. Bulletin. 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 G
. Bulletin. 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 indicated by the sample taken at B. COOPER RETURNS. The Cooper workings at the Lance mine extend in a broad areasouth from the shafts under the river and flats, and one gangway. Figure 24.—Sketch map of worked area in Cooper bed, Lance mine. reaches beyond the corner of Carey Avenue and Division Street, inWilkes-Barre. The Cooper bed is only 50 to 60 feet above theBennett bed, and the course of the Bennett gangways, shown infigure 24, gives an idea of the structure. There is a long descentinto the central basin, and then a rise on the south side. In thecentral and southern part of the workings the depth below the sur-face is about 700 feet. A sample (Lai). No. 1272) of return air from the slopes and anirregular flat basin to the east was taken at the point designated A GAS IN NORTHERN PENNSYLVANIA ANTHRACITE FIELD. 115 (fig. 24) in No. 23 tunnel, where the volume of air was 41,500 feet aminute. This air contained per cent, equivalent to 431 cubicfeet a minute, of methane. About 428,500 square feet of coal wasexposed in the area ventilated by this air, so that slightly morethan 1 cubic foot of gas was given off for every 1,000 square feet of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
