A HISTORY OF SCIENCE 



clusively that some gaseous substance different from 

 nitrogen was to be found mixed with the samples of 

 this gas as he obtained it from the atmosphere. This 

 conclusion of Cavendish, put forward indeed but ten- 

 tatively, had been quite ignored by his successors. 

 Now, however, it transpired, by experiments made 

 jointly by Lord Rayleigh and Professor Ramsay, that 

 the conclusion was quite justified, it being shown pres- 

 ently that there actually exists in every portion of ni- 

 trogen, as extracted from the atmosphere, a certain 

 quantity of another gas, hitherto unknown, and which 

 now received the name of argon. It will be recalled 

 with what astonishment the scientific and the un- 

 scientific world alike received the announcement made 

 to the Royal Society in 1895 f the discovery of argon, 

 and the proof that this hitherto unsuspected constitu- 

 ent of the atmosphere really constitutes about one per 

 cent, of the bulk of atmospheric nitrogen, as previously 

 estimated. 



The discovery here on the earth of a substance 

 which Professor Lockyer had detected as early as 1868 

 in the sun, and which he had provisionally named 

 helium, excited almost equal interest; but this element 

 was found in certain minerals, and not as a constituent 

 of the atmosphere. 



Having discovered so interesting a substance as 

 argon, Professor Ramsay and his assistants naturally 

 devoted much time and attention to elucidating the 

 peculiarities of the new substance. In the course of 

 these studies it became evident to them that the pres- 

 ence of argon alone did not fully account for all the 

 phenomena they observed in handling liquefied air, and 



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