260 ESSAYS anp OBSERVATIONS 
contrary, keeps always an open fire, the 
inflammable part of which is fo far fron 
harting metals, that it preferves their mal- 
leability, by fupplying with its own ful- 
phur that which is dettroved or carried off 
from the metal, by the intenfe heat em-, 
ployed in the imelting ; and this is fo far 
true, that iron reduced toa ca/x or friable 
fabttance by calcination, has its mallea- 
bility reftored by being fluxed with pow- 
dered charcoal only. And this we may 
here obferve, by the bye, as an inftance | 
of the difference of fub{tituting a vegeta- 
ble in place of a mineral fulphur, 
THE peat then being intirely a vege- 
table fubftance, there feems nothing more 
requifite to make it a proper fewel for 
{melting iron, but the being able to raife 
by its means a heat fufficient for that pur- 
pofe. This, experience fhews, cannot be 
done with the peats we now have, The 
mott likely mechod of obtaining this end, 
I think, is, to bring them to be as folid 
and compa¢t a fubftance as poflible. The 
denfett bodies, ceteris paribus, when tho= 
roughly heated, are the hotteft: Hence 
if 
Foy :. 
