BLEACITING OF COTTON AND LINEN FAIIRICS.—The substances requiring to begot rid of in the purification of cotton and linen cloth arc (1) the organic coloring matter natur a' ly present in the fiber; (2) resinous and fatty bodies, also inherent in the fiber; (3) weavers' dressing and perspiration taken up during the process of spinning; and (4) certain .saline or earthy substances. The first stage in the 13. is the singeing of the cloth, which is accomplished by drawing the cloth rapidly over a red-hot iron cylinder, or a numerous series of gas jets, which burn off the minute particles of fiber, resembling in appearance short hairs or down, and leave the cloth perfectly smooth. The second stage is the washing or scouring of the cloth. which consists in rolling up the pieces of calico or linen into bundles like coils of rope, and throwing a number of pieces into a large vat among lukewarm water, and allowing them to lie till fermentation begins, and proceeds some length, when the cloth is taken nut, autl thoroughly washed in the dash-wheels; which are large horizontal cylinders divided into several compartments, into each of which a stream of water keeps running while the wheel is turning. The third stage is boiling with lime-water, or bucking. The apparatus employed is called the banking or bucking trier, and consists of two compartments. The lower part is a boiler containing the lime-water, and the upper part is n capacious circular tank. into which the cloth in bundles, es it comes from the dash-v:heets, is placed. By au ingenio4 arrangement, the lime-water is alternately forced up, by the compression of the steam, through a pipe into the upper compartment, and falls in a shower upon the cloth, through which it perco lates and sinks again through perforations into the boiler, to be again propelled into the upper compartment. Instead of using lime alone, a mixture of lime and carbonate of soda (NaOCO,) is occasionally employed, which acts by forming the inert carbonate of lime or chalk and caustic soda (Nat)), which possesses high detergent proper ties. The chemical action which the boiling lye exerts on the cloth is in the formation of a soap with the resinous and fatty substances naturally inherent in the cotton or linen fiber, or communicated to it in the process of weaving, the greater portion of which is detached by the lye in the bucking kier and ultimately removed by a subsequent washing with water. This takes place either in the dash-wheels, or in a more effectual washing
arrangement, consisting of a series of boxes or vats of different depths, placed side by side, into which the cloth is made to dip successively by passing over and under two sets of rollers. As the cloth moves on from the lower vats to the higher, it is passing from the soiled water to the more pure, as a stream •of pure water is kept constantly running through the vats from the higher to the lower. The fourth eage in B. is the souring or chemicking in dilute sulphuric acid, of the strength of one gallon of the acid to from 25 to 30 gallons of water. The weak acid liquid is put into a large stone vat, and the goods are steeped in it. The acid acts beneficially in removing tha remaining traces of the lime-soap which have adhered to the cloth, and a second washing in water, followed by bucking or scouring in soda lye, and a third washing in water are generally found necessary to obtain the cloth in the condition best suited for the subsequent opera tions. The fifth stage is chemieking with B. liquor, obtained by dissolving B. powder (q.v.) in water, and allowing the impurities or insoluble matter to subside. The B. liquor is much diluted with water, and the cloth is steeped in it for about six hours, then taken out, and allowed to soak for other six hours in a second vat containing water, after which it is drawn out and exposed to the atmosphere. when the carbonic acid of the air sets free a portion of the chlorine from the B. powder, imbibed by the cloth. The sixth stage is another souring process, during which the cloth is immersed for about four hours in a steeping vat, containing dilute sulphuric acid of the strength rang ing from 1 to S gallons of acid in 200 gallons of water. This acid liquid, as it soaks the cloth, encounters the B. liquid which previously saturated the fiber of the cloth, and the acid combining with the lime of the B. the chlorine, which attacks the remaining traces of color and removes them from the cloth.