42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



For nitrogen there are abundant measurements made upon the element 

 itself, and also good data for nitrous oxide, nitric oxide and ammonia. 



The earlier determinations of the density of nitrogen were all made 

 upon nitrogen derived from the atmosphere. But the supposed nitrogen 

 contained, as we now know, the heavier argon, and the value obtained 

 was therefore incorrect. It is, however, worth while to examine the 

 data, and to see whether a correction for argon may not be advantageously 

 made. The very early work of Biot and Arago, Thomson, Dulong and 

 Berzelius, Lavoisier and others can be neglected, and, as in the case 

 of oxygen, we need consider only the results obtained by Dumas and 

 Boussingault, Eegnault, and several more recent investigators. 



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



atmospheric nitrogen to be — 



.970 

 .972 



.974 



Mean, .972, ± .00078 



For oxygen, as was seen in our discussion of the : H ratio, the same 

 investigators found a mean of 1.10567, ±.00006. The ratio between 

 this and the nitrogen figure is 16 : 14.0657, ±.0113. 



By Eegnault" much closer work was done. He found the density of 



atmospheric nitrogen to be as follows : 



.97148 

 .97148 

 .97154 

 .97155 

 .97108 

 .97108 



Mean, .97137, ± .000062 



For oxygen, Eegnault's mean value is 1.105633, ±.000008. Hence, 

 combining as before, N = 14.057, ±.0009. 



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

 ence in volume between the weighing globes when full and when empty. 

 This correction, in the case of Eegnault's data, was measured by Crafts,* 

 who gives 1.10562 for the density of oxygen, and 0.97138 for that of 

 nitrogen. The changes are so small that the ratio remains practically 

 unaltered. The correction in this particular instance, is negligible. 



Von Jolly,* working with electrolytic oxygen and witli nitrogen pre- 



1 Compt. Rend., 12, 1005. 1841. 

 ='Compt. Rend., 20, 975. 1845. 

 "Compt. Rend., 106, 1664. 

 * Annalen der Physik. (2), 6, 529. 1879. 



