500 Bolticood — Life of Radium. 



This solution was tested for the growth of radium for a 

 total period of 539 days from the time of its first preparation. 

 The results obtained are given in the following table (Table I). 



The first column gives the number of each test, the number 

 1 signifying first test, 2 second test, etc. ; the second column 

 gives the time in days which elapsed from the time that the 

 solution was first prepared and sealed up to the time that any 

 given test was made; the third column gives the amount of 

 radium emanation obtained in each test expressed in terms of 

 the weight of radium with which it would be in equilibrium ; 

 the fourth column gives the amount of radium produced per 

 day during the different periods as calculated in the manner 

 already explained. 





Gi 



Table I. 

 •oivth of Radium in Soh 



ition 1. 





I 



II 



III 



IV 





1 



2 

 3 

 4 



69 days 

 263 " 

 376 " 

 539 " 



5-5SX10" 9 g. 



9-22 " " 

 11-38 " " 

 14-43 " " 



0-0187X10- 

 0-0192 " 

 0-0188 ■" 



3 gram, 



u 



The amount of radium produced per day calculated from 

 the results of the first and the last test only was - 0188xl0 -9 

 gram, and the amount of radium present in the solution at the 

 start calculated from this number and the result of the first 

 test was 4*40 XlO -9 gram. The amount of radium produced 

 in this solution in one year would therefore be approxi- 

 mately 6-yxlO" 9 gram. Assuming that all of the ionium in 

 the original mineral was contained in this solution, the constant 



6*9 X 10 _,J 

 of change (X) for radium is given by : = 2'2XlO 4 , 



B W e J 3-1 X10- 5 



and the half-value period indicated is about 3100 years. 



Jonium Solution 2. 



The preparation of this solution has also been described in 

 a previous paper.* It was prepared from a kilogram of car- 

 notite containing 3-1 Xl0~ 5 gram of radium. The chemical 

 treatment to which the mineral was subjected was more 

 elaborate than in the first instance and was designed to effect, 

 if possible, a more complete separation of the ionium. The 

 data obtained from the measurements conducted on this solu- 

 tion are given in Table II, in which the arrangement is similar 

 to that in Table I. 



* This Journal, xxv, 372, 1908. 



