ATOMIC WEIGHTS 43 



pared by passing air over hot copper, compared the weights of equal vol- 

 umes 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 1.269515 

 1.442562 1.269443 

 1.442478 1.269478 



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



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

 leigh, the ratio between the weights becomes 14.0805. 



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

 measurements of the density of atmospheric nitrogen, giving a mean of 

 .97203, with extremes of .9719 and .9721; but he neglected to cite the 

 intermediate values. Taking the three figures given as representative, 

 and assuming a fair distribution of the other values between the indi- 

 cated limits, the probable error of the mean is not far from 0.00002. 

 For oxygen he found 1.10514, ±.000032. The ratio between the two 

 densities is 16 : 14.0729, ±.0005. 



Lord Eayleigh,'* who prepared nitrogen from the atmosphere by several 

 methods, and weighed it in a standard globe in direct comparison with 

 oxygen, obtained the following weights: 



Oxygen. Nitrogen. 



2.6272 2.31035 



2.6271 2.31026 



2.6269 2.31024 



2.6269 2.31012 



2.6271 2.31027 



Mean, 2.62704, ± .00004 2.31025, ± .000025 



In a later paper ^ Rayleigh gives the following additional weights for 

 atmospheric nitrogen, which are directly comparable with the foregoing 

 series. 



2.31017 



2.30986 



2.31010 



2.31001 



2.31024 



2.31010 



2.31028 



2.31163 



2.30956 



iCompt. Rend., 113, 186. 1891. 

 2Proc. Roy. Soc, 53, 134. 1893. 

 8Proc. Roy. Soc, 55, 340. 1894. 



