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black and opaque, whilst diamond is colourless and transparent; it is one of the softest (H= I) of minerals, and diamond the hardest of all; it is a See also:

GOOD, JOHN MASON (1764-1827)

good conductor of See also:

ELECTRICITY

electricity, whilst diamond is a See also:

BAD, BCD

bad conductor. The specific gravity is 2.2, that of diamond is 3.5. Further, unlike diamond, it never occurs as distinctly See also:

DEVELOPED

developed crystals, but only as imperfect six-sided plates and scales. There is a perfect cleavage parallel to the See also:

SURFACE

surface of the scales, and the cleavage flakes are flexible but not elastic. The material is greasy to the See also:

TOUCH (derived through Fr. toucher from a common Teutonic and Indo-Germanic root, cf. " tug," " tuck," O. H. Ger. zucchen, to twitch or draw)

touch, and soils everything with which it comes into contact. The lustre is See also:

bright and metallic. In its See also:

EXTERNAL

external characters graphite is thus strikingly similar to See also:

MOLYBDENITE

molybdenite (q.v.). The name graphite, given by A. G. See also:

Werner in 1789, is from the See also:

Greek 'ypatbew, " to write," because the mineral is used for making pencils. Earlier names, still in See also:

COMMON

common use, are See also:

PLUMBAGO (from Lat. plum-bum, lead)

plumbago and black-See also:

lead, but since the mineral contains no lead these names are singularly inappropriate.

Plumbago (See also:

Lat. plumbum, lead) was originally used for an artificial product obtained from lead ore, and afterwards for the ore (See also:

GALENA

galena) itself; it was See also:

con-fused both with graphite and with molybdenite. The true chemical nature of graphite was determined by K. W. See also:

SCHEELE, KARL WILHELM (1742-1786)

Scheele in 1779. Graphite occurs mainly in the older crystalline rocks—See also:

GNEISS

gneiss, See also:

GRANULITE (Lat. granulum, a little grain)

granulite, schist and crystalline See also:

LIMESTONE

limestone—and also sometimes in See also:

GRANITE (adapted from the Ital. granite, grained; Lat. granum, grain)

granite: it is found as isolated scales embedded in these rocks, or as large irregular masses or filling See also:

VEINS

veins. It has also been observed as a product of contact-See also:

METAMORPHISM (Gr. ise-rci, change of, and liop¢i, shape)

metamorphism in carbonaceous See also:

clay-slates near their contact with granite, and where igneous rocks have been intruded into beds of See also:

COAL

coal; in these cases the mineral has clearly been derived from organic See also:

MATTER

matter. The graphite found in granite and in veins in gneiss, as well as that contained in meteoric irons, cannot have had such an origin. As an artificial product, graphite is well known as dark lustrous scales in See also:

grey See also:

pig-See also:

IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron, and in the " See also:

KISH, or KAIS (the first form is Persian and the second Arabic)

kish " of iron furnaces: it is also produced artificially on a large See also:

scale, together with See also:

CARBORUNDUM

carborundum, in the electric See also:

FURNACE

furnace (see below). The graphite veins in the older crystalline rocks are probably akin to metalliferous veins and the material derived from deep-seated See also:

SOURCES

sources; the decomposition of metallic carbides by See also:

WATER

water and the reduction of See also:

HYDROCARBON

hydrocarbon vapours have been suggested as possible modes of origin. Such veins often attain a thickness of several feet, and sometimes possess a columnar structure perpendicular to the enclosing walls; they are met with in the crystalline limestones and other Laurentian rocks of New See also:

York and See also:

CANADA

Canada, in the gneisses of the See also:

AUSTRIAN

Austrian See also:

ALPS

Alps and the granulites of See also:

CEYLON

Ceylon. Other localities which have yielded the mineral in large amount are the Alibert mine in See also:

IRKUTSK

Irkutsk, See also:

SIBERIA

Siberia and the Borrowdale mine in See also:

Cumberland, The See also:

SANTA

Santa Maria mines of Sonora, See also:

Mexico, probably the richest deposits in the See also:

WORLD

world, See also:

SUPPLY (through Fr. from Lat. supplere, to fill up)

supply the See also:

AMERICAN

American lead See also:

PENCIL (Lat. penicillus, brush, literally little tail)

pencil manufacturers. The graphite of New York, See also:

Pennsylvania and See also:

ALABAMA

Alabama is " flake " and unsuitable for this purpose.

Graphite is used for the manufacture of pencils, dry See also:

LUBRICANTS

lubricants, See also:

GRATE (from Lat. crates, a hurdle)

grate See also:

POLISH

polish, paints, crucibles and for foundry facings. The material as See also:

MINED

mined usually does not contain more than 20 to 50% of graphite: the ore has therefore to be crushed and the graphite floated off in water from the heavier impurities. Even the purest forms contain a small percentage of volatile matter and ash. The Cumberland graphite, which is especially suitable for pencils, contains about 12 % of impurities. (L. J. S.) Artificial Manufacture.—The alteration of carbon at high temperatures into a material resembling graphite has See also:

long been known. In 1893 See also:

Girard and See also:

Street patented a furnace and a See also:

PROCESS

process by which this transformation could be effected. Carbon See also:

POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder compressed into a See also:

rod was slowly passed through a See also:

TUBE (Lat. tuba)

tube in which it was subjected to the See also:

ACTION

action of one or more electric arcs. E. G. Acheson, in 1896, patented an application of his carborundum process to graphite manufacture, and in 1899 the See also:

INTERNATIONAL, THE

International Acheson Graphite Co. was formed, employing electric current from the See also:

Niagara Falls.

Two procedures are adopted: (I) graphitization of moulded carbons; (2) graphitization of See also:

ANTHRACITE (Gr. avOpaE, coal)

anthracite en masse. The former includes electrodes, See also:

LAMP (from Gr. Xag ras, a torch, Xaµaav, to shine)

lamp carbons, &c. See also:

Coke, or some other See also:

FORM (Lat. forma)

form of amorphous carbon, is mixed with a little See also:

tar, and the required See also:

ARTICLE (from Lat. articulus, a joint)

article moulded in a See also:

PRESS (through Fr. presse from Lat. pressare, frequentative of premere, to crush, squeeze, press)

press or by a See also:

die. The articles are stacked transversely in a furnace, each being packed in granular coke and covered with carborundum. At first the current is 3000 amperes at 220 volts, increasing to 9000 amperes at 20 volts after 20 See also:

HOURS, CANONICAL

hours. In graphitizing en masse large lumps of anthracite are treated in the electric furnace. A soft, unctuous form results on treating carbon with ash or See also:

SILICA

silica in See also:

SPECIAL

special furnaces, and this gives the so-called " deflocculated " variety when treated with gallotannic See also:

ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid. These two modifications are valuable lubricants. The massive graphite is very easily machined and is widely used for electrodes, See also:

DYNAMO (a shortened form of " dynamo-electric machine," from Gr. Sbvaµis, power)

dynamo brushes, lead pencils and the like. See " Graphite and its Uses," See also:

Bull. Imperial See also:

INSTITUTE (from Lat. instituere, to establish or set up)

Institute, (1906) p. 353, (1907) p.

70; F. Cirkel, Graphite (See also:

OTTAWA

Ottawa, 1907). (W. G.

End of Article: GRAPHITE

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