160 PHILLIPS — RADIUM I.V AN AMERICAN ORE. [Aprils, 



with dilute acids, as it was intended in this case to boil the insolu- 

 ble residue in a concentrated solution of sodium carbonate, to 

 extract the last of the radium. After the acid treatment the residue 

 from the 3500 gms. originally taken weighed 2200 gms. and gave 

 an activity of 1.40. The solution contained 1300 gms. of the 

 amount taken. 



If the activity is calculated to gramme units compared to uranyl 

 nitrate the 3500 gms., activity 1.71 = 5985 units. 



Residue insoluble in dilute acids, 2200 gms., activity 1.40 = 3080 

 units. The solution contained, therefore, 2905 units, considerable 

 of which would be due to the uranium dissolved and emanation from 

 the radium. The dilute acid extracted nearly all of the uranium, but 

 there was still some found in the residue. This ore contained con- 

 siderable barium and a large amount of calcium. No barium was 

 therefore added to the solutions, as before. After precipitation of 

 the sulphates, and the separation of barium from other bases, 3.8 

 gms. of barium carbonate were obtained, which gave an activity of 

 35.8, or 135 units compared to uranium nitrate. This activity was 

 measured upon the same day {i.e., yesterday) that the barium salt 

 was separated from the c ther bases ; it may be expected that its 

 activity will increase, from the accumulation of the emanation; this 

 increase may in some cases amount to several times the original 

 activity of the compound when first prepared. 



This demonstrates that dilute, acids, while they dissolve consider- 

 able of the barium salts present, the greater proportion of the radium 

 is still left in the residue ; but even this amount, which is small com- 

 pared to that left in the residue, as indicated by the radio-activity 

 of the residue, if calculated upon the basis of a ton, would yield a 

 gramme of chlorides of 11,300 activity as compared to uranium. 



These facts prove beyond question that carnotite will become a 

 commercial source of radium. 



Pri7iceton University, March 7, igo4. 



