NOTES ON COAL AND FUEL. 165 
iron-black colour, with a metallic lustre and foliated texture ; and 
consists almost entirely of charcoal. 
Unlike most other kinds of coal, this occurs both in stratified masses, 
and in lumps, nested in clay. It is found in several countries of the 
European Continent, in Wales, Scotland, and near Kilkenny in Ireland. 
When laid on burning coals, it becomes red hot, emits a blue 
lambent flame in ' the same manner as charcoal ; and is, at length, slowly 
consumed, leaving behind a portion of red ashes. No smoke or soot is 
produced from this coal ; but, on the contrary, it whitens the place 
where the fume is condensed; and the effluvia which it gives out 
is extremely suffocating. This coal is chiefly used in the drying of 
malt. 
Bovey Coal, Brown Coal, or Bituminous Wood, is of a brown colour, 
and in shape exactly resembles the stems and branches of trees, but is 
usually compressed. It is soft, somewhat flexible, and so light as 
nearly to float when thrown into water. 
The greatest abundance of this coal occurs at Bovey, near Exeter, 
from which place it derives its name. The lowest stratum is worked 
at the depth of seventy-five feet beneath the surface of the earth. It is 
also found in Scotland, Ireland, and Germany. 
As fuel, the Bovey coal is used only by the poorest classes, as, not- 
withstanding its burning with a clear flame, it emits a sweetish but ex- 
tremely disagreeable sulphurous gas, which is injurious to health. It is 
principally used for the burning of lime, and for the first baking of 
earthenware. 
Jet, or pitch coal, is a variety of cannel coal, and is a solid, black, 
and opaque mineral, harder than coal, and found in detached masses 
from an inch to seven or eight feet in length, having a fine or regular 
structure, and a grain resembling that of wood. It differs from cannel 
coal by its superior hardness. Jet cannot without difficulty be scratched 
with a knife, whilst cannel coal may be marked by the simple pressure 
of the nail. 
The name of jet has been derived from Gages, a river of Lycia, 
whence the ancients are said to have obtained this substance. It is fre- 
quently cast on shore on the eastern coasts of England, together with 
pieces of amber and curious pebbles, particularly near Lowestoft in 
Suffolk, and Whitby in Yorkshire, where many persons employ their 
leisure in searching for it, and forming it into various kinds of 
trinkets. Jet is found in several countries of the Continent. 
Culm is a species of coal frequently used in England and Ireland for 
lime burning. It contains much earthy matter, will not kindle in an 
ordinary fireplace, yet produces considerable heat and flame in a furnace 
to which a strong current of air can be introduced. 
Modes of purifying coals are being gradually introduced under 
patents in England, France, Germany, and elsewhere. In 1851, at the 
Great Exhibition, Messrs. Berard and Co., in the French Department, 
