204 



radium may be extracted from them, and the extent to which 

 the activity can be concentrated without having to resort to 

 fractional crystallization. The best specimens of ore possess 

 an activity about one-twelfth of that of UgOg. The first 

 active product which I obtain from them has an activity of 

 about 10, or one hundred and twenty times that of the origi- 

 nal ore. My second product has an activity of 200, over 

 two thousand times that of the original ore. Pitchblende 

 residues, j^ossessing an activity of four or five, after a great 

 deal of expensive chemical work, yield a radium barium 

 chloride of activity 60, or only fifteen times that of the resi- 

 dues, and fractional methods have then to be employed for 

 further concentration. 



In considering this question of concentration of activity, 

 the extremely small amount of radium present in the ore — 

 roughly, one part in twenty million — must be taken into ac- 

 count. This amount is so minute that it is improbable that 

 it would be precipitated at all, even from solutions contain- 

 ing sulphuric acid, in the absence of other insoluble sulphates. 

 In working up the kilogramme of ore the volume of the solu- 

 tion from which the active sulphate was finally separated 

 out was not less than tv/o litres, or forty million parts of so- 

 lution to one of radium. 



The fact that the insoluble sulphate, which carries the 

 radium down with it, consists principally of lead and not 

 of barium sulphate, accounts for the readiness with which 

 the activity can be further concentrated, as the removal of 

 the lead sulphate, by means of ammonium acetate, appears 

 to leave practically the whole of the activity in the small in- 

 soluble residue. 



In the event of active ores being found in quantity at 

 Moonta, this readiness with which the radium can be ex- 

 tracted from them would, of course, be of economic import- 

 ance, as it is questionable if the usual methods of separation 

 could be applied with any prospect of profit to such low-grade 

 material. 



In conclusion, I desire to express my indebtedness to the 

 General Manager of the Company, Mr. H. Lipson Hancock, 

 for his readiness to facilitate the research in every possible 

 way, and to the Manager of the Smelting Works, Mr. G. C. 

 McMurtry, for suggestions as to the practical treatment of 

 the ore, and also for checking a number of measurements on 

 active products. 



