AMMONIA-COBALT BASES. 



43 



Fhj. 15. 



Fig. 16. 



Fig. 17. 



Fig. 18. 



The sulphate is rather insoluble in cold but is freely soluble in hot water; the 

 dilute solution is yellow, the concentrated solution dark sherry wine colored. By 

 double decomposition with salts of barium it yields the other salts of Luteocobalt. 

 The sulphate like the chloride is dichrous, the ordinary image being pale rose-red 

 while the extraordinary image is bright orange. The color of the salt in coarse 

 powder approaches the orange No. 5 of the first circle. 



Sulphuric acid does not precipitate this salt from its solution, but chlorhydric 

 and nitric acids throw down in the cold mixtures of the chloride with the sul- 

 phate and nitrate. The salt is decomposed with very great difficulty by long 

 boiling, even after the addition of a little ammonia. No new base is formed during 

 the decomposition. When, however, the dry salt is gently heated in a porcelain 

 crucible, ammonia is evolved, and if the heat be regulated so that no sulphate of 

 ammonia is given off, while the mass is constantly stirred, there remains after a 

 few minutes a red mass, which on solution in water gives a fine red liquid contain- 

 ing a sulphate of a red base, which is probably Purpureocobalt. The reaction is, 

 however, a very uncertain one, and has succeeded in our hands but once. We have 

 in most cases obtained by the process described only a mixture of sulphate of 

 Luteocobalt, sulphate of cobalt, and sulphate of ammonia. We shall consider this 

 subject more fully hereafter. Sulphuric acid, if not too dilute, readily decom- 

 poses the sulphate of Luteocobalt when the solution is heated. It appears pro- 

 bable that there exists an acid sulphate of this base, as there is an acid carbonate, 

 but we have not been able to obtain it as yet. 



Sulphate of Luteocobalt has the formula 



6NH 3 .Co 2 3 ,3S0 3 +5HO 

 as the following analyses satisfactorily show. The salt analyzed was dried by 

 pressure between folds of bibulous paper only. 



0.3618 grs. gave 0.1600 grs. sulphate of cobalt = 16.83 per cent, cobalt. 



0.4993 grs. " 0.2205 grs. " " = 16.80 ' 



0.4790 grs. " 0.2122 grs. " " = 16.85 



1.2023 grs. " 1.2020 grs. sulphate of baryta = 34.32 per 



0.8203 grs. " 0.8250 grs. " " = 34.52 ' 



0.9355 grs. " 0.5650 grs. water = 6.71 per 



1.1194 grs. " 0.6722 grs. " = 6.67 ' 



1.0005 grs. gave 205 c. c. nitrogen at 12°. 5 C. and 753 mm 



and 760°"° = 24.00 per cent, nitrogen. 

 0.9018 grs. gave 185.5 c. c. nitrogen at 19° C. and 763 rara 



and 760 ram = 23.85 per cent, nitrogen. 



cent, sulphuric acid. 



cent, hydrogen. 



61 (at 12°7) = 191.16 c. c. at 0° 



36 (at 19°.5) = 171.26 c. c. at 0° 



