between Uranium and Radium. 



485 



Table I, 



Standards. 











Date. Ra(xl0- 12 g.). 



Leak (d.p.m 



). Constant. 



0-1898 g.BaCl 2 ... 17/4/1919 



123-8 



6-89 



1797 



0-5683 g. Ba01 2 ... 18/4/1919 



370-5 



21-68 



17-09 



J. Pitchblende 1 09/4/1910 

 0-1042 mg. U.j -"/*/A»l» 



354-3 



19-76 



1793 



0-0454 g. Ba01 2 ... 29/4/1919 



29-6 



1-70 



17-40 









Mean 



17-60 



0*5683 g.Ba01 2 ... 29/7 



1919 



370-5 



' 22-27 



16-64 



03981 g. BaCl~... 31/7/1919 



259-5 



15-14 



17-14 



0-0454 g.BaCC.. 4/8/1919 



296 



1-77 



16-72 









Meai 



1 16-83 



Uranium Preparations. 









Date. 



Age (Years) 



Leak. 



Constant. 



Ra(xl0" 12 ). 



No. IV 19/4/1919 



9-87 



13-88 



17-6 



244-3 



No. IV 30/7/1919 



10-15 



14-38 



16-83 



242-0 



No. III. ... 1/5/1919 



12-33 



2-66 



176 



46-8 



No. III. .. 1/8/1919 



12-58 



3-08 



16-83 



51-8 



No. II 7/8/1919 



12-98 



2-57 



16-83 



43-2 



No. 1 6/8/1919 



13-87 



3-02 



16-83 



50-9 



Uranium Residues. 



(Exper. VI. Phil. Mag. xiv. p. 



293,1907,) 



3/7/1907 









4-0 



22/5/1908 



0-95 



3-4 



5-78 



19-6 



21/7/1908 



111 



3-37 



5-78 



19-4 



9/5/1909 



1-91 



6-96 



5-78 



40-2 



29/8/1910 



3-22 



14-2 



5-2 



73-8 



9/3/1912 



4-75 



19-4 



5-35 



103-8 



1/8/1914 



7-12 



27-7 



5-35 



148-2 



5/9/1914 



7-24 



24-6 



5-35 



1320 



6/5/1915 



7-89 



10-07 



15-66 



157-7 



5/8/1919 



12-14 



13-85 



16-83 



233-1 



long before ionium was discovered, in 1904 from uranium pre- 

 parations purified from radium by means of barium sulphate. 

 After the discovery of ionium this was to be expected from 

 ionium contained in the commercial preparations, and not sepa- 

 rated by this purification process. The corresponding graph 

 is shown in fig. 1, and shows a steady linear growth of radium 

 with the time. The graph is of interest as showing that 

 throughout the long term of years over which these mea- 

 surements have been conducted there has been no serious 



