834 Mr. G. N. Antonoff on Radium I) 



and taking 



Ai= : 2 , 08XlO~ 6 (sec. -1 ) as the constant of emanation, 

 X 2 = about 1*19 x 10~ 9 „ „ radium D, 



X 3 =l-60xl0- 6 „ „ radium E, 



X 4 = 5-81 x 10- 8 „ „ radium F, 



we get B = 1-02^. 



A4 



Similaily we find D = l-09^. 



A 4 



Consequently 



X40 



IT 



=\ 2 (1'02 e-^-l-OS e-^*). 



Since the time period of radium D (about 16 years) is 

 long- compared with the time of observation (less than one 

 year) the value e~ x J is very nearly 1. Its value is found 

 with sufficient accuracy by taking the value of \ 2 found by 

 the approximate calculation. Since X4S is equal to the total 

 number of a particles expelled from radium F per second, 

 and the values of N and X4 are known, the value of X2 can 

 at once be deduced. 



Experimental Method. 



The emanation tubes in which the growth of polonium 

 was observed were of the shapes shown in figs. 3 and 4. 



Eur. 3. 



ttz&&&& 



~ mesZBXas: ^ms^ 



Fiar. 4. 



These had been used in experiments upon the decay of the 

 radium emanation. The initial amount of emanation had 

 been accurately measured by the 7-ray method. The emana- 

 tion decayed in situ in the tubes, and had practically dis- 

 appeared before the tubes were examined for their content 

 of polonium. For this purpose the tubes of the shape shown 

 in fig. 3 were cut in two, and the number of a particles 



