This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Dragon's blood is a resinous secretion produced on the fruits of Doemondrops propinquus, Beccari, D. ruber, Martius, and probably other species. The two species named were formerly included in Calamus Draco, Willdenow (N.O. Palmoe); they are climbing palms with long, flexible stems, and are indigenous to Sumatra and Borneo.
The plant produces numerous small fruits about the size of a cherry, covered with hard, yellowish, imbricated scales, which overlap one another from apex to base. From between these scales a red resin, probably produced in the pulp of the fruit, exudes and more or less completely covers the fruit. The fruits are shaken together in a basket, and the separated resin mixed with water, pressed into moulds, and then melted; or it is made into a cake which is wrapped in a cloth, steeped in hot water and pressed to form a solid block. It is said to be nearly always mixed with the milky juice of Garcinia parviflora, Miquel (Treub, 1891).
Dragon's blood occurs in lumps of very varying size and shape. They are often large rounded masses, sometimes weighing several kilograms, bearing the impress of sacking or reed-matting, or they may be rounded, flattened cakes 10 cm. or more in diameter and about 5 cm. in thickness; sometimes the cakes are smaller and thinner. Occasionally it is imported in sticks about 20 to 25 cm. long and 2 to 3 cm. thick, or 30 cm. long and
1.5 cm. thick, each carefully wrapped in a palm leaf. These varieties are known as 'lump,' 'saucer,' 'reed,' etc, dragon's blood.
Good samples of the drug usually have a dull, dark red colour, and are more or less covered, where the pieces have rubbed against one another, with a crimson powder. They are brittle and friable, breaking with a glossy but irregular, uneven fracture, minute fragments being translucent and of a deep garnet-red colour.
The drug yields when crushed a bright crimson powder, has no odour, and is practically tasteless, breaking up when chewed into a fine gritty powder. Inferior qualities are duller in colour and tougher. They yield a duller crimson or even brick-red powder, and exhibit less powder on the surface of the lumps. Such specimens frequently contain numerous fragments of the fruit scales, which are easily seen when the drug is broken, or are left when it is exhausted with alcohol.
Tears, in which form the drug is now seldom seen, give a glassy, conchoidal fracture, thin flakes being of a clear garnet-red colour.
Dragon's blood consists principally of a red resin (56.8 per cent.), a compound of dracoresinotannol with benzoic and benzoylacetic acids. Other constituents are a white, amorphous dracoalban (2.5 per cent.), a yellow resinous dracoresene (13.58 per cent.), vegetable debris (18.4 per cent.), and ash (8.3 per cent.).
It is frequently considerably adulterated both with earthy matter and with fragments of the scales of the fruits, the amount of residue insoluble in alcohol amounting sometimes to as much as 40 per cent, of the drug.
Dragon's blood is chiefly used for colouring varnishes, etc.
The term ' dragon's blood' has also been applied to several other resins resembling Sumatra dragon's blood in appearance. They may be distinguished by their insolubility in benzene and carbon disulphide. The only one of these that appears in commerce is Socotrine dragon's blood which is occasionally imported from Bombay and Zanzibar and is technically termed 'Zanzibar drop' dragon's blood. It is obtained from Dracoena Cinnabari, Balfour. It occurs in small tears or fragments seldom exceeding 2 cm. in length with a vitreous fracture, thin splinters being of a ruby red colour. It does not when heated evolve an odour of benzoic acid, and contains no scales similar to those found in Sumatra dragon's blood.