Repository: UIHistories Project: Board of Trustees Minutes - 1878 [PAGE 187]

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187 southern part of the state, with 10 per cent less volatile combustible matter, gave within three-tenths of a cubic foot as much fixed gas. There can be no doubt then, that the nature of bituminous matter is quite different in different kinds of coal. Our estimate in cubic feet of gaseous matter is considerably less than that obtained practically in the manufacture of illuminating gas. An average specimen of Youghoiugheny coal gave us about 3£ cubic feet per pound of coal, whereas, practically, from four to H\e cubic feet are obtained. This difference may be accounted for in the fact, that in the gas works a re-distillation of the tarry matter, which collects in the "stand-pipes," takes place, as it drips back into the retort. Again, the increased temperature at which the gas is usually measured will make an important difference, as a variation of five degrees will change the volume of gas about one per cent.

FIXED CARBON.

T h e percentage of fixed carbon varied from 44.56, in a coal from Vermilion county, to 66.50 per cent, present in a coal from Jackson county. The column designating the quality of the coke, gives an idea of the nature of the coal whether " c a k i n g " " or "free-burning." The terms cellular and swollen, are applied to those cokes in which there has been a rapid rise of gas or vapor from the partially fused mass. Hence this coal is called a " c a k i n g " coal. T h e term " dryb u r n i n g " is given to those coals which burn freely and are not given to caking.

SULPHUR.

The lowest amount of sulphur found in any coal examined was .60 per cent, present in a Jackson county coal, while the highest limit reached was 4.62 per cent of the coal. I t was formerly supposed that about one-half of the sulphur left the coal with the volatile matter, in the process of coking, but this is by no means certain. In some coals nearly the whole of the sulphur leaves the coke, while in others only a small proportion escapes with the volatile matter. In ascertaining the value of a given coal, for making gas or furnace purposes, it is not sufficient to know simply the amount of sulphur in the native coal, but we must also know the amount evolved in the process of coking. Thus, then, with reference to the sulphur alone, a coal may be well suited for furnace purposes but objectionable for gas-making, while another with even more sulphur may be better adapted for gas-making but quite unfit for use in the furnace. W e now add, in tabular form, the composition of the coals analyzed, with the counties from which they were obtained:—