“Black damp” is pure carbonic acid gas, containing two parts of oxygen to one of carbon. It is the principal constituent of after damp, which may, indeed, contain no other elements in appreciable quantities. The two mixtures are therefore often spoken of as being the same, and the miners apply the term “choke damp” indiscriminately to either.
Black damp is also given off by the coal in the same manner that fire damp is, and frequently the two mixtures are evolved together. Carbonic acid gas is also one of the products of burning coal, of burning oil, and of the respiration of man and beast. It is about one and a half times as heavy as air, and is therefore always found next to the floor of the mine. This gas is not inflammable. Its presence may be detected by the conduct of the flame of the lamp. In an atmosphere containing but a small percentage of it the lamp light will grow dim, and, as the proportion of gas increases, will become more and more feeble until it is finally extinguished. An atmosphere containing from eight to ten per cent. of this gas may be breathed without immediate danger; it will simply occasion dullness of intellect and numbness of body. This condition changes into one of insensibility as the inhalation continues, or as the percentage of gas is increased, and to enter an undiluted body of it means sudden death. It is stated that the workmen in the Creuzot mine, in France, descended the shaft one morning, on their way to work, not knowing that carbonic acid had formed in the mine during the night. Following one after another along the main passage, they had reached a point not far from the foot of the shaft when the leader suddenly entered into a body of black damp and fell, stricken with asphyxia, before he could utter a cry. The man following him fell also. The third, bending over to draw his comrade out of danger, was himself prostrated, and the fourth, by reason of a similar effort, shared the fate of the others. But the fifth, being an experienced master miner, turned quickly in his tracks and obliged those behind him to ascend the shaft. The black damp is thus quick and terrible in its effect. The greatest danger from it, however, exists, not at the working faces, where it is usually swept away in the ventilating current, but in abandoned workings, where it often accumulates unnoticed.
“White damp” is a more dangerous gas than either of the others, but is not so frequently found. It is carbonic oxide, and consists of equal portions of carbon and oxygen. It is a very little lighter than air, and has a tendency to rise. When present in a sufficiently pure state it burns with a blue flame, but ordinarily it is incombustible and produces no effect upon the flame of the lamp. It is tasteless and odorless, and its presence cannot be detected before it has done its dangerous work. To breathe an atmosphere containing a very small percentage of it will speedily produce a fatal result. It acts on the system as a narcotic, and its effect is produced even more quickly than is that of black damp. It is not thought to be given off in appreciable quantities by the coal at the open faces; but it is formed when the carbonic acid passes through any ignited carbonaceous material, or when steam passes over burning coal. It is therefore produced most frequently by smouldering gob fires, by burning wood in the mines, or by a shaft on fire, and may exist as one of the results of an explosion of fire damp or of blasting powder. It is the most to be dreaded of any of the gases which the miner has to encounter. He may possibly avoid the surging flame of the fire damp, he may escape from the falling after damp, and make his way unharmed through bodies of black damp lying thick about his feet, but if he has still to encounter this terrible white damp his good fortune will have been of little avail; death will almost surely seize him.
In connection with this may be mentioned the fact that under certain conditions coal dust may become violently explosive. When it is mixed with air, with or without the presence of fire damp, and is set into sudden and intense vibration by a heavy powder blast, a fall of roof, or other means, it may explode with greater destructive force than even fire damp is capable of. Happily such explosions are not frequent, all the conditions necessary being rarely present at the same time. It is obvious, moreover, that an accident of this kind could occur only in a very dry mine. It is true also that the dust of bituminous coals is much more liable to be explosive than the dust of anthracite. No well authenticated instances of coal dust explosions have been reported from the anthracite regions, while in mining soft coals they have undoubtedly occurred. Two cases of this kind were reported from France, one in 1875 and one in 1877. No longer ago than November 9, 1888, a terrible explosion of coal dust occurred in a bituminous coal mine at Pittsburg, Kansas, by which more than one hundred lives were lost.
In some mines the inflammable and poisonous gases are given off in such abundance by the coal that it is dangerous to remain in them for even an hour after ventilation has been stopped. At such collieries when, on account of accident, or for any reason, the fan stops running, the men are called out immediately, and are not allowed to enter again until a new circulating current has been established. One of the most notable mine disasters of recent years was caused by the quick accumulation of black damp and white damp in a mine, the ventilating system of which had been destroyed and the shaft burned out by fire. This was at Avondale, near Plymouth, in Luzerne County, Pennsylvania, on the 6th of September, 1869. There were three conditions here, the presence and coöperation of which made this calamity possible. First, the mine was ventilated by a furnace at the foot of the shaft; second, the breaker was built over the mouth of the shaft; and, third, the shaft was the only outlet from the mine. The partition of the ventilating flue took fire from the furnace draught. At ten o’clock in the forenoon a young man by the name of Palmer Steele stepped on the carriage with a load of hay to take to the inside stables. Half way down the shaft the hay took fire from the burning buntons. The engineer saw the flames rise from the mouth and let the carriage, with the young man on it, as quickly as possible to the bottom. There were then in the mine one hundred and eight men. Not one of them came out from it alive. In an incredibly short space of time the flames leaped to the top of the breaker, one hundred feet from the ground, and by the middle of the afternoon the great building was a mass of ruins, covering over and blocking up the only entrance to the mine. It was far into the night before the débris had been sufficiently cleared away to permit of descent into the shaft. Then two men, Thomas W. Williams and David Jones, went down to search for the imprisoned miners. They were scarcely beyond the foot of the shaft when they stumbled into a body of white damp and were stricken with death. The fire occurred on Monday. It was not until ten o’clock Tuesday morning that a sufficient ventilating current had been established to make it safe for men to descend. The greatest distance that it was possible to go from the foot of the shaft on Tuesday was seventy-five feet. Beyond that point the danger from suffocation was still imminent. Only three bodies had been thus far found.
Wednesday morning a rescuing party went up the plane at some distance from the foot of the shaft, and at the head of the plane they found a barrier across the gangway. It had been formed by placing a mine car in position and packing the space between it and the walls with clothing and refuse. This barrier was broken down, but there was no one behind it. Later another party was able to go a little farther, and came to a second barrier. Outside of this lay the dead body of John Bowen. He had come out for some purpose from behind the barricade, leaving open an aperture through which to crawl back, but before he could do so he had died from asphyxia. This barrier was broken down, and behind it lay the victims, one hundred and five of them, all dead, suffocated by the foul gases of the mine. The story of their experiences, their struggles, their sufferings, can never be known.
The disaster which occurred at the West Pittston mine on May 27, 1871, was similar in many respects to that at Avondale. In this case also the breaker, built over the shaft, the only opening to the mine, took fire and burned to the ground, closing the avenue of escape to thirty-six men and boys. These prisoners shut themselves into a chamber, building a barricade across the foot of it to keep out the foul gases; but when the rescuing party broke in to them on the following day fourteen of them were found dead and the rest were unconscious. Of those who were brought out alive four died soon after reaching the surface.