118 G. F. BECKER RELATIONS OF RADIOACTIVITY TO COSMOGONY 



All three groups of radioactive bodies include remarkable substances, 

 called emanations, which are of very great importance from the geo- 

 logical point of view. They are all gases which diffuse slowly into air 

 and obey the ordinary laws of gases. They are known as radium emana- 

 tion, thorium emanation, and actinium emanation. These gases are not 

 acted on to an appreciable extent by any chemical or physical agent, and 

 Messrs Eutherford and Soddy have subjected radium and thorium 

 emanations to treatment such that no gas excepting one of the argon- 

 lieHum family could possibly have survived. 



The three emanations thus belong to the group of inert gases, which 

 also includes xenon, kr}'pton, argon, neon, and helium, so that in all 

 there are eight members of the group. According to the disintegration 

 theory, all the emanations degenerate by losing successive atoms of 

 helium and only in this manner. The analogies expressed by the periodic 

 law, on the other hand, would lead to the expectation either that there 

 should be other heavy inert gases, as yet unknown, which would break 

 down by shedding off neon and argon,^- or, as an alternative, that the 

 known emanations should under certain conditions emit molecules of 

 neon and argon. The former of these hypotheses would seem a priori 

 less probable than the second, for no group is yet known to contain more 

 than nine elements, while eight inert gases have already been discovered. 

 On the other hand, the supposition that the emanations may emit other 

 light inert gases besides helium would rob the theory of radioactivity of 

 its wonderful simplicity. It could no longer be maintained that radio- 

 activity proceeded irrespective of chemical or physical environment. 



ISTow ]\Ir A. T. Cameron and Sir William Eamsay ^^ have recently 

 published papers the conclusions of which are very novel and will not be 

 generally accepted in toto rmtil confirmed by others. They reach results 

 of two kinds. They incline to believe that they have isolated lithium, 

 and perhaps sodium, from copper salts b)^ radioactive processes, and 

 this is the conclusion which has attracted most attention. To me it 

 seems less fundamentally important and interesting than their unqualified 

 assertion that under certain conditions argon and neon result from the 

 degradation of radium emanation. When the emanation is dissolved in 

 water they state that it yields almost exclusively neon, as its gaseous 

 educt, while when a copper salt is simultaneously present in the solution, 

 argon is the main product. As every one knows, Sir William was not 



^ Mr R. .7. Strutt regards it as possible that all the light inert gases have been pro- 

 duced by degeneration, but that only those which produce helium now survive. The 

 Becqiierel rays and the properties of radium, 1904, p. 174. 



" Journal of the Chemical Society, vol. 91, 1907, p. 1593. 



