PROBLEMS OF MODERN SCIENCE 



that other agencies such as electrons or high- 

 frequency X-rays will be able to cause instability 

 in atomic nuclei. An indefinite supply of either 

 of these could be obtained by known laboratory 

 methods. There is an unpleasant possibility in 

 the nuclei of atoms which I should like to mention 

 in passing. It is possible that if these effects get 

 going at any time on any considerable scale they 

 may spread from atom to atom with ^explosive 

 violence, and that would be the end of all things. 



I now come to the last problem which I shall 

 consider. Is the hydrogen nucleus the positive 

 electron out of which all the other nuclei are built 

 up ? I think there can be little doubt that it is. 

 In the first place it has an electric charge equal 

 and opposite to that of the negative electron, and 

 it is the only body in the universe which has this 

 charge. This in itself is a sufficiently astonishing 

 fact which may prove to be one of the ultimate 

 riddles of Nature. But, you may say, if the 

 hydrogen nucleus is the unit out of which the nuclei 

 of the other atoms are constructed, why are the 

 atomic weights what they are ? For example, why 

 are they H= 1-008, C= 12-00, O= 16-00, 

 Cl = 35-5 and not H= i-ooo, C= 12-00, 

 O= 1 6 -oo, Cl = 35-00? The answer in the 

 case of chlorine has been given by Aston, who has 

 shown that it is a mixture of two isotopes whose 

 atomic weights are 35-0 and 37-0. Similar 

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