68 Memoir on Nickel. 



posited Itself unfertile form of flakes, which gradually as- 

 sumed consistence. It was of a beautiful green colour, and 

 a solution of it in acids did not change colour by gall-nuts. 

 'J'he precipitate formed in it by ammonia immediatelv dis- 

 solved in an excess of alkali. 1 was convinced of its purity; 

 but that there might not be room for the lea.^t suspicion,. I 

 subjected it a second time to the same course of operation* 

 already described; and even after having combined it with 

 nitric acid, I caused that salt to crystallize, and took care ta 

 employ that only which was in the form of well-detined 

 rhon)boidal cr^'Stals, 1 found means to unite thirty-three 

 grammes of that oxide thus prepared, respecting the purity 

 of which chemical analysis could excite no doubt, and 

 formed it into a paste v.-ith oil, lamp-black, and twice its 

 weight of very pure borax, matters which could not bring to 

 it anv iron. I enclosed this paste in a double Hessian cru- 

 cible, and subjected it for half an hour to the action of a 

 xiolent forge heat ; the nickel was reduced, but it did not 

 fuse. I observed only in the mass, which was slightly ag- 

 glutinated, some metallic globules, which were brittle in 

 consequence of the charcoal or borax they coni:.ined. I re- 

 peated the experiment without better success, though I 

 urged the lire so stronglv, that the Hessian cruci!)les began 

 10 fuse. I then resolved to try the fusion a third time, 

 making use of Kussingcr's crucibles, which are still more 

 refractory than tb.e Hessian. I had at my disposal the forge 

 of the Sciiool of Mines, in which are fused without any ad- 

 dition two kilogranuiies of soft iron ; I took every possible 

 precaution to ensure success ; f added borax, and urged the 

 fire in such a manner, that, the crucibles were softened, 

 tunk down, and formed onlv an orbicular mass : and yet I 

 ubiained onlv globules, which .were indeed ductile, but very 

 little larger than those of the first experiments. I even 

 tould obtain but a very small quantity ; several of them 

 v.ere volatili/ied, and adhered to the cover of the crucible ; 

 most of t'ticm were disseminaled in the glass, and scarcely 

 perceptible bv a magnifyinp;-gli.ss ; a portion perhaps had 

 fiovvcd with tl\e Mux mto the a-^hcs. I think I should have 

 succeeded, if, havJrig collected all these globults in ari ex- 

 cellent crucible, 1 had exposed them to a strong heat without 

 uny kind of flux. I intend to try this method, which I 

 consider as good, as soon as I can obtain oxide sufficiently 

 pure. It is however certain that this metal is one of the 

 most ditHcult to be fused ; and this propertv of being in 

 some measure fire-proof, of which no chemist has yet 

 <>poken, inclines me more and more to believe that hitherto 

 I ' '" it 



