36 SODDY, Evolution of Matter by Radio-active Elements. 



only a rays. The activity under consideration was found 

 to consist of both a and |3 rays, but the proportion of the 

 j3 rays is very small, being only one-tenth of that for the 

 case of a thin layer of uranium oxide. The matter 

 causing the activity is not, however, homogeneous. A 

 portion is very easily volatilised when the glass on which 

 it is deposited is heated in a test-tube over a bunsen flame, 

 and this part is deposited on the quite cold walls of the 

 tube. It will be remembered that polonium is easily 

 volatilised. Perhaps more definite information will be 

 given when the specimens are re-examined after an 

 interval, and possible intermediate changes have completed 

 themselves. The point of course is that unless polonium 

 can be accounted for in this way there must exist another 

 more or less permanent radio-element in pitchblende, for 

 the matter causing the induced activity with slow dissi- 

 pation must go on accumulating in pitchblende until its 

 activity is comparable with that of the other disintegration 

 products. 



The view that polonium is a disintegration product of 

 radium is at first sight strongly confirmed by some 

 experiments of Giesel* Giesel, repeating the method 

 applied by Marckwald for the separation of polonium 

 from pitchblende, kept pieces of bismuth, palladium, and 

 platinum respectively in solutions of powerful radium 

 preparations. He obtained a sensibly permanent activity 

 consisting only of a rays from the metals after they had 

 been freed from every trace of radium and left to them- 

 selves for a few days. He remarks that this is in support 

 of his earlier expressed view that " Polonium durch 

 Radium inducirtes Wismuth sein konne." It would seem 

 that polonium might equally well be described as induced 

 platinum, or induced palladium. On the disintegration 

 * (Ber. d. Deutsch. Chem. Ges., 1903, p. 2368.) 



