2 PROCEEDINGS OP THE AMERICAN ACADEMY 



cobaltic chloride, CoClg, is mixed with ammonic nitrate, and then with 

 a solution of ammonic nitrite, containing much free ammonia, the solu- 

 tion soon becomes deep orange, and after twenty-four hours deposits 

 orange-brown crystals in large quantity. The mother liquor of these 

 crystals is olive-green. By re-solution in hot water containing a few 

 drops of acetic acid, and filtration, beautiful orange-yellow needles may 

 be obtained as this filtrate cools. The crystals are perfectly free from 

 chlorine, and represent the nitrate of a new series of ammonia-cobalt 

 salts, the formula of the salts being 



Co,(NH3)3(NO,),(N03V 



The formation of this salt is accompanied by an absorption of oxygen 

 from the air, and may be expi-essed by the equation : — 



2CoCl, + 2NH, . NO3 -f 8NH3 -f 4NH, . NO^ + = 



Co,(NH3)3(NO,),(N03), + 4NH,C1 + 2(NHJ,0. 



2. Action of a Mixtiure of Ammonia and Potassic Nitrite upon Cohaltic 

 Sulphate. — When cobaltic sulphate is dissolved in water and a mixture 

 of ammonia and potassic nitrite is added, the liquid speedily becomes 

 brown upon the surface, and after a few hours orange-yellow crystals 

 form upon the bottom and sides of the containing vessel, while a green 

 flocky matter is at the same time deposited. When large quantities of 

 material are operated upon, the complete oxidation requires sevei'al 

 days. On filtering, a bright green mass mixed with orange-yellow 

 crystals remains upon the filter: the filtrate is olive-green, and after 

 standing often deposits small, brilliant orange-yellow scales. If the 

 mass on the filter is treated with hot very dilute sulphuric acid, it 

 instantly becomes bright orange, and by boiling dissolves. The filtered 

 solution then deposits, on cooling, a splendid salt, which has the formula 



Co,(NH3)3(NO,),SO„ 



and which is the sulphate corresponding to the nitrate already mentioned. 



3. Action of a Mixture of Ammonia and Potassic Nitrite upon Cohaltic 

 Nitrate. — When cobaltic nitrate is dissolved in water and a mixture of 

 ammonia and potassic nitrite is added, the liquid speedily becomes 

 brownish-orange, and after an hour begins to deposit bright orange- 

 yellow crystals, mixed with a green flocky mattei-, precisely as in the 

 case of the sulphate. By dissolving the orange-yellow crystals in boil- 

 ing water, a few drops of acetic acid being added to prevent decompo- 

 sition, a fine sherry-wiue-colored solution is obtained, which, on cooling, 

 deposits crystals of two different forms, the larger portion being in 

 octahedrons, the smaller in prismatic forms. By careful mechanical 



