MINERALOGY. -241 



thefe metals, or infrft upon it, that one is pro- 

 duced from the other. 



It is remarkable, that the precipitates of nickel 

 give a blue colour to the fpirit of fal ammoniac, 

 when they are diflblved in it ; without (hewing 

 befides any marks of copper, which, however, 

 could not be concealed if there were any ; for if a 

 fmall quantity of copper is melted with the nickel, 

 and kept in a flrcng fire with it, the copper loon 

 feparates, and fcorifies, tinging the glafs rirft of a 

 reddifh brown opaque colour, and, the fire being 

 further forced, it then makes it transparent and 

 green, as ufual. 



There is no danger attending the encreaflri°* 

 the number of the metals. Aftrological influences 

 are now in no repute among the learned, and we 

 have already more metals than planets within our 

 fclar fyftem. It would perhaps be more ufeful to 

 difcover more of thefe metals, than idly to lofe 

 our time in repeating the numberlefs experiments 

 which have been made, in order to difcover the 

 confliruent parts of the metals already known. 

 In this perfuafion, I have avoided to mention any 



potheles about the principles of the metals, the 

 proceffes of mercurifkation, and other things of 

 the like nature, with which, to tell the truth, I 

 have never troubled myfelf. 



R APPENDIX, 



