332 W. Gibbs and F. A. Genth 
they are too small to admit of accurate measurement, The 
formula of this salt is , ir 
6NH:s.CosCys+Co2Cys +HO. 
0°4835 grs. gave 0°3923 grs. sulphate of cobalt — 30°88 per cent cobalt. 
B19“ hydro 
07652 gers. gave 03580 yrs, water = gen. 
21845 grs. gave 06800 grs. carbonic acid ss Iss .°“ carbon, 
Eqs. Calculated. Found. 
Cobalt, - - 4 80°57 80°88 
Carbon, - - 12 18-70 18°82 
Hydrogen, - 19 4:93 5:19 
A solution of ferridcyanid of potassium produces a most beau- 
tiful precipitate of orange-yellow needles in solutions of Luteo- 
cobalt. These, under the microscope, have the same form as 
the corresponding cobalt salt, and their formula is therefore 
6NH:s.Co2zCys+Fe:Cys+HO. 
SULPHATE OF LUTEOCOBALT. 
The sulphate of Luteocobalt is easily procured mixed with ~ 
the chlorid, when solutions of both chlorid and sulphate of co- 
balt are rendered ammoniacal and exposed to the air after the 
addition of coarsely powdered chlorid of ammonium in large 
excess. The mass of yellow crystals formed upon the bottom 
of the vessel, after a few days, is a mixture of the two salts. 
To obtain the sulphate from this mass, the solution in hot water 
is to be filtered and digested with sulphate of silver, after addi- 
tion of a few drops of sulphuric acid. In this manner the whole 
of the chlorid may be decomposed, and the filtered solution on 
evaporation will yield fine crystals of the sulphate. We have 
frequently prepared large quantities of the sulphate by this 
method. Another mode of preparing the sulphate of Luteoco- 
balt, which is often very convenient, consists in pouring ammo- 
nia upon the sulphate of Roseocobalt, thrown down by cautious 
addition of sulphuric acid to perfectly oxydized solutions of the 
ammoniacal sulphate of cobalt. When this sulphate is pow- 
dered, and strong ammonia poured upon it, its color frequently 
changes from red to a dull buff, while the supernatant liqu! 
es a fine red color. The buff powder on solution in_ hot 
water and evaporation yields crystals of sulphate of Luteocobalt. 
The red liquid is merely solution of sulphate of Roseocobalt 10 
monia. The reaction which takes place in this case may be 
represented by the equation 
5NHs.C20s, 8802 +NH:=6NHs.Co20:, 3880s, 
the sulphate of Roseocobalt simply absorbing one equivalent of 
ammonia, The quantity of s ees of Roseocobalt dissolved 
in the ammonia is very variable, being sometimes ; 
small. In other cases, however, no sulphate of Luteooobalt 3s 
