430 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



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/ endorsing the former's work and object- 

 ing to the results of Eussell. 



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 pure metallic nickel and cobalt could precipitate from a 

 neutral solution of sodio-auric chloride. 



In order to obtain pure cobalt Winkler prepared purpureocnbalt 

 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 cliloride 

 was prepared, which, after sublimation in dry chlorine, was also reduced 

 by hydrogen. One hundred parts of gold are precipitated by the quan- 

 tities of nickel and cobalt given in the third columns, respectively. In 

 the cobalt series I include one experiment by Weselsky, which was pub- 

 lished by him in a paper presently to be cited : 



.43G0 grm. nickel precipitated .9648 grm. gold. 45.191 



.4367 " .9666 " 45.179 



.5189 " 1.1457 " 45.291 



.6002 " 1.3286 " 45.175 



Mean, 45.209, ± .019 

 Hence Ni = 59.46. 



.5890 grm. cobalt precipitated 1.3045 grm. gold. 45.151 



Mean, 45.151, ± .025 



Hence Co = 59.38. 



Weselsky's paper,' already quoted, relates only to cobalt. He ignited 

 the cobalti cyanides of aiiimonium and of phenylammonium in hydrogen, 

 and from the determinations of cobalt thus made deduced its atomic 

 weight. His results are as follows : 



.7575 grm. (NHJ,,Co,Cy,o gave .166 grm. Co. 21.914 per cent. 



.5143 " .113 " 21.972 



Mean, 21.943, ± .029 

 Hence Co = 59.09. 



1 Pofrgend. .\nnalen, 130, 310. 



^Zeit. anal. Chem., 6, 18. 1S67. 



" Ber. Deiitseh. chem. Gesell., 2, 592. 18C8. 



