ANNATTO.

427

annatto, whereby the fermentation is evaded, and the pulp simply washed outfrom the capsules, and off the seeds. In this way a produdt is obtained fromfive to six times more valuable than the ordinary annatto, and the produdt hasbecome known as bixin, since it yields better and purer shades. The ordinaryannatto of commerce is a homogeneous undtuous paste, of a dull yellowishred externally, more bright internally, and giving off a disagreeable urinoussmell. It contains on an average—Water, 72 per cent; leaves and other foreignorganic matters, 22 per cent; colouring matter, 6 per cent. The annatto asusually met with in trade is frequently adulterated, either designedly, or byignorant preparation, with red- or yellow-coloured mineral matters, as ochre,colcothar, ground-up bricks. These impurities are detected by drying the sub-stance first at ioo°, and then igniting it in a platinum crucible. Annatto ofgood quality does not yield more than from 8 to 13 per cent of ash, of ayellowish colour. As regards the quantity of real colouring matter containedin annatto, this varies according to the quantity of water present, which isestimated by drying at ioo° about 10 grms. of the substance. The colouringmatter is estimated by a dyeing process, for which M. Girardin gives thefollowing instructions :—For cotton he takes of previously dried (at zoo 0 ) andground annatto, 5 grms.; carbonate of potassa, 10 grms.; water, 400 grms.For silk—Annatto, 0* * * § 5 grm.; carbonate of potassa, 1 grm.; water, 200 grms.The mixture is heated to boiling, along with 12 grms. of cotton-thread or yarn,or 2 grms. of skein silk; the ebullition is continued for fifteen minutes; thevessel is then removed from the source of heat, and left standing for an hour;the yarn is then taken out, squeezed, and dried in the shade. This assay ismade in comparison with a standard sample.

The colouring matters of annatto have been investigated by Chevreul,*Bousingault,f Kernot,;*; Picard,|| Bolley, and Mylius§. When treated withwater, annatto yields a yellow colouring matter, soluble in water and alcohol,insoluble in ether, and capable of imparting a yellow colour to tissues pre-viously mordanted with alum. The colour has been named orellin. Theresidue, after exhausting the annatto with water, contains its chief colouringmatter, bixin, which may be obtained, according to Bolley, as follows :—Cayenne annatto is first washed with water and dried, next exhausted withvery strong boiling alcohol; the tin&ure is filtered, and then evaporated on awater-bath; the residue digested with ether, which dissolves a portion thereof,leaving a cinnabar-red powder, fusible at zoo®, soluble in alcohol, but insolublein water; not affedted by a heat of 145 0 , nor by boiling with dilute sulphuricacid, soluble in weak alkaline solutions, and in soap-water, exhibiting a yellowor orange-yellow colour. According to Dr. Bolley, the formula of this substanceis C 5 H60 2 ; the matter soluble in ether has not been further investigated.

According to Kerndt, there is left on the evaporation of the ethereal solutiona substance which fuses at ioo°, and the formula of which should be C12H22O.Picard considers this to be an error, stating that the product is a mixture ofsubstances, including fatty matters. The impure bixin (obtained as above

* “ Lemons de Chimie Appliquee la Teinture.

t “ Annales de Chimie et de Physique [2], xxviii., 440.

t “ Jahresbericht der Reinen und Angewandten Chemie,” &c., by Liebig and Kopp, 1849, p. 457.

R Schweitzerische, “ Polytechnischc Zeitschrift,” 1861. “ Repert. de Chimie Appliquee,”1861, 4ig.

§ Schweitzerische, “ Polyteehnische Zeitschrift,” ix., 134