26 
stances, and Earthy Substances . In conformity to that ar¬ 
range nlent, having noticed the metallick substances which 
are found in our country, I proceed briefly to mention those 
belonging to the other divisions, which are native. 
Coal is an article arranged under the class of Inflammables. 
This substance, which is daily becoming more valuable on 
account of the increasing scarcity and price of wood, has 
been found in various situations. It is now generally al¬ 
lowed, that it has a vegetable origin, but theorists differ as 
to its formation. The Wernerian attributes it to an aque¬ 
ous process, while the Huttonian supposes heat acting un¬ 
der partial compression, to be the cause.! The phenome¬ 
na attending the discovery of coal in this country may pro¬ 
bably strengthen one or the other of these hy potheses. Coal 
in a general Way may be classed into two divisions. Bitumi? z- 
pus coal, a kind which is highly inflammable, and burns with 
a vivid flame. ' This species is used for fuel, and answers the 
required purpose ; but for various mechanical occupations, 
such as the smelting of iron ore, drying malt, burning of 
lime, and making earthen ware, coal is required that will 
give a strong, and steady heat, without evolving any 
smoke or bituminous vapour. For this purpose, the English 
coal, which is generally of the bituminous kind, is exposed 
to a great heat, and its volatile parts expelled. It is then 
called Coke. Some years since the Earl of Dundonakl sug¬ 
gested a plan of saving these volatile products, which was 
adopted by him with great success-! The bitumen was 
condensed into tar, and it is said that by this method the 
English marine, was for several years, supplied with that 
important item in ship building.§ Another species of coal is 
that which is found destitute of bitumen, and in consequence 
is used in the arts without any previous preparation. Of 
.this nature is the Kilkenny coal, which from analysis is 
t Vide Murray’s System of Chemistry, 2nd edit. vol. 3, p. 636. 
For some curious facts connected with this : ubjeet, vide the no¬ 
tice of, and extracts from the paper of Dr. Nugent, on the pitch 
lake of Trinidad, in Edin. Rev. No. 37, art. 9. 
£ 120 tons of coal yielded 3 1-2 tons of tar. Nicholson’s Dic¬ 
tionary. 
§ Chaptal’s Chemistry, vol. 3, p. 342* 
( 
