856 



SCIENCE 



[N. S. Vol. XLH. No. 1094 



PoUnmnv 



t t 



chanpinoto cKiTifliroto 



amount present is shown by two cubes 

 wbose volumes are proportional to the num- 

 ber of atoms involved in the transformation. 

 In the second diagram (Fig. 2) the first 

 cube on the left is supposed to be of the 

 same size as the smaller cube in the first 

 figure. Since the constant of change of 



ionium is as yet undetermined, it has been 

 assumed for convenience to be approxi- 

 mately the same as that of radium, and the 

 amount of ionium in the mineral is there- 

 fore indicated as of the same order as the 

 amount of radium. "With this limitation, 

 and omitting the slight complications in- 



