CARBON (Lat. mrbo. coal). One of Ihe most important chemical elements. It exists in large quantities. both in the free state and in combination to ith other substances. It occurs uncombined in the mineral graphite. or black lead. and in the diamond, which is pure crystal lize41 ea•on. It is much more abundant, how ever, in a state of combination. United with oxygen, it occurs as carbonic acid in the atmos phere and in natural water. and it is similarly combined in limestone, dolomite. and ironstone. In coal it is found with hydrogen and oxygen, and in plants and animals it (wenn: as one of the elements building Op wood. starch, gum, sugar, oil. hone (gelatin), and flesh (fibrin). Indeed, there is no other element which is so char acte•istic of plant :Ind animal organisms as car bon. Carbon is often set free by the decomposi tion of organic matter. Thu: charcoal forms during, the imperfect combustion of wood. volatile organic substances, especially those rich in carbon, burn with a smoky flame, soot being but finely divided earl The decom position of vegetable refuse under water gives rise to the fortnation of peat. The formation of humus (black earth) is due to the carbonization of vegetable matter in moist air. At elevated temperatures carbon combines direetly with oxygen, sulphur, silicon, and many metals. (See CAntams.) If heated with oxygen or with a strong oxidizing agent like nitric acid, carbon forms carbonic-acid gas; if the amount of avail able oxygen is, however, small, carbonic oxide is produced, which contain: a much lower per centage of oxygen. At ordinary temperatures carbon is. like nitrogen, extremely inert: so much so that it is customary to char the ends of piles of wood which are to be driven into the ground. so as by this coating of non-decaying carbon to preserve the wood. In a similar man ner. the interior of wooden vessels intended to hold water during sea voyages is charred ed with carbon) to keep the wood from passing into deeay and thus to preserve the water 'sweet.' Th•ec allotropic modifications of carbon are known—viz.. amorphous carbon, graphite, and diamond. The chemical identity of those sub stances is proved by burning them, equal quanti ties yielding precisely the same amount of ear honie acid, though there is a marked difference in the readiness with they Intro.
amorphous earbon takes tire readily; gra phite is so non-combustible that erucildes made of this material withstand a high heat for a con siderable length of time: diamond eompletel• resists most ordinary modes of setting fire to it. but can he burned readily in an atmosphere
of pure oxygen, by means, of the electric current. The specific gravities, the hardness. and other physical properties of the three allotropic modi fications of carbon are likewise very different. experiments have been made with the ob je•t. of transforming the less valuable varieties of carbon into diamond. Only very minute Imuan tities of diamond have hitherto been made arti fieially. After diamond was found to be ae companied in meteors by iron and sulphur, the distinguished French chemist Charles Friedel endeavored to produce diamond by heating cast iron rich in carbon with sulphur, at MO° C., when a small amount of an exceedingly hard substance was produced; the quantity was. how ever, so slight that it was impossible to demon strate conclusively the formation of diamond. Even by the use of the electric furnace. Moissan, in IS93, succeeded in obtaining, only traces of diamond. Graphite, on the contrary, is read ily formed from charcoal by heating; this is the effect, for instance, of the vetion of a pow erful galvanic current on charcoal. Pure carbon may be prepared by charring organic substances, such as sugar, that leave no ash; to prepare it from lampblack, this substance is carefully washed with alcohol and etl,er and heated to a high temperature. Lampblack is largely used for making black paint, printers' ink, etc.; it is obtained by burning substanees rich in carbon, such as tar, natural gas, etc. Graphite, which ()emirs in large quantities in nature, is used for the manufacture of pencils. after being powdered and freed from earthy matter. The carbons used in electric lighting are likewise made of graphite, which is obtained in a very dense form by mix ing powdered coal with syrup to a pasty mass, giving the latter the desired shape, and applying an intense heat. Charcoal has been utilized for making the carbonic acid used in sugar-works, and for other purposes in the arts; it is em ployed for &colo•izing solutions (see BoxE taAcK) : and as, when dry, it readily absorbs gases, it is used as a disinfectant and deodorant. It is also SI nnetimes used in medicine as an anti dote against vegetable poison:, such as Opium, aconite, etc. Carbon is infusible and insoluble in any known liquid. The atomic of the element is 12, and it is denoted in chemical for mulas by the symbol C. The molecule of carbon probably constitutes a complex system of atoms.
See CHARCOAL; COAL DIANIOND ;