SIR WILLIA^I RAMSAY. v 



atmosphere. Lord Rayleigh, in a research which is a model of 

 experimental acumen and conscientious execution, was the first to 

 suspect the existence of such gases ; his careful study of the density 

 of nitrogen from different sources had proved chemical nitrogen 

 (prepared from nitric acid and ammonia) to be distinctly less in 

 density than the residue of the atmosphere from which oxygen and 

 carbon dioxide had been separated. Lord Rayleigh had shown that 

 the dift'erence was not due to any impurity of hydrogen in the 

 chemically prepared nitrogen, and that hence it must probably be 

 due to an unknown impurity in the atmospheric nitrogen. He had 

 begun on the task of burning this rather incombustible gas with the 

 help of the electric spark, in order to discover the nature of the 

 residue, a task which Cavendish long before had crudely attempted, 

 and which is now executed on a huge scale commercially. Ramsay, 

 stimulated by Lord Rayleigh's experiments and by the latter's 

 request for air from chemists, suggested another method of fixing 

 atmospheric nitrogen by conducting the gas over heated magnesium. 

 The two investigators worked in harmony, and in 1894 succeded in 

 showing that the residues left after the nitrogen was combined by 

 these two dift'erent methods were identical ; and that this common 

 residue consisted primarily of a hitherto unsuspected gas, which 

 they named argon, existing to the extent of about i per cent, in the 

 atmosphere. Sir William once told me that on hearing of Lord 

 Rayleigh's first experiments and turning to the original description 

 of Cavendish's experiments in his own library, he found the pencilled 

 annotation, " Look into this matter," placed opposite the line where 

 Cavendish states that a small bubble, not over i per cent, of the 

 whole, remained unconsumed by the sparking with oxygen. If 

 Ramsay had followed this early suggestion of his own, he. instead 

 of Lord Rayleigh, might have been the first to point out that the 

 small bubble remaining in Cavendish's experiment, was probably 

 a hitherto unknown gas. As it was, Ramsay's greatest credit lay 

 especially in his later work in this field. Remembering a discovery 

 of Hillebrand's that an inert gas had been found to exist included in 

 a certain ore of uranium, Ramsay secured a specimen of this ore in 

 order to discover if this gas might not be argon. To his amaze- 

 ment he found that the gas possessed a dift'erent spectrum, the chief 



