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THE POPULAR SCIENCE MONTHLY. 



represents only a more advanced state of carbonization than bitumi- 

 nous coal ; the difference seems, in some way, to have been brought 

 about by the play of the gigantic forces that gave rise to the moun- 

 tains, 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. 



' mm 



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 whicii 

 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 cai'bonization. That perfection is finally reached, how- 

 ever, in the gem of gems, the diamond, the only examjile 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 aristo- 

 cratic Koh-i-noors of Golconda. 



