ig 5

DYEING AND CALICO PRINTING.

Therefore the triamine azaleine has been transformed into a monamine blue,by a new chemical rea&ion ; for aldehyde not only adts as a reducing agent,but converts a part of the nitrogen into ammonia. M. Lauth has alsoobtained a blue colour similar to the above by adting on methylaniline withbichromate of potassa. A blue also produced by the redudtion of magenta,but resisting the adlion of acids and also of light, was patented by Girard inJanuary, 1861, and is made by heating for several hours, at a temperature of329° F., equal weights of magenta and aniline, and allowing the whole tocool; the substance produced is mixed with weak hydrochloric acid, whichremoves excess of aniline and red dye, and leaves a purple colour, which isfurther reduced into a blue colour by boiling it several times with a mixtureof hydrochloric acid and alcohol. . It is then washed with boiling water. Thesubstance thus obtained is of a fine blue, with a coppery lustre. Bleu de Parisis another instance of the redudtion of magenta into a purple and blue. It isprepared by heating for thirty hours, in a closed vessel, at a temperature of356° F,, 1 part of anhydrous bichloride of mercury with 2 parts of aniline.The mass is then treated with boiling water, and precipitated by the additionof common salt, this treatment being repeated several times until all traces ofa green colour are removed. The blue thus produced resists the adtion ofweak acids and alkalies, but assumes a red hue when adted on by these agentsin a concentrated state. Sulphurous acid has no adtion, and it dyes animalfibres with facility. The formation of Bleu de Midhouse is one of the mostinteresting redudtions of aniline red, in a commercial point of view. It wasinvented by Messrs. Gros-Renaud and Schaeffer: in 1 litre of boiling waterthey dissolve—50 grms. bleached shellac; 18 grms. carbonate of soda; 50grms. of a solution of azaleine, made up of 125 grms. of azaleine dissolved in£ litre of water and £ litre of alcohol. The whole is kept at a boil for an hour,care being taken to maintain the fluid at its original bulk by the addition ofwater.

The most valuable and most scientific method of manufadturing aniline blueis that discovered by M. Marnas, of the firm Guinon, Marnas, and Bonnet, ofLyons, not only because it is based upon a novel chemical readtion, but alsobecause the blue is produced diredtly from aniline, which is gradually oxidisedinto a blue by means of peonine. 5 parts of peonine are mixed with 8 parts ofaniline, and the whole heated to the boiling-point for some hours, until nearlyall the material is transformed into a blue colour, which is purified by suc-cessive washings ; the first with boiling water, acidulated with sulphuric orhydrochloric acid ; the second, with hot oils of tar ; the third, with a dilutedsolution of caustic alkali; and the last with slightly acidulated water. Theazuline, or Bleu de Lyons, so prepared presents itself as a reddish powderwith a golden lustre, soluble in alcohol or methylated spirits. The solutionscan be used for dyeing or printing. According to M. Willm, azuline is com-posed of C z 4 H I2 N04, which, in his opinion, may be considered as dioxy-phenylamide, or—

N C IZ H, 0 ;

As regards the dark blue aniline colours resembling indigo, M. Fritzscheobserved, during some of his researches on aniline, the produdtion of a darkblue substance, which he prepared by mixing together equal volumes of 3