DETERMINATION OF ATOMIC WEIGHTS 529 



14*01. The value 14*003 was obtained by the physical method 

 as early as 1895 by Rayleigh and Ramsay (1) but the value 

 14*04, derived mainly from the work of Stas, was published in 

 the International Table as late as 1906. Meanwhile, the low 

 figure was confirmed by Leduc (2), Berthelot (3), Guye and 

 his collaborators (10) and Gray, all using the physical method. 

 The first chemical work to yield the low value 14*01 was the 

 analysis of nitrous oxide by Guye and Bogdan (40) in 1904 and 

 after this result was confirmed by Gray's analysis of nitric oxide 

 (39), the value N = 14*01 was adopted in the International Table. 

 Ladenburg's discovery (26) in 1902 of an error in Stas's value 

 for the atomic weight of iodine was followed some years later by 

 the discovery, due to Richards and Wells (29), that Stas's value 

 for chlorine was in serious error. Since then, the values of 

 the fundamental atomic weights have been subjected to a most 

 careful revision, in the course of which the value 14*01 for 

 nitrogen has received further confirmation. The three following 

 ratios have been determined with the utmost care by Richards 

 and others (29, 30, 31) : 



AgCl : Ag = 1*32867. 

 NH 4 C1 : AgCl = 0-373217. 

 AgN0 3 : Ag = r57479. 



From these results, assuming with Morley that H = i*oQ76, 1 it is 

 easy to deduce that N = 14-009, 01 = 35*457, Ag= 107*88. The 

 value here given for silver was proposed by Guye (10) in 1905, 

 as a necessary consequence of adopting the value 14-01 for 

 nitrogen and has now been substituted for the old value 10793, 

 due to Stas. 



To the analytical evidence in favour of N = 14-01 already 

 quoted, it is necessary to add the analysis of nitrogen peroxide 

 by Guye and Drouginine (36), from which the value 14-009 was 

 deduced, also the synthesis of the peroxide from nitric oxide and 

 oxygen, from which Wourtzel (38) deduced the value 14-007. 



Turning to the atomic weight of chlorine, the value 35*457 

 derived above received the following confirmation. Firstly, 

 the ratios 



LiCIO, : LiCl = 2*50968 

 LiCl : Ag = 0-392997 



established by Richards and Willard (33), lead to CI = 35*454 

 1 The assumption that H = 1-0078 leads to almost identical results. 



