AMMONIA-COBALT BASES. 55 



of the sulphate of Xanthocobalt, under these circumstances, may be represented 

 by the equation 



2CoO,S0 3 +5NH3+N03=N0 2 .5NH 3 .Co 2 03,2S03 



if we suppose the oxidizing agent to be N0 3 . If, however, we consider the active 

 agent to be N0 4 , we may represent the action by the equation 



2CoO,S03+6NH3+2NO,+HO=N0 2 .5NH 3 .Co 2 3 ,2S0 3 +NH 4 0,NO a . 



A large quantity of free nitrite of ammonia is always formed during the pro- 

 cess, as we believe, by the direct action of N0 3 upon ammonia and water. The 

 addition of an acid to the mother liquor from which the sulphate has crystallized, 

 produces an active effervescence arising from the decomposition of the nitrite 

 of ammonia. 



The process which we have indicated has generally proved perfectty satisfactory 

 in preparing the sulphate. It is proper to state, however, that in some experi- 

 ments, made for the purpose of revision, we obtained by the process above given 

 no sulphate of Xanthocobalt, but only the nitrate. The cause of this we are at 

 present unable to assign, and further experiments are wanting to explain so unex- 

 pected a result. 



The sulphate of Xanthocobalt crystallizes in thin plates, the form of which we 

 have not been able to determine; they appear to belong to the right rhombic 

 system. The crystals have a fine brown-yellow color, which, however, we cannot 

 define by means of the chromatic scale. The salt is rather soluble in hot, but 

 much less soluble in cold water. Heat readily decomposes the neutral solution, 

 a black powder being thrown down, while ammonia is given off. The dry salt is 

 decomposed like the chloride. 



Strong sulphuric acid dissolves the sulphate to a red oily liquid, but little deut- 

 oxide of nitrogen being given off. The addition of water to this solution causes 

 a violent effervescence from the escape of deutoxide of nitrogen, and probably 

 nitrous acid. There remains a red liquid consisting chiefly of the double sulphate 

 of cobalt and ammonia, but almost always containing a little acid sulphate of 

 Purpureocobalt. Even very dilute sulphuric acid readily decomposes sulphate of 

 Xanthocobalt by boiling. Long boiling with chlorhydric acid also decomposes this 

 salt, the products of the decomposition being, as already stated, chloride of Pur- 

 pureocobalt, free sulphuric acid, and deutoxide of nitrogen. 

 Sulphate of Xanthocobalt has the formula 



N0 2 .5NH 3 .Co 2 3 ,2S0 3 +HO 

 as the following analyses show : 



0.5776 grs. gave 0.3142 grs. sulphate of cobalt = 20.69 per cent, cobalt. 



0.5630 grs. gave 0.3060 grs. " " = 20.68 



1.2370 grs. gave 1.0150 grs. sulphate of baryta = 28.16 



1.1472 grs. gave 0.9242 grs. " " = 27.65 



0.7713 grs. gave 0.3868 grs. water = 5.56 



0.4468 grs. gave 0.2285 grs. " = 5.68 



0.6020 grs. gave 169.48 c. c. nitrogen at 14° C, and 769" 



at 0° and 760""° = 29.37 per cent. 

 1.2624 grs. gave 300 c. c. nitrogen, at 5° C, and 775 m '".20 (at 5°.3 C.) = 296.68 c. c, at 0° 

 and 760""" = 29.51 per cent. 



sulphuric acid, 

 hydrogen. 

 61 (h = 91 mm ) = 140.87 c. 



