The weekly Alaska citizen., 1917-11-05


 etc. Approximately l5,OOO persons, mining engineers, attended. The principal field exhibits were wit messed hy President Taft and many national and state officials. Teams Of miners trained in first-aid work from every coal mining state, were in attendance and took part in the demonstration. These exhibits, to- gether with the Mine Safety Train which last year made the tour of the states, have proved a great stimulus in 'h" adoption of safer and more efficient methods of min ing.
 In connection with the mine res cue work of the Bureau it is of in- terest to know that hundreds of miners in the states owe their lives directly to this work of the Bu- reau. and that several of the Blu , rcau's workers have heroiCaIly lost their lives in attempts to penetrate mines after dangerous explosions and rescue entombed men.
 Mine accident investigation has | developed along various lines: CD In tn" mines themselves. to deter mine the conditions leading to mine disasters the presence and relative applicability of mine gas and coal dust, the causes of mine fires and the means of preventing and limit ing explosions and fres-studies which have led to recommendations and suggestions, many of which have become incorporated into laws: . | 4p ln olot safety of the various explosives used in coal mining, which tests have led to standardization of mine explo- sives invaluable to both operator and miner; (3) Tests to determine the safety of various types of miners 1 lights, a perfect type having just recently been perfected and is about to be put on the market, under the approval of the Bureau, by a manu- facturer; (4) Tests of the various types of breathing apparatus, such as engineers and miners must use in examining mines immediately fol- | lowing mine explosion or in res cuing entombed miners in mines containing poisonous gases.
 That coal dust raised into the air 1 by concussion and ignited may cause mine explosions more widespread and
 errible than those of fre-damp, fact doubted formerly by many min ing men, was definitely established by the Bureau through investigation of mine explosions, laboratory tests, and large scale experiments in the Bureaus own mine. The explosi- | bility of a mixture of coal dust and air under test conditions having been repeatedly demonstrated at the ex- | pertinent Station of the Bureau at Pittsburgh, as early as 1911 the Bu- rcau of Mines obtained tract of
 land near Brucetown. Pa, about 10 niles south of Pittsburgh, where it opened small experimental mine to study coal dust explosions under ac- tual mining conditions. Here the be- havior of different types of explo- slves is studied, the conditions that determine the ignition of gas or 1 dust, or mixtures of gas and dust and air, and the factors involved in | the spread of the resulting explo- i slons. The main purpose is of course to discover the most efficient methods of preventing such explosions.
 A cylindrical or chamber of iron plate, lined with fire brick, has all so been constructed at the Pittsburgh Station, in which various experi- ments with coal fires, especially those ot spontaneous origin, have been made. The commoner causes of fires in coal mines are the use of long flame explosives, open lights, short circuits of electricity, lighting of accumulation of gas, and spontaneous fires. The increased use of per missible explosives, the gradual re placement of open lights by cleo trlclty, the increased attention to ventilation and the gas content of air currents, the better guarding of trolley wires, and the study of spon- taneous fires, as we'll as the prac- tice of f1re-proofing stables, shafts, and shaft bottoms, and surface plants, all contribute to the gradual decrease of mine fires.
 When the work of the Bureau of Mines was initiated, black powder, with its long hot flame, was in gen eral use throughout the coal fields of the country even in mines where the presence of intlammabIe gas and dust rendered it's use most danger ous. The explosives investigations of the Bureau have been largely in- strumental in bringing about the adoption, in these more dangerous mines at least, of the new type of explosives with a short and relative Iy cool flame. The use of what are now termed permissible" ex- plosives, of this type, has increased n general use widely all over the country, due in good part to the edu- cational propaganda of the Bureau of Mines. This revolution has not only aided in reducing the number of mine disasters, but also in re- ducing the number of individual ac- cldents. Miners, operators and engi- neers have expressed the opinion that the work of the Bureau in this investigation of explosives alone has been of far greater value to the min ng industry than the entire cost of the maintenance of the Bureau since it's inception.
 As indicating the efficacy of cer- tain of the Bureaus investigations of explosives, leading to the advo- cacy of loW-temperature, quick flame permissible powders, the president of company operating one of the largest metal mines in the country (the Alaska -TreadwelD recently stat ed in a public address that the re- suits of the Bureaus explosives work | had hroup pht ahout an oct,,l c,,,;, ,-