122 Ellen Gleditsch — Life of Radium. 



the Institute of Mineralogy of the University in Kristiania and 

 I am glad to have here an opportunity to express my gratitude. 



100 grams of the pulverized mineral were brought into solu- 

 tion in nitric acid. The residue weighed 3'4 gram and a treat- 

 ment with hydrofluoric acid and sulphuric acid removed the 

 silica and reduced it to 2*4 grams. It was now melted with 

 an excess of potassium hydrosulphate. The mass was boiled 

 with water and filtered; the solution contained no uranium ; a 

 precipitate obtained with ammonia was dissolved in nitric acid 

 and added to the main solution. 



The residue undissolved in boiling water was treated with 

 hydrochloric acid, which dissolved the niobic and tantalic acid. 

 The slight residue was boiled with sodium bicarbonate in excess 

 and filtered. To the undissolved part was added dilute hydro- 

 chloric acid ; only 0*2 gram was left and its activity was 

 negligible. 



To the solution of the mineral was added hydrogen sulphide 

 and the sulphides removed exactly as given under broggerite 1. 

 When the excess of hydrogen sulphide was expelled the solu- 

 tion was heated to boiling in a platinum dish and hydrofluoric 

 acid was added. The liquid was allowed to cool and the fluor- 

 ides were filtered off. A solution of three grams of oxides of 

 rare earths was added to the mineral solution and again pre- 

 cipitated as fluorides and removed. All the fluorides were 

 converted into sulphates by the ordinary manipulations. The 

 sulphates were dissolved in water and the hydroxides were 

 precipitated live times. The final precipitate was dissolved and 

 brought into a glass bulb as Sol. 1. The results of the meas- 

 urements are given in Table 8. 



Table 8. 



Growth of radium in the niain solution frorn Broggerite 2. 



Radium emanation found 

 Time from start expressed in Growth of radium 



Test in days terms of radium per day 



1 4- 0-224 X 10~ 9 



2 68- 1-826 X 10- 9 0-0231 X 10" 9 



3 140- 3-623 X 10~ 9 0-0241 X 10- 9 

 Average growth of radium per day, 0-0236 X 10 -9 gram. 



The radium present in the solution at the start was : 

 0-40 x 10 -9 gram. 



To the solution from which the fluorides had been removed 

 a new quantity of rare earths was added and again precipitated 

 as fluorides. These fluorides were treated exactly like the 



