58 THE ATOMIC WEIGHTS. 



NITROGEN. 



The atomic A\'^ight of nitrogen has been determined from the density 

 of the gas, and from a considerable variety of purely chemical ratios. 



Upon the density of nitrogen a great many experiments have been 

 made. In early times this constant was determined by Biot and Arago, 

 Thomson, Dulong and Berzelins, Lavoisier, and others. But all of these 

 investigations may be disregarded as of insufficient accuracy ; and, as 

 in the case of oxygen, we need consider only the results obtained by 

 Dumas and Boussingault, by Regnault, and by recent investigators. 



Taking air as unity, Dumas and Boussingault* found the density of. 

 nitrogen to be — 



.970 

 .972 

 .974 



Mean, .972, ± .00078 



For hydrogen, as was seen in our discussion of the atomic weight of 

 oxygen, the same investigators found a mean of .0693, ±: .00013. Upon 

 combining this with the above nitrogen mean, we find for the atomic 

 weight of the latter element, N = 14.026, ± .0295. 



By Regnault f much closer work was done. He found the density of 

 nitrogen to be as follows : 



.97148 ' ' 



.97H8 



.97154 ' 



.97155 



.97108 



.97108 



Mean, .97137, ± .000062 



For hydrogen, Regnault's mean value is .069263, ± .000019. Hence, 

 combining as before, N = 14.0244 ± .0039. 



Both of the preceding values are affected by a correction for the dif- 

 ference in volume between the weighing globes when full and when 

 empty. This correction, in the case of Regnault's data, has been meas- 

 ured by Crafts,t who gives .06949 for the density of H, and .97138 for N. 

 Corrected ratio, N = 13.9787. If We assume the same proportional cor- 

 rection for the determination by Dumas and Boussingault, that becomes 

 N = 13.9771. 



*Compt. Rend., 12, 1005. 1841. 

 t Compt. Rend., 20, 975. 1845. 

 J Coinpt. Rend., 106, 1664. 



