721 



Coke. This variety of carbon is produced by the ignition of pit-coal. The largest 

 quantities are produced in the manui'acturo of .coal-gas. It of course varies greatly 

 in quality with the coal from which it is procured. The density of coke varies not 

 only with the quality of the coal, but also with the greater or less rapidity of the 

 firing and the duration of the operation. See COKE. 



Anthracite is a very dense natural variety of carbon, its specific gravity varying from 

 1'390 to 1-7. It differs considerably in quality, some kinds being almost as free from 

 extraneous matters as graphite, while others approach nearer to the nature of coals. 

 Thus the hydrogen in anthracite oscillates between 1 - and 4'0 per cent. Some varieties 

 of coal have only 4'5 to 5'0 per cent, of hydrogen, thus approximating to those anthracites 

 which have high hydrogens. See ANTUKACITK and COAL 



Charcoal. There are several varieties of charcoal : among them may be mentioned 

 those from wood, bones, and the peculiar substance found between the layers of 

 certain pit coals, and known as ' mineral charcoal.' Ordinary charcoal from wood 

 contains many substances besides carbon, among which may be mentioned oxygen, 

 hydrogen, traces of nitrogen, and ashes. 



Bone-charcoal contains a large quantity of earthy phosphates and carbonates, 

 besides other matters. See CHARCOAL. 



For a description of the method of preparing the variety of carbon known as 

 Lamp-Black, see LAMP-BLACK. 



The description of the charcoal best adapted for pyrotechnic purposes will be found 

 under the head GUNPOWDER. 



Carbon combines with several elements, forming in general well-marked and highly 

 important substances. Several of these compounds will bo found described under 

 the heads CARBONIC ACID, CARBON BISULPHIDE, HYDROCARBON, &c. 



CARBON, BISULPHIDE OF, or CARBON BISULPHIDE (formerly 

 Carburet of Sulphur or Sulphuret of Carbon, also called by the elder chemists tho 

 Alcohol of Sulphur). A limpid, volatile, colourless, highly refractive liquid, possessing 

 a penetrating fetid smell and an acrid burning taste. Its specific gravity is T27 ; its 

 formula is CS 2 . 



Bisulphide of carbon may be prepared by distilling, in a porcelain retort, pyrites, 

 the bisulphide (bisulphuret) of iron, with a fourth of its weight of well-dried char- 

 coal, both in a state of fine powder and intimately mixed. The vapour from the 

 retort is conducted to the bottom of a bottle filled with cold water to condense it. 



The method now usually employed for preparing bisulphide of carbon consists in 

 passing tho vapour of sulphur over charcoal or coke heated to redness. In Peroucel's 

 apparatus, a large cylindrical fire-clay retort, set vertically, is filled with pieces of 

 coke, and strongly heated. Sulphur is then introduced through a special tubulurc, 

 and the vapour, formed by volatilisation of the sulphur, combines with the heated 

 carbon. The vapours of bisulphide of carbon thus formed are conducted first into a 

 receiver, where a portion condenses, and then through a worm in a condensing appa- 

 ratus, where the remainder is liquefied. 



The crude bisulphide of carbon thus obtained may be purified by re-distillation 

 over either zinc or bichloride of mercury (corrosive sublimate). 



The bisulphide of carbon is insoluble in water, but it is soluble in alcohol. It 

 dissolves sulphur, phosphorus, and iodine. The solution of phosphorus in this liquid 

 has been employed for electrotyping very delicate objects, such as grasses, flowers, 

 feathers, &c. Any of these are dipped into the solution : by a short exposure in the 

 air the bisulphide of carbon evaporates and leaves a film of phosphorus on the surfaces ; 

 they are then dipped into nitrate of silver, by which silver is precipitated in an 

 exceedingly minute film, upon which, by the electrotype process, any thickness of 

 silver, gold, or copper can be deposited. If a few drops of the bisulphide of carbon 

 are put in a solution of the cyanide of silver, from which the metal is being deposited 

 by the electroplating process, it covers the article quite brightly, whereas, without the 

 bisulphide, the precipitated metal would be dull. See ELECTROTYPE. 



Bisulphide of carbon is an excellent solvent of caoutchouc, and is therefore largely 

 used in the vulcanisation of India-rubber. It also dissolves fats and oils, and is 

 consequently employed in extracting fat from bones, shoddy, and other greasy refuse, 

 and in dissolving oils from seeds ; the last traces of olive oil may thus be obtained 

 from the compressed pulp of the olive after having yielded the greater portion of the 

 oil by expression. Liquid bisulphide of carbon is remarkable for its high dispersive 

 power, and hollow glass prisms filled with tho bisulphide are often used in optical 

 researches. As tho liquid has never been frozen, it has been occasionally employed in 

 the construction of thermometers for measuring very low temperatures. Bisulphide 

 of carbon is highly inflammable, and the vapour, if mixed with nitric oxide, burns 

 with an intense light possessing strong actinic properties ; hence this light has boon 

 employed for photographic purposes. The vapour of bisulphide of carbon is highly 



VOL. I. 3 A 



