ATOMIC WEIGHTS 



429 



The weight of the hydrogen in these determinations was doubtless 

 computed from Eegnault's figures for the density of that gas. Correcting 

 by the new value for the weight of a litre of hydrogen, .089872 gramme, 

 the ratios become : 



Foi- nickel 3.4211, ± .0010 



For cobalt 3.4112, ± .0009 



Hence M= 58.92 and Co = 59.09. 



Some time after the publication of Eussell's first paper, but before the 

 appearance of his second, some other investigations were made known. 

 Of these the first was by Sommaruga/ whose results, obtained by novel 

 methods, closely confirmed those of Schneider and antagonized those 

 of Dumas, Marignac and Eussell. The atomic weight of nickel Som- 

 maruga deduced from analyses of the nickel potassium sulphate, 

 K,]S'i(S04)2.6HoO, which, dried at 100°, has a perfectly definite compo- 

 sition. In this salt the sulphuric acid was determined in the usual way 

 as barium sulphate, a process to which there are obvious objections. In 

 the third column are given the quantities of the nickel salt proportional 

 to 100 parts of BaSO, : 



Mean, 93.6505, ± .001 



Hence Ni = 58.79. 



For cobalt Sommaruga used the purpureocobalt chloride of Gibbs 

 and Genth. This salt, dried at 110°, is anhydrous and stable. Heated 

 hotter, C0CI2 remains. The latter, ignited in hydrogen, yields metallic 

 cobalt. In every experiment the preliminary heating must be carried 

 on cautiously until ammoniacal fumes no longer appear: 



iSitzungsb. Wien. Akad., 54, 2 Abth., 50. 1S66. 



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