116 Ellen Gleditsch-s-Life of Radium. 



were filtered off. All the oxalates precipitated 1, 2 and 3 were 

 gently heated together and the oxides formed converted into 

 sulphates and brought into solution. The hydroxides were 

 precipitated several times in order to remove all radium and 

 the final precipitate was dissolved in dilute hydrochloric acid 

 and introduced into a glass bnlb where the growth of radium 

 could be measured from time to time. The results are given 

 in Table 1: Solution 1 from nraninite, North Carolina. 



Table 1. 



Growth of radium in the main solution from nraninite, N. Carolina. 



Kadiurn emanation found 



Growth of radium 

 per day 



0-023 X lO" 9 

 0-024 X lO" 9 

 0-023 X lO- 9 

 0-024 X lO" 9 



Average growth of radium per day, 0'024 X 10 -9 gram. 



The mineral solution was evaporated to dryness and the oxalic 

 acid destroyed ; the residue was moistened with nitric acid, 

 evaporated to dryness and dissolved in warm water. Nearly 

 three grams of rare earths were added and again precipitated 

 with oxalic acid. The oxalates were filtered off, treated ex- 

 actly as the first ones and brought in solution in a glass bulb, 

 where the growth of radium was measured. The growth of 

 radium is shown in Table 2. 



Table 2. 



'est 



Time from start 

 in days 



expressed in 

 terms of radium 



1 

 2 

 3 

 4 

 5 



8-75 



46-00 



77 00 



100-00 



541-00 



0-228 X lO" 9 

 1-07 X lO" 9 

 1-86 X lO" 9 

 2-31 X lO" 9 

 13-11 X lO" 9 





Growth of radium 



in test solution from nraninite 

 Radium emanation found 



, N. Carolina. 





Time from start 



expressed in 



Growth of radium 



Test 



in days 



terms of radium 



per day 



1 



2 

 3 

 4 



7-06 



98-00 



511-00 



540-00 



1-345 X lO" 9 

 1-970 X lO" 9 

 4-62 X lO" 9 

 490 X lO- 9 



o-ooi x i° -9 



0-00092 X 1<» -9 

 0-0009 X lO" 9 



Average growth of radium per day, 0-001 X 10 -9 gram. 



I had expected this solution to be free from ionium, but this 

 was not the case. I therefore repeated the operations once 

 more, added rare earths, precipitated them with oxalic acid, 

 transformed the oxalates and finally got a third solution : Solu- 

 tion 3 from nraninite, N. Carolina. 



