ATOMIC WEIGHTS 47 



1.00737 

 1.00698 

 1.00714 

 1.00718 



Mean, 1.00717, ± .000054 



To this value, however, a correction is yet to be applied; namely, for 

 the increase in volume of the iron wire consequent upon oxidation. This 

 demands a deduction of 0.00030, which reduces the mean to 1.00687. 

 That is, one litre of nitrous oxide, decomposed, yields 1.00687 litres of 

 nitrogen. Hence the following calculation: 



1 litre N2O weighs 1.97775 gramme.i 



1.00687 N2 weighs 1.25066 X 1.00687 = 1.25925 



Oxygen in N^O, 0.71850 



From these data, : N,:: 0.7185 : 1.25925, = 28.0417, and N = 14.0208, 

 ±.0030. The probable error is computed from the figures already given 

 relative to the densities of the gases. 



For the density of nitric oxide there are two modern investigations. 

 First, by Gray ; ' second, by Guye and Davila.' Gray gives two series of 

 weights, in which nitric oxide is directly compared with an equal volume 

 of oxygen. Two supplementary determinations are cited as additions to 

 series 2. 



Oxygen. NO, I. NO, II. 



.38230 .35845 .35851 



.38229 .35852 .35848 



.38227 .35851 ■ .35852 



.38225 .35849 .35850 



.38226 .35859 .35848 



.38230 .35856 .35855 



Mean, .38228, ± .0000058 Mean of all, .35851, ± .0000076 



From these weights the crude density ratio is 

 Oj:NO:: 32: 30.0102, ±.0007 



Guye and Davila prepared their nitric oxide by three distinct methods, 

 and obtained the following figures for the normal litre-weight. 



^ Jaquerod and Bogdan assume, for the litre-weights of No and NoO, 1.25045 and 1.97772, respec- 

 tively. I here use the weights previously computed in this chapter. Jaquerod and Bogdan find 

 N = 14.015. 



*Journ. Chem. Soc, 87, 1601. 1905. 



^Compt. Rend., 141, 826. 1905. 



