Ellen Gleditsch — Life of liadium. 119 











Table 4. 









Growth of rad: 



ium 



in the main solution from cleveite. 



Test 



Time from start 

 in days 



Radirnn emanation found 



expressed in 



terms of radium 



Growth of radium 

 per day 



1 



1-83 







0-82 X H~ 9 





00342 X lO- 9 



2 



34 







3-756 X 1C" 9 





0-03405 X 10~ 9 



3 



80 







5-310 X 10~ 9 





0-0342 X lO" 9 



4 



144 







7-507 X 10- 9 







5 



192 







9-119 X 10- 9 





0-0340 X lO" 9 





Growth of 



radi 



um 



per day : 0*0341 

 per year : 12 '45^ 



X 

 X 



10~ 9 gram. 

 10~ 9 gram. 



Table 5. 

 Growth of radium in test solution from cleveite. 

 Radium emanation found 



Test 



Time from start 

 in days 



expressed in 

 terms of radium 



Growth of radium 

 per day 



1 



383 



0-33 X lO" 9 





2 



41- 



0-30 X 10" 9 





3 



104- 



0-33 X 10- 9 



o-oo 



There is no augmentation of radium in this solution and 

 consequently it contains no ionium. The precipitation by 

 hydrolluoric acid so proves to be very complete. 



The growth of radium in the cleveite solution is : 



per day : 0-0341 x 10~ 9 gram, 

 per year: 12-45 x 10 -9 gram. 



The amount of radium present in the solution at the start 

 was 2-8 X 10~ 9 gram. 



The radium contained in 180 grams of the mineral was 

 3-19 X 10~ 5 . The fraction \ of the radium changing per year 

 was therefore : 



12-45 x 10" 9 , . , 



= 3-90 X 10" 4 (year)- 1 



3-19 X lO" 5 VJ ; 



and the half-value period of radium is : 



m °'693 „ „ 



T = = 1777 years. 



3-9 X 10- 4 J 



3. Ionium solution from Broggerite, Norway. 



Broggerite is a well-crystallized uraninite from Raade, Nor- 

 way. It crystallizes in the regular system and can easily be 

 separated from accompanjang minerals except columbite. 

 This mineral, which contains tantalates and niobates of iron, 



