MANUFACTURE OF RADIUM MATIGNON 229 



tails as a consequence the retiring during the operations of only a 

 small quantity of the poorer liquids, since only 2.76 milligrams of 

 radium are discarded during the process. From time to time we 

 eliminate by a current of hydrogen sulphide the lead which always 

 exists in small quantities in the solution, xis indicated in the above 

 table the resulting sulphide of lead carries down with it some of 

 the radioactive matter. 



The table shows the flexibility of the fractionation and hoAV it 

 can be varied to suit the end desired. 



The above data comes from Prof. Howard H. Barker, of the 

 University of Missouri, who made very important researches on 

 carnotite. He has pushed the concentration even further. He pro- 

 poses to conduct the operations so as to have a radium bromide 

 nearly 90 per cent pure. The following table gives some of the 

 data relative to the proposed fractionation : 



Milligrams 

 Radium yi the initial salt 1.1 per cent pure 06. 04 



Radium obtained as the broiiiide 88 per cent pure 92. 60 



Radium obtained as a salt at 1.46 per cent pure 3. 51 



Radium obtained as a salt at 0.08 per cent pure .52 



96.5 per cent of the radium is accordingly obtained in the form of 

 bromide 88 per cent pure. 



All the tubes of radium bromide thus prepared are stored in a 

 room very distant from the physical laboratory. They are ex- 

 amined several times to determine their richness in radium. Gen- 

 erally three determinations of the radium imprisoned in each tube 

 are made by means of the y-rays: First, soon after the closing of 

 the tube when there is .sensibly no emanation; second, four days 

 later corresponding to the time for the growth of one-half the ema- 

 nation for equilibrium; and finally, about a month later v.hen radio- 

 active equilibrium is practically attained. 



The works and the laboratory establish a definite schedule of oper- 

 ations. They keep an accurate account of the amount of radium in 

 the original material, the mineral in the works, the radioactive car- 

 bonates for the laboratory and the quantity of radium obtained at 

 the end of the operations, the carbonates for the w^orks and the tubes 

 for the laboratory. From this final result may be judged the effi- 

 ciency of the various steps. 



TREATMENT OF PITCHBLENDE 



The industrial treatment of pitchblende residues as carried out by 

 the Austrian Government in the works at Joachimstahl is practically 

 the same as the method first elaborated by Mme. Curie and M. 

 Debierne. The chemists at the works at Oolen, while deriving ideas 

 from the previous process, have conceived for the treatment of the 

 76041—26 16 



