92 feet 3 inches. Depth from surface. pounds lately tried in the Polnick-Astrau colliery, Austria, all of which are superior to gunpowder or dynamite: 1. Peralite is a coarse-grained powder, containing 63 per cent. of nitrate of potassium, 30 per cent. of coal, and 6 per cent. of sulphate of antimony. ་་ 4 2 46 51" 149 66 81 35 ... 184 66 81 "10 Slate, with header... 10 of coal. Rock and slate.............189 Slate........................... 21 ༣ 2. Ialine, which contains from 65 to 75 per cent. of nitrate of potassium, 10 per cent. of sulphur, 10 to 20 per cent. of lignite, 3 to 8 per cent. of picrate of soda, and 2 per cent. of potassium, is less inflammable and to Mam. less violent in its action than peralite, but brings away larger quantities of coal and in larger pieces. bed. These were but the beginning of a series of enterprises for the development of the Lower large coalseams, which must undoubtedly form the chief sources of supply for future demands. Among others were Brown's shaft to the Primrose, at Mount Laffee, on West Norwegian Creek. Miller's shaft, 85 yards deep, to the Lewis coal-bed; thence a slope, 100 yards, on the dip of the coal. Also, on West Norwegian Creek, near Pottsville. The Eagle Hill shaft, east of St. Clair, sunk in 1846; Dow working. The Snyder shaft, at Pine Forest, 300 feet deep, to the Mammoth coal-bed, in Crow Hollow, near St. Clair; sunk in 1866. The Donaldson (Sharp Mountain) shaft, near Tamaqua, 364 feet deep; sunk in 1862. The Kaska William shaft of the Alliance Coal Company, in the Upper Schuylkill Valley, now sinking; recently cut 13 feet of coal. The Silver Brook shaft, on lands of the Catawissa Railroad Co., sunk in 1861 to a depth of 140 feet, to the Mammoth coal-bed. The William Penn Colliery shaft, 250 feet deep, west of Shenandoah; sunk in 1864. The Kohinoor shaft, in West Shenandoah, sunk in 1870; 403 feet, to the bottom of the Mammoth bed. Plank Ridge shaft, sunk in 1870; 257 feet to the Seven-foot bed, here 14 feet thick; thence to the Mammoth, 33 feet thick. Other shafts in Schuylkill county are-Thomaston, north of Mine Hill; Ellangowan, east of Shenandoah (see fig. 39); Bear Valley shaft, at Shamokin; and others. The Wyoming coal-region in 1871 had the following number of coal-shafts: 7 3. Carbazotine, which contains about 610 parts per 1000 of nitrate of potassium, 8 of sulphate of iron, 247 of soot or lampblack, and 135 of sulphur, has only half the weight of gunpowder, and is very hygrometric, but may readily be dried by the heat of a stove. Its action is slow, and it ignites with difficulty, so that it is perfectly safe, and may be recommended when great precaution is needed. 4. Coal Dynamite No. 3 is similar to Nobel's cheap dynamites, and consists of a mixture of nitro-glycerine and gunpowder of inferior quality, which in this case takes the place of porous silica. The proportion of large, medium, and small coal produced by the different substances is as follows: As the use of nitro-glycerine compounds by persons who are unacquainted with their special properties is a frequent cause of accident, the following suggestions for the guidance of those who employ these compounds in mining pursuits are published by the British mine inspectors: "1. In mines these explosives should be kept in a metal box with a hinged cover. "2. Frozen cartridges should be thawed in a double metal box, the outer compartment being filled with warm water. "3. Frozen cartridges should not be placed on any metal, stone, or brick work directly heated by fire. "4. Frozen cartridges should not be placed in boreholes, as they are not exploded by ordinary detonators. "5. Packages containing cartridges must be kept dry. "6. Packages showing any exterior water-damage 5 should be carefully examined, to see if any nitro14 glycerine has exuded from the cartridges. 12 Delaware and Hudson Company.... Total. .............. EXPLOSIVES form a very important branch of study in mining operations. In few mines, and those not the most valuable, is the coal so soft that it can be profitably dug with pick and shovel. Sometimes, especially in thin beds, "holing" is resorted to, the miner lying on his side and laboriously cutting away the under side of the coal, so that the mass will fall of its own weight; but this is both difficult and dangerous, since, should he miscalculate and cut a little too far, the mass falls on, and crushes, him. Gunpowder, dynamite, nitro-glycerine, and all other known explosives have been freely used in the work of mining coal, but there are objections to all of them, the most serious being that they vitiate the air and are apt to fire explosive gases, thus often causing terrible disasters. Efforts are still being made to discover more powerful and less dangerous explosives, but success thus far has been only moderate. The following is a list of new comVOL. II.-24 9. Waste material containing nitro-glycerine and fragments of cartridges must not be thrown into water; they should be destroyed by firing with a detonator, or by mixing them with an excess of sulphate of iron (copperas), or by burning small quantities at a time in an open fire. "10. In burning the waste, care should be taken not to inhale the fumes, as they are more poisonous than the substance itself. "11. Bore-holes in wet ground should not be bored upward. "12. In wet ground a hole must not be put in below a missed shot. |