ATOMIC WEIGHTS 



377 



precipitation with mercuric oxide, 

 above, are subjoined : 



D 



VO.,. 



' 8.9363 

 7.9659 



12.4385 



'12.8855 

 5.7089 

 9.6270 



'13.1855 

 9.9973 



-15.8996 

 7.4326 



General mean, 3.9276, ± .0003 



In short, Ebelmen's mean vanishes when combined with Ziramer- 

 mann's. From Zimmermann's mean 17 = 239.58. 



Zimmermann's second method was essentially that of Wertheim, 

 namely, the ignition of the double acetate UO._,(CoH30o)o.]SraC2H30o, the 

 residue being sodium uranate, iN'aoUoO-. 



General mean, 67.549, 



.0025 



From Zimmermann's figures 11 = 239.71. 



An entirely different method for determining the atomic weight of 

 uranium Avas adopted by Aloy.^ Pure uranyl nitrate was ignited in a 

 suitable apparatus, and the nitrogen evolved was collected and measured. 

 The residual green oxide of uranium was reduced to uranous oxide, which 

 was weighed. From this weight and that of the nitrogen, as computed 

 from its volume, the atomic weight of the metal was calculated. Un- 

 fortunately, Aloy gives only the volumes of gas and the corresponding 

 atomic weight, but not the weight of the oxide. His data, therefore, as 



^ Ann. Chim. Phys. (7), 24, 418. Preliminary paper in Compt. Rend., 182, 551. 



