AMMONIA-COBALT BASES. 17 



the anhydrous nitrate of Roseocobalt is a direct product of the oxidation of the 

 ammoniacal liquid. This, however, is not the case. If the oxidized liquid be 

 filtered from the nitrate of Luteocobalt and allowed to evaporate spontaneously, 

 very fine large oblique rhombic crystals are formed, which are the hydrous nitrate 

 of Roseocobalt. 



The crystals of this nitrate belong to the monoclinic or oblique rhombic system, 

 according to Prof. Dana's determination. The observed forms are /, li, ii, -li, i\, 

 or in other symbols, oo, 1- co, go- go, — 1- go, go- go. Fig. 7. The angles are 



1:1 =103° 

 1* : ii = 136° 

 -li : ii = 140° 30' 

 li : -li = 96° 30' arurts 30' 



The hydrous nitrate of Roseocobalt is readily soluble even in cold water ; the 

 hot neutral solution is very easily decomposed with evolution of ammonia and 

 precipitation of a black powder. The addition of a few drops of nitric acid pre- 

 vents the decomposition. An excess of nitric acid added to a cold solution of the 

 nitrate produces a brick-red precipitate, which is readily soluble in cold water, and 

 which is the unchanged salt. The solution has a dark brick-red color, and exhibits 

 all the reactions of the chloride of Roseocobalt. When boiled with an excess of 

 nitric acid for some time, the brick-red color gradually becomes violet-red, and there 

 remains at last a beautiful violet precipitate, which is the anhydrous nitrate of 

 Roseocobalt. From this it appears that, in some cases at least, and particularly 

 when nitrate of ammonia is present during the oxidation, the hydrous nitrate of 

 Roseocobalt is the first product of the oxidation of an ammoniacal solution of 

 nitrate of cobalt, and that it is the action of nitric acid upon this salt which con- 

 verts it into the anhydrous nitrate. The nitrate of Roseocobalt obtained by direct 

 oxidation may be recrystallized by adding to its solution a few drops of nitric acid 

 and allowing it to stand a few days for spontaneous evaporation. In this manner 

 beautiful crystals are obtained, adhering to the bottom of the evaporating vessel, 

 and mixed with a dull-red matter in crystalline crusts, which exhibits the same 

 reactions with the large and clear crystals, and appears to have the same constitu- 

 tion, though upon this point we cannot speak with certainty at present. 



We consider the formula of the hydrous nitrate of Roseocobalt as most probably 

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



as the following analyses indicate : 



0.8265 grs. gave 0.3T03 grs. sulphate of cobalt = 1*7.05 per cent, cobalt. 



0.5275 grs. gave 0.2370 grs. " " = 17.09 



0.8012 grs. gave 217.8 c. c. nitrogen at 11°.5 C. and 76r nm .48 (at 11°.4 C.) = 206.05 c. c. at 



0° and 760 mm = 32.30 per cent. 

 0.7667 grs. gave 207 c. c. of nitrogen at 14° C. and 766 mm .56 (at 14°.2 C.) = 194.91 c. c. at 



0° and 760"'°' = 31.92 per cent. 



The formula requires 



Eqs. Calculated. Found. 



Cobalt ... 2 16.95 17.05 17.09 



Nitrogen . . 8 32.18 32.30 31.92 

 3 



