LECTURE XVI.] HISTORY OF CHEMISTRY. 347 



ascertained in a preliminary manner to be 45. It should pro- 

 bably be much higher, however, as the gas was still mixed with 

 lighter gases, especially with argon. In the case of crypton, 

 the ratio of the specific heats has also been ascertained to be 

 1.66, so that this gas is also a monatomic element, the position 

 of which in the periodic system is still undetermined. 



As regards other discoveries, Ramsay found, by the syste- 

 matic fractionation of argon 7r ' (which he condensed by means 

 of liquid air), three new substances which he considers to be 

 elements. These are, neon, with atomic weight 19.3 to 19.5, 

 which is clearly to be placed therefore between helium and 

 argon and before sodium; xenon, with density 65 (H = 2) 

 which might, as Ramsay supposes, be raised to 81 by further 

 purification, so that it would be placed beyond bromine ; and 

 finally, metargon, an easily condensable and even solidifiable 

 gas, which shows the spectrum of carbonic oxide even after it 

 has been mixed with oxygen and exposed for a long time to 

 the passage of electric sparks. 76 



Even although all doubt as to the individuality and the 

 elementary nature of these gases is not yet removed, 77 still 

 these investigations are unquestionably amongst the most suc- 

 cessful that have been carried out during the last twenty years. 

 Liquid air served not merely as starting material for the 

 investigations, but Ramsay also employed it, or at least the 

 liquid oxygen obtained by its aid, in an ingenious manner for 

 the purpose of separating the various new elements. 



The question as to the position of these " elements " in the 

 periodic system has been much discussed, and up to the 

 present it is not finally solved. On the other hand, we may now 

 say that even if our views respecting the connection between 

 the properties of the elements and their atomic weights should 

 be modified on account of these newly discovered facts, still 

 the periodic law has rendered excellent service as an invaluable 

 guide in this obscure region. 



7f) Berichte. 31, 3117. 76 Ibid. 31, 3119. 77 Compare Brauner, Ibid, 

 32, 708. 



