Eqs. 



Calculated. 



Found. 



4 



30.51 



30.88 



12 



18.10 



18.82 



19 



4.93 



5.19 



40 RESEARCHES ON THE 



COBALTIDCYANIDE OF LUTEOCOBALT. 



Cobaltidcyanide of potassium produces in solutions of Luteocobalt a pale yellowish 

 flesh-colored precipitate of the double cyanide of cobalt and Luteocobalt. The salt 

 is insoluble in cold water, and easily decomposed by boiling water. It cannot, 

 therefore, be re-crystallized for analysis. Under the microscope the crystals are 

 seen to belong to the oblique rhombic system ; they are too small to admit of accu- 

 rate measurement. The formula of this salt is 



6 NH 3 .Co 2 Cy 3 + Co 2 Cy 3 + HO. 



0.4835 grs. gave 0.3923 grs. sulphate of cobalt = 30.88 per cent, cobalt. 

 0.1652 grs. gave 0.3580 grs. water = 5.19 per cent, hydrogen. 



2.1845 grs. gave 0.6800 grs. carbonic acid = 18.82 per cent, carbon. 



Cobalt . 

 Carbon . 

 Hydrogen 



A solution of ferridcyanide of potassium produces a most beautiful precipitate of 

 orange-yellow needles in solutions of Luteocobalt. These, under the microscope, 

 have the same form as the corresponding cobalt salt, and their formula is therefore 



6NH 3 .Co 2 Cy 3 + Fe 2 Cy 3 + HO. 



SULPHATE OF LUTEOCOBALT. 



The sulphate of Luteocobalt is easily procured mixed with the chloride, when 

 solutions of both chloride and sulphate of cobalt are rendered ammoniacal and 

 exposed to the air after the addition of coarsely powdered chloride of ammonium 

 in large excess. The mass of yellow crystals formed upon the bottom of the vessel, 

 after a few days, is a mixture of the two salts. To obtain the sulphate from 

 this mass, the solution in hot water is to be filtered and digested with sulphate of 

 silver, after addition of a few drops of sulphuric acid. In this manner the whole 

 of the chloride may be decomposed, and the filtered solution on evaporation will 

 yield fine crystals of the sulphate. We have frequently prepared large quantities 

 of the sulphate by this method. Another mode of preparing the sulphate of 

 Luteocobalt, which is often very convenient, consists in pouring ammonia upon the 

 sulphate of Roseocobalt, thrown down by cautious addition of sulphuric acid to 

 perfectly oxidized solutions of the ammoniacal sulphate of cobalt. When this 

 sulphate is powdered, and strong ammonia poured upon it, its color frequently 

 changes from red to a dull buff, while the supernatant liquid takes a fine red 

 color. The buff powder on solution in hot water and evaporation yields crystals 

 of sulphate of Luteocobalt. The red liquid is merely a solution of sulphate of 



