56 RESEARCHES ON THE 



The formula requires 





Eqs. 





Calculated. 



Mean. 



Found. 



Cobalt 



2 



59 



20.55 



20.68 



20.69 20.68 



Sulphuric acid 



2 



80 



21.94 



27.90 



27.65 28.16 



Hydrogen . 



16 



16 



5.57 



5.62 



5.56 5.68 



Nitrogen 



6 



84 



29.26 



29.44 



29.37 29.51 



Oxygen 



12 



96 



16.68 



16.30 



— — 



335 100.00 



A solution of sulphurous acid dissolves sulphate of Xanthocobalt without decom- 

 position. On boiling, however, a complete decomposition takes place, bubbles of 

 gas are given off, and there remains a red solution of the double sulphate of cobalt 

 and ammonia. The gas which is evolved produces no red vapors on contact with 

 the air, and is probably protoxide of nitrogen. The sulphate of Xanthocobalt is 

 also decomposed by boiling with urea, an abundance of a colorless gas without 

 odor being given off. The reactions of the sulphate are similar to those of the 

 chloride. 



NITRATE OF XANTHOCOBALT. 



The nitrate of Xanthocobalt may be prepared like the sulphate, by passing a 

 current of NO x into an ammoniacal solution of nitrate of cobalt. The formation 

 of the nitrate goes on very rapidly, and crystals are usually deposited in abun- 

 dance long before the oxidation is complete. It is best in this case, as in the prepa- 

 ration of the sulphate, to employ a pure salt of cobalt and pure ammonia, as the 

 subsequent purification of the nitrate of Xanthocobalt becomes much more easy. 

 The equations representing the formation of the nitrate are similar to those which 

 we have given for the sulphate. 



The nitrate of Xanthocobalt may also be easily prepared by the action of NO x 

 upon neutral, acid, or alkaline solutions of the chlorides, sulphates and nitrates of 

 Eoseocobalt and Purpureocobalt. We have alluded to the formation of the nitrate 

 of Xanthocobalt by this process already, and will here enter more into detail. 



It is almost a matter of indifference which salt is selected, as the nitrate is 

 prepared with nearly equal facility from all. The salt is to be dissolved in water, 

 and, to hasten the process, ammonia added ; a large excess of ammonia is not 

 necessary, but the process always goes on more rapidly in an ammoniacal than in 

 an acid or neutral solution. The current of gas resulting from the action of nitric 

 acid upon starch or sawdust is then to be passed into the liquid, which speedily 

 becomes hot and gradually changes its color from violet to orange-red, and at last 

 to orange, while orange-yellow crystals of the nitrate of Xanthocobalt are pre- 

 cipitated. The liquid on cooling gives more crystals; the process should not be 

 continued after the whole mass has assumed a clear orange-yellow color. The 

 mother-liquor from which the crystals of the nitrate of Xanthocobalt have sepa- 

 rated contains only salts of ammonia, with a little nitrate in solution. The 

 whole process is very easy to execute, and yields a very pure nitrate. The reac- 

 tions which occur in this process are remarkably beautiful, and may be expressed, 



