A SUGGESTION CONCERNING THE 

 ORIGIN OF RADIOACTIVE MATTER 



By H. S. SHELTON, B.Sc. 



The suggestion here put forward was written by me several 

 years ago, in 1908, but, finding that it had been anticipated, I 

 made no attempt to publish it. Recent correspondence in 

 scientific journals indicates the probability that others may take 

 it up and expand it. I therefore take this opportunity of stating 

 it explicitly. 



The suggestion is, briefly, that radioactive substances, par- 

 ticularly uranium compounds, are synthesised from other 

 elements as a result of the conditions of great temperature and 

 pressure found in the Earth's interior. 



The anticipation will be found in Prof. Rutherford's Radio- 

 active Transformations (p. 194), where the suggestion is credited 

 to Dr. Barrell. It is mentioned there only in a sentence with 

 no indication whatever of the possible implications of the idea. 

 So far as I am aware, this is the first suggestion of the kind that 

 has been made. 



The manner in which it arose in my own mind will best 

 be indicated by quoting verbatim from my MS. written in 1908 : 



"The result of Prof. Joly's investigations discloses a great 

 disparity between the known radioactive content of the crust 

 of the Earth (36 x 10 ~ 12 parts of radium per unit mass) and the 

 calculated radioactive content of the interior (4'6x io~ 14 parts of 

 radium per unit mass less the necessary allowance for the 

 radioactive content of the crust). In consequence, on the usual 

 supposition concerning the interior of the Earth, we need to 

 assume either an almost entire absence of radioactive matter in 

 the interior, or an interior, with an absence of convective action, 

 heating gradually to some colossal temperature. May not the 

 following suggestion provide a possible solution of the 

 difficulty ? 



" Is it not possible that extreme physical conditions, par- 

 ticularly of temperature and pressure, may affect the rate of, 



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