THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



XV II. The Relation hetween Uranium and Radium. — Pari VI. 

 The Life-Period of Ionium. Bij Frederick Soddy, M.A., 

 F.R.S., and Miss Ada F. R. Hitchins, B.Sc, Carnegie 



Research Scholar, University of Aberdeen* . 



AN experimental examination of the question whether 

 radium is produced from uranium has been in progress 

 by one of us since 1902. A clear growth of radium in a 

 uranium solution, initially purified from radium by precipi- 

 tating barium sulphate in the solution, was observed in 

 1904 f, but the extreme slowness of the growth suggested the 

 existence of a long-lived intermediate parent of radium, 

 which was separated by l'oltwood in 1907 and named ionium. 

 The present series of experiments were started in conjunction 

 with Mr. T. D. Mackenzie in 1905. Uranium preparations 

 were purified as carefully as possible by methods designed 

 to eliminate all other substances, so that neither radium nor 

 the hypothetical intermediate parent of radium would 

 initially be present J. Accounts of the progress of the 

 measurements on the quantities of radium in the various 

 solutions have been published from time to time§. In 1912, 



* Communicated by the Authors. 



t F. Soddy, ' Nature,' Mav 12, 1904 ; Jan. 26, 1906 ; Phil. Mag. I 6] 

 ix. p. 768 (1905) ; compare W. 0. D. Whetham, ' Nature,' May 5, 1904 ; 

 Feb. 2, 1905. 



X F. Soddv and T. 1). Mackenzie, Phil. Mag. [6] xiv. p. 272 (1907). 



§ F. Soddy, Phil. Mag. [6] xvi. p. 632 (1908) ; xviii. p. 846 (1909) ; 

 xx. p. 340 (1910). 



Phil Mag. S. 0. Vol. 30. No. 176. Aug. 1915. P 



