NICKEL AND COBALT. 297 



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 Russell. The atomic weight of nickel Som- 

 maruga deduced from analyses of the nickel potassium sulphate, 

 K2Ni(SO,),.6H.,0, 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, : 



0.979S grm. gave 1.0462 grm. BaSO^. 93-653 



1.0537 " 1.1251 " 93-654 



1.0802 " 1. 1535 " 93-645 



I I. 1865 " 1.2669 " 93-654 



3.2100 " 3-4277 " 93649 



3.2124 " 3-4303 " 93-648 



Mean, 93.6505, rt .001 



For cobalt Sommaruga used the purpureocobalt chloride of Gibbs 

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

 hotter, CoCL 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 : 



.6656 grm. gave .1588 grm. Co. 23.858 per cent. 



23.814 " 

 23.846 " 



23.813 " 



23-847 " 



23.806 " 

 2:;. 808 



Mean, 23.827, ±z .006 



Further along this series will be combined with a similar one by Lee. 

 It may here be said that Sommaruga's paper was quickly followed by 

 a critical essay from Schneider,t endorsing the former's work and object- 

 ing to the results of Russell. 



In 1867 still another new process for the estimation of these atomic 

 weights was put forward by Winkler, ;|: who determined the amount of 

 gold which ])ure metallic nickel and cobalt could precipitate from a 

 neutral solution of sodio-auric chloride. 



In order to obtain pure cobalt Winkler prepared puri)ureocobalt 

 chloride, which, having been four or five times recrystallized, was ignited 

 in hydrogen. His nickel was repeatedly purified by precipitation with 

 sodium hypochlorite. From material thus obtained pure nickel chloride 



* Sitzungsb. Wien. Akad., 54, 2 Abth., 50. 1866. 

 ■f Poggend. Annalen, 130, 310. 

 t Zeit. Anal. Chem., 6, iS. 1S67. 



