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2. Dying.
This art is yet imperfectly understood; but the progress ofchemical scieifce will doubtless lead to its improvement. Wooland silk are more easily dyed than the vegetable substances flaxand cotton ; but the colours of the former are both more brilliantand permanent than those of the latter.
Fast and Fancy Dyes .—The dyes or tints given to goods arepartly fast and permanent, or such as can resist the action of air,soap and water ; and partly fugitive, or such as yield to the ac-tion of these substances. The blue dyes from indigo, the bufffrom iron, and the green from these united, are fast colours;but those from the tincture of woods and other vegetables aregenerally fugitive, especially on cotton and linen.
Turhey-red, Sfc .—The beautiful and permanent colour termedTurkey, or Adrianople red, is the most expensive and difficultto be given of all the cotton dyes. It was introduced by M. Pa-pillon, a Frenchman ; and an extensive dye-work was erectedon the banks of the Clyde by the late Mr Dale. * The secret,however, having been discovered, 10 large works were erectedin the neighbourhood of Glasgow which employ from 3 to 400persons. Besides these permanent colours, fancy dyes are givento cotton cloths and yarns as well as to linens, and the blue-dy-ing of linen yarn for checks, stripes, threads, &c. is an extensivebranch of the art.
Discharging colours .—There is a peculiar method of discharg-ing colours, connected with the dying business, which it maynot be improper to notice here. Bandana handkerchiefs, whichare generally of one uniform colour, are folded in squares of thesize intended, and being placed in a press between two metalplates, with parallel orifices, the bleaching liquor (oxymuriaticacid) is poured into the perforations, and the colour is dis-charged. The handkerchiefs are thus spotted, as the parts notexposed to the action of the acid retain their original colour.There are from 42 to 50 presses in Scotland for this work, situ-ated in the neighbourhood of Glasgow , each press generally re-quires two men who can finish 60 dozen of handkerchiefs perday. At Paisley, there are some Bandanas made of silk, butthe spots are produced by tying with a thread each distinct placein the handkerchief intended to be kept white; the cloth is thendyed, the parts tied up receiving none of the colouring mat-ter. This is the eastern method of spotting silk and cottonhandkerchiefs.