38 PROCEEDINGS OF THE AMERICAN ACADEMY 



has yet been given, and of the two green chlorides. The mother 

 liquor contains cobaltic chloride, the two green chlorides, Co2(Nn.;)g 

 C\^-\-20U,, and Co, (N 113)^01^+20112, and traces of all the other 

 salts. 



Rose determined quantitatively the proportions in wliich the differ- 

 ent salts were formed when different relative quantities of ammonia 

 and cobaltic chloride were employed. His results do not sustain in 

 his opinion the view taken by Genth and myself, that in the oxidation 

 chloride of luteocobalt and an oxy chloride which we should now 

 write, C().,(NH.,)j„.O.Cl^, are formed. This view, since the publication 

 of the first part of this memoir, appeared to be strongly supported by 

 experiments of Blomstrand, which showed that iodo-sulphates of roseo- 

 cobalt and luteocobalt are formed when a solution of cobaltic sulphate 

 in strong ammonia-water is heated with iodine. Blomstrand rei)re- 

 sents the reaction in this case, as regards the formation of the iodo- 

 sulphate of luteocobalt, by the equation, — 



The formation of the corresponding iodo-sulphate of roseocobalt ma}"- 

 be explained with equal facility. It was natural to expect the similar 

 reaction expressed by the equation, — 



2 Co(NIl3),.Cl,+0 = Co,(NH3)i„.O.Cl,+2NH3; 



but Rose's results show that the role of the oxygen is, in most cases at 

 least, different from that of the iodine, at least Avhen free oxygen is the 

 oxidizing ngent. Rose failed to determine the nature of the brown 

 compound which is formed during the oxidation of an ammoniacal 

 solution of cobaltic chloride, and which is, in his opinion, the source of 

 all the other chlorides. It is consequently impossible to express the 

 derivation of these chlorides fi'om their [)rinaitive by means of otjuations. 

 But with cobaltic nitrate and ammonia the case is different. Fremy 

 long since showed that in this case the nitrate of " oxycobaltiaque," to 

 wliich he gives the formula, Co,(NII,,),-.0,.(NO,,,)_,+OII,„ is formed. 

 Bypassing a rapid current of air through a solution containing cobaltic 

 nitrate, ammonia, and amnionic nitrate, I obtained an olive-brown 

 solution, which after twenty-four hours deposited dark olive-green 

 prisms in abundance. These were dried by pressure between folds of 

 pa[)er, and then for twelve hours over sulphuric aelu. Of this salt, — 



