98 Of the Iron 



fulphur and quickfilver, and that mod eafily and 

 conftantly *, and there may fpeedily, though not 

 conftantly, be prepared a formal antimony from 

 regulus and fulphur : But in compounding ful- 

 phur and iron, the parts into which a pure iron- 

 writes is evidently reibluble, it does not fucceed. 

 The reafon of this difference is, in the firft place, 

 to be fought for in the metallic earth of iron, 

 which is highly coarfe and fixed, nay the crudeft 

 of all, and proximately derived from the univerfal 

 unprepared earth itfelf, and confequently not fo 

 combinable with the tender, volatile, elaborated, 

 mercurial, reguiine earths. 2dly, The fulphur, 

 which is fomething highly tender, volatile, and 

 diffipable, fiies off and is deftroyed, before ever 

 the iron can, by ignition, be brought to con- 

 ception ; or the iron comes to be unfit for the 

 purpofe, by lofing its metallic form, and turning 

 to a ruft, in which the fulphur cannot find a due 

 ingrefs to coalefce with it. And hence it is, the 

 fulphur is fo fuperficially combined with the iron in 

 the pure iron-pyrites, that without any force or 

 violence, fuch as cinnabar and antimony require 

 to feparate out of it, barely by the external heat, 

 nay, by the bare accefs of the air, without fire at 

 all, it may be made to operate on its accompanying 

 iron : which is the formal reafon of the crumbling 

 and vitriolifation of the pyrites. It, however, from 

 hence and other inftances appears, that the rule, 

 implying the necefTity of proving analyfis by fyn- 

 ihefis^ among ores and decompounds, fuch as ores 

 commonly are, ought not to be looked upon as 

 univerfal ; fome bodies evidently bearing analyfis, 

 but with difficulty, if at all, fynthefis \ for inftance, 

 the pyrites \ others again eafily bearing compofition, 

 but difficultly, or not at all, refolution •, as the 

 neutral falts. 



We 



