STANDS SCIENCE WHERE SHE DID? THOMAS 241 



though there is no evidence that as master of the mint he produced 

 fjohl by any means other than were customary. But the tide was 

 turning. The Honorable Robert Boyle initiated an age of sceptical 

 chemists, and Edward Gibbon could write with that supercilious- 

 ness which no one else has ever approached : 



Philosojihy, witli the aid of experience, has at length banished the study 

 of alchyiiiy; and the present age, however desirous of riches, is content to 

 seek them by tlie humbler means of commerce and industry. 



That, however, was not the end of the story. Depth in philos- 

 ophy, and greater experience, have brought back from exile the 

 idea of transmutation banished by Gibbon. Toward the end of 

 the nineteenth century it was found that certain elements were 

 actually being transformed into other elements without man's aid; 

 in fact, man could do nothing to accelerate or even hinder the 

 process. They were the radioactive elements, whose atoms were 

 very heavy and complicated, and therefore unstable, with a tend- 

 ency to break up into simpler atoms. In this way lead was left 

 behind when uranium disintegrated. Man could only watch the 

 process, but it furnished him with the means by which he himself 

 could transmute one element into another. For radioactive sub- 

 stances emitted alpha-particles, or helium nuclei, at enormous veloc- 

 ities, and these could be used as projectiles to bombard matter in 

 the hope of transmuting it. The hope was realized; thus when 

 Lord Rutherford fired alpha-particles into nitrogen a form of oxygen 

 was obtained. This was not a disintegration of matter, as in radio- 

 activity, but a building up of atoms, the oxygen atom being heavier 

 than the nitrogen. 



But there was still a weakness in this process — man had no con- 

 trol over the source of his projectiles. Another step forward was 

 taken last year by Dr. Cockcroft and Dr. AValton when protons 

 obtained by the passage of electricity through hydrogen were fired at 

 a lithiinn target. Sometimes, apparently, a lithium nucleus would 

 capture a proton and would sj^lit up into two helium nuclei. The 

 process, which was wholly under the control of man, has subsequently 

 been extended to other elements, and alchemy may now be said to be 

 a well-organized science. The newly discovered neutrons have also 

 proved themselves excellent projectiles for transmuting matter by 

 bombardment. (It should perhaps be pointed out, in view of popular 

 beliefs to the contrary, that the " splitting of the atom " holds out 

 no immediate hope of a new source of power. It is true that when 

 a single atom is transformed more energy is obtained than is put 

 into it; but only a small fraction of the projectiles fired into atoms 

 are successful in making hits on nuclei, and on the whole far more 

 energy is put into the process than is obtained out of it.) 



