2o6 Of the Arsenic 



fulphur -pyrites, that are but a little arfenical, require 

 more time and labour, nay even (how almoil an im- 

 poflibility of difiblution. It is fomewhat pecu- 

 liar 1 to the fmak-cobalds, that they drike out a kind 

 of peach-blooms •, and alfo under certain encheir- 

 ies> yield a peculiar vitriol •, nay the pure fort do 

 the fame, even fuch as manifell neither the lead i u 1 - 

 phur, nor J 'ulphur- pyrites ; though it may be queried, 

 whether the bifmuth-ore, which oiten quite unob- 

 ferved, lies interfperfed amongft it, be, if not the 

 principal and fole caufe, as feems probable, at lead 

 a concurring caufe : or, whether the cobald itfelf, 

 which may here be alledged indead of the genuine 

 arfenic-py rites, be itfelf capable of fuch a change. 



(3.) The relation of the white-pyrites to the 

 fire may be confidered, partly in regard to the fire 

 itfelf, partly to the other bodies. As to the firft, 

 mod of the remarks, that give any light to the 

 knowledge f this ore, have been mentioned above : 

 but fome things (till want to be cleared up ; which 

 may be bed done by comparing it with the fulphur- 

 pyrites, and reducing what we have to fay on this 

 head to a few fhortpropofitions. 



(1.) The white-pyrites parts with its arfenic, of 

 itfelf, without any additions, in which it agrees with 

 the fulphur •-pyrites, tho' not with the fame prompt- 

 ness, but rather reluctantly, and not without a con- 

 fiderable degree of fire. The reafon is, becaufe ar- 

 feme dicks clofcr to its earth than fulphur does to its 

 earth, which in the former is fomewhat more crude, 

 in both, irony -, infomuch, that in fomewhat too brilk 

 a fire, it is apt to cake or run, rather than to fepa- 

 rate, whereas the fame does not happen, fcarce even 

 by means of art, with refpect to x\\z fulphur -pyrites. 

 1 his the arfenic very plainly fhews, when com- 

 bined 



