4 i4

DYEING AND CALICO PRINTING.

a myrtle-green coloured ground is required, the goods are first dyed with quer-citron and pomegranate bark, and next with Brazil wood. It is evident thatby varying the nature of the mordant and that of the dye-ware to be super-imposed on the yellow, olive, or grey produced by quercitron or its allies, it iseasy to produce a series of various shades and colourations too many to behere enumerated. Among the more important of these mixtures are those bywhich greens are produced with yellow and blue, about which more will besaid when we shall have treated of blue colours.

We confine our observations here to the following:—When a fabric, pre-viously dyed a vat blue, is mordanted with acetate of alumina, and next dyedwith quercitron, weld, or berries, it assumes a green shade ; and when amixture is made of such materials as will produce steam blue and steamyellow, the result will be the produdtion of a green: this, except the Chinesegreen, “ Lo-kao,” and the aniline green, is the only means of producing uponfabrics a green dye of organic origin.

When cotton yarn has to be dyed yellow it is first sumached, next mor-danted with red liquor (sp. gr. 1-014), squeezed, and immediately placed in a hotquercitron bath, to which tin-salt has been added; the cotton is next washedand dried. For greens the yarn is mordanted with solution of acetate ofalumina (sp. gr. 1-034), squeezed, washed with warm water, dyed with quer-citron, aged, mordanted with weak red liquor, well squeezed, and next dyed withextradt of indigo. Silk is dyed yellow with quercitron by the following pro-cess:—It is first mordanted with alum (i part of alum and 10 of water), nextdyed in a quercitron bath, to which alum or tin-salt has been added, and thefabric next cleared with soap. If weld or fustic is applied the same process isused for silk ; and if it is desired to produce green it is first dyed yellow, andnext indigo carmine is added to the contents of the dye-beck. Wool is firstmordanted in a boiling-hot bath, made up of cream of tartar and alum, or of2 kilos, of alum and 20 grms. of sulphuric acid for 10 kilos, of wool; thespecific mordant for wool or yellow spirit consists of 4 kilos, of water, 4 kilos,of sulphuric acid, and 1 kilo, of tin crystals.

In steam-and application-colours the more or less concentrated decoftions ofthe yellow dye-ware are frequently used upon cotton, wool, mixed fabrics, andsilk; these decodtions yield when alone, and with suitable mordants, the sameshades as when applied in the dye-beck; and in association with other dyematerials for either red or blue or other colours, a large and varying series oftints are produced. Decodlion of Persian berries is often preferred for thispurpose, on account of the greater solubility of its colouring matter, and alsobecause that pigment has not, as is the case with quercitron, a tendency, whenin decodlion, to separate from the liquid. Extradts of fustic are little usedexcept in mixtures, as for green, because the yellow pigment of this ware isnot pure enough for use by itself in the steaming process, and has a tendencyto become rust-coloured.

Upon Cotton.—The fixing basis for yellow matter is alumina, to whichare added sometimes tin preparations, and sometimes also preparations ofcopper, these latter playing a secondary part and adting as oxidisers.

The following are the chief substances in use for steam-yellows:—Extradtsof quercitron, Persian berries, and fustic. The mordants are—Acetate ofalumina (weak red liquor, as for madder); small quantities of proto- and