14 DISCOVERY AND NATURE OF RADIOACTIVITY 



the radium atom results from the disintegration of the atom of 

 uranium. Two years later McCoy ^^ stated that the results of his 

 experiments confirm the conclusion that uranium is the parent, not 

 only of radium, but also of all other active substances that accompany 

 it in uranium compounds.* 



Soddy '-^ also finds experimental evidence that there is a steady 

 production of radium from uranium, though the observed amount is 

 of a lower order of magnitude than is indicated by the disintegration 

 theory. This discrepancy between observation and theory is doubt- 

 less due to the fact, discovered by Boltwood^* in 1906, that the 

 transformation of uranium into radium is not direct. The interme- 

 diate transformation product was later found to be, not actinium as 

 at first thought, but a new radioactive element, which " emits both a 

 and /9 radiations, which produces no emanation and which resembles 

 thorium in its chemical properties." For this new substance Bolt- 

 wood ^^ proposed the name ionium^ from ion, because of its ionizing 

 properties due to its emission of a radiations. 



Conceptions on this subject obtaining at the time of this writing 

 will doubtless be more or less modified by researches now in progress. 



Bibliography 



1. Ashworth, J. R. ^-rays from radium. Nature 69: 295. 1904. 



2. Becquerel, H. Sur les radiations emises par phosphorescence. Compt. 



Rend. Acad. Sci. Paris 122: 420. 1896. 



3. . Sur les radiations invisibles emises par les corps phosphores- 



cents. Compt. Rend. Acad. Sci. Paris 122: 501. 1896. 



4. . Sur quelques proprietes nouvelles des radiations invisibles emises 



par divers corps phosphorescents. Compt. Rend. Acad. Sci. Paris 

 122: 559. 1896. 



5. . Sur les radiations invisibles emises par les sels d'uranium. 



Compt. Rend. Acad. Sci. Paris 122: 689. 1896. 



6. . Sur les proprietes differentes des radiations invisibles emises par 



les sels d'uranium, et du rayonnement de la parol anticathodique d'un 

 tube de Crooks. Compt. Rend. Acad. Sci. Paris 122 : 762. 1896. 



7. . Emission de radiations nouvelles par I'uranium metallique. 



Compt. Rend. Acad. Sci. Paris 122: 1086. 1896. 



*The investigations of Coppock,^^MartinJ* Winkler,"^ Boltwood,i^ Murray,^" and of 

 Cameron and Ramsay ,^^ and Ramsay and Soddy,** which rendered highly probable, if not 

 positively demonstrated, the evolution of the chemical elements by radioactive trans- 

 formations, are not reviewed here, as they have only a reinote bearing on the purpose 

 of this resume. 



