DYEING. 



269 



ftoctsxs ingredients, if necessary. Brick colours are given by 

 ot Dyeing, dipping the silk, prepared with solution of galls, mixed 



will) a certain quantity of solution of iron, in an annotta 



bath. 



III. Processes for Dyeing Coilon or Linen, Orange, ij-c. 



Shades of 405. For the different shades of marrone, cotton is 

 mairone. galled, and then dipped, and worked in the usual man- 

 ner, in a bath to which more or less of the pyrolignite 

 of iron has been added ; it is then washed in a bth, 

 with which verdegrise has been mixed, welded, and dyed 

 in a bath of fustic, to which a solution of soda and alum 

 are sometimes added. After the cotton thus prepared 

 has been completely washed, it is well maddered, then 

 dipped in a weak solution of sulphate of copper, and, 

 lastly, in soap suds. 



Cinnamon 406. Cinnamon and mor-dore colours are given by dye- 

 and mor- ; n g them first with verdigrisc and weld ; they are then 

 dipped in a solution of sulphate or acetate of iron, wrung, 

 and dried. When dry, they are galled, in the propor- 

 tion of three ounces of galls to the pound of stuff, dried 

 again, alumed as for red, and maddered. When dyed 

 and washed, they are put into very warm soap-suds, and 

 turned until they are sufficiently bright. Decoction of 

 fustic is sometimes added in the aluming. 



Wire. 407. Accordinsto M. le Pilcur d'Apligny, n fine olive 



may be communicated to thread and cotton, by boiling 

 separately four parts of weld with one of potash, in a 

 sufficient quantity of water, and Brazil-wood which has 

 steeped over night with a little verdigrisc, and then mix- 

 ing the two solutions in different proportions, according 

 to the shade required, as a dyeing bath. The cotton 

 and thread are then dipped in it, in the usual way. 



CHAP. V. 



Proceistsfor Dyeing Black. 



408. The appearance called black, consisting strictly 

 Sh * n tne aos encc of all colour, the processes for producing 

 it upon stuffs could not with propriety be introduced ci- 

 ther under simple or compound colours ; it ought to be 

 remarked, however, that die dyer is but little influenced 

 by the prismatic distinctions, and regards as a colour 

 every palpable change produced on the appearance of 

 stuffs by the union of vegetable matter. Black is there- 

 fore usually treated, by the writers on dyeing, as a sim- 

 ple colour ; but with no great propriety, for though this 

 appearance may certainly be communicated to stuffs by 

 means of a mordant, and a single vegetable colouring 

 matter, the most beautiful and perfect blacks are given 

 by a combination of several colours. These considera- 

 tions have induced us to allot to it a separate Chapter, 

 and to give the processes for dyeing black, after having 

 described the methods of applying colours, properly so 

 called. At the same time, that we may not increase to 

 n unnecessary degree the subdivisions of this article, 

 founded upon distinctions of colour, we shall annex the 

 methods of dyeing such shades of colour as may be con- 

 sidered to be modifications of black with other colours. 

 An absolute 40Q. Perhaps no substance in nature possesses the 

 P r P ert y ^ absorbing all the rays of light ; and, accord. 

 in g' v > tnci e Mn scarcely be said to be any colouring mat- 

 ter which is capable of dyeing, alone, a deep and per- 

 manent black. The juice of the cashew-nut communi- 



black in 

 dyeing. 





cates to linen a dark colour, but it cannot be called black. 

 The same may be said of the anacardium occidentale, 

 and several other plants, which produce similar effects. 

 And, indeed, as Dr Bancroft justly remarks, a substance 

 which was perfectly black, and neither reflected nor trans- 

 mitted a single ray of light, would be absolutely invisi- 

 ble, and incapable of exciting any sensation of colour 

 whatever. What we commonly denominate black, there- 

 fore, does not result from a total absorption of the rays 

 of light, but from a feeble reflection or transmission of 

 those which are dark-coloured. Black may, accord- 

 ingly, be produced upon stuffs by a condensation of such 

 matters as reflect the dark rays most imperfectly, parti- 

 cularly blue and violet. 



410. Several subst-inces both animal and vegetable, The per- 

 possess the property of forming very dark compounds 



with the oxide of iron, at a maximum of oxidation : this 

 is the case with the prussic acid, and more especially 

 with what is called the astringent principle. Blacks are, 

 therefore, usually communicated to stuffs by means of 

 the salts of iron, and the astringent principle. A ground 

 of blue is generally given, before the application of the 

 black dye, as then a less quantity of the ingredients is 

 necessary to produce a deep tint, and the stuff is less apt 

 to be injured by the ferruginous mordant. A ground of 

 any other dark colour may be used instead of blue, but 

 the black will be inferior in deepness and glossiness. 



I. Processes fur Dyeing Wool, Black, SfC. 



411. According to the process described by Hellot, Hcllot's 

 woollen cloth, which is to be dyed black, ought previ- P 

 ously to receive a deep blue ground, to be washed in the 



river immediately after being taken out of the vat, and 

 afterwards cleansed at the fulling-mill. For a hundred 

 pounds of stuff, ten pounds of logwood, and an equal 

 quantity of Aleppo galls in powder, are put into a bag, 

 and boiled for twelve hours in a copper, with a sufficient 

 quantity of water. One-third of this bath is transferred 

 to another copper, with two pounds of verdigrise, and 

 into this the stuff is immersed, turning it continually for 

 two hours, and keeping the bath very hot, without allow- 

 ing it to boil. The stuff is then taken out, and a portion 

 of the bath, equal to the former, is put into the copper, 

 with eight pounds of sulphate of iron. While the sul- 

 phate of iron is dissolving, the fire is diminished, and 

 the bath suffered to cool for half an hour ; the stuff 19 

 again put in, moved well about for an hour, and again 

 taken out to air. The remainder of the bath is now 

 added, taking care to press the bag well, which contains 

 the dyeing ingredients. Fifteen or twenty pounds of 

 surnach are also added ; and the bath being brought just 

 to the boiling point, the ebullition is instantly checked 

 with a little cold water. Two pounds more of sulphate 

 of iron are added, and the stuff is immersed for another 

 hour. It is then taken out, washed, aired, and return- 

 ed again to the copper for another hour, during which 

 it is constantly stirred. Lastly, it is taken out, well wash- 

 ed at the river, and fulled. When the water comes off 

 clear, another bath is prepared with weld, which is made 

 to boil for a moment, apd, after being cooled, the stuff 

 is passed through it, to soften it, and give the black a 

 better body. 



412. Hellot describes another process, which is less A 

 tedious and complicated than the preceding, but it pro- pr01 

 duces an inferior black. He recommends for fifteen ells 



of deep blue clotb^ a bath composed of a pound and a. 



