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 in the flamboyant style and many other works of art, the most striking features are the height of the nave and the boldness of the columns supporting the vaulting. The chief of the other churches of Amiens is St Germain (15th century), which has some good stained glass. The hôtel de ville, begun in 1550, a belfry of the 14th and 18th centuries and several old mansions are of interest. Amiens has a rich library and admirable collections of paintings, sculptures and antiquities in the museum of Picardy. Its learned associations include the Société des Antiquaires de Picardie, by whom the museum was built in 1854–1864. The city is the seat of a bishop, a prefect, a court of appeal and a court of assizes, and headquarters of the II. Army Corps. There are also tribunals of first instance and of commerce, a board of trade-arbitrators, a chamber of commerce and a branch of the Bank of France. The educational institutions include lycées for boys and girls, training-colleges for teachers, a preparatory school of medicine, a school of music and a school of iron-working and wood-working. The textile industries for which Amiens has been celebrated since the middle ages include manufactures of velvet, cotton-, wool-, silk-, hemp- and flax-spinning, and the weaving of hosiery and a variety of mixed fabrics. Manufactures of machinery, chemicals, blacking, polish and sugar, and printing, dyeing and iron-founding are also carried on. Market gardens, known as hortillonnages, intersected by small canals derived from the Somme and Avre, cover a considerable area to the north-east of Amiens; and the city has trade in vegetables, as well as in grain, sugar, wool, oil-seeds and the duck-pasties and macaroons for which it is renowned.

Amiens occupies the site of the ancient Samarobriva, capital of the Ambiani, from whom it probably derives its name. At the beginning of the 4th century Christianity was preached there by St Firmin, its first bishop. During the middle ages its territory formed the countship of Amiénois. The authority of the counts was, however, balanced by that of the bishops, and early in the 12th century the citizens, profiting by this rivalry, gained a charter of enfranchisement. The fief became for the first time a dependency of the French crown in 1185, when Philip of Alsace, count of Flanders, ceded it to Philip Augustus. It more than once passed out of the power of the French kings, notably in 1435, when, by the treaty of Arras, it came into the possession of the dukes of Burgundy, to whom it belonged till 1477. Surprised by the Spaniards in 1597, the city was recaptured from them after a long siege by Henry IV. Till 1790 it was the capital of the gouvernement of (q.v.). The famous treaty between Great Britain, France, Spain and Holland which took its name from Amiens was signed in the hôtel de ville on the 25th of March 1802. During the war between France and Germany, Amiens, after an important action, fell into the hands of the Prussians on the 28th of November 1870. (See .)

AMINES, in chemistry, derivatives of ammonia in which one or more of the hydrogen atoms are replaced by alkyl or aryl groups. The replacement of one hydrogen atom by one alkyl or aryl group gives rise to primary amines; of two hydrogen atoms by two groups, to secondary amines; of three hydrogen atoms by three groups, to tertiary amines. The tertiary amines possess the power of combining with one molecular proportion of an alkyl iodide to form quaternary ammonium salts. The structural relations of these compounds may be shown thus: ;

Aliphatic amines.—These compounds possess properties very similar to those of ammonia, the lowest members of the series being combustible gases readily soluble in water. The next higher members of the series are liquids of low boiling point also readily soluble in water, the solubility and volatility, however, decreasing with the increasing carbon content of the molecule, until the highest members of the series are odourless solids of high boiling point and are insoluble in water. They are all strong bases, readily forming salts with the mineral acids and double salts with the chlorides of gold, platinum and mercury. They are ionized in aqueous solution to a much greater extent than ammonia, the quaternary ammonium bases being the most ionized, and the secondary bases being more strongly ionized than the primary or tertiary bases. For data concerning the conductivity of the organic bases see G. Bredig (Zeit. für phys. Chem., 1894, 13, p. 289).

Many methods have been devised for the preparation of the amines, the first amine having been isolated in 1849 by A. Wurtz on boiling methyl isocyanate with caustic potash, CON·CH3 + 2KHO=CH3NH2 + K2CO3. The primary amines may also be prepared by heating the alkyl iodides with ammonia (A. W. Hofmann); by the reduction of nitriles with alcohol and sodium (A. Ladenburg, Ber., 1886, 19, p. 783); by heating the esters of nitric acid with alcoholic ammonia at 100° C. (O. Wallach, Ber., 1881, 14, p. 421); by the action of reducing agents on nitroparaffins; by the action of zinc and hydrochloric acid on aldehyde ammonias (German Patent 73,812); by the reduction of the phenylhydrazones and oximes of aldehydes and ketones with sodium amalgam in the presence of alcohol and sodium acetate (J. Tafel, Ber., 1886, 19, p. 1925; 1889, 22, p. 1854; H. Goldschmidt, Ber., 1886, 19, p. 3232); by the action of dilute hydrochloric acid on the isonitriles, R·NC + 2H2O=R·NH2 + H2CO2; by heating the mustard oils with a mineral acid, by the hydrolysis of the alkyl phthalimides (S. Gabriel, Ber., 1887, 20, p. 2224; 1891, 24, p. 3104),

by distilling the amino-acids with baryta; by the action of bromine and caustic potash on the acid-amides (A. W. Hofmann, Ber., 1885, 18, p. 2734; 1886, 19, p. 1822); CH3CONH2→CH3CONHBr→CH3CONKBr→CH3NCO→CH3NH2; and by the hydrolysis of substituted urethanes (Th. Curtius, Ber., 1894, 27, p. 779; 1896, 29, p. 1166),

The secondary amines are prepared, together with the primary and tertiary, by the action of ammonia on the alkyl iodides (see below), or by the hydrolysis of para-nitroso derivatives of tertiary aromatic amines, such as para-nitrosodimethylaniline, thus: NO·C6H4·N(CH3)2 + H2O = NO·C6H4·OH + NH(CH3)2. By the action of ammonia on the alkyl iodides a complex mixture of primary, secondary and tertiary amines, along with a quaternary ammonium salt, is obtained, the separation of which is difficult. The method worked out by A. W. Hofmann is as follows:—the mixture is distilled with caustic potash, when the primary, secondary and tertiary amines distil over, and the quaternary ammonium salt remains behind unaffected. The aqueous solution of the amines is now shaken up with diethyl oxalate, when the primary amine forms a crystalline dialkyl oxamide and the secondary amine an insoluble liquid, which is an ethyl dialkyl oxamate, the tertiary amine not reacting: (CO2C2H5)2 + 2NH2R = (CO·NHR)2 + 2C2H5OH; (CO2C2H5)2 + NHR2 = C2H5O2C·CONR2 + C2H5OH. The tertiary amine is then distilled off, the residual products separated by filtration and finally hydrolysed by a caustic alkali.

The primary, secondary and tertiary amines may be readily distinguished by their behaviour with various reagents. Primary amines when heated with alcoholic potash and chloroform yield isonitriles, which are readily detected by their offensive smell. The secondary and tertiary amines do not give this reaction. With nitrous acid, the primary amines yield alcohols, the secondary amines yield nitrosamines and the tertiary amines do not react: R·NH2 + ONOH = R·OH + N2 + H2O; R2NH + ONOH = R2N·NO + H2O. With benzene sulphochloride in the presence of alkali, the primary amines yield compounds of the type C6H5SO2NHR, soluble in alkalies, whilst the secondary amines