NITROGEN. 59 



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

 pared by passing air over hot copper, but not with hydrogen, compared 

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



Oxygen. Nitrogen. 



.442470 1.269609 



.442579 .269389 



.442489 .269307 



.442570 .269449 



442571 .269515 



.442562 .269443 



.442478 . .269478 



Mean, 1.442545, .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, 

 dz .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, .0138. 



Lord Rayleigh,^ 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. 

 fCompt. Rend., 113, 186. 1891. 

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

 I Chem. News, 69, 231. 1894. 



