242 SCIENCE PROGRESS 



in quantity which can only be determined spectroscopically. 

 She finds that there exists no simple relation between the copper 

 and lithium present in such minerals, whilst the mineral which 

 contains the largest amount of lithium, a sample of carnotite, 

 is one of the least radioactive. She concludes that whilst the 

 results do not contradict Ramsay's theory, neither do they 

 support it. 



Now that it has been proved that one element can be trans- 

 formed into another, it is inevitable that attempts should be 

 made to explain these facts, and at the same time to suggest a 

 reasonable theory of element-synthesis. 



Prout's hypothesis has been revived in new guise. At no time 

 can it be said to have altogether lost support. As originally 

 put forward, it was easily proved untenable, with the advent of 

 exact atomic weight determinations. Nevertheless, the periodic 

 system, and latterly spectroscopic evidence, pointed ever more 

 strongly to some underlying relationship between all the 

 elements. And the development of radioactivity once more 

 concentrated attention on these ideas. 



Lockyer, considering the spectra of nebulae, of which the 

 degree of complexity increases as the nebula gets less simple, 

 considers that this points to a gradual building up of elements 

 from the simplest forms. 



Perhaps the most ingenious of recent theories of element- 

 synthesis is that put forward by A. C. and A. E. Jessup, which 

 starts with the same idea. From spectroscopic evidence they 

 conclude that matter in the nebula stage consists of four 

 elements, termed protons ; of these, two only, hydrogen and 

 helium, are known. These protons are formed from primary 

 corpuscles — the original form of matter — by aggregation into 

 stable integral systems. Other atoms are formed by a process 

 of condensation of corpuscles round the proton-groups, the 

 various atoms representing groups of maximum stability in a 

 gradual and continual process. The authors state that the 

 formation of successive elements is attended by the escape of a 

 large quantity of energy ; the systems are steadily progressing 

 from higher to lower energy content. " The whole process 

 of evolution is entirely governed by the possibility of energy 

 leaving the system." They suggest instability as the reason of 

 disintegration, and this is undoubtedly true. The fact, however, 



