1^6 ESSAYS AND OBSERVATIONS 



flamable part of which is fo far from hurt- 

 ing metals, that it preferves their malleability, 

 by fupplying with its own fulphur that which 

 is deftroyed or carried off from the metal, 

 by the intenfe heat employed in the fmelt- 

 ing J and this is fo far true, that iron redu- 

 ced to a calx or friable fubftance by calcina- 

 tion, has its malleability reftored by being 

 fluxed with powdered charcoal only. And this 

 we may here obferve, by the bye, as an in- 

 ftance of the difference of fubftituting a vege- 

 table in place of a mineral fulphur. 



The peat then being intirely a vegetable 

 fubflance, there feems nothing more requi- 

 fite to make it a proper fewel for fmelting 

 iron, but the being able to.raife by its means 

 a heat fufficient for that purpofe. This, ex- 

 perience fliews, cannot be done with the 

 peats we now have. The moft likely me- 

 thod of obtaining this end, I think, is, to 

 bring them to be as folid and compact a fub- 

 flance as poiTible. The denfeft bodies, c<re- 

 ieris paribus^ when thoroughly heated, are, 

 the hotteft: hence it is, that metals as they are 

 the heavieft bodies, fo they reach the great- 

 eft degree of heat. The fame holds in fewel j 

 the hardefl: woods are made choice of, 



wheA 



