ARNATTO 209 



now cultivated in Guiana, St. Domingo, and in the East Indies. In the ' Annalos de 

 Chimio ' we have tho following description of the arnatto tree : ' The tree produces 

 oblong bristled pods, somewhat resembling those of a chestnut. These are at first 

 of a beautiful rose-colour, but, as they ripen, change to a dark brown ; and bursting 

 open, display a splendid crimson farina or pulp, in which are contained from thirty to 

 forty seeds, somewhat resembling raisin-stones. As soon as they arrive at maturity, 

 these pods are gathered, divested of their husks, and bruised. Their pulpy substance, 

 which seems to bo tho only part which constitutes the dye, is then put into a cistern, 

 with just enough water to cover it, and in this situation it remains for seven or eight 

 days, or until tho liquor begins to ferment, which, however, may require as many 

 weeks, according to circumstances. It is then strongly agitated with wooden paddles 

 or beaters, to promote the separation of tho pulp from the seeds. This operation is 

 continued until these have no longer any of the colouring-matter adhering to them ; 

 it is then passed through a sieve, and afterwards boiled, the colouring-matter being 

 thrown to the surface in the form of scum, or, -otherwise allowed to subside : in either 

 case, it is boiled in coppers till reduced to a paste, when it is made into cakes and 

 dried.' 



Instead of this long and painful labour, which occasions diseases by the putrefac- 

 tion induced, and which affords a spoiled product, Leblond proposed simply to wash 

 the seeds of the bixa till they are entirely deprived of their colour, which lies 

 wholly on their surface ; to precipitate the colour by means of vinegar or lemon- 

 juice, and to boil it up in the ordinary manner, or to drain it in bags, as is practised 

 with indigo. 



The experiments which Vauquolin made on the seeds of the bixa, imported by 

 Leblond, confirmed the efficacy of the process which he proposed ; and the dyers 

 ascertained that tho arnatto obtained in this manner was worth at least four times 

 more than that of commerce ; that, moreover, it was more easily employed ; that it 

 required less solvent ; that it gave less trouble in the copper, and furnished a purer 

 colour. 



Arnatto dissolves better and more readily in alcohol than in water, when it is 

 introduced into the yellow varnishes for communicating an orange tint. 



The decoction of arnatto in water has a strong peculiar odour, and a disagreeable 

 taste. Its colour is yellowish-red, and it remains a little turbid. An alkaline solution 

 renders its orange-yellow clearer and more agreeable, while a small quantity of a 

 whitish substance is separated from it, which remains suspended in the liquid. If 

 arnatto be boiled in water along with an alkali, it dissolves much better than when 

 alone, and the liquid has an orange hue. 



The acids form with this liquor an orange-coloured precipitate, soluble in alkalis, 

 which communicate to it a deep orange colour. The supernatant liquor retains only 

 a pale yellow hue. 



When arnatto is used as a dye, it is always mixed with alkali, which facilitates its 

 solution, and gives it a colour inclining less to red. The arnatto is cut .in pieces, and 

 boiled for some instants in a copper with its own weight of crude pearl-ashes, provided 

 the shade wanted do not require less alkali. The cloths may be afterwards dyed in 

 this bath, either by these ingredients alone, or by adding others to modify tho colour ; 

 but arnatto is seldom used for woollen, because the colours which it gives are too 

 fugitive, and may be obtained by more permanent dyes. Hellot employed it to dye a 

 stuff prepared with alum and tartar ; but the colour acquired had little permanence. 

 It is almost solely used for silks. 



For silks intended to become aurora and orange, it is sufficient to scour them at the 

 rate of 20 per cent, of soap. When they have been well cleansed, they are immersed 

 in a bath prepared with water, to which is added a quantity of alkaline solution of 

 arnatto more or less considerable, according to the shade that may be wanted. This 

 bath should have a mean temperature between that of tepid and boiling water. 



When the silk has become uniform, one of the hanks is taken out, washed, and 

 wrung, to see if the colour be sufficiently full ; if it be not so, more solution of 

 arnatto is added, and the silk is turned again round the sticks : the solution keeps 

 without alteration. 



When the desired shade is obtained, nothing remains but to wash the silk, and give 

 it two beetlings at the river, in order to free it from tho redundant arnatto, which 

 would injure tho lustre of the colour. 



When raw silks are to be dyed, those naturally white are chosen, and dyed in tho 

 arnatto bath, which should not be more than tepid, or even cold, in order that the 

 alkali may not attack the gum of the silk, and deprive it of the elasticity which it is 

 desirable for it to preserve. 



What has now been said regards the silks to which the aurora shades are to bo 

 given : but to make an orange hue, which contains more red than the aurora, it is 



Vol.. I. P 



