2. Lump Dragon’s Blood (Sanguis draconis in massis) is imported in large rectangular blocks or irregular masses. From the fine Reed Dragon’s Blood, just described, it differs in containing a larger proportion of remains of the fruit, including numerous entire scales. Hence it has a coarser fracture, and the fractured surface is less intense in tint. Its taste is slightly acrid. Exhausted with alcohol it leaves a residue amounting in the specimen we tested to 27 per cent.
Dragon’s blood is abundantly soluble in the usual solvents of resins, namely, the alcohols (even in dilute spirit of wine), benzol, chloroform, bisulphide of carbon, and the oxygenated essential oils, as that of cloves. The residue left after the evaporation of these liquids is amorphous and of the original fine red colour. The drug is likewise dissolved by glacial acetic acid as well as by caustic soda; the latter solution on addition of an excess of acid yields a dingy brown, jelly-like precipitate, which on drying turns dark red like the original drug. In ether dragon’s blood is sparingly soluble, and still less so in oil of turpentine; but in the most volatile portions of petroleum, the so-called petroleum ether we find it to be entirely insoluble. It has a slightly sweetish and somewhat acrid taste; melts at about 120° C., evolving the aromatic but irritating fumes of benzoic acid; boiled with water the resin becomes soft and partially liquid.
Chemical Composition—Dragon’s blood is a peculiar resin, which according to Johnston[2510] answers to the formula C₂₀H₂₀O₄. By heating it and condensing the vapour an aqueous acid liquid is obtained, together with a heavy oily portion of a pungent burning taste and crystals of benzoic acid. The composition of these products has not yet been thoroughly ascertained, but the presence of acetone, Toluol, C₆H₅(CH₃), Dracyl of Glénard and Boudault (1844), and Styrol, C₈H₈ (Draconyl), has been pointed out,[2511] the latter perhaps due to the existence in the drug of metastyrol ([p. 274]), as suggested by Kovalewsky.[2512] Both these hydrocarbons are lighter than water; yet we find that the above oily portion yielded by dry distillation sinks in water, a circumstance possibly occasioned by the presence of benzoic alcohol, C₆H₅(CH₂OH).
As benzoic acid is freely soluble in petroleum ether it ought to be removed from the drug by that solvent: on making the experiment we got traces of an amorphous red matter, a little of an oily liquid, but nothing crystalline. Cinnamic acid, on the other hand, is always present, according to Hirschsohn (1877). As to the watery liquid, it assumes a blue colour on addition of perchloride of iron, whence it would appear to contain phenol or pyrogallol rather than pyrocatechin ([p. 196]).
By boiling dragon’s blood with nitric acid, benzoic, nitro-benzoic, and oxalic acids are chiefly obtained, and only very little picric acid. Hlasiwetz and Barth melted the drug with caustic potash, and found among the products thus formed phloroglucin ([p. 243]), para-oxybenzoic, protocatechuic, and oxalic acids, as well as several acids of the fatty series. Benzoin yields similar products.
Commerce—Dragon’s blood is shipped from Singapore and Batavia. Large quantities are annually exported from Banjarmasin in Borneo to these places and to China.[2513]
Uses—In medicine, only as the colouring agent of plasters and tooth powders; in the arts, for varnish.
Adulteration—Dragon’s blood varies exceedingly in quality,[2514] of which the principal criterion regarded by the dealers is colour. Some of the inferior sorts make only a dull brick-red mark when rubbed on paper, and have an earthy-looking fracture. The sticks moreover do not take the impression of the enveloping leaf as when they are more purely resinous. A sample of inferior Reed Dragon’s Blood afforded us 40 per cent. of matter, insoluble in spirit of wine.
Other sorts of Dragon’s Blood.
Dragon’s Blood of Socotra—We have already stated ([p. 672]) that the Cinnabar mentioned by Dioscorides was brought from Africa. That the term really designated dragon’s blood seems evident from the fact that the author of the Periplus of the Erythrean Sea,[2515] written circa a.d. 54-68, names it (Κιννάβαρι) as a production of the island of Dioscorida, the ancient name of Socotra.