141

a—6

mine, at Haydock Collieries, employing for the purpose coal-dust from all parts of the country, and the result went to prove that coal-dust, in any mine, whether fiery or not, where gunpowder shots are fired, is an element of danger. With high explosives, Mr. Hall was able to proceed without firing the dust, but when gunpowder was used in conjunction with the same coal-dust, violent explosions sometimes occurred, and more than once flame issued from the top of the shaft. To the best of my recollection, the shaft used for these experiments was about 600 ft. deep.—J". Hayes. Altoft's Colliery (Pope and Pearson's, Normanton, near Leeds ; explosion on 2nd October, 1886. The jury in returning their verdict found, "That the explosion was caused through the ignition of coal-dust, consequent on the firing of a badly-drilled shot."— Colliery Manager, January, 1887, page 3. Messrs. W. N. and J. B. Atkinson, Inspectors of Mines, England, in their work on " Explosions in Coal-mines" (1886), which gives the result of their investigations of six large colliery-explosions in the North of England, from 1880 to 1885, give, among others, the following particulars : — "In the Whitehaven Colliery explosion (1882) coal-dust could have played no part. It was one of gas and air, a large volume of explosive mixture, which was known to exist, being probably ignited by a defective safety-lamp ; its effects, so far as violence was concerned, were confined to the immediate vicinity of the explosive mixture. The violence or force of the explosion was less than in any other of the five. The flame had not extended 50 yards from where the explosive mixture had been before ignition. The workmen in the field of the explosion had all been under some alarm before the explosion ; and after it had moved about 100 yards, one of them escaped alive. Their bodies exhibited no signs of the severe burning and blacking in common after explosions in dusty pits. The part of the mine in which the explosion occurred was wet. Estimated quantity of explosive mixture, 32,800 cubic feet. The other five colliery explosions (Seaham, 1880; Trimdon Grange, 1882; Tudhoe, 1882 ; West Stanley, 1882 ; and Usworth, 1885) all present the following features : In the absence of a knowledge of the danger of coal-dust, they could not have been expected. No accumulations of gas were known to exist approaching in quantity what would be necessary to cause the wide-spread destruction, nor were such accumulations considered possible. In all cases the violence and flame of the explosions were confined to those roads on which there was much coal-dust, the greatest force being on the intake- and haulage-roads, where gas could be least expected, and where naked lights were used daily. In many cases the explosions were arrested where the haulage-roads were wet or damp. In no case was there any evidence of alarm among the workmen prior to explosion. Carbonic oxide was evidently present in the after-damp, rescuers being overpowered while the lamps burned brightly. In some instances workmen's lights had continued to burn till all the oil in the lamps was consumed, the workmen having apparently died from the poisonous nature of the gas while the lights were still burning. Mr. William Seddon (in a paper before the Western Pennsylvania Mining Institute, 29th October, 1887) states : " In firing a shot in our working-places, we do not always get complete combustion. Who is there that has not returned immediately after he has fired a shot and ignited the powder smoke ? Now, if the result of an explosion of powder give us free nitrogen and carbonic acid, we have nothing combustible in the smoke : how is it that it flashed or burned when we applied our light, when we feel confident that there is no firedamp present ? Answer : Incomplete combustion, which causes carbonic oxide to be present instead of carbonic acid." Colliery Explosions. Mr. James Ashworth, M.E., in treating on the effects produced by the sudden compression of the air in mines [see cause of mine-explosions, Colliery Engineer, January, 1896, p. 128], considers it conclusively proved that at the Albion Colliery explosion (June 23rd, 1894) the heavy coking effects noticed in some working-faces " were due to the spontaneous combustion of coal-dust in the presence of highly-compressed oxygen, and not actual flame." Mr. D. M. Stuart, M.E., F.G.S. (lecture at Technical Schools, Derby), considers "that an explosion in a mine is characterised by numerous local explosions, each disturbance being isolated and preceded by a length of mine-passage in which the materials were practically in their normal state, or had not been subjected to violent forces. . . . Coal-dust, always and everywhere prevalent in mines, is capable of giving rise to explosions and of producing the phenomenon of subsidiary local explosions." Mr. Stuart is referring to explosions in bituminous coal-collieries. The Colliery Engineer, commenting on the lecture says : " The low percentage of volatile hydro-carbons in anthracite coal renders it freer from dust explosions than the various other classes of coal. In fact, this feature indirectly proves the coal-dust theory. Some of the anthracite-mines in Pennsylvania rank among the most gaseous in the world, and there has never been a gas explosion in one of them that has not been purely local in its effects. In both British and American bituminous mines, however, the case has frequently been different. Explosions of small accumulations of gas have frequently been propagated by dust, and carried with varying intensity throughout all or the major portion of the mine-workings. Sudden outbursts of gas, authenticated by positive proof, have occurred in anthracite-mines, and have caused disastrous explosions, but the limit of the explosive force was comparatively small. Such outbursts undoubtedly occur in bituminous seams, and are sometimes the origin of explosions, but we are of the firm opinion that the extent of the workings affected, outside a limited area, depends entirely on the quantity of dust present, and the chemical composition of the coal,"