The coal of Torbane Hill, Scotland, is so highly inflammable, that it
has been disputed at law whether it be true coal, or only asphaltum,
or bitumen. Dr. Redfern describes it as laminated, splitting with
great ease horizontally, like many cannel coals, and like them it may
be lighted at a candle. In all parts of the bed stigmaria and other
fossil plants occur in greater numbers than in most other coals; their
distinct vascular tissue may be easily recognised by a common pocket
lens, and 65½ of the mass consists of carbon.
Dr. Redfern considers that all our coals may be arranged in a scale
having the Torbane-Hill coal at the top and anthracite at the bottom.
Anthracite is almost pure carbon; Torbane Hill contains less fixed
carbon than most other cannels: anthracite is very difficult to ignite,
and gives out scarcely any gas; Torbane-Hill burns like a candle, and
yields 3000 cubic feet of gas per ton, more than any other known coal,
its gas being also of greatly superior illuminating power to any other.
The only differences which the Torbane-Hill coal presents from others
are differences of degree, not of kind. It differs from other coals
in being the best gas-coal, and from other cannels in being the best
cannel.