l62 ABSOLUTE ATOMIC WEIGHT. 



both of these forms oipure nitrogen secundum artem contain 

 some material not jet known (impurity) in the then state of 

 the chemical art. 



Investigation, carried on by this master, assisted by the 

 chemist Ramsay, led to the separation of argon from the 

 air. Argon is much heavier than nitrogen, but not removed 

 from it by the purifying absorbents in use prior to 1894 in 

 chemical art. 



The density determinations of Lord Rayleigh, published 

 in 1897 (Chemical News, v. 76, 315), for atmospheric air as 

 unit, are copied in the next table, to which I have added a 

 column of atomic weights for O = 16 exactly. Of course, 

 for air and atmospheric nitrogen this number must only be 

 taken as a density referred to O r= 16. 



Density. Atomic Weight. 



Air, free from H2 O and C O2, i.oo ooo H-47 5 1 



Oxygen, O2, i.io 535 16.00 oo 



Nitrogen (atm.) with Argon, 0.97 209 14-07 n 



<; (chem.) no Argon, 0.96 737 14.00 27 



Hydrogen, 0.06 960 i.oo 28 



Argon, 1.37 752 19.91 97 



Jahrbuch d. Chemie, 1898, p. 4, quotes from Proceedings 

 Royal Society, v. 62, pp. 204-209, the following molecular 

 weights, for O2 32 : 



Nitrogen, N2 28.060 



Carbon Oxide, C O, 2 7-999 



Carbon Dioxide, C O2, 44.268 



From these data we learn, that pure nitrogen, free from 

 argon, has an atomic weight of 14.003 only, according to 

 Lord Rayleigh's density determination. 



Incidentally we notice that hydrogen is 1.003 on ty> a l s 

 that by subtracting the one oxygen from the carbon oxide, 

 we obtain as atomic weight of carbon 11.999. 



Now, since this last value is true (within the limit of 

 precision), namely, conform to the results obtained by 

 Dumas and his followers by the combustion of the diamond, 

 the true atomic weight of nitrogen can, according to Lord 

 Rayleigh's determinations, not deviate more than 0.003 

 our standard value of 14 exactly. 



