Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/33

Rh. The barrels, which were Swedish, were held in a moderate red heat till they burst, when they were instantly withdrawn and cooled in water to prevent the further volatilization of the bituminous matter. As the opening was generally no larger than a pin hole there was no difficulty in cooling the apparatus in time. In this way, among some failures, I procured a perfect fusion of the jet, which exhibited the true characters of coal, and was taken out with the impression of the irregularities in the barrel. I need not add that in this case the produce had not merely the colour and inflammability but the fracture of coal and its odour on burning. It is not unlikely that by a sufficient repetition of these experiments with better regulated heats and more leisure than I possessed, several varieties of coal might have been in this way produced. Indeed some of the specimens exhibited a dry, and others a fat appearance, but it was impossible in general to detach them from the barrels without reducing them to small fragments. Two other circumstances occurred deserving of notice. In one or two cases where the heat had been too great, a portion of the jet was reduced to charcoal, which continued attached to the coaly matter, and the clay was in every instance blackened to a considerable distance from the jet, and converted into a hard compact substance resembling bituminous shale in its smell and consistence.

Reverting to the chemical nature of the other lignites, there is very little reason to doubt that those among them which approach the nearest to a state of perfect bituminization, would have given results nearly similar, but I could not pursue the investigation for want of sufficient specimens. From peat we should expect but a mixed matter, varying between the bitumen of wood and true bitumen, according to the degree of change previously undergone; for that the process of bituminization is the effect of water, and not