January 10, 1913. THE COLLIERY GUARDIAN 73 MINE FIRES * By George S. Rice. Equipment Useful in Fighting Fires. (Concluded from page 38.) An excellent emergency stopping, such as might with advantage be a part of the fire-fighting equipment of every mine or mine-rescue station, is a pneumatic mattress designed in Germany, which can be easily carried to a point close to the fire, and can then be rapidly inflated to fit the heading. It is 14 in. thick, and in other dimensions approximates the size of the headings of the mine. There are central plates to which the hose of a portable air pump can be attached. There is a mica window in this plate for purposes of observa- tion ; a valve for sampling gases could be added. The mattress is temporarily supported by four legs, two on either side, which afterwards serve as braces. When the mattress has been tightly inflated it fits into the irregularities of the walls, roof, and floor. It is stated that the mattress can be put in place and inflated in four minutes. Such rapid setting up would be of great advantage if the conditions were dangerous or if there was not a suitable place for a permanent stopping. On the other hand, the mattress has to approximate the opening in which it must be placed—a necessity that limits its application. From the results of many inspections and analyses of gases from behind stoppings by engineers and chemists of the Bureau, it seems evident that slow combustion goes on after the active flame has been extinguished, until the oxygen content has fallen below 10 per cent. There then appears to be a slow absorption of oxygen by the coal, so that some carefully enclosed areas after a number of months have shown practically no oxygen. Where the area gives off methane, which might be •explosive but for the carbon dioxide and low oxygen content, it gradually pushes out the other gases. Therefore, before taking down a stopping, careful sampling of the gases through the relief valve, and analysis of the gases are necessary. Although the active fire may be out, heat remains, and if the heated material is covered with the ashes of the fire and with fallen material, dangerous temperature may exist for a long time. This occurred in a mine in Southern Illinois. Before opening the fire area, several months after inclosure, an analysis of the gases was made by an engineer of the Bureau. Little oxygen was found, methane being the chief gas. Investigation was made through a temporary air lock by the engineer with breathing apparatus; the area was found cool, but on starting the ventilation a smouldering fire under a heavy fall was soon revived. When a fire beyond control has been enclosed by stoppings or fire walls, there are the following four ways of dealing with it:—(1) Flooding it with water; (2) letting the fire stand until it has burned out and •cooled; (3) when the superficial fire has been put out, ^attacking it with fire apparatus with or without the help, of breathing apparatus ; (4) smothering the fire by introducing gases that do not burn. The flooding of an enclosed fire area with water is the safest and best method when feasible. However, it is only feasible under exceptional or extreme circumstances, as when the area is small and the water can be easily obtained. In many cases it has been deemed wisest to allow an enclosed fire to stand until the partial consumption of the oxygen and the damping effect of the gases produced by the fire have put it out and the heated material have put it out and the heated material has cooled. The experience of the engineers and chemists of the Bureau is that this process usually takes many weeks or months. Much depends upon the seal; the concrete stoppings may be practically airtight, but the surface around the openings and the linings of the shafts or the drifts may leak air. In the case of underground stoppings the adjacent strata and the coal itself will permit circulation of air. It is not generally realised how great an effect a change of barometric pressure has upon a sealed area. The movement back and forth through the strata is usually so rapid that, before the area of high barometer has passed, the barometric pressure within a closed area will often equal that of the adjacent open part of the mine. In other words, no pressure will be shown by a water-guage inserted in the stopping. The same condition will be found when there is an extended period of low barometric pressure. It is best to check this effect as much as possible by plastering or grouting carefully with cement all the walls and also any enclosing coal pillars that may be thin. Many have considered the possibility of putting out * From Technical Paper 24, United States Bureau of Mines. more rapidly an enclosed mine fire by introducing gases. Carbon dioxide, sulphur dioxide, nitrogen, carbon tetrachloride, steam, and other gases have been proposed and some of them tried in fighting various mines fires. The chief obstacle to extensive use, as when the entire mine has been sealed, is the large amount of gas needed. Nitrogen is an inert gas and doubtless would be efficient so far as concerns the reduction of the oxygen content of the atmosphere surrounding the fire. It would be rather costly to use, and it is not known to have been used on a large scale for fighting fires. Sulphur dioxide has been proposed because it can be made easily by burning sulphur. A trial was made in a large fire in Ziegler mine, Franklin County, Ill., but the result was reported to be inconclusive. One difficulty appears to be to burn the sulphur in such a way that the oxygen content of the gases from the sulphur fire is kept below 12 or 13 per cent. The gas that has been more experimented with than any other for putting out enclosed mine fires is carbon dioxide (CO2). A perfect seal is a rarity, but a non-inflammable gas like carbon dioxide forced in at the main opening tends to exclude the air, and therefore is advantageous. With porous strata, as in Colorado, this exclusion of air is important. In the Engleville mine in Colorado an extensive fire in 1909 was fought successfully by this method. The carbon dioxide was generated at the mouth of the mine in wood tanks by the action of sulphuric acid on broken limestone, and was forced through a pipe in the fire stopping. This method of generating carbon dioxide is i slow and expensive. Some easier and more practical method of making it probably will be evolved. To burn i fuel to produce carbon dioxide, as in the furnace of a i boiler, is not effectual, because the oxygen content of ' flue gas is high if the carbon monoxide is kept down to proportions safe enough for direct application. Another suggested method is to make producer gas in a producer built at the mine; then to burn the gas with a limited, but sufficient supply of air, and to blow the resulting gaseous product into the fire area through a pipe in the stopping. It is reported that in the anthracite-mine fires, and in some metal-mine fires, live steam has been used with success, but chiefly in small fire areas. The main effect is to exclude oxygen as long as a pressure of steam is maintained above atmospheric pressure. In large areas the steam must certainly condense to water and be without effect. It is often very important to reopen a fire area before there is time for the fire to burn itself out. When this is done, it is far safer to use breathing apparatus in attaching the fire with hose and not restore ventilation until it is known that the area is cool in every part. Then if analysis of the gases shows dangerous quantities of carbon monoxide and methane, the ventilation must be restored with great care. The ventilation must be arranged so that the inflammable gases are not brought past the spot where fire has existed as it may be revived.* For many years analyses have been made of gases from mine fires to determine the progress of the fires. One systematic series of analyses was made in connec- tion with an extensive fire in the Warrior Run mine, near Wilkes-Barre, Pa., in 1907. Soon after the beginning of the mine accidents investigations, estab- lished first under the United States Geological Survey, as the result of an experience at a mine fire where it was uncertain whether explosive gases were being produced, it was decided to equip the mining engineers with portable gas-analysis apparatus. This has been valuable in studying the progress of a mine fire, and in deter- mining whether or not there were explosive gases forming behind the fire stoppings, also whether there would be danger in opening the stoppings. * A Bulletin on recovering mines after fires will soon be published by the Bureau of Mines. A most excellent hand- book is, “ Rules for Recovering Coalmines after Explosions and Fires," by W. E. Garforth, London, 1909. It contains an outline for an organisation, refers to fire doors, training of rescue teams, and stores to be kept at rescue stations, and suggests rules for guidance after an accident; it contains I also a description of the recovery of the Altofts pit after an explosion. Hull Coal Export I.---The official return of the exports of ooal from Hull for the week ending Tuesday, December 31, , is as follows:—Antwerp, 2,706 tons ; Amsterdam, 2,001 ; Ahus, 1,074; Alexandria, 8,209; Bremen, 1,705; Bombay, 656; Christiania, 1,153 ; Drontheim, 219 ; Drammen, 1,341; Elsinore, 1,331; Ghent, 1,048 ; Gothenburg, 274; Harburg, 1,497 ; Hamburg, 3,261 ; Harlingen, 1,654; Hoboken, 1,869; Horsens, 974; Karachi, 154; Libau, 808; Leghorn, 602 Livorno, 392; Memel, 1,310; Naples, 906; Nakskov, 1,330; Newfairwater, 407; Odense, 1,212; Orth, 352; Oxelosund, 4,072; Randers, 628; Rendsborg, 1,401; Riga, 25,552; Reval, 8,736 ; Rotterdam, 12,525; Stockholm, 542 ; Stettin, 285; Stavanger, 676; Tuborg, 1,231; Uddevalla, 952; Venice, 795; total, 95,810 tons. Corresponding period 1911, 52,786 tons ; 1910, 71,358 tons. THE VENTILATION OF THE BENTLEY COLLIERY. Home Office Summonses Dismissed. There was a large attendance of mining officials and others interested in the colliery world at the West Riding Police Court, Doncaster, on Saturday, to hear the decision in what has now become known as [the Bentley Colliery Case.* It will be remembered that the Home Office, through Mr. T. H. Mottram, HM. inspector of mines for the Yorkshire and North Midland district, issued three summonses against Mr. John William Fryar and Mr. Robert Clive, agent and general manager respectively for Messrs. Barber, Walker and Co., of Best wood, Nottingham, owners of the Bentley Colliery, for not having the pit properly ventilated on three dates in July. The prosecution was conducted for the Home Office by Mr. W. M. Gichard, of Rotherham, the defence being in the hands of Mr. Norman Craig, K.C., M.P., and Mr. H. T. Waddy, instructed by Mr. Robert Barker, solicitor, of Nottingham. During the hearing of the case the Home Office was severely criticised by Mr. Craig; and Dr. Haldane, who was one of the expert witnesses for the defence, came forward and gave evidence voluntarily. The magistrates present on Saturday were Mr. G. B. C. Yarborough (in the chair), General Bewicke Copley, and Mr. J. W. Hodgson. The Chairman said the Bench had had under careful consideration the whole of the evidence they heard during the three or four days over which the case had extended. It was a case which presented very considerable difficulties. They were very much indebted to the learned counsel on each side for the way in which they had presented the case to the Bench. They had had on both sides gentlemen eminently calculated to deal with what was to them (the Bench) naturally a very complicated measure. This was a prosecution for a breach of a certain section of this Act of Parliament. To begin with it was a criminal case, could be punished by penalty, and if the penalty was not paid might be punishable by imprisonment. The Bench thought that every criminal case which came before them must be capable of strict proof. They had considered the whole of the evidence, and weighed it most carefully upon both sides, and they were of opinion that the evidence for the prosecution was inconclusive, and that the information must therefore be dismissed. In reply to the Chairman, Mr. Gichard said there were two other summonses, but he did not propose going on with them that day. The Chairman: Would you like time to consider whether you wish to go on with them ? Mr. Gichard: I should, sir. I will consult with those by whom I am instructed. Mr. R. Barber, of Nottingham, who appeared for the defendants, said they were very anxious this matter should be disposed of quickly. If the other summonses were to be gone on with, he would like to have someltime fixed that day. Mr. Gichard said he would know in a week's time if the other summonses were being proceeded with, but he could not be there that day week, although he could that day fortnight. He would let Mr. Barber know yes or no whether he was going forward, and then something might be done to arrange a date to suit the convenience of the Bench. The Chairman said the Bench could understand defen- dants did not want these prosecutions hanging over their heads, and that they wanted them settled as they had been about months now. Mr. Gichard: I am quite content, Sir, if I decide to go on» it should be a fortnight to-day, if that would be convenient to the Bench. The Chairman said it would probably be well if these further summonses were gone into, that they should be heard by the same Bench. It would save so much time. Mr. Gichard said it would save a great deal of time. It was decided that on Saturday, January 18, Mr. Gichard should intimate whether the other cases were to be proceeded with or not. * See Colliery Guardian, November 2, 1912, p. 1042; December 6, 1912, p. 1145 ; and December 20, 1912, p. 1246. North Staffordshire Institute of Mining and Mechanical Engineers.—An informal general meeting of the members will be held at the North Stafford Hotel, Stoke-on-Trent, on Monday, the 13th inst., at 5 p.m. The subject for discussion will be “ Endless Rope Haulage," and will be introduced by Mr. E. B. Wain. Manchester Geological and Mining Society.—An ordinary meeting of the members of the Manchester Geological and Mining Society will be held at Queen's-chambers, 5, John Dalton-street, Manchester, on Tuesday, January 14,1913, at 4 p.m., when the following papers will be read :—" The Pre- vention of Misfires and of Accidents in Blasting Opera- tions," together with a demonstration of the P.P. safety shot- firing appliance, by Mr. J. S. King, B.So., A.C.I.S. ; “ The Hydraulic Stowing of Goaves," by Mr. George Knox (to supplement paper read by him at the December 10, 1912, meeting, entitled “ The Relation Between Subsidence and Packing, with Special Reference to the Hydraulic Stowing of Goaves.") The following paper will be open for discussion: *( A New Mining Dial,” by Mr. Frederick P. Mills.