330 BELL SYSTEM TECHNICAL JOURNAL 



It will be noticed that in these photographs the Hnes of each pair 

 are of approximately equal brightness; whereas in the original work of 

 Urey, Brickwedde and Murphy, the one due to H^ was always by far 

 the fainter. The gain is due to the fact that G. N. Lewis has dis- 

 covered an amazingly potent method for separating H^ from HS of 

 which the efficiency outruns by far anything that was formerly hoped 

 for or dreamed of; it is said that samples of hydrogen or of hydrogen 

 compounds may be obtained, in which the heavier isotope exceeds the 

 lighter by more than one hundred to one ! This appears to be a god- 

 send to the chemists, as there is reason to suspect that the properties 

 of "heavy" hydrogen and of its compounds may be markedly and even 

 fantastically different from those of "light" hydrogen and its com- 

 pounds; a whole new province of chemistry seems to be opened to 

 explorers. Here, however, we are concerned only with the mass of 

 the nucleus; and in the original samples there was sufficiently much of 

 H^, to permit of its mass being measured by Bainbridge with the result 

 and with the accuracy which I have quoted already. As for the 

 question of the relative abundance of H^ and H^ in "ordinary" 

 hydrogen, it is now in a quite unsatisfactory state; for various experi- 

 ments give various results, mostly disagreeing with the prediction 

 which had a share in the discovery. 



