584 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
resenting about one one-hundred-and-twentieth of the volume of 
nitrogen. But the observation had passed unnoticed, and until the 
researches of Lord Rayleigh, the nitrogen in the air had been con- 
sidered as a simple gas, identical with “chemical nitrogen.” 
While Lord Rayleigh, taking up again the experiments of Caven- 
dish, verified the fact that atmospheric nitrogen does indeed leave, 
after the action of the oxygen and the spark, a residue which could 
not be overlooked, Ramsay attacked the problem by a purely chemical 
method, that of absorbing the nitrogen by magnesium at red heat. 
The repeated action of this metal increased the density of the gas. 
From 14, its weight in relation to hydrogen, the density increased 
little by little to become fixed in the neighborhood of 20. What re- 
mained was a new gas, absolutely distinct from nitrogen, character- 
ized, aside from its density, by a peculiar spectrum very rich in lines 
in all regions and, a fact without precedent, by absolutely no ability 
to combine with any other substance whatsoever. 
At the British Association meeting at Oxford in 1894, at the 
memorable session of August 13, Lord Rayleigh and Ramsay an- 
nounced in turn that the nitrogen of the air is not pure nitrogen, and 
that it contains a small proportion of a gas more dense and much 
more inert, to which they gave, on account of its chemical inertness, 
the name of argon (« priv.; epyoo, energy). This communication 
caused a great sensation among the audience, and the daily press took 
up the matter at length. 
But chemists are generally conservative, and although the discovery 
was affirmed by two scholars so well qualified, many remained in- 
credulous. It was not certain that argon was a simple substance. 
The molecular weight, according to the density, being 40, it might be 
a form of nitrogen cyanide CN,; it was noticed also that a triatomic 
molecule of nitrogen N, would have a weight of 42, a figure not far 
from the one given above. 
A few months sufficed for Ramsay to clear up the question and 
dissipate all doubts. The comparison of the specific heats at a con- 
stant volume and at constant pressure shows an equally unexpected 
fact—that the molecule is monatomic, and consequently the new gas 
can only be an element. . 
There is never anything fundamentally new except that which 
could not be foreseen; that which is foreseen is implicitly contained, 
like the corollaries of a theorem, in that which is already within 
the domain of knowledge. To find in the air a new gas, and, in 
addition, one of absolute chemical inertness, is indeed a truly great 
discovery. It brought at once to the authors a deservedly great 
renown. Ramsay was not slow in adding to it through other re- 
searches not less surprising. And it was here again that a fortunate 
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