Second variety, from the yard vein at
the same place.1,656
Third variety from Bienew, near
Llandillo.1,416
Fourth variety from lllios, near
Polity Barren. 1,272
Fifth variety from the Vale ofGwen-
drath.1,292
Sixth variety, from ditto, .... 1,486
W hen we consider the before mentioned varietiesof coal in an economical point of view, as fuel tobe used in the gas-light process, for heating theretorts, it appears from a series of experiments thathave been made under my direction, that thesecond class of coal comprehending those varietiesw hich contain a larger quantity of carbon thanbitumen (p. 45,) afford the most economical fuel,they act less on the grate bars, and fire bricks ofthe furnace than those varieties which take fireeasily and burn briskly with a strong blaze. A
mixture of Welch Stone coal, and Newcastle coalforms an excellent economical fuel, where an intenseglowing fire is required.