. Bulletin. wers in themine. One, which continued to give off gas for many months, wasfrom a crevice more than 16 feet deep. Another was in the roof atthe end of the main gangway. AIR SAMPLES FROM RED ASH RETURNS. In investigating conditions in the Hoyt mine the Red Ash bed wasselected because the amount of gas in its different returns varied con-siderably and the air currents were advantageously arranged for beingsampled separately. The following table gives the results of analysesof five samples of return air, and the volume and velocity of the airat the points of sampling on November 18, 19
. Bulletin. wers in themine. One, which continued to give off gas for many months, wasfrom a crevice more than 16 feet deep. Another was in the roof atthe end of the main gangway. AIR SAMPLES FROM RED ASH RETURNS. In investigating conditions in the Hoyt mine the Red Ash bed wasselected because the amount of gas in its different returns varied con-siderably and the air currents were advantageously arranged for beingsampled separately. The following table gives the results of analysesof five samples of return air, and the volume and velocity of the airat the points of sampling on November 18, 1910. The returns werealso measured and sampled April 29, 1912, after mining had been sus-pended nearly a month. The results of the later work are given onpage 145. In figure 29 are shown the extent of the workings in theRed Ash bed up to the end of 1910, the points at which air wassampled, the direction of the air currents, and the location of work-ing faces. GAS IN NORTHERN PENNSYLVANIA ANTHRACITE FIELD. 135. 136 EXPLOSIVE GASES IN COAL MINES. Analyses of return air in Red Ash ivorkings, Hoyt colliery. Return. Place of sampling. Air current. Methane. Lab-ora-torvNo. Vol-ume perminute. Veloc-ity perminute. Pro-por-tion inmineair. Vol-ume perminute. Carbondiox-ide. 1158 Red Ash 150 feet southwest of sta-tion 611, 106 feet abovesea level. Return from north of sta-tion 895. Station 679 22,491 16,626 33,80475,68013,388 978 485946?200 Per 254 460961126 Per 11401157 Red Ash, west split Red Ash, main return Red Ash, south slope .11 .08 1160 .08 1139 210 feet southwest of shaft. .07 To ventilate the Red Ash workings in the Hoyt mine an air currentof about 76,000 cubic feet a minute was used. It passed down themain shaft and was distributed through the mine in various larger split passed directly out through the east workings andthen, circling to the north, drained all territory south and east of thedotted line in figu
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