THE MYSTERY OF RADIOACTIVITY 65$ 



and corresponds, it may be supposed, to that which happens 

 when terms in the radioactive series are formed without any 

 apparent change in the weight of the molecule — changes in 

 which only /3 and 7 rays are given out. 



Finally, we have to consider the rates at which Radium and 

 other radioactive materials undergo change — why the rate is 

 constant in each particular case. Why, as Radium decomposes 

 so slowly, does it decompose at all ; why does it not all blow up 

 suddenly, like an ordinary explosive ? There is but one ex- 

 planation — that, like the other mere chemical compounds Prof. 

 Soddy speaks of so slightingly, it is always being decomposed 

 reversibly — into protohelium and something else, the which 

 products reunite more frequently than they part company and 

 escape, the protohelium after it has united with itself; the 

 Radium does not blow up, because of the intense affinity of 

 protohelium for its companion product of change ; for a similar 

 reason, heat is without influence on the rate of change and 

 there is no helium to be seen in the spectrum of Radium. 



It would be surprising that Prof. Soddy and other workers 

 have so long overlooked the potentialities of protohelium, were 

 it not human nature to have chief affection for one's own children : 

 to be blind to their faults and disinclined to seek virtues in 

 those of others. I venture, however, to suggest that it were 

 time to discard the fiction that the gases of the argon family are 

 monatomic molecules which has so long retarded progress. 



Protohelium apparently is the wondrous material at the root 

 of radioactivity. 



The terms of short life in the radioactive series are to be 

 regarded as compounds in which the affinity of the constituent 

 radicles for each other is slight. Radium or uranium even and 

 the most ephemeral of the radioactive products which it 

 furnishes may be contrasted the one with say sodium chloride 

 or carbonate, the other with nitrogen chloride or ammonium 

 carbonate : they are separated by a wider energy interval but 

 only in degree. 



What has been said, it may be hoped, will in no way diminish 

 the attractiveness of Prof. Soddy's tale of wondrous scientific 

 achievement. 



H. E. A. 



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