30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



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, Fonrcro}^, Vauquelin, and Se- 

 guin; 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 Boussingault "^ published their determinations of 

 gaseous densities. For hydrogen they obtained values ranging from .0691 

 to .0695; but beyond this mere statement they give no details. Fbr 

 oxygen three determinations were made, with the following results: 



1.1055 

 1.1058 

 1.1057 



Mean, 1.10567, ± .00006 



If we take the two extreme values given above for hydrogen, and re- 

 gard them as the entire series, they give us a mean of .0693, ±.00013. 

 This mean hydrogen value, combined with the mean for oxygen, gives 

 for the latter, when H = l, the density ratio 15.9538, it .031. 



Eegnault's researches, published four years later,' were much more 

 elaborately executed. Indeed, they long stood among the classics of 

 physical science, and it is only recently that they have been supplanted 

 by other measurements. 



For hydrogen three determinations of density gave the following 

 results : 



.06923 

 .06932 

 .06924 



Mean, .069263, ± .000019 



For oxygen four determinations were made, but in the first one the 

 gas was contaminated by traces of hydrogen, and the value obtained, 

 1.10525, was, therefore, rejected by Eegnault as too low. The other three 

 are as follows: 



1.10561 



1.10564 



1.10565 



Mean, 1.105633, ± .000008 



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

 paper already cited. All the other determinations are taken from Gmelin's Handbook, Caven- 

 dish edition, v. 1, p. 279. 



='Compt. Rend., 12, 10O5. Compare also with Dumas, Compt. Rend., 14, 537. 



'Compt. Rend., 20, 975. 



