426
DYEING AND CALICO PRINTING.
raw material cannot be difficult. The lichens are best treated with an alkalinelye, and then precipitated by an acid ; the precipitate thus obtained is dissolvedin alcohol or ether, and these solutions left to crystallise.
Chrysophanic, Rumicinic, or Rhubarbaric Acid, also called Lapathin.*—Formula, C IO H 80 3 . Yellow needle-shaped crystals, which turn red by theadtion of nitric acid, and dissolve in concentrated sulphuric acid, yielding a redsolution. It also dissolves in caustic potassa, yielding likewise a red liquid,which on evaporation deposits a blue flocculent matter, soluble in water, andthen again producing a red solution. This acid is decomposed when stronglyheated, yielding a yellow flocculent sublimate.
Vulpic Acid.—Chrysopicrin, scarcely soluble in water, either hot or cold;soluble in 588 parts of cold and 88'3 parts of boiling alcohol, and soluble inether; fuses at 110°; sublimes at 120°; the sublimate forms brilliant golden-yellow, scaly particles, soluble in alkaline liquids. This solution is not adtedupon by air; when treated with hypochlorite of lime it yields an oily liquidand a red resin. This acid does not yield good results in dyeing.
Usnic Acid is a scaly, crystalline yellow substance, insoluble in water,sparingly soluble in boiling alcohol, soluble in ether and alkalies. These last-named solutions become carmine, and at last black, on exposure to air. Ifsubmitted to dry distillation this substance yields beta orcin.
Chrysinic Acid above mentioned is of no importance at all, and hithertonone of these substance have been applied industrially.
Gentianic Acid.—The well-known gentian root contains a yellow acid,forming needle-shaped crystals, sparingly soluble in water, more readily so inalcohol and ether; with alkalies it yields golden-yellow crystallisable salts;nitric acid converts it into a green insoluble substance, which appears to benitro-gentianic acid.
Annatto, or Anotto, also known as Rocon, Bixin, or Orleans.Annatto is mainly the pulp which surrounds the fruit of the Bixa orellana,a shrub native of South America, and cultivated in Mexico, Brazil, Guiana,and the Antilles. When the fruit has reached maturity the fruits are gathered,the seeds pulled from the capsules and coarsely pounded up with the pulpwhile placed in water, and left to ferment for several weeks. After this timethe pulp and liquid are passed through a sieve; the colouring matter soonsettles to the bottom of the liquid, and having been collected is evaporated byheat, put in boxes, and dried in the sun.
Annatto is imported into Europe in the shape of cakes, weighing from 5 to8 kilos., packed in banana leaves (Guiana anotto), or as cakes packed in casks(from Brazil), or in tinned iron boxes from Cayenne. This latter kind is abouttwice as rich in colouring matter as the ordinary annatto of commerce ; itscolour is bright, its smell pleasant; it contains about 5 per cent of mineralmatter, and from 67 to 70 of water.f It has been regularly manufadtured atCayenne since 1837 by M. Daubriac.
In the year 1848 Dumontal introduced an improved mode of preparation of
* “ Annalen der Chemie,” cvii., 324. “ Repertoire de Chimie Pure,” iv. ( 371. “Journal fur
Prakt. Chemie,” lxxxiv., 436.
+ “ Girardin, “Memoire sur la Bixin.” “Joum. de Pharm. et de Chimie,” xxi. 174 C 3 l •Girardin, “Memoire sur la Falsification du Rocon.” “Journal de Pharmacie, Cahier deMars,” 1836.