Sanguis Draconis. Dragons' Blood.
Dragons' blood is a resin secreted by the fruits of Calamus Draco, Willd. (N.O. Palmae), and other species, climbing palms indigenous to Sumatra. These palms bear small fruits about the size of a cherry, covered with hard, imbricated scales, which become encrusted with a red resin; this is removed by shaking the fruits in sacks, and sifting out the resin, which is then softened by warming, and made into elongated, flattened or rounded masses, the latter sometimes weighing several pounds. The former are generally wrapped in a leaf, the latter often bear the impress of coarse matting in which they have been packed. When of good quality dragons' blood is usually covered with a dull crimson powder. The pieces are brittle, the fractured surface being vitreous and nearly black, but thin fragments have a garnet-red colour by transmitted light. The powder is of a bright crimson colour. Melting-point, about 76°. Inferior qualities are duller in colour and fracture, and often contain scales or portions of the fruits, sand, etc., easily visible even to the naked eye. It is odourless and tasteless, and breaks up when chewed to a gritty powder. The resin itself is entirely soluble in alcohol, but the commercial drug may yield as much as 40 to 50 per cent. of insoluble residue consisting of vegetable debris and mineral matter. The term dragons' blood has been applied to a number of red, resinous or astringent substances. The above description is that of the commonest commercial variety, and is best designated Sumatran dragons' blood. Socotran dragons blood, or "Zanzibar drop," is the produce of Dracaena Cinnabari, Balf., which grows in Somaliland. It differs from Sumatran in being in tears, in containing no fruit scales, and in not exhaling an odour of benzoic acid when warmed. Canary dragons' blood is a resin obtained from Dracaena Draco, Linn.;it is not a commercial article.
Constituents.—The soluble portion of dragons' blood consists of about 56 per cent. of a red resin (dracoresinotannol combined with benzoic and benzoyl-acetic acids), 13 per cent. of a bright yellow amorphous resene (dracoresene), and 2.5 per cent. of a white amorphous body (dracoalban). The latter may be detected in Sumatran dragons' blood by boiling 10 grammes of powdered resin in 50 mils of ether, concentrating to 30 mils and pouring into 50 mils of absolute alcohol; on allowing it to stand for an hour, a white, flocculent precipitate of dracoalban is obtained.
Uses.—Dragons' blood is sometimes used for colouring plasters, but it is much more largely used for colouring lacquers and varnishes.
