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Page:Popular Science Monthly Volume 18.djvu/632

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THE POPULAR SCIENCE MONTHLY.

represents only a more advanced state of carbonization than bituminous coal; the difference seems, in some way, to have been brought about by the play of the gigantic forces that gave rise to the mountains, for in all the region disturbed by those forces—in all the region in which the rocks have been folded and crumpled and changed—the coal is anthracite, and anthracite rarely occurs in other situations.

PSM V18 D632 Restoration of sigillaria.jpg
Fig. 6.—Restoration of Sigillaria.

Passing over the Alleghanies, we find the disturbing forces have acted with even greater energy on their eastern side, and accordingly in many places the only thing that bears any resemblance to coal is a black substance more perfectly carbonized than anthracite. It is to this substance that we are indebted for the universal use of the lead-pencil, for it is nothing less than black-lead or graphite. And here in a measure we lose track of our series; we find no gradations by which to trace it further, and yet it is as certain as anything can be that graphite is not the ultimate term, for in it we have not yet reached the perfection of carbonization. That perfection is finally reached, however, in the gem of gems, the diamond, the only example of absolutely pure, crystallized carbon. Though the steps between graphite and diamond are not known, we feel sure that those steps, or something corresponding to them, have been taken some time, and that diamond, graphite, coal, peat, and growing forest, all belong to the same series, and represent different conditions of the same thing. And so oar piece of coal acquires interest and dignity, and becomes, altogether, a thing not to be lightly despised, for, in addition to its own real worth, it enjoys the advantage of being able to claim kindred with the aristocratic Koh-i-noors of Golconda.