2i2 DYEING AND CALICO PRINTING.

of the aniline, an objedt easily attained by using chlorate of aniline instead ofchlorate of potash.

Aniline black may be considered as the result of two totally different re-adtions :—(i). Decomposition of the chlorate of aniline. (2). Oxidation of theaniline salt which is mixed up with the chlorated salt. By the decompositionof the chlorate of aniline, chlorinated produdts of aniline arise. Many degreesof substitution may be thus formed which would explain the difference of theresults. Besides these chlorinated produdts, which form only a portion of theaniline black, another produd is formed, the result of the oxidation of theaniline salt.

Aniline black, commonly so called, consists of two blacks: the one formedby the chlorinated substitutions of aniline is very stable, and resists almostall chemical reagents. Its tone, however, is not so fine as that produced bythe admixture of the second produd, formed by the oxidation of the anilinesalt. This second has an intense violet-blue colour, which when sufficientlyconcentrated is black. It is much less stable than the other, as it turns greenwith a trace of free acid, though it resists soaping. The two blacks, the brownand the blue shade combined, form the ordinary aniline black.

The earliest aniline black was printed on calico by the late Mr. John Light-foot, of Broad Oak Print-Works, Accrington, as early as July, i860. Hiscolour mixture was—

Starch-paste (i£ lbs. per gallon). 1 gallon.

Chlorate of potash.4 ozs.

j Aniline .8 „

l Hydrochloric acid (3 2° Tw.).8 „

Sal-ammoniac.4 ,,

Nitrate of copper (88° Tw.). 2 ,,

The colour was printed with madder-pink ground, aged two nights ; then theblack and pink passed through “ Higgins’s ” alkaline arseniate of soda, mixedwith water at 180° F., washed, dunged, dyed in madder, and soaped.

In 1863 this process was patented, with certain modifications. Fie describeshis method thus :—“ I take 1 gallon of water, and dissolve in it 4 ozs. chlorateof potash; to this I add aniline, or any analogous, homologous, or isomericmatter, using by preference aniline, in the proportion of 8 ozs., previouslycombining it with 8 ozs. of hydrochloric acid at 32° Tw. After stirring well,I add 1 pint of acetic acid and 8 ozs. measure of perchloride of copper at 88°Tw.; then I add 4 ozs. sal-ammoniac, or an equivalent quantity of othersuitable alkaline chloride. I steep the fabric or yarn in this solution, wringout to dry, then I expose the goods in a room at from 6o° to 70° F. for two orthree days; the goods are now passed through water alone, or a solution con-taining alkaline or metallic salts, which develope the black much sooner andbetter. The alkalies and alkaline earths may be used for raising the black,such as caustic soda, potash or ammonia, or lime-water; or the goods may bepassed, after printing and dyeing, through a box containing rollers suppliedwith ammoniacal gas (which I prefer when the black is printed along withsteam colours, prior to steaming the goods). When the black is printed alongwith madder or garancine colours they are aged, at from 60° to 70° F., forthree days, and dunged, dyed, washed, and passed through a solution of soapor dilute bleaching-lime, whereby an intense black is produced.”