Page:The American Cyclopædia (1879) Volume VI.djvu/350

34:2 DYEING Its aqneous extract yields beautiful yel- low precipitates with alum, chloride of tin, and acetate of lead. Alum and cream of tartar are generally used together as the mordant for this color. The use of weld for wool dyeing has been abandoned in England, but is retained on the continent, and is also largely used there in silk dyeing. It has only about one fourth the tinctorial power of quercitron, which has so greatly superseded it. Fustic or yellow wood is generally considered the most suitable material for working with other colors, and is therefore extensively used. Quer- citron bark has, however, more tinctorial power, and is largely used. Either dyestuff is made into a decoction with boiling water, and the goods are mordanted with alum, to which there is sometimes added chloride of tin, which increases the brilliancy of the color. Wool is dyed red with cochineal, with madder, and with coal-tar colors. Madder is used for the more common goods, but for the finer, on ac- count of their superior brilliancy, cochineal colors, and for their peculiar hues the coal-tar colors, are used. The process with madder consists in mordanting the goods with a warm solution of alum and cream of tartar, and afterward immersing them in a madder bath, containing two parts of madder, by weight, to one of the goods, which after dyeing are thoroughly washed. The preparations of mad- der, such as flowers of madder and garancine, may be used in place of the pulverized root. The dried and ground root, besides containing the two chief coloring principles, alizarine and purpurine, also contains some resinous fawn- colored dyes, which exert an injurious effect when dissolved in the dye ; but as they require a higher heat than the two named, it is usual in making a decoction of madder root not to raise it to the boiling point. Flowers of mad- der and garancine contain scarcely any other coloring matters than alizarine and purpurine. Instead of using the ground root which has undergone a slow fermentation by which the alizarine and purpurine are produced, E. Kopp has invented a process entirely different, and which consists in dissolving the unaltered coloring principle of the living plant, rubian, in sulphurous acid, and subsequently changing it into alizarine and purpurine by the action of sulphuric acid and heat. The process is extensively employed by MM. Schaif and Lauth of Strasburg. (See MADDER.) Woollen may be dyed a scarlet or a crimson by the use of cochineal. In dyeing scarlet, cream of tartar, chloride of tin, and cochineal are used together as a mordant, the dyeing liquor being composed of cochineal and tin salt. If a crimson color is desired, it may be communicated by a single process, or the material may be first dyed scarlet. If by one process, a solution of 2 oz. of alum and 1 of cream of tartar for every pound of stuff is used aa a mordant, the dyeing being done with an ounce of cochineal and a smaller quantity of tin salt than is used for dyeing scarlet. Scarlet may be turned to crim- son by using a bath containing an alkaline solu- tion or alum, the latter being generally used. Wool is usually dyed green by first dyeing it blue, mordanting with cream of tartar and alum, and dyeing again with fustic or weld. Sometimes, as in dyeing the woollen fabric for covering billiard tables, alum, cream of tartar, Saxony blue, and fustic are all put together and the cloth immersed in the mixture and boiled two hours, then thoroughly washed and bright- ened in a second bath of fustic and Saxony blue. Woollen goods may be dyed black with aniline black or with a salt of iron and tannic or gallic acid. To obtain the finest and fastest colors, they are first dyed with madder or indigo. The goods are then mordanted with sulphate of iron and put in a bath made of a decoction of logwood, sumach, or galls. The celebrated Sedan black is produced by first dyeing blue with woad, washing, again dyeing with sumach and logwood, boiling three hours, and then adding a solution of sulphate of iron. Wool, by reason of its great affinity for tar colors, may be dyed with them of almost any hue or shade by simple immersion, subsequent exposure to the air, and washing. Silk, after treatment in the hot soap bath to remove the varnish, may be dyed without bleaching (sulphuring) ; but when bright colors are required the goods should be bleached. It may be dyed black by means of logwood with an iron mordant ; with logwood and bichromate of potash ; with gallic or tannic acid in any form, with iron mordant ; or, according to a recent method of Jules Per- soz, by mordanting with bichromate of potash and sulpbate of copper and immersing in a solution of aniline. Silk may be dyed blue with indigo, Prussian blue, or aniline blue. When indigo is used, it is commonly in the form of sulphindigotic acid, or indigo carmine. It is dyed with Prussian blue by using a mordant of nitrate of iron. Napoleon blue is produced by using a mordant of nitrate of iron and chlo- ride of tin, passing through a boiling soap so- lution, and dyeing with a solution of ferrocy- anide of potassium to which has been added hydrochloric acid. The brilliancy is increased by subsequent treatment with solution of am- monia. Silk is dyed with aniline blue by sim- ple immersion for a sufficient time in a solution of the dye in wood spirit or alcohol. Coal-tar colors are now used extensively in dyeing silk, especially the various shades of red, and have largely taken the place of cochineal, al- though the latter continues to hold its superi- ority for producing scarlet and crimson. In cochineal dyeing the silk is mordanted with alum, washed, and then immersed in a dye bath made by boiling 2 oz. of white galls for every pound of silk, adding 3 oz. of powdered cochineal, and afterward one fourth of an ounce of cream of tartar, and when it is dis- solved, the same quantity of chloride of tin. Silk is more often dyed with fuchsine, coral- line, or naphthaline red, the process being the