The Gold Deposits of Mount Morgan, Queensland. .■'>.' , » , .> 



to its composition. Hence the announcement above referred to was 

 met with much scepticism, in spite of the eminent character and skill 

 of the' men who made it; and the whole chemical world has waited 

 anxiously and impatiently for a full account of the work. This has 

 now been given in a paper by Lord Rayleigh and Professor Ramsay, 

 which was read before the Royal Society at a special meeting on 

 January 31. The long delay between the preliminary announcement 

 and the presentation of the paper is fully accounted for by this state 

 ment of Lord Rayleigh's : 



11 Idle research has been in many respects a very difficult one. 1 am 

 not without experience in experimental difficulties, but certainly I 

 have never encountered them in anything like so severe and aggravat- 

 ing a form as in this investigation. Every experiment that one 

 attempts takes about ten days or a fortnight to carry out to any 

 definite conclusion, and the result has been of necessity much less 

 progress than we could have hoped for, and many of the questions 

 have been left open that we could have wished to settle." 



The history of the discovery is in brief as follows : In the course of 

 a series of determinations of the densities of some of the more perma- 

 nent gases, Lord Rayleigh found in the case of nitrogen that if 

 obtained from chemical compounds it was about onedialf per cent, 

 lighter than if extracted from the atmosphere. This discrepancy was 

 naturally thought at first to be due to contamination with impurities 

 consisting of known substances. When experiment had demonstrated 

 that this was not the case, the dissociation of the molecules of the 

 nitrogen derived from chemical sources into detached atoms suggested 

 itself as a possible explanation of its greater lightness. But both gases 

 subjected to the action of the silent electric discharge retained their 

 densities unchanged. This was discouraging, and a further experiment 

 of a different kind disposed of this explanation in a still more decisive 

 manner. It was exceedingly improbable that the nitrogen of chemical 

 origin could be a mixture, as that would necessitate the existence of 

 two kinds of nitric acid. The simplest remaining explanation was to 

 admit the existence of a second ingredient in the nitrogen obtained 

 from the atmosphere. If the supposed gas had a density half as much 

 again as that of nitrogen, the presence of one per cent would suffice to 

 explain the observed differencesin density. This explanation brought the 

 investigators face to face with the great improbability that a gas 

 all about us and present in such enormous quantity could have 

 remained so long unsuspected. Its demonstration demanded the 

 isolation and identification of the new gas, and to the solution of this 

 problem the research was now directed. 



It is interesting to note here that Cavendish, more than a hundred 

 years ago, in his careful and exact study of atmospheric nitrogen, had 

 really raised this same question of possible admixture with another gas. 



