DIAZEUCTIC TONE. 211 so that the lowest tone of the higlier tetrachortl was at the same time the highest toue of the lower tetraehord. Then the diazeiiutic tone was either above the highest or below the lowest tet- rachord. ( See Greek Music. ) In the following modes the diazeuctic toue is iuarked+ : DIBDIN. Dorian e' — d' -Eolian a !Mixolydiau b — a — g — f — e— d — e — 13. DIAZO-COMPOUNDS (from Gk. Sis, dis, twice -|- (i:(j-U; old name of nitrogen, from Gk. a, fl priv. + fiietf, :6chi. to live). An impor- tant gi'oup of carbon compounds discovered by Griess in ISOO. They are produced by the action of nitrous acid on salts of amido-compounds, such as aniline hydrochloride. Thus, diazo-bcn- zene cliloride is produced according to the follow- ing equation: C.H,XH:.HC1 + HXO, = C,H,X = X.Cl + 2H:0. Anillnt^ hydro- Kitrous Diazo-beuzene chloride aiid chloride Tile fatty amines (see Amines) cannot thus be converted into diazocompounds. The diazo-conipounds are usually obtained in solution and are immediately transformed into other compounds. They may, however, be readily isolated. When pure and dry, they are colorless crystalline solids, chemically unstable and more or less highly explosive, ilany important carbon compounds, including a number of very valuable dyestuffs { see Coal-Tab Colors ) . can be pre- pared from the diazocompounds. The following are the most important transformations of these peculiar substances: (1) When an aqueous solution of a diazo-com- pound is warmed, the compound is transformed into the corresponding phenol. (See Phenols.) Thus, diazo-benzene nitrate (obtained by the action of nitrous acid on aniline nitrate) gives ordinary phenol (carbolic acid), according to the following equation: C„H,X = X.XO, -f H,0 = Diazo-benzene nitrate Water CcH.OH + N. + HXO, Carbolic acid Nitrogen Nitric acid (2) When heated with alcohol, a diazo-com- pound is transformed into the corresponding hydrocarbon. Thus, diazo-benzene chloride yields benzene, as follows: C,H,N„=X.C1-J- C.H,OH = Diazo-benzene Alcohol chloride C.H, + CH,CHO + X, + Ha Benzene Aldehyde (3) With cuprous salts diazocompounds form additive products, which, on heating, break up according to the following equations: CJI;X=N.Cl.Cu,Cl, = C,H,C1 + Cu.ri, + N, . Diazo-benzenp chloride, Chloro- Ciii)roii8 cnprouB chloride benzene chloride r.H,N= X.I.Cu J, = r„HJ 4- Cu J. + N. Diazo-bf-nz^np io(Ji<Ie, Iod'»- ruproiia enproufl iodide benzene iodide c^^ = X. ( ex ) .Cu; ( ex ) .= Diazo-benzene c.vnnide, cuprous cyanide C,H,eX + Cu:(CX), + N, Ph«'n.vl Cnproii» cyanide cyanide (4) When diazo-compounds are subjected to the reducing action of stannous chloride and hydrochloric acid, they are transformed into de- rivatives of hydrazine (q.v.), the well-known phenyl-hydrazii.e, for instance, being thus read- ily obtained from diazo-benzene compounds. The four transformations just noted may evi- dently be employed in the preparation of the im- portant series of aromatic compounds known re- spectively as hydrocarbons, phenols, halogen derivatives of the hydrocarbons, and hydrazines. Moreover, since the cyanides (nitrites) "of liydro- carbon radicals are readily transformed into the corresi)onding acids (e.g. CJljCX into benzoic acid, t'sH;COOH), the aromatic acids, too, may be added to the list of substances that may be prepared from diazo-compounds. And, remem- bering that the diazo-compounds themselves arc readily obtained from the amido-compounds, which are in turn readily obtained by the trans- formation of the hydrocarbons abundantly found in coal-tar. it is easy to see that, by means of the diazo-reaction, there is no dilliculty whatever in obtaining a very large number of" organic com- pounds. See also Azo-Bexzexe. Diazo-Bexzexe. The mother-substance of the diazo-compounds is diazo-benzene, a very unsta- ble substance, which has never been isolated in the pure state, and which probably corresponds to the formula C^H^X = X'.OH. DIBES. An English name of a game of great antiquity, played by boys and girls. In Russia it is played sometimes even by old men. It con- sists in throwing up the small joint-bones of the legs of sheep, and catching them tirst on the palm and then on the back of the hand. The antiquity of this simple kind of play is proved by figures on Grecian vases, on which women are seen kneeling and engaged in the sport. In Scot- land, where the game is more usually played with small pebbles or shells, it is called 'the chucks.' Out of -dibbs' developed the game of jack-stones. DIBOJIN, Charles (1745-1814). An English dramatist and song-writer. He was bom at Southampton, and began his literary career with an opera called The l^hepherd's Artifice, produced at Covent Garden Theatre in 1762. Already a popular actor, he gained great celebrity, in 1789, by a series of musical entertainments, entitled The Whim of the Moment. He died in straitened circumstances. Dibdin wrote about seventy dra- matic pieces, and, according to his own account, 900 songs, of which the best known are "Poor Jack" and "Tom Bowling." He composed the music of his songs and sang them himself. Of his sea-songs, he said: (they) "have been the solace of sailors in long voyages, in storms, in battle: and they have been quoted in mutinies to the restoration of order and discipline." His sons, Charles and Thomas John, wrote songs and dramas. Consult Dibdin, The Dihdins (London, 1888). DIBDIN, Thomas Frogkall (1776-1847). A Britisli bililiographer. He was born at Calcutta, India; studied at Oxford, and, after a short career as a lawyer, entered the Established Church in 1804. He began his work in 1707, and, until 1844. produced a great number of publica- tions of a bibliographical and antiquarian char- acter, which, while they show an immen-ie amount of labor, are so full of inaccuracies as to be almost totallv unreliable. His Bibliomania
