POUNDS.
In addition to the aromatic and fatty com pounds, others are known which do not prop erly come under either heading. Thus the structural formula of furfuran contains a closed ring, formed by the union of four atoms of carbon and one of oxygen. Closed rings, consisting of three, four and five atoms of carbon, are also known. The pronounced analogies and affinities that exist among the members of the aromatic and fatty groups, respectively, have forced those two groups upon the attention of chemists. Those com pounds of carbon which are not strictly in cluded within either have not yet been classified upon a similarly broad basis.
The principal phenomena of the carbon compounds are given under special headings. In addition to those already given, see, par ticularly, ISOMEXISM ; and RADICAL For an excellent presentation of the whole subject, consult Hjelt, 'Principles of General Organic Chemistry.) Among the inorganic carbon compounds the more important are dealt with under sepa rate headings: see CARBONIC OXIDE, CARBON DIOXIDE and CARBON DISULPHIDE. With few exceptions the others are interesting chiefly as chemical substances, with no distinctive use in the arts. The most useful of all is Carbon tetrachloride (CC14), at first pro duced by exposure of chlorine and chloroform in mixture to the action of sunlight, it is now generally prepared by the chlorination of carbon disulphide in the catalytic presence of powdered aluminum chloride. It is a colorless liquid, with a pungent aromatic odor, boiling at 170° F.
i It is soluble in alcohol and ether, and is itself a solvent of fatty organic substances. Through this property it is of considerable importance in manufactures, replacing carbon disulphide, as its vapor is not inflammable. In its effects on the human system it closely resembles chloroform.
Carbon trickloride (C304) is produced by exposing ethylene chloride (or other deriva tives of ethyl and ethylene) to the action of chlorine in sunshine; or by heating propyl chloride with iodine trichloride. It is colorless and nearly tasteless, and has an aromatic odor resembling camphor. It is insoluble in water, but dissolves in all oils and in ether and alcohol, from which it crystallizes in right rhombic prisms. It vaporizes at ordinary tem peratures.
Carbon dichloride (GC14) is prepared by adding carbon trichloride in small portions to an alcoholic solution of hydrated potassium sulphide as long as sulphureted hydrogen is evolved. The liquid is then distilled, and the
distillate diluted with water, upon which the carbon dichloride separates. It is a stable liquid at zero F. and boils at 240°. It dis solves in alcohol, ether and the oils, but not in water, acids or alkalis. It absorbs bromine, in direct sunshine, forming carbon chloro bromide.
Carbon oxychloride (C0C12), a 'colorless liquid obtained when a mixture of carbon monoxide and chlorine is exposed to sunshine; and also by heating a mixture of chloroform, potassium dichromate and sulphuric acid. Its boiling point is 47° F.
Carbon suboxide (GOO, or carbon car bonyl, discovered by Diels and Wolf in 1906, is formed by treating a solution of dibrom malonyl chloride in ether with zinc shavings. The pure suboxide is a colorless liquid with a pungent odor resembling mustard oil, and is quite poisonous. It boils at 44° and is solid at —224°. At low temperatures carbon suboxide is quite stable, but between and 60° if even a trace of impurity be present, it polymerizes into a dark red solid. It is inflammable, burn ing with a bright blue flame and the emission of much smoke.
Carbon nitride (C31%), see CYANOCEN.
Carbon subnitride (Cas1,), at temperatures below 70° a solid substance crystallizing in fine white needles. Above 70° it is a liquid with an odor resembling cyanogen, boiling at 170°, and breaking into flame if heated to 265°.
Carbon oxysulphide (COS), a colorless gas soluble in water, with an odor resembling sul phureted hydrogen, and highly suffocative. It has the notable specific gravity of 2.10, and may easily be poured from one vessel into another. It is inflammable, passing when burn ing into carbon dioxide and sulphur dioxide. At zero F., and under a pressure of atmo spheres it becomes a colorless and highly re fractive liquid which dissolves sulphur, and mixes with either ether or alcohol, but not with water.
Several compounds of carbon and bromine are important to the student of chemistry. They are carbon tetrabromide (CBr4); carbon tribromide, or hexabromide (C.Br.) ; carbon dibromide (C.Br.) ; and carbon bromide (C:CBr,). The last named is spontaneously inflammable in contact with atmospheric air, and highly explosive. From these carbon com pounds with bromine springs an extended list of derivatives.