MINERALOGY. 
'241 
thefe metals, or infill 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 ammoniiic, 
when they are dilTolved in it j without Hiewing 
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 fcrong lire with it, the copper foon 
feparates, and fcorifies, tinging the glafs firll of a 
reddilli brown opaque colour, and, the fire being 
further forced, it then makes it tranfparent and 
green, as ufual. 
There is no danger attending the encreafing 
the number of the metals. Affrological influences 
are now in no repute among the learned, and we 
have already miOre metals than planets within our 
folar fyflem. If would perhaps be more ufefui to 
difcover miore of thefe metals, than idly to lofe 
our time in repeating the numberiefs experiments 
which have been made, in order to difcover the 
Conftituent parts of the metals already known. 
In this perfuafion, I have avoided to mention any 
hypothefes about the principles of the metals, the 
procefles of mercii'riflcation, and ether things of 
the like nature, with which, to tell the truth, I 
have never troubled myfelf 
k , . APPENDIX- 
