x6o Of the Principles 



matters, but fiich as arc more tender, flowing, and 

 fimple than the coarfe, footy, ftubborn, and earthy 

 particles of fire, which in open or chinky veffels 

 mix more of the flame with the fubjecl:. The prin- 

 cipal effect of the air here is by its tenderly mixing 

 the fubtile, dry parts with the moid in a clofer man- 

 ner than can be affected by the fire. 



In regard to mineral damps, particularly thofe 

 for the formation of the pyrites, three things are to 

 be confidered. 



(i.) Of what they confift. 



(2.) Their origin, and the manner of it. 



And, (3.) How they become pyrites. 



As to the firft, namely, in what the pyrites damps 

 confift : we are not to fuppofe the univerfal air-par- 

 tides, as the proximate matter and feeds ; feeing 

 this would be going too far back : neither on the 

 other hand, are we to conclude them to be fuch 

 mixtures, wherein the parts of the pyrites^ namely, 

 the fulphur, arfenic, iron, £sfr. are formally and 

 fubftantially contained. But rather taking the 

 mean, to fuppofe them to be damps of a middle 

 fubftance, not common to all the three kingdoms, 

 nor formal parts of the pyrites, but a kind of fatty, 

 tough glue. 



Here we muft readily allow, (1.) That the proxi- 

 mate and firft feminal forms of the pyrites may con- 

 fift in crude unmetallic earths. 



(2.) That crude earths are in their mineralifation 

 and metallifation, primarily appropriated to iron, 



and 



