THE DISCOVERY OP NEW ELEMENTS. 243 



and Professor I^amsay ' separated from atmospheric uitrogeii an elemen- 

 tary gas of great density wliicb, by reason of its chemical indifference, 

 they called argon. They proved that this gas formed about 0.8 or 0.9 per 

 cent of the volume of nitrogen, from which it could be separated either 

 by incandescent magnesium or by the continued action of the electric 

 spark. It was established beyond doubt that Cavendish produced this 

 gas a hundred years ago by the use of the electric spark.'^ Argon, either 

 alone or accompanied by helium, has also been found in natural waters 

 as well as in minerals. Its discovery in a meteorite of Augusta County, 

 Virginia, United States of America, may perhaps lead us to ascribe to 

 it an extraterrestrial origin. 



The physical properties of argon are very distinct, and its charac- 

 teristic spectrum enables us to at once distinguish it with certainty 

 from any other substance, but from a chemical point of view this gas 

 is most extraordinarily inactive, and we have not yet succeeded in 

 making it form combinations as the other elements do. This pecal- 

 iarity, and also the impossibility of finding a place in the periodic 

 system for a simple body having the molecular weight of argon (39.88), 

 have given rise to all sorts of hypotheses relative to the nature of this 

 gas. Should it be considered as a monatomic element having an atomic 

 weight of 37 and a place in the system between chlorine and potassium, 

 01 a diatomic one with an atomic weight of 20, which would place it 

 after fluorine and before sodium? May it not be an allotropic form of 

 nitrogen, N3, having a molecular weight of 42, or a tria;tomic element 

 Avhose atomic weight would not exceed 13? The question has not as 

 yet been answered. 



Another most interesting discovery was that of helium, made by 

 Professor Ramsay.^ In 1891 Hillebrand showed that uranium ore and 

 ores of the same family when dissolved in acids or fused with alkaline 

 carbonates, or even merely heated in a vacuum, may give off as much as 

 3 per cent of nitrogen. Professor Eamsay* obtained this gas from cleve- 

 ite and by means of spectroscopic examination demonstrated the pres- 

 ence of argon; and in the course of his experiments — in March, 1895 — 

 he observed beside the spectrum of argon another bright, yellow line 

 that did not belong to that spectrum, and which Crookes^ recognized 

 as identical with the line D^ that Lockyer'^ had already observed in 

 1868 in the spectrum of the solar chromosphere, and which he had 

 attributed to an element as yet unknown upon the earth — helium. The 

 same line had also been distinguished in the spectra of other fixed 

 stars, particularly in the spectrum of Orion, so that it may be admitted 

 that helium exists in large quantities extraterrestrially. 



1 Lord Eayleigh et W. Ramsay, Journ. prakt. Chem., 51. 



2 Cavendish, Crell. Ann., 1786. 



^ W. Ramsay, Comptes rendus, 120. 

 "^ W. Ramsay, Chem. News, 71. 

 6 C. Crookes, Chem. News, 71. 

 6 N . Lockyer, Nature, 53. 



