Bleaching. The process of freeing textile fibers and fabrics from their natural color, and rendering them white or nearly so. The ancient method of bleaching by exposing to the action of the sun's rays and frequent wetting, has been nearly superseded (at least where the business in prosecuted on a large scale) by more complicated processes in connection with powerful chemical preparations. Among these preparations, the chief are chlorin and sulphurous acid, the latter being employed for the animal fibres (wool and silk) while the vegetable fibres are bleached with chlorin, the bleaching in both cases, however, being preceded with certain cleansing processes. Glass is bleached with salt peter, arsenic and red lead. [See Linen, Wool, Cotton]

A hundred years ago the process of bleaching was known as "whiting." We find "whiting time" spoken of in Shakespeare, and in the Merry Wives of Windsor allusion is made to the "whitsters" of Datchet Mead. At this time the work of bleaching could only be carried on in the open air in the manner followed from time immemorial, and consequently the summer months alone were suitable, the operations, if the weather happened to be unfavorable, not being always completed during the time at command. The exposure of fabrics on the open ground in England and Ireland led to a practice of stealing linen, for preventing which several severe laws were passed from time to time. For instance, George II enacted that "every person who shall, by day or night feloniously steal any linen, fustian, calico or cotton cloth; or cloth worked, woven, or made of any cotton or linen yarn mixed; or any linen or cotton tape, incle, filleting, laces, or any fabric, laid to be printed, whitened, crofted, bowked or dried to the value of 10 shillings, or shall knowingly buy or receive any such wares stolen, shall be guilty of felony without benefit of clergy." Felony of this degree was at that period punishable with death. Holland early acquired a reputation for bleaching, and it was an ordinary practice to send linens there in the spring to be returned in the autumn. The tedious character of the operations, when the use of cotton goods had increased so vastly through the inventions of improved machinery caused attention to be directed to chlorin, a gaseous substance contained in common salt, discovered in 1774. Bleaching by chlorin is now in extensive use, and allows the buyer of the cheapest calicoes a whiter material than his ancestors could obtain in costly linens after months of laborious operations. The old system of crofting or whiting is yet followed for fine fabrics in the north of Ireland.