GRAPHITE. 



BY JOSEPH STRUTHERS. 



[Joseph Struthers, mineralogist; bom at New York city in 1865, and attended the 

 School of Mines, Columbia college (now Columbia university), graduating in the 

 course of chemistry in 1885; for fifteen years after his graduation he was on the staff 

 of instructors of the- department of metallurgy at Columbia universitj'; organized and 

 conducted the first summer school in practical metallurgy of Columbia university 

 (189G), which was at Butte, Mont. Dr. Struthers has visited many metallurgical 

 plants in the United States and Europe, and he has carried on special metallurgical 

 investigations; he has written numerous articles for the Engineering and Mining 

 Journal, Mineral Resources of the United States, Twelfth Census of the United States 

 and School of Mines Quarterly, and is the assistant editor of the Transactions of the 

 American Institute of Mining Engineers; appointed Field Assistant to the United 

 States Geological Survey for 1901 and 1902, and in May, 1903, special agent for the 

 United States census.] 



The name graphite is derived from the Greek ypd(f)eiv, 

 to write, and refers to the use of the mineral for that pur- 

 pose. Graphite is sometimes called plumbago or black lead, 

 because of its lead like appearance, although it contains no 

 lead. Graphite was known to the ancients. Up to the 

 latter part of the eighteenth century, however, the names 

 plumbago and molybdena seem to have been applied indis- 

 criminately to graphite and to molybdenite (molybdeniun 

 sulphide, M0S2), both of which leave a black mark when 

 rubbed on paper. Graphite appears to have been first dis- 

 tinguished as early as 1565, by Conrad Geissner, but the pop- 

 ular misconception as to the two substances prevailed until 

 1779, when the famous chemist Scheele showed them to be 

 entirely distinct. 



Graphite occurs as a form of carbon, and constitutes 

 the last stage in the mineralization of vegetable matter. In 

 the first stage of this process the woody tissue is converted 

 into peat; the peat to a lignite; the substance then passes 

 through the range of bituminous coals to semianthracite, 

 anthracite, graphitic anthracite, and finally it is converted 

 into graphite, which is practically pure carbon. There is 

 no strict line of demarcation between these various forms of 

 carbon, which merge gradually into one another. In struc- 

 ture and purity, specimens from different deposits show a 

 wide divergence. 



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