96 W. Gibbs and F. A. Genth 



represents the actioa when the nitrate of Xanthocobalt is formed 

 directly by the action of KOx upon an ammoniacal solution of 

 the sulphate of cobalt, is possibly the following 



2CoO, S03+VXH3+N03-f 3N04-[-2HO:=N02,oXH3.Co203, 2XO0-I- 



2NH4O, SO3+NO2. 



"When the chlorid of cobalt is employed instead of the sul- 

 phate, other products are always formed simultaneously with 

 the nitrate of Xanthocobalt, and the reaction becomes therefore 

 more complicated. 



The nitrate of Xanthocobalt crystallizes in small brilliant 

 crystals, which, according to Prof Dana's measurement, belong 

 to the dimctric system. The only form observed as yet is an 

 octahedron, the angle at the base being 100° 45'- — 101° 15^ 



The salt is dichrous, the ordinary image being pale orange, 

 while the extraordinary is bright orange-yellow. 



The salt has a clear brown-yellow color, and the mass of crys- 

 tals is usually very brilliant. It is quite soluble in hot, but 

 rather insoluble in cold water; the solutionis readily decom- 

 posed by boiling, with evolution of ammonia and precipitation 

 of a heavy black powder. The dry salt is readily decomposed 

 by heating, abundance of red vapors being given off, while a 

 black oxyd remains. The nitrate is completely decomposed by 

 boiling with chlorhydric acid, red vapors mixed with chlorine 

 being given off, while there remains a solution of Purpureoco- 

 balt, from which crj^stals of this salt are deiDOsitecl on cooling. 

 When boiled wnth nitric acid, a similar decomposition is pro- 

 duced, and crystals of nitrate of Roseocobalt are obtained, in 

 small quantity. It is probable that nitrate of Purpureocobalt is 

 the first product of this reaction, and that this by boiling with 

 excess of acid, passes into the nitrate of Eoseocobalt. As a 

 general rule, the quantity of nitrate of Eoseocobalt produced is 

 small, and the decomposition results in the conversion of the 

 nitrate of Xanthocobalt into the nitrates of cobalt and ammonia, 



Nitric acid precipitates nitrate of Xanthocobalt from its solu- 

 tion without sensible decomposition in the cold. By long boil- 

 ing acetic acid completely reduces nitrate of Xanthocobalt, and 

 a solution of cobalt is obtained which is free from ammonia- 

 cobalt bases. Oxalic acid also reduces the nitrate by boiling, 

 oxalate of cobalt being thrown down. 



Nitrate of Xanthocobalt has the formula 



XO. ,5NH3.Co.03, 2N05+nO 



as the following analyses appear to show : 



3917 gra. gave Oi927 grs. sulphate of cobalt = 18-72 per ceut cobalt. 

 0*6960 gi-9. gave 0-3406 grs. « « = 18-76 *• '* 



0-5935 grs. gave 02925 grs. « " =18*76 « « 



0*5685 grs. gave 0"2535 grs. -water = 504 " hydrogen. 



0*4968 grs. gave 0*2330 gra « =5 21 « " 



C-9483 grs. gave 0'4270 grs. « = 6-09 *" * 



"v 



