428

DYEING AND CALICO PRINTING.

described) is first dissolved in alcohol, soda solution is next added, and thealcohol distilled off; the liquid is then shaken up with ether, which extradts asoft fatty matter, and afterwards treated with carbonic acid, whereby a soda-soap is precipitated. Acetic acid is then added to neutralise the alkali, andthe ensuing precipitate of organic matter is treated with ether, which, onevaporation, yields an amorphous blood-red pulverulent substance, sparinglysoluble in ether and alcohol when cold, but soluble in boiling alcohol andin benzol. As this substance is not fusible at 100°, orellin is, according toDr. Kerndt, derived from bixin, by having become altered by the adtion of airand water. - Concentrated sulphuric acid dissolves bixin as well as annatto,yielding a deep blue-coloured liquid. From these particulars it will be evidentthat the chemical history of annatto is very incomplete.

Annatto is used in dyeing and printing tissues, and for colouring oils, grease,butter, cheese, and varnishes. The shades yielded by annatto upon tissuesare bright, and resist the adtion of acids and soap; but though even chlorinescarcely affedts this dye, it fades on exposure to light and air. When annattois used alone it yields bright orange-red or orange-yellow colours, and it issometimes used to enhance the brightness of other dyes which produce red,yellow, orange, or pink. In order to dye cotton with this ware it is first dis-solved in carbonate of potassaor soda, the liquor boiled, or in some instances(according to the nature of the fabric) heated to 60°; the goods dyed are leftin the bath for a quarter of an hour, after which they are pressed out, andwashed in slightly acidified water. Better results are, however, obtained byfirst mordanting with stannate of soda and sumach, and by nearly neutralisingthe alkaline bath with sulphuric acid, so as to prevent the precipitation of thecolouring matter, and yet keep the the latter quite ready to become fixed im-mediately on the fibre. For printing on cloth a solution of annatto in caustic

potassa is used, the tissue next aged, and then placed in either

a weak acid

bath or in a weak solution of alum or chloride of tin.

For steam colours the

following mixture may be used:—

Caustic soda solution (sp. gr. 1-086, containing)about y8 per cent of adtual soda .. .. J

8 litres

6 litres i

1

Annatto paste .

750 grms.

5 kilos.

Boil for ten minutes, and add next of—

Tartaric acid.

go grms.

70 grms.

Alum .

350 ,,

1 kilo.

These preparations are thickened with gum or farina-water, and next printed,steamed, and washed. Silk requires no mordant for dyeing with annatto; thebath is made up of equal parts of annatto and crystallised carbonate of soda,to which sometimes soap is added; the temperature is 50°, and the silk isworked for a quarter of an hour. The reddish yellow or deep orange shade isrendered yellow-orange by rinsing the fabric through lemon-juice or a weaksolution of tartaric acid.

Green Colouring Matters.

Chinese Green. Lo-kao.*—During the first portion of the year 1848D. Kcechlin-Schouch found, while examining some cotton cloth brought from

* Dingler’s “Polytechn. Journ.," cxxvi., 238; cxlvi.; cxlix., 140; clxv., 397. “ Comptes

Rendus de l’Academie des Sciences," xxxv., 538. “ Bulletins de la Societe d’Encouragement,"