hy 
7 
‘i PHYSICAL ann LITERARY. 259 
hard woods; any attempt made to do it 
wey? ; 
- with pit-coal, fo far as I can learn, has 
Fi hitherto proved unfuccefgful ; and indeed, 
from the nature of that fubftance, there 
‘ feems little hopes of ever bringing it to 
~ anfwer the end, the bituminous or inflam- 
-mable part of pit-coal haying nearly the 
fame effect upon iron which common ful- 
phur has. It deftroys, as experience fhews, 
the malleability of iron and all other me- 
tals, Pit-coal has likeways another bad 
quality, which I have often found to my 
coft. With a ftrong heat it runs intoa 
glally. fubftance, which in time, by its 
fticking fo clofely together, and to the 
fides of the furnace, quite choaks it up, and, 
by its tenacity, hinders the metallic parts 
from finking downwards, as they would 
_do by their natural gravity. What is 
chiefly wanted in finelting, is an open fire; 
‘the furnaces are commonly fufficiently 
clogged with the itony andother hetero- 
Bencos bodies united with the ore, which 
rs ‘un into elafs without the addition of any 
‘ fach foreign matter as has a tendency to 
5 
Mitrification.. The charred wood, on the 
contrary, » 
