56 SCIENCE PROGRESS 



transmuting the elements, and, had these had their way, perhaps 

 the struggles of the alchemists might have so been brought to a 

 cul-de-sac. There were, however, some who were not un- 

 mindful of the alchemists' dream and the hypothesis of Prout, 

 which assumed without absolute proof a primordial substance 

 common to all elements. And these were bold enough to 

 speculate on the problem of the fundamental nature of matter, 

 and to seek an answer to this riddle which has excited interest 

 and taxed ingenuity since the beginning of civilisation. But, 

 in most instances, ordered experiment was dominated by idle 

 speculation ; and so it came that only within the last decade 

 or so, true transmutation has been established as an experi- 

 mental fact. Even in the early 'nineties, it was not infrequently 

 maintained that, the science of physics having put its house in 

 order, further advances could only be looked for along the lines 

 of precise measurement. Such pessimism was, nevertheless, 

 soon to be utterly confounded by a sequence of discoveries such 

 as the boldest imagination had never projected. And indeed no 

 reflecting mind can even now survey the present state of physics 

 without realising that we have not yet extracted a tithe of the 

 potency which lies in the shadowy boundaries of the unknown. 



The first stepping-stone to the " new physics " was the dis- 

 covery of " electrons " by Sir J.J. Thomson at Cambridge in 

 1 897. The discovery resulted in the present accepted theory of 

 the constitution of matter. It paved the way for a ready 

 recognition of the amazing properties of the radioactive elements, 

 then on the point of discovery ; and it led to the establishment 

 of a new school of physics which accepted as a creed the theory 

 of the transmutation of the elements. It can be readily under- 

 stood that the placid existence of chemistry was rudely startled ; 

 but, as events proved, the atomic foundation-stones, though 

 threatened, were left undisturbed. What happened was that 

 a fresh storey had been added, though not, as was at first antici- 

 pated, at the expense of the stability of the structure. 



Meantime, in 1895, Prof. Rontgen, working in Bavaria, had 

 discovered the X rays, and achieved world-wide fame. In 

 1896, only two months later, Becquerel showed in Paris that 

 uranium salts were spontaneously " radioactive " and, like 

 X rays, could affect a photographic plate even through a sheet 

 of paper or metal. This was followed presently by the crowning 

 achievement of Prof, and Mme. Curie in Paris. They per- 



