vi OBITUARY NOTICES. 



yellow line in which w'as identical w^ith that in the spectrum of the 

 sun ascribed to an element, unknown on earth, called helium. 

 Before Ramsay's discovery this substance had indeed been suspected 

 in the spectrum of volcanic ejections from Vesuvius, but no one 

 had any idea of its nature. The excitement of the discovery was so 

 great that Ramsay was obliged to voyage to Iceland for a long rest. 

 The existence of two inert gases with atomic weights respectively 

 about 4 and 40 suggested to Ramsay the possibility that there might 

 also be others fitting in to other corresponding places in the periodic 

 system of the elements ; and after an eager search, in a brilliant 

 investigation, Ramsay announced the discovery of the whole series, 

 including neon, crypton and xenon, obtained by fractional distillation 

 at very low temperatures of the residues from large amounts of 

 liquid air or liquid argon. This work was carried out with the 

 help of Travers, using the methods for the liquefaction of the so- 

 called permanent gases which had only recently been developed by 

 others. It was about this time, between 1895 '^"^l 1898. that I 

 remember Sir William's having said to me : " Nothing in this world 

 is too strange to be true if properly substantiated by adequate ex- 

 periments." This feeling animated Ramsay in all his researches, 

 and was a good preparation for the yet more astounding things 

 which were to come. For during these years the extraordinary 

 properties of radium and the revolutionary phenomena of radio- 

 activity began to become known to mankind, and Ramsay, with 

 eager interest in anything capable of throwing new light upon the 

 processes of nature, welcomed to his laboratory Frederick Soddy, 

 who had just come from Montreal, where he had helped Ruther- 

 ford in his epoch-making studies concerning this subject. It was 

 Ramsay's admirable technique in dealing with small quantities of 

 gases that enabled him, in collaboration with Soddy in 1903, to 

 give the first experimental evidence that helium is formed from 

 radium — a phenomenon suspected by Rutherford, but not experi- 

 mentally proved by him. Soon afterwards, in 1908, with the help 

 of Cameron, Ramsay showed that the emanation from radium, 

 which had been proved by Ramsay's earlier work with Gray to be 

 a heavy but unstable gas, had, in spite of its instability, a spectrum 

 of its own. 



