RESEARCHES ON THE AMMONIA-COBALT BASES. 



PART I. 



The facility with which alkaline solutions of many metallic protoxides absorb 

 oxygen from the air, attracted the attention of chemists at an early period. The 

 protosalts of iron, manganese and cobalt, are particularly remarkable in this 

 respect. In the presence of an excess of the fixed caustic alkalies and their 

 carbonates, salts of the protoxides of these metals are more or less rapidly con- 

 verted into basic salts of their higher oxides. A similar effect appears to be pro- 

 duced by all of the more powerful fixed bases, while it is remarkable that neutral 

 or acid solutions of the same salts are oxidized much more slowly, an effect which 

 is perhaps owing to the tendency which per-salts in general exhibit to become basic, 

 and to the influence which an excess of acid exerts in producing neutral or acid 

 compounds. 



Ammonia acts like potash and soda in causing the oxidation of solutions of iron 

 and manganese. In the case of these two metals either basic salts or hydrates of 

 the peroxides are formed, which contain no ammonia, at least in chemical com- 

 bination. With salts of protoxide of cobalt the result of the oxidation is very 

 different. The sesquioxide of cobalt at the instant of its formation unites with a 

 certain number of equivalents of ammonia so as to produce a conjugate base of 

 which ammonia forms an integral portion. The new base partakes in some mea- 

 sure of the properties of the alkalies, the peculiar character of the salts of cobalt 

 being wanting. It is with this class of bases that we have at present to deal. 



The earliest observations which we possess upon the oxidation of the salts of 

 cobalt are due to Leopold Gmelin, who, in a memoir, published in 1822, 1 described 

 the changes of color which are produced when ammoniacal solutions of the chlo- 

 ride, sulphate, and nitrate of cobalt are exposed to the air. The solutions under 

 these circumstances absorbed oxygen and became brown, and Gmelin consid- 

 ered it probable that they contained a cobaltic acid. Dingier, 2 who subsequently 

 endeavored to determine the amount of oxygen absorbed, inferred that the cobaltic 

 acid consisted of one equivalent of cobalt and two equivalents of oxygen, since the 

 brown solution gave with sulphide of ammonium a black precipitate of bisulphide of 

 cobalt. Winkelblech 3 denied the existence of a metallic acid in the solution, but 



1 Neues Journal der Chemie und Physik. Xeue Reihe, V, 235. 

 3 Kastner's Archiv, XVIII, 249. 

 Annalen der Pharaacie, XIII, 148, 253. 



