D U S 



207 



D W I 



finest in Dusseldorf, the convent of Franciscans, the hos- 

 ]iital for paupers ; the five fauxbourgs, particularly the 

 fauxbourg of Neustadt; and the market-place and 

 Charles' Square. The fortifications of the town were de- 

 molished during the war of the revolution ; and the cas- 

 tle, which is now a heap of ruins, was burned in the 

 bombardment of 1 794. 



Dusseldorf possesses an academy of painting and de- 

 sign, and a college ; but it has been chiefly celebrated 

 lor its splendid gallery of paintings. This gallery was 

 carried off to Munich, and nothing was left but a single 

 picture of Cignani or Rubens, painted upon wood. It 

 has lately been sent back to the town ; and it contains 

 the chef d'oeuvres of Vandyck, Vanderwerff, Rubens, and 

 other Flemish masters. The collection of plasters and 

 designs belonging to the academy, and the physical ca- 

 binet of the college, deserve also to be noticed. 



The manufactures of Dusseldorf consist of silks, glass, 

 vinegar, and refineries of sugar. 



The chief promenades are the garden of the court, the 

 walks of Neustadt, and the Place d'Armes. 



At the distance of about half a league from the town Dusseldorf 

 stands the convent of La Trappe, where the religious ma- P 

 nufacture and sell snuff-boxes with cyphers, which are held vj^'"^ 

 in high estimation. Cromford and its manufactories, the 

 fine view from the summit of the Grafenberg, and the 

 cavern in the mountain of Klutter, are also worthy of 

 being seen. At the distance of 41 miles from Dussel- 

 dorf are the baths of Schwelm, which are much frequent- 

 ed in summer. The population of the town is 12,000, 

 Its position, according to trigonometrical observations, is 

 in East Long. 6 46' 25", North Lat. 51 13' 42". An 

 account of the Dusseldorf gallery of paintings will be 

 found in the Galerie Electorate de Dusseldorf, par Nico- 

 las de Pigage, Bale, 1777, folio; and engravings of them 

 in the Almanack of M. Mohn, entitled Niederrheinischcs 

 Taschenbuch, which is published annually. An account 

 of the baths of Schwelm will be found in Ueber den Sche- 

 trelmer Gesundbrunnen, von D. Castringius, Dortmund, 

 1800. (*) 



DWARF. See PIGMY. 



DWINA. See DVINA. 



DYEING. 



Dyeing. 1. JL/YEiNG is the art of extracting the colouring princi- 

 *" "Y"""*' pie. under its various modifications, from the different 

 substances witli which it exists in a state of combination ; 

 transferring it to stuffs, heightening its brilliancy, and 

 rendering it as far as possible permanent. It is there- 

 fore of the last importance to the dyer to ascertain the 

 nature of the colouring principle, and to determine its 

 relations with the stuffs to which it is to be applieil ; ;is 

 well as the qualities of the chemical agents which may 

 be necessary to give it fixity, and improve its beauty. 



2. Before chemistry had attained its present advan- 

 ced state, the most absurd theories were employed to 

 explain the principles of dyeing. It was long maintain- 

 ed, that the colouring matter was merely deposited in 

 the pores and cavities of the stuffs; and that the various 

 processes to which the latter were exposed, were mere 

 mechanical operations to open and dilate the interstices 

 of the cloth, or other matter to be dyed, for the recep- 

 tion of the colour. This theory, which was suggested by 

 Heilot, and adopted by Macquer, was universally admit- 

 ted to afford a true explanation of the principles of dye- 

 ing, until Bergman and Berthollet turned their attention 

 to the subject, and demonstrated, by a scries of accurate 

 experiments, that the processes of the art are in reality 

 particular exemplifications of the laws of affinity ; and 

 that the colouring matter is attached to the stuff by the 

 influence of chemical action alone. 



3. In some instances, this action is the immediate re- 

 suit of a mutual affinity subsisting between the colouring 

 principle and the stuff; while in others it is so feeble, 

 that recourse must be had to an intermediate substaiu e, 

 having a decided attraction for each, and thus serving as 

 a bond of union between them. These intermediate sub- 

 stances, so very important in the practice of dyeing, recei- 

 ved the name of mordanlx from the earlier French writers, 

 on account of the mechanical action which they were 

 supposed to exert upon the stuff; and they still retain 

 the same appellation, though the opinions which gave 

 rise to it have been completely disproved. 



4. In discussing the subject of dyeing, we propose to 



begin with a historical sketch of the origin and progress History, 

 of the art. In the next place, we shall take a view of the '* "Y""' 

 various kinds of colouring matters employed by the dyer, 

 and describe the processes to which they must be sub- 

 jected before they are presented to the stuff. We shall 

 then examine the properties of the different stuffs to 

 which dyes are usually applied; and, after considering 

 the action and preparation of mordants, give an account 

 of the methods of preparing, by means of them, the stuffs 

 for the reception of colouring matters. And, lastly, we 

 shall conclude with a detailed account of the practical 

 methods of dyeing. 



SECTION I. 

 HISTORY OP DYEING. 



5. THE perception of colour seems to be accompanied History ei 

 with immediate pleasure ; and though the effect is pro- dyeing, 

 bably heightened by association, it is so instantaneously 

 produced, that we are only conscious of the pleasing emo- 

 tion, and seldom think of searching beyond it for the 

 source of our delight. Long before we are capable of 

 analyzing our feelings, the eye is caught with the bril- 

 liancy of colour, and the splendour of illumination. Even 

 the lower animals are not altogether insensible to the 

 beauties of rich and variegated tints ; and man in his 

 rudest state, has always regarded colour as a principal 

 constituent of ornament. Nor is it only in the judgment 

 of the infant or the savage that colours rank high among 

 the elements of beauty ; in the most refined periods of 

 human society, they retain an undiminished attraction, 

 or rather acquire a more powerful influence by the culti- 

 vation of taste. " Among the several kinds of beauty," 

 says Mr Addison, " the eye takes most delight in co- 

 lours. We no where meet with a more glorious or plo.i- 

 sing show in nature, than what appears in the heavens at 

 the rising and setting of the sun, which is wholly made 

 up of those different stains of light, that show themselves 

 in clouds of a different situation. For this reason we 



