582 SCIENCE PROGRESS 



Dealing with the question of the present possibility of 

 artificial transmutation, one conclusion should be widely noted. 

 The question of artificially disintegrating elements by physical 

 means, such as by the electric discharge in vacuum tubes, freshly 

 raised a short time ago by experiments made by Prof. Collie, 

 has been very widely discussed. The frequent appearance of 

 helium and neon in such experiments has been taken to be 

 evidence of transmutational changes. But Sir J. J. Thomson 

 concludes, " I have never, however, been able to get any 

 evidence that I regard as at all conclusive that the atom of 

 one element could by such means be changed into an atom 

 of a different kind ; in other words, that by such means we 

 could produce a transmutation of the elements." The Hon. 

 R. J. Strutt's recent experiments also point in the same direction. 

 On the other side, however, Prof. Collie and his co-workers, 

 who have maintained that the apparently miraculous appearance 

 of helium and neon in vacuum tubes submitted to the electric 

 discharge is not a consequence of faulty experimentation and 

 contamination by air, have recently renewed the discussion in 

 the current number of the Proceedings of the Royal Society and 

 reaffirm their view that the phenomenon is inexplicable on 

 ordinary lines. 



The ratio of mass to weight being constant, for all elements 

 from the lightest to the heaviest and even for radioactive sub- 

 stances, and the view that, in the formation of elements generally, 

 changes may occur in mass, lead to the conclusion that even in 

 the region of subatomic changes mass must be proportional to 

 weight. This, if sound, would be of fundamental importance in 

 the theory of gravitation. But, as regards the electrons, it is 

 unknown whether these possess any weight at all, or whether, 

 as might be expected on one of the electrical theories of gravi- 

 tation, the weight may be abnormally large in comparison with 

 their mass. It will be realised how far we still are from the 

 profitable discussion of the significance of atomic weights. The 

 difference of o'2 unit noted between the atomic weight of uranium 

 and that of its products, it seems, may arise in at least three 

 ways : (i) by the loss of energy, as Sir J. J. Thomson suggests ; 

 (2) by the two electrons, which the atom loses, being abnormally 

 heavy in regard to their mass ; (3) by the existence of stable 

 isotopes of uranium differing in atomic weight. Two such are 

 in fact known, differing in atomic weight by four units, but one 



