16 RESEARCHES ON THE 



A solution of sulphurous acid converts the nitrate of Roseocobalt, at first into 

 an orange-colored compound containing S0 2 , and afterward reduces this completely 

 to nitrate and sulphate of cobalt and nitrate of ammonia. 



Nitrate of Roseocobalt has the formula 



5NH 3 .Co 2 3 ,3N0 5 



as the following analyses show : 



0.2308 grs. gave 0.1081 grs. sulphate of cobalt = 17.82 per cent, cobalt. 



0.1272 grs. gave 0.0599 grs. " " =17.92 " " 



0.1448 grs. gave 0.0681 grs. " " = 17.90 



0.9370 grs. gave 0.3915 grs. water = 4.64 per cent, hydrogen. 



0.6632 grs. gave 0.2862 grs. " = 4.79 



2.7312 grs. gave 1.1258 grs. " . = 4.57 " " 



0.5564 grs. gave 168 c. c. nitrogen at 24° C. and 766""".31 (at 24°.5) = 150.54 c. c. at 0° and 



760°"" = 33.98 per cent. 

 0.7400 grs. gave 213 c. c. nitrogen at 13°.5 C. and 764 ram .28 at (13.°8) = 200.55 c. c. at 0° and 



760 mm = 34.03 percent. 



The formula above mentioned requires 





Eqs. 



Calculated. 



Mean. 





Found. 





Cobalt . 



2 



59.0 17.87 



17.88 



17.82 



17.92 



17.90 



Hydrogen 



15 



15.0 4.55 



4.60 



4.64 



4.79 



4.57 



Nitrogen 



8 



112.0 33.93 



34.01 



33.98 



34.03 



— 



Oxygen 



18 



144.0 43.65 



43.51 



100.00 



_ 





— 





330.0 100.00 





When nitrate of Roseocobalt is dissolved in water containing much nitrate of 

 ammonia and a little ammonia, and the solution is allowed to evaporate sponta- 

 neously, beautiful purple-red scaly crystals separate. These crystals cannot be 

 purified by recrystallization, as they are decomposed by solution in water. When 

 boiled with chlorhydric acid there is copious effervescence and a purple-red solu- 

 tion is obtained, which appears to contain the chloride of Purpureocobalt. The 

 empirical formula of the scaly nitrate appears to be 5NH 3 .Co 2 3 ,2NO fl -l-7HO. 

 From the effervescence with muriatic acid we are disposed to consider it 4NH 3 . 

 Co 2 3 ,N0 3 -r-NH 4 0,N0 3 +6HO, but further investigation is required before we can 

 pronounce with certainty on this point. 



HYDROUS NITRATE OF ROSEOCOBALT. 



When ammonia is added in excess to a solution of the nitrates of cobalt and of 

 ammonia and the solution is exposed to the air, oxidation takes place with con- 

 siderable rapidity, and as we have already stated when speaking of the anhy- 

 drous nitrate, the solution becomes dark purple-red, while yellow scales of the 

 nitrate of Luteocobalt are more or less abundantly deposited upon the bottom 

 of the vessel. When the red liquid is boiled with nitric acid in excess, a dark 

 crimson precipitate of nitrate of Roseocobalt is formed, while a portion of the 

 same salt remains in solution. It has hitherto been supposed from these facts that 



