. Bulletin. Bottom of basin XXPLANATION — — Property line _£, Dlpe SCALE Figure 22.—Sketch map of worked area in Ross bed,Lance mine. GAS IN NORTHERN PENNSYLVANIA ANTHRACITE FIELD. 113 volume of 21,663 cubic feet a minute and carried per cent ofmethane, or 70 cubic feet a minute. The average daily productionwas 55 tons, so that this amount of gas was at a rate of nearly 2,000cubic feet to the ton of coal mined. The surface of coal exposed inthis area was about 90,000 square feet, so that 70 cubic feet of methaneindicates the escape of cubic feet of methane per minute forevery 1,000 s
. Bulletin. Bottom of basin XXPLANATION — — Property line _£, Dlpe SCALE Figure 22.—Sketch map of worked area in Ross bed,Lance mine. GAS IN NORTHERN PENNSYLVANIA ANTHRACITE FIELD. 113 volume of 21,663 cubic feet a minute and carried per cent ofmethane, or 70 cubic feet a minute. The average daily productionwas 55 tons, so that this amount of gas was at a rate of nearly 2,000cubic feet to the ton of coal mined. The surface of coal exposed inthis area was about 90,000 square feet, so that 70 cubic feet of methaneindicates the escape of cubic feet of methane per minute forevery 1,000 square feet of coal exposed. Another sample (Lab. ) was taken at the point designated B in figure 23 near theextreme south end of the workings on No. 4 slope on the south pitch,. Figure 23.—Sketch map of worked area in Bennett bed, Lance mine. 300 feet below a large feeder that had been active for a long this feeder and the point at which the sample was taken,however, the gas had been diluted by nearly fresh air with a volumeof 15,000 feet a minute. The sample contained per cent ofmethane, equivalent to 360 cubic feet a minute, practically all ofwhich is discharged by the gas feeder. The foreman stated that attimes the proportion of gas appeared to be much greater. Anothersample (Lab. No. 1275) taken at the point designated Cin figure 23represents air from the same current sampled at B, but here the vol-ume of the return was 41,505 cubic feet a minute as it included air47004°—Bull. 72—15 8 114 EXPLOSIVE GASES IN COAL MINES. from other returns and from a split that ventilated six nearbyworking faces. The methane content of this sample was percent, which indicated a volumo of 818 cubic feet a minute, or verymuch more than that indic
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
