Metallic Sulftances. 219 



phofphoric has been found only in one in- 

 ftance ; metallic fubftances mineralized by 

 fixed air are called calciform ores, from their 

 refemblance to the calces formed by art. 



6. It is true that fome mineralogifts of the 

 firft rank exclude arfenic from the number of 

 mineral izers, as it is itfelf a metallic fub- 

 ftance, faying, that with equal propriety 

 other metallic fubftances that render metals 

 brittle might be called mineralizers ; they 

 alfo add, that arfenic is never united to metals 

 but in its reguline ftate, and therefore that 

 the compound it forms mould rather be called 

 an alloy than an ore .; and, indeed, if this laft 

 circumftance always took place, I mould not 

 hefitate to agree with them ; but it feems 

 clear to me that the calx of arfenic, and even 

 its acid being capable of uniting with metals, 

 (an union which the calx of no other me- 

 tallic fubftance is capable of contracting) thefe 

 metals cannot unite to that calx or acid with- 

 out lofing fome part of their phlogifton, and 

 confequently without being mineralized in the 

 ufual fenfe of that word ; yet if regulus of 

 arfenic be combined with metals without any 

 lofs of phlogifton (an union which art may 

 produce by means of the black flux) I will 

 allow the compound fhould rather be called 

 an alloy ; but fuch an union I believe feldom 

 or ever takes place in the mineral kingdom. 



Hence 



