222 



SCIENCE PROGRESS 



The fact that many, probably the majority, of the elements 

 are mixtures of isotopes renders the chemistry of their com- 

 pounds, theoretically, excessively complicated. On the other 

 hand, it must be remembered that, so far as one can tell, the 

 separation of the isotopes is so extremely difficult that prac- 

 tically this matter is unimportant, while the whole theoretical 

 aspect of mass is most advantageously simplified by the whole 

 number relation. 



Table of Elements and Isotopes 



Element. 



H . 

 He . 

 B . 

 C . 

 N . 

 O . 

 F . 

 Ne . 

 Si . 

 P , 

 S , 



CI 



A 



AS 



Br 



Kr 



X 



Hg 



(Numbers in brackets provisional only.) 



