag. S. 6. Vol. 12. No. 67. JiCuj 1906. G 



