234 _. W. Gibbs and F. A. Genth 
Art. XXX.— Researches on the Ammonia-cobalt Bases; by 
Wo.corr Grsss and F, A. Gentu. Part I. ' 
[Reprinted from the ninth volume of the Smithsonian Contributions to Knowledge 
by special permission of the Secretary, who has also permittedthe use of the 
~ original woodcuts.] 
- Tue facility with which alkaline solutions of many metallic 
protoxyds 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 
resence of an excess of the fixed caustic alkalies and their car- 
nates, salts of the protoxyds of these metals are more or less 
tapidly converted into basic salts of their higher oxyds. A 
similar effect appears to be produced by all of the more goin 
ful fixed bases, while it is remarkable that neutral or acid solu- 
tions of the same salts are oxydized much more slowly, an effec 
which is perhaps owing to the tendency which per-salts in gene- 
ral exhibit to become basic, and to the influence which an excess 
of acid exerts in producing neutral or acid compounds. 
mmonia acts like potash and soda in causing the oxydation 
of solutions of iron and manganese. In the case of these two 
metals either basic salts or hydrates of the peroxyds are formed, 
which contain no ammonia, at least in chemical combination. 
With salts of protoxyd of cobalt the result of the oxydation is 
very different. The sesquioxyd of cobalt at the instant of its 
ormation unites with a certain number of equivalents of ammo- 
nia so as to produce a conjugate base of which ammonia forms 
an integral portion. The new base partakes in some measure 
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 oxydation 
of the salts of cobalt are due to Leopold Grielin, who, in a me- 
moir, published in 1822,* described the changes of color whic 
are produced when ammoniacal solutions of the chlorid, sulphate, 
hati: 
. ? 
and nitrate of cobalt are exposed to the air. The solutions ua 
acid. Dingler,+ who subsequeritly endeavored to determine 
amount of 
gen, since the rown solution gave with sulphid of ammonium 
a black precipitate of bisulphid of cobalt. Winkelblecht denied 
* Neues Journal der Chemie und Physik. Neue Reihe, V, 236. : 
Kastner’s Archiv, xviii, 249. 
} Annalen der Pharmacie, xiii, 148, 253. 
