MINE GASES AND VAPORS.
The principal and most dangerous gas produced in coal-mines, with but rare excep tion, is carburetted hydrogen, which exists in various forms and in different volumes of carbon and hydrogen, as coal-gas, oil-gas, oil of turpentine, naphtha, petroleum, &c. It consists in this state of about 85 parts carbon and 15 parts hydrogen ; but light carburetted hydrogen gas is one part carbon and two parts hydrogen ; heavy carbu rotted hydrogen is one equivalent of each.
Light carburetted hydrogen gas is the most dangerous, difficult, and abundant gas with which the miner is troubled. It issues from nearly all coal-seams, at certain depths from the surface, but generally in greater volumes from the bituminous than from the anthracite coals. It is not confined, however, to the coal-seams, but appears to exist in greater abundance in the rocks below the coal measures, under certain conditions, than in the coal itself, as is abundantly proved by the immense volumes of this gas which issue from the oil-wells, and by the existence of the oil itself, which is only a heavier compound of those gases, or a maximum of carbon and a minimum of hydrogen.
We think we are safe in saying that even the coal itself is a compound of these gases, with probably certain traces of oxygen. Anthracite contains the smallest amount of hydrogen and the greatest of carbon; the rich bituminous contains more hydrogen and less carbon. Asphaltic coal,•mineral pitch, bitumen, coal-oil, petroleum, and naphtha owe their character to the increase of hydrogen and the decrease of carbon; while the carburetted hydrogen gas, which escapes from fissures in our coal-mines and rises from the oil-deposits beneath them, contains still less of carbon and still more of hydrogen.