AMMONIA-COBALT BASES. 51 



large, have a faint reddish tinge. They are usually very well defined, and exhibit 

 a beautiful iridescence upon their surfaces, but we cannot at present describe their 

 form. The salt is quite soluble in hot water, but the solution is easily, though only 

 partially, decomposed at a boiling heat, and even, when quite neutral, at a lower 

 temperature. On boiling, ammonia is evolved in abundance, while a heavy black 

 precipitate is thrown down ; it requires very long boiling to produce a complete 

 decomposition. The salt is rather insoluble in cold water; chlorhydric acid pre- 

 cipitates it unchanged in the cold, and the same effect is produced by the solutions 

 of the alkaline chlorides. Acids, even when dilute, easily and completely decom- 

 pose the chloride of Xanthocobalt by boiling. Chlorhydric acid in large excess, 

 by long boiling, converts the salt completely into chloride of Purpureocobalt, 

 deutoxide of nitrogen, and occasionally chlorine, being given off. Sulphuric and 

 nitric acid also decompose the chloride, but with these acids the decomposition 

 generally goes so far as to produce salts of cobalt, or double salts of cobalt and 

 ammonia. Oxalic acid also produces complete decomposition by long boiling, 

 oxalate of cobalt and oxalate of ammonia being formed. Even strong acetic 

 acid produces, on boiling with the salt, a partial decomposition. Alkalies readily 

 decompose a solution of the chloride when heated, ammonia being evolved, while 

 a black powder is thrown down. The dry chloride is easily decomposed below a 

 red heat. An abundance of red vapors is at first given off, afterward ammonia is 

 evolved, and finally a black superoxyd of cobalt remains. 



Eeducing agents, in certain cases, completely decompose the solution of the 

 chloride of Xanthocobalt, giving salts of cobalt and ammonium. Thus a current of 

 sulphydric acid gas passed for some time through the solution gives a precipitate of 

 sulphur and sulphide of cobalt, while nitrogen gas escapes, and chloride and sul- 

 phide of ammonium remain in solution. The decomposition is similar in an acid 

 solution, but of course no sulphide of cobalt is precipitated. 



We made this experiment in the hope of decomposing the N0 2 in the chloride 

 in a manner similar to the well known reaction in the case of organic compounds 

 containing N0 4 . For the same reason we also boiled the chloride with acetic acid 

 and iron filings, in the hope of obtaining a reaction analogous to that which is pro- 

 duced under the same circumstances with nitro-benzol, nitro-naphtalin, &c, as 

 observed by Bechamp. The experiments, however, led to no interesting result. 



Chloride of Xanthocobalt has the formula 



N0 2 .5NH 3 .Co 2 0,Cl 2 +HO, 



as the following analyses show : 



0.2652 grs. gave 0.1557 grs. sulphate of cobalt = 22.34 per cent, cobalt. 



0.5865 grs. gave 0.3435 grs. " " = 22.29 " 



0.8240 grs. gave 0.8980 grs. chloride of silver = 26.94 per cent, chlorine. 



1.5200 grs. gave 1.6740 grs. " *" = 27.22 



0.4983 grs. gave 0.2773 grs. water = 6.18 " hydrogen. 



0.5897 grs. gave 0.3272 grs. " = 6.16 " " 



1.0768 grs. gave 297 c. c. nitrogen at 16°.9 C. and 758 nnD .43 (at 17°.2 C.) = 273.02 c. c. at 0° 



and 760 ram = 31.84 per cent. 

 1.0657 grs. gave 297 c. c. nitrogen at 19°.5 C. and 763 mm .26 (at 20° C.) = 271.30 c. c. at 0° 



and 760 mm = 31.97 per cent. 



