6 THE ATOMIC WEIGHTS. 



By Dumas O — 15.9607, dr .0070 



By Erdmann and Marchand O = 15.9733, d= .0113 



General mean O = 15.9642, zh .0060 



In discussing the relative density of oxygen and hydro- 

 gen gases we need only consider the more modern researches 

 of Dumas and Boussingault, and of Regnault. As the older 

 work has some historical value, I may in passing just cite 

 its results. For the density of hydrogen we have .0769, 

 Lavoisier ; .0693, Thomson ; .092, Cavendish ; .0732, Biot 

 and Arago ; .0688, Dulong and Berzelius. For oxygen there 

 are the following determinations : 1.087, Fourcroy, Vauque- 

 lin, and Seguin; 1.103, Kirwan; 1.128, Davy; 1.088, Allen 

 and Pepys; 1.1036, Biot and Arago; 1.1117, Thomson; 

 1.1056, De Saussure ; 1.1026, Dulong and Berzelius ; 1.106, 

 Buff; 1.1052, Wrede.* 



In 1841 Dumas and Boussingaultf published their deter- 

 minations of gaseous densities. For hydrogen they obtained 

 values ranging from .0691 to .0695 ; but beyond this mere 

 statement they give no details. For oxygen three determi- 

 nations were made, with the following results : 



I-I055 

 I. 1058 

 I. 1057 



Mean, 1. 10567, dz .00006 



If we take the two extreme values given above for hydro- 

 gen, and regard them as the entire series, they give us a 

 mean of .0693, ± .00013. 



This mean hydrogen value, combined with the mean 

 oxygen value, gives for the atomic weight of the latter ele- 

 ment the number 15.9538, ± .031. 



Regnault's researches, published four years later,t were of 



* For Wrede's work, see Berzelius' Jahresbericht for 1843. ^^^ Dulong and 

 Berzelius, see the paper already cited. All the other detenninations are taken 

 from Gmelin's Handbook, Cavendish edition, v. I, p. 279. 



f Compt. Rend., 12, 1005. Compare also with Dumas, Compt. Rend., 14, 537. 



I Compt. Rend., 20, 975. 



