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The following table exhibits the maximum quantity of gas obtainable from the second class of coal.ssss1

ssss1 Own Experiments, made at the Royal Mint Gas-Works.

One Chaldron of Coal, produces Cubic feet of Gas. Newcastle coal, First variety, (Russel’s Wall’s End) 16,876 Second variety, (Bewick and Craister’s Wall’s End) 16,897 Third variety, (Heaton Main) 15,876 Fourth variety, (Killingsworth Main) 15,312 Fifth variety, (Benton Main) 14,812 Sixth variety, (Brown’s Wall’s End) 13,600 Seventh variety, (Mannor Main) 12,548 Eighth variety, (Bleyth) 12,096 Ninth variety, (Burdon Main) 13,608 Tenth variety, (Wears Wall’s End) 14,112 Eleventh variety, (Eden Main) 9,600 Twelfth variety, (Primrose Main) 8,348

The third and last class of coals includes those which are destitute of bitumen, being chiefly composed of carbon in a peculiar state of aggregation, evidently combined chemically with much earthy matter. Coals of this class require a still higher temperature to become ignited than any of the former classes, they emit little or no smoke. When laid on a fire they burn away with a feeble lambent flame, indeed some varieties give no flame at all, but burn merely with a red glow, somewhat like charcoal, and at length become consumed without caking. They leave a small portion of heavy ashes.