ARGON, 



A NEW CONSTITUENT OF THE ATMOSPHERE. 



By Lord Rayleigh and Professor Williaji Ramsay. 



"Modern discoveries have uot beeu made by large collections of facts, with sub- 

 sequent discussion, separation, and resulting deduction of a ti'utb thus rendered 

 perceptible. A few facts have suggested an liyfotheM^, which means a supposition, 

 pi'oper to explain them. The necessary results of this supposition are woi-ked out, 

 and then, and not till then, other facts are examined to see if their ulterior results 

 are found in Nature." — De Morgan, " A Budget of Paradoxes," Ed. 1872, p. 55. 



I. — Density of Nitrogen from Various Sources. 



In a former paper ' it has been shown that nitrogen extracted from chemical 

 compounds is about one-half per cent lighter than "atmospheric nitrogen." 



The mean numbers for the weights of gas contained in the globe used were as 

 follows : 



From nitric oxide 2.3001 



From nitrous oxide 2.2990 



From ammonium nitrite 2.2987 



while foi' " atmospheric " nitrogen there was found : 



By hot copper, 1892 2.3103 



By hot iron, 1893 2.3100 



By ferrous hydrate, 1894 2.3102 



At the suggestion of Prof. Thoi'pe experiments were subsequently tried with 

 nitrogen liberated from urea by the action of sodium hypobromite. The carbon 

 and hydrogen of the urea are supposed to be oxidized by the reaction to COg and 

 ' Proceedings of the Royal Society, vol. LV, p. 340, 1894. 



