THE TERRESTRIAL DISTRIBUTION OF RADIUM 23 



authority than Arrhenius. 1 Rutherford, 2 however, has suggested 

 that at the enormous temperature of the sun it is possible that 

 a process of transformation may take place in ordinary elements 

 analogous to that observed in the radioactive elements. This 

 implies inhibition under conditions not of high but of low 

 temperatures. 



Mr. Shelton himself, in an article on "The Age of the Sun's 

 Heat" 3 says, "Elements which are absolutely stable under 

 conditions which we can produce in our laboratories would, in 

 the colossal furnaces of stellar heat, change, decompose, and 

 gradually assume other and stabler forms." He then suggests 

 that such a transformation would make available sufficient 

 energy to maintain the sun's heat for thousands of millions of 

 years. What Mr. Shelton states, then, is this : that stable 

 terrestrial elements when subjected to high temperatures, such 

 as that of the sun, would assume stabler forms with emission 

 of energy. This is inconsistent with Le Chatelier's law of 

 reaction, for obviously at high temperatures the terrestrial 

 ejements would, according to that law, change into stabler forms 

 with absorption of energy. Apparently what is meant, however, 

 is that elements, stable under terrestrial conditions, would, if 

 present in a star or nebula, and subject to a high and rising 

 temperature, disintegrate into stabler forms with absorption of 

 energy. Later, when the temperature had begun to fall, this 

 process would be reversed, and the nebular or stellar elements 

 (e.g. helium and hydrogen) would re-unite with emission of 

 energy to build up the terrestrial types of elements, and so to 

 sustain the falling temperature. According to Mr. Shelton, 

 " Uranium and thorium are compounded beyond the limits of 

 stability." This implies that he believes that the radioactive 

 parent elements are formed with absorption of energy under 

 conditions of high and falling temperature, but that when 

 cooling has progressed sufficiently and the temperature is 

 lower, they again disintegrate with evolution of the energy 

 previously stored up. That is to say, that, under conditions 

 of falling temperature, energy is first absorbed and then 

 emitted. 



However, quite apart from Mr. Shelton's self-made difficulty, 



1 The Life of the Universe, vol. ii. p. 237, 1908. 



2 Radioactive Substances and their Tratisformations, p. 656, 191 3. 



3 Contemp. Review, p. 846, June 1913. 



