THE ELEMENTS OP THE CHEMIST 135 



Further work led to the conclusion that atmospheric air 

 contains an ingredient hitherto unnoticed by chemists. The 

 announcement made at the Oxford meeting of the British 

 Association in the summer of 1894 was received with a certain 

 amount of incredulity by the chemical world, in view of the 

 immense number of incontestably accurate analyses of air 

 which had been made during the previous half-century. In 

 these, however, the new ingredient, with its characteristic 

 chemical inactivity, had always passed as nitrogen gas. 



Lord Rayleigh had by this time secured the co-operation of 

 Professor Ramsay, and the two investigators joined in laying 

 before the Royal Society the results of their work. The interest 

 excited was so great that a special meeting had to be held on 

 January 31, 1895, in the theatre of the University of London 

 with Lord Kelvin, the president, in the chair. 



In the paper then published the authors give reasons for 

 suspecting a hitherto undiscovered constituent in air, and, as 

 their statement contains so many interesting features, the follow- 

 ing extracts from it will be welcomed by the reader. They say : 



" When the discrepancy of weights was first encountered 

 attempts were naturally made to explain it by contamination 

 with known impurities. Of these the most likely appeared to 

 be hydrogen, present in the lighter gas in spite of the passage 

 over red-hot copper oxide. But inasmuch as the intentional 

 introduction of hydrogen into the heavier gas, afterwards 

 treated in the same way with cupric oxide, had no effect upon 

 its weight, this explanation had to be abandoned, and finally it 

 became clear that the difference could not be accounted for by 

 the presence of any known impurity. 



" At this stage it seemed not improbable that the lightness of 

 the gas extracted from chemical compounds was to be explained 

 by partial dissociation of nitrogen molecules, N 2 , into detached 

 atoms. In order to test this suggestion both kinds of gas were 

 submitted to the action of the silent electric discharge, with the 

 result that both retained their weights unaltered. This was 

 discouraging, and a further experiment pointed still more 

 markedly in the negative direction. The chemical behaviour of 

 nitrogen is such as to suggest that dissociated atoms would 

 possess a high degree of activity, 1 and that even though they 



1 It is interesting to notice that this hypothesis has been verified fifteen year s 

 later by Lord Rayleigh's son, Professor Strutt. See chapter on Active Nitrogen. 



