114 Iron « 
pentine) from coal tar, though offensive when smelt, has 1 
on that account a very beneficial effect against worms* 
when used for paying of the bottoms of ships* 
Pit-coal, usually produces more than the same bulk of 
coak or cinder, when not over burnt ; but the weight is 
greatly diminished : Dr. Watson had a ton of coal coaked 
in the usual way, and it weighed when cold, 1 1 cwt** 
The coak of pit-coal (that is, the charcoal of stone-coal) 
cannot as I think be well made unless out of bituminous 
coal, that burns with a flame and smoke and runs to a 
light grey-black cinder of a silvery lustre. This cinder 
yields greatly more heat than the charcoal of wood ; for 
141b. of brass that took an hour and a quarter to be melt- 
ed in a portable furnance with charcoal , was melted with 
coak in 48 minutes. But it is apt to run together, be- 
fore it is entirely consumed by the supply of air. Hence 
among other reasons, in England, all the furnaces have 
gradually increased their blast. 
I have thus dwelt upon pit-coal of stone-coal as a foe 1 ? 
because I foresee the time approaching when this sub- 
stance must be resorted to in Pennsylvania. Of stone- 
coal there are two principal varieties ; 1st. Bituminous 
coal that may be converted into a coak cinder, which \ 
bums with smoke and flame and soot ; 2dly. Anthracite, 
or coal that bums with a slight blue lambent flame, with- 
out smoke or soot, and which is gradually converted into j 
a white ash as its surface consumes. The first kind is 
found at Chingleclamoose and Sinnam ahoning on the west 
branch of Susquehanna, and abounds throughout the whole 
of Pennsylvania in a line directly west of those places, and 1; 
north and south of that west line : Pittsburgh seems to be 
almost in the centre of the coal district. 
The anthracite, or second kind of coal, is found on the 
head waters of the Lacawana and Lehigh that run into the 
* I find by recent trial, that a bushel of pine charcoal weighs 
upib; of oak 221b, T. C> 
