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A COMPLETE SYSTEM OF DYEING, IN ALL ITS VARIETIES To prepare mordants

DYING, is a chemical process, and consists in combining a certain colouring matter with fibres of cloth. The facility with which cloth imbibes a dye, depends upon two circumstances; the union of the cloth and the dye-stuff, and the union of the dye-stuff, or dyeing material, and the fluid in which it is dissolved. Wool unites with almost all colouring matters, silk in the next degree, cotton considerably less, and linnen the least of all. To dye cotton or linen, the dye-stuff, or colouring material, should; in many cases, be dissolved in a substance for which it has a weaker connexion than with the solvent employed in the dying of wool or silk. Thus we may use the colour called oxide of iron, dissolved in sulphuric acid, to dye wool; but to dye cotton and linen, it is necessary to dissolve it in acetous acid. Were it possible to procure a sufficient number of colouring substances, having a strong affinity for cloths, to answer all the purposes of dyeing, that art would be exceedingly simple and easy. But this is by no means the case. This difficulty has, however, been obviated by a very ingenious contrivance. Some other substance is employed which strongly unites with the cloth and the colouring matter. This substance, therefore, is previously combined with the cloth, which is then dipped into a solution containing the colour. The colour then combines with the intermediate substance, which being firmly combined with the cloth, secures the permanence of the dye. Substances employed for this purpose are denominated mordants.