THE ANTHRACITE COAL PRODUCTION OF PENNSYLVANIA, IN TONS OF 2240 LBS.
A. is the purest form of natural carbon, except the diamond. The carbon varies from 95 per cent in specimens picked from the best veins, to 80 or 85 per cent. Coal con taining less than 80 per cent of carbon is not classed as anthracite. The volatile matter present is water, oxygen, hydrogen, and nitrogen; the ash contains oxide of iron, iron pyrites, silica, alumina, lime, etc. Pennsylvania anthracites have usually 86 to 94 per cent of carbon, 1i to 7 per cent of volatile matter, and lf to 7 per cent of ash ; the density varies from 1.4 to 1.63. A. was derived from bituminous coal by heat acting under great pressure, and probably caused by pressUre in the geological changes which threw the anthracite regions, as in eastern Pennsylvania, into great mountain waves. The heat drove off all volatile matters which it would develop from the bituminous coal, and left the more stable material behind as a natural coke, differing from artifi cial coke only in its superior density. The loss of vegetable matter by decomposition in the formation of bituminous coal is estimated at about three fifths of the material, and in the production of A. at about three fourths; the added compression leaves the
resulting bulk about one fifth or one eighth the original mass. It follows, then, that to produce a vein of A. 30 ft. thick, 240 ft. of vegetable matter must have existed. The coal deposits, as found in the A. formation near Pottsville in the Schuylkill valley, include 15 groups, with 30 beds or veins more than 2 ft. thick, and 20 seams less than 2 ft. The thickest, or mammoth vein, is a single bed from 20 to 70 ft.. thick, in some places divided into 3 layers by seams of slate. About four fifths of the present pro duction of A. comes from this vein. The aggregate thickness of the coal veins at this point is 113 ft., of which 80 ft. may be profitably mined. See COAL. The possibili ties of the production of A. in America may be gathered from the following table, issued Jan. 3, 1880, by the Engineering and Mining Journal, and compiled by Richard P. Rothwell: