Coal; its history and uses . atmosphere of coal-mines ; it constitutesthe fire-damp of the miner. The fire-damp oozes imper-ceptibly from the face of the coal or escapes from cracksor fissures in jets, known as blowers. Occasionally themass of the coal is so highly saturated with the gas thatit continues to escape from it for some time after it hasbeen raised; a fact well known to persons engaged instoring or shipping coal; it not unfrequently happens thatthe coals in a ships hold, for example, give out such alarge quantity of this occluded gas that the air in theimmediate neighbourhood become
Coal; its history and uses . atmosphere of coal-mines ; it constitutesthe fire-damp of the miner. The fire-damp oozes imper-ceptibly from the face of the coal or escapes from cracksor fissures in jets, known as blowers. Occasionally themass of the coal is so highly saturated with the gas thatit continues to escape from it for some time after it hasbeen raised; a fact well known to persons engaged instoring or shipping coal; it not unfrequently happens thatthe coals in a ships hold, for example, give out such alarge quantity of this occluded gas that the air in theimmediate neighbourhood becomes highly explosive. In a vacuum, especially at a gentle heat, this occludedgas is readily disengaged from the pores of the coal. Theflask standing in the water-bath (Mg. 31) is filled withpieces of the freshly-raised coal: on exhausting the appar-atus by the aid of the Sprengel pump and then raising thetemperature of the bath to the boiling-point the gas isevolved and may be collected in the tube previously filled 182 Fig. 31.—Apparatus for the collection of gases occluded in Coal. ciiAP. V. THE CHEMISTRY OF COAL. 183 •with mercury and placed over the end of the fall-tube ofthe pump. A study of the nature of the gases contained in thepores of different varieties of coal is calculated to throwconsiderable light on the mode of their formation. Quiterecently Mr. J. W. Thomas has published a series ofanalyses of the gases obtained by exhaustion in finds that the bituminous coals of the South Walesbasin, which contains one third of the available coal ofGreat Britain, contain very little gas, and that little isalmost exclusively carbonic acid. The atmosphere of theworkings of these mines is almost free from marsh gas,the chief gaseous impurity being the carbonic acid. Withthe increase in the carbon, both the total volume of theoccluded gas and the relative proportion of the marsh-gasbecome larger; this is especially the case in the hardcompact steam coals. Anthrac
Size: 1250px × 1999px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlo, booksubjectcoal
