Coal; its history and uses . enobtained from wood, we may say that this artificial marshgas has been indirectly formed by the decomposition ofwoody fibre, as in nature. It is highly inflammable, burn-ing with a bluish flame of feeble luminosity. Whenmixed with about nine or ten times its bulk of air itexplodes with great violence on the approach of a light,or when it is otherwise heated to a sufflciently high tem-perature. When the proportion of air is increased totwelve volumes or diminished to six volumes, the mixtureis neither inflammable nor explosive. The products of itscombination or exp
Coal; its history and uses . enobtained from wood, we may say that this artificial marshgas has been indirectly formed by the decomposition ofwoody fibre, as in nature. It is highly inflammable, burn-ing with a bluish flame of feeble luminosity. Whenmixed with about nine or ten times its bulk of air itexplodes with great violence on the approach of a light,or when it is otherwise heated to a sufflciently high tem-perature. When the proportion of air is increased totwelve volumes or diminished to six volumes, the mixtureis neither inflammable nor explosive. The products of itscombination or explosion are carbonic acid and gas has only half the density of air; hence it can N 2 180 COAL. be poured upwards. If a bottle filled with tbe gas beinverted under a vessel counterpoised on a balance, tbeequilibrium will be at once disturbed, owing to tbe lightermarsb-gas displacing tbe air (Fig. 30). There is therefore this very essential difference betweentbe process of decay of woody matter in free air and under. Fig. 30.—Experiment for showing the relative density ofMarsh-gas and Air. water, that whereas in the first case we have the formationof carbonic acid and water; in the second, we have theadditional production of the marsh gas. In tbe one casethe carbon meeting with a liberal supply of oxygen is CHAP. V. THE CHEMISTRY OF COAL. 181 eliminated entirely as carbonic acid ; in tlie other wherethe supply of oxygen is but small only a portion of theescaping carbon is oxidized, the rest is evolved in union?with hydrogen, partly derived, it may be, from the woodymatter itself and partly from the associated water. It isprobable, as will be shown hereafter, that under certaincircumstances other gaseous products are produced, but inquantity too small to affect the general result. Nevertheless it would be quite futile to attempt toformulate by chemical equations the process of transform-ation of woody matter into coal. Such equations have,indeed, been devised, but wit
Size: 1544px × 1618px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlo, booksubjectcoal
