on the Ammonia-cobalt Bases. 2438 
To obtain the chlorid of Roseocobalt from the oxydized solu- 
tion, cold and strong chlorhydrie acid is to be added to it, the 
slightest elevation of temperature being carefully avoided. A 
brick-red precipitate is thrown down, which is to be washed with 
strong chlorhydric acid and then with ice-cold water, thrown 
Upon a filter, and dried by pressure, great care being taken to 
operate at as low a temperature as possible. 
As the formula of the chlorid of Roseocobalt is 5NHs.Co2Cls 
+2HO, its formation by the oxydation of the ammoniacal solu- 
tion of chlorid of cobalt may be explained by the equation 
6CoC1+10NH:+30=2(6NHs.CozCls)+Co20s. 
Th those cases in which no sesquioxyd of cobalt is precipitated, 
We niay suppose that the sesquioxyd unites directly with ammo- 
nla, as represented by the equation 
rectly with five equivalents of ammonia to form a chlorid ex- 
actly analogous to the chlorid of Roseocobalt, and having the 
formula 5NHs.Rh2Cls. We have made various experiments 
Strong ammonia-water added, and te whole allowed to stand 
or some time in a closed bottle and in a rather dark closet. 
Even after many weeks, however, only traces of chlorid of : 
: balt could be detected. A quantity of sesquioxyd of 
Cobalt was dissolved in strong acetic acid, and to the solution 
chlorid of ammonium and ammonia-water added. In this case 
chlorid of Roseocobalt was formed after a few days, but it is 
oubtful whether its formation was not due to the oxydation of 
& small quantity of protoxyd of cobalt in the sesquiox d em- 
Ployed. In another experiment, strong ammonia was added to 
* Si db : ; hi a a » to the sesqui- 
lori op 09,80 "e ras written, Claus has exten-ed his observation fo the scagu 
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