NITROGEN. 59 



Von Joll}' * working with electrolytic oxygen and with nitrogen pre- 

 pared by passing air over hot copper, ])ut not with hydrogen, compared 

 the weights of equal volumes of the two gases, with results as follows : 



Oxygen. Nitrogen. 



1.442470 ' 1.269609 



1.442579 1.269389 



1.442489 1.269307 



1.442570 1.269449 



1. 442571 I. 269515 

 1.442562 1.269443 

 1.442478 1.269478 



Mean, 1.442545, dz .000013 Mean, 1.269455, ±.000024 



The ratio, when O = 16, is N = 14.0802, ± .0003. Corrected by Ray- 

 leigh, the ratio between the weights becomes 14.0805. If = 15.879, 

 ± .0003, the final value for N, deducible from Von Jolly's data, is N = 

 13.974, ± .0004. 



The next determination in order of time is Leduc's.f He made nine 

 measurements of the density of nitrogen, giving a mean of .97203, with 

 extremes of .9719 and .9721; but he neglects to cite the intermediate 

 values. Taking the three figures given as representative, and assuming 

 a fair distribution of the other values between the indicated limits, the 

 probable error of the mean is not far from 0.00002. For hydrogen he 

 found .06948, ± .00006745. The ratio between the two densities gives 

 N = 13.9901, d= .0138. 



Lord Rayleigh,J preparing nitrogen by passing air over hot copper, 

 and weighing in a standard globe, obtained the following weights : 



2.31035 

 2.31026 

 2.31024 

 2.31012 

 2.31027 



Mean, 2.31025, ± 000025 



With corrections for temperature, shrinkage of the globe when ex- 

 hausted, etc., this becomes 2.30883, as against 2.37512 for the same volume 

 of air. Hence the density of N = .97209, ± .00001. His former work 

 on hydrogen gives .06960, ± .0000084, for the density of that gas. The 

 ratio is N = 13.9678, ± .0017. 



The foregoing data, however, all apply to nitrogen derived from the 

 atmosphere. In a later memoir Rayleigh § found that nitrogen from 



* Poggend. Annalen (2), 6, 529-530. 1879. 

 fConipt. Rend., 113, 186. 1891. 

 X Proc. Roy. Soc, 53, 134. 1894. 

 g Chem. New.s, 69, 231. 1894. 



