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CHAPTER V.

COLOURING MATTERS OF VARIOUS ORIGIN.

Chica, Crajura, or Carajara.

PIGMENT used by the Indians in Central America, and which is applied

to their bodies mixed with the fat of the alligator. The chica is obtainedfrom the leaves of the Bignonia chica, which the Indians boil for a long timewith water, decant the liquid, which contains a reddish-coloured fecula in sus-pension, and add to the liquid some particles of the bark of a tree known asaryane, which causes the precipitation of the colouring matter. This, whendried, is a vermillion-red, tasteless and inodorous mass, specifically heavierthan water ; it soils the fingers, and assumes, when rubbed on the nail, ametallic aspedt. This substance is decomposed by heat without previousfusion.

Chica is insoluble in water, but boiling alcohol, at 36 per cent, dissolves it,becoming thus ruby-coloured. It is also soluble in ether. The alcoholicsolution is not precipitated by water unless heat is simultaneously applied.Alkalies dissolve chica with a vinous-red colour, the solution being precipi-tated by acids. Caustic potassa, ammonia, and carbonate of potassa dissolvechica, the solutions exhibiting an orange or orange-red colour. Con-centrated acetic and hydrochloric acids also dissolve this substance, yieldinga reddish-brown liquid ; chlorine turns its original colour to a bright brown;with dilute sulphuric acid it yields, when heated, an orange liquid, from which,on cooling, a granular, orange-red mass is separated, while addition of ammoniacauses in the remaining liquid the formation of a deep purplish precipitate.When chica is treated, in a sealed tube, with a mixture of any alkali and glucose,it yields, by reduction, a bluish liquid, which becomes rapidly brown again onexposure to air, and from which hydrochloric acid precipitates an orange-redflocculent matter. Nitric acid attacks chica, converting it into a mixture ofpicric, oxalic, anisic, and hydrocyanic acids.

According to M. Boussingault, chica—which, he says, contains no nitrogen—dyes cotton a yellowish-orange colour. Dr. Erdmann assigns to chica theformula CsH80 3 ,—that is to say, it is an isomer of anisic acid.

Chica is rarely met with in Europe, but, from the results of experimentsmade to ascertain its applicability as a dye, it was found that after treatmentwith an acid, or with muriate of tin, it would dye very deep shades uponwool; and by treating it with acid, and washing the free acid away, it yields,with mordanted cotton (alumina and tin mordants), shades very similarto those produced by lac-dye. The colours are not so bright as those of