Practical Stone Quarrying; A Manual for Managers, Inspectors, and Owners of Quarries, and for Students

Practical Stone Quarrying; A Manual for Managers, Inspectors, and Owners of Quarries, and for Students

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ... this danger, powder is no longer given out in paper bags, with the result that fewer premature explosions have taken place. Further, it has been forbidden to use the powder dust which is found in the bottom of the canisters, or to mix it with the other powder. Dust of this nature is particularly liable to become inflamed, as is shown by the disastrous explosions in coal-mines and flourmills. Even in the absence of dust, granular powder may b? brought to ignition by heating the air sufficiently. Dr. J. Uppmann 1 shows that granular powder ignites at a temperature between 270 degrees Cent, and 320 degrees Cent. Meal povder 1 Das Schiesspulver, p. 154. ignites more readily at a lower temperature. It has been calculated that a compression of ordinary air to 10 atmospheres at mean barometric height may raise its temperature from 20 degrees Cent, to 300 degrees Cent. According to his further experiments, it is possible, by using tight-fitting tamping, by means of quick heavy blows, to compress the air to a pressure of 10 atmospheres, and thereby to ignite powder with absolute certainty. Possibly fine dusty powder, offering a largo surface, would be brought to the ignition point at a still lower pressure. Of the forty-one shot-firing accidents from premature explosions enumerated as occurring in Saxony between 1896 and 1902, it may be mentioned, in confirmation of the above theory, that forty occurred in hardstone (granite, porphyry, etc.) and only one in sandstone. At first sight this seems curious, when it is remembered that soft rocks are blasted at least as much as hard rocks. The explanation appears to be that hard rocks, by reason of their compactness, afford no opportunity for the compressed air to escape. Even when air is heated more

Product details

  • Paperback | 150 pages
  • 189 x 246 x 8mm | 281g
  • United States
  • English
  • black & white illustrations
  • 1236897641
  • 9781236897640