368 Elements of Mineralogy. 



not be in the leaft magnetic j befides this ar- 

 gument would fubvert Mr. Monnet's own opi- 

 nion, for nickel is alfo always magnetic. 



12,. Mr. Rome' de Li/le thinks that nickel 

 confifts of iron, cobalt and copper intimately 

 united :* although Mr. Bergman has demon- 

 ftrated that this opinion is deftitute of any 

 proof, either fynthetic or analytic ; for, in 

 the firft place, he mixed thefe fubflances in 

 various proportions, but could produce no- 

 thing that refembled nickel ; and, in the id 

 place, he fhewed that copper is very feldom 

 mixed with it, and when it is, may eafily 

 be feparated, and cobalt alfo may be fepa- 

 rated though more difficultly. But Mr. 

 Rome looks on the blue colour which volatil 

 alkalis produce in the folutions of nickel, as 

 an evident {ign of its containing copper. 

 To make this proof of any weight, we muft 

 aflfume this principle ; that two different me- 

 tals cannot give the fame colour to the fame 

 menftruuni) which is evidently falfe, for gold 

 and platina give the fame colour to aqua 

 regia, to fay nothing of the various me- 

 tals, whofe folutions in nitrous acid are 

 colourlefs. The only confequence ftriftly de- 

 ducibie from the colour of a menftruum is 

 purely negative; namely, that it does not 



* Chryftilographie, p, 91, 



finely 



