On the Separation of Nickel from CoLali. IQb 



evaporation. After having parted with a little cobalt mixed 

 with nickel of a pale green, the sahne part collected it- 

 self, by little and little, into crystals of a blueish green, 

 which could here and there be perceived to be prisms, to 

 which, in different points, were attached some small crys- 

 tals of calcareous sulphate. To free, as much as possible, 

 these crystals from the adhering mulhcr liquor, they were 

 washed with distilled water, and dried between leaves of 

 blotting-j)aper. Although the remainder of the lixivium 

 showed no disposition to deposit other regular crystals, I 

 wa-^ not able to recognise any difference between the metal 

 which it contained and that in the crystals : it was in both 

 an oxide of nickel mixed with cobalt. The crystals, which 

 weighed live half-ounces, were redissolved in 32 ounces of 

 boiling w .Iter; the solution was evaporated to the formation, 

 of a til ill pellicle, and, after having been filtered, it was put 

 in the vicinitv of a stove, to cool slowly and to crystallize. 

 At the end of 4S hours the greater part of the salt was crys.- 

 tallizcd iu beautiful tetraedral and rhoniboidal pyramids, 

 short, and of a yellow green, of which the lateral surfaces 

 Ibrnicd an angle of 1 1.5 and G5 degrees, often with a trun- 

 cated cxireuiity, and always with an angle of 132 degrees 

 f)f inclination towards the terminal surface. This result 

 proves th.-it the salt can more easilv be formed in regular 

 crvstals bv refrigeration than by slow evaporation. All 

 fhcse collected crvstals havins;beeu washed with water were 

 redissolved, and the separation of, the oxide of nickel was 

 clfectcd by boiling it with carbonate of potash till the am- 

 monia was disengaged. 



4. As much for the sake of having this oxide free from 

 carbonic acid, as for jiulging if it was purged of cobalt, I 

 dissolved it in nitric a':id, and treated it afterwards witii pure 

 ammonia, in the nianacr which has been often mentioned. 

 I evaporated to drvnc's the beautiful blue liquor which had 

 been freed by filtration from a residue of live grains, which 

 showed itself to be an impure oxide of cobalt. After a sub- 

 serpient solution there was deposited an oxide of a beautiful 

 clear green, which, after being washed and dried, weighed 

 a half-ounce. Tlu: liquor which passed through the hltcr 

 was analysed by carbonate of potash at a heat of boiling 

 water, which stiil gave 3 70 grains of oxide of nickel con- 

 taining carbonic acid of a pale green. 1 dissolved a little 

 of it in nuniatic acid, and apphcd the solution to liapcr. 

 On heating it afterwards, the stains became yellow, inclinini^ 

 (jiily .t little towards grv.cii. But wlien the oxide of nickel, 

 wliieh had been .scp.Matcd iVom ihe i-auic during evipora- 



