Nothing but practice will qualify you for this and all pattern dyeing: the way, and the only good way to obtain practice, is to work with all possible regularity. In the dyeing of fancy cloths in the clothing districts of Yorkshire, Gloucestershire, and other fine cloth manufactories, the manufacturers who dye their own cloths, as well as dyers of the greatest eminence, always number, measure, weigh, and time all the component parts of their various processes of dyeing. Such in fact ought to be the universal practice; and then a person of ordinary abilities may soon be able to perfect his processes and obtain the best results.
Hence, however, it is very necessary that the dyer should have a competent knowledge of chemistry and drugs, that he may be able to judge of the goodness of the articles which he uses, and of the numerous and extraordinary combinations into which they enter. To chemistry, in particular, every able and scientific dyer must be largely indebted; for this reason it is that we have endeavoured, in this introductory chapter, to sketch some of the most important facts in this universal and interesting science.
In possession of these qualifications, and working upon the above plan, the dyer can never be far from the desired result in all his processes. His deviations, if any, will be few, as from his knowledge, he will soon perceive the first approach of any incorrectness, and be able to adjust it generally without much inconvenience.
The chemical terms now introduced into treatises on dyeing are chiefly taken from the Greek language, and are used in such a manner as to convey, by their etymology, an idea of the nature of the substances to which they are applied. Oxygen implies the producer of acid: hydrogen, the producer of water; nitrogen, the producer of nitre, &c. The term gas has been explained above. Caloric is a term used by chemists for heat; but caloric is used in a more extensive signification than the term heat, thus: although a gas might possess no sensible heat, yet being in a gaseous state, it is assumed to contain a certain portion of caloric which keeps it in its gaseous state; the same observation will apply to liquids whether aqueous, oleous, or metallic.
All the measures mentioned in this work unless otherwise described, are those usually called in this country WINE MEASURE, and not those which have been introduced by a late act of parliament, called IMPERIAL MEASURES.
[2] Cochineal was at first supposed to be a grain, which name it still retains by way of eminence among dyers. Ure.
[3] For the cultivation of Woad in England, see Parish's paper in vol. xii. of the Bath Society's Report, or Tilloch's Mag. vol. xxxviii.
[4] What are called iron moulds in cotton, linen, &c. are, it is well known, nothing but the marks of a buff colour, usually left by ink and other matters which contain iron: acids, of course, dissolve, and discharge these buff colours; the oxalic acid does so without decomposing the cloth.
[5] "Acetate of Alumina is now most frequently made for the Calico-Printers by dissolving alum in a solution of crude acetate of lime, (pyrolignite); a gallon of the acetate, of specific gravity, 1.050 or 1.060, being used with two pounds and three-quarters of alum. A sulphate of lime is formed, which precipitates, while an acetate of alumina mixed with some alum floats above. The acetate of alumina employed as a mordant for chintz, is still commonly made by the mutual decomposition of alum and acetate of lead."—Ure's Berthollet, vol. ii. p. 331.
[6] Berthollet.