 with extractive, gum, and sometimes probably a little resin, but we need a careful analysis of the different well-ascertained varieties. The aqueous solution is precipitated by gelatin, the soluble salts of iron, silver, lead, and antimony, mercuric chloride, and sulphuric, nitric, and hydrochloric acids. The precipitate with iron is of an olive or greenish-black color. The alkalies favor the solubility of kino in water, but essentially change its nature and destroy its astringency.
1. EAST INDIA KINO. Malabar Kino.—This is the variety at present probably most used and most highly esteemed, and the only one recognized by the British and United States Pharmacopoeias. Its origin was long unknown. It is now ascertained, through the researches of Pereira, Royle, Wight, and others, to be the product of Pterocarpus Marsupium, a lofty tree growing upon the mountains of the Malabar coast of Hindostan. Kino is the juice of the tree extracted through longitudinal incisions in the bark and afterwards dried in the sun. Upon drying it breaks into small fragments, and is put into wooden boxes for exportation. It is collected near Tellicherry, and exported from Bombay. It is sometimes imported into this country directly from the East Indies, but more commonly from London. From a communication in the Journal of the Asiatic Society of Bengal, by F. Mason, it appears that kino is also collected in the Tenasserim provinces, in Farther India, and has been exported from Maulmain to Europe. It is produced by a tree called Pa-douck, which Christison recognized from a description furnished to him by Begbie, of Maulmain, as Pterocarpus Marsupium, so that this kino has the same origin as that from Malabar. Pterocarpus indicus, of the Mauritius Islands, where it is known as sang-dragon, also yields a red kino to commerce.
When kino is boiled in water, the decoction deposits, on cooling, a bright red substance, and a similar deposition takes place when a cold filtered aqueous solution is long exposed with a broad surface to the air. According to Hennig, kino consists of tannic acid about 40 per cent, with a trace of gallic acid, kinoic acid, pectin, ulmic acid, and inorganic salts, with excess of earthy bases. (See A. J. P., xv, 544.) C. Etti obtained a new constituent, kinoin, by extracting kino with ether. He finally adopted the following method as more practicable. One part of gum kino is added to 2 parts of boiling diluted (1 to 5) hydrochloric acid. Kino-red immediately separates as a soft mass, becoming gradually solid on cooling, while the kinoin, mixed with a small quantity of kino-red, remains in solution. The solid residue is once more boiled with water, the liquids are united and shaken with ether. The ethereal solution, on evaporation, leaves a crystalline reddish residue, which is dissolved in hot water, on tile cooling of which tolerably pure crystals of kinoin are obtained. By continued recrystallization they are obtained colorless. Their formula is C14H12O6, and kino-red is the anhydride of this:
2C14H12O6—H2O = C28H22O11
This kino-red heated to 160° to 170° C. (320°-338° F.), parts with a molecule of water and yields a lower anhydride, C28H20O10. Both anhydrides are precipitated by gelatin, but kinoin itself is not. When heated with hydrochloric acid to 120° to 130° C. (248°-266° F.), kinoin yields methyl chloride, gallic acid, and catechol, and hence probably has the constitution of a guaiacol or methyl-catechol gallate. Kino contains about 1.5 per cent. of kinoin. (Ber. d. Chem. Ges.; N. R., Feb., 1897.) Kremel found Malabar kino, Butea gum, eucalyptus kino, and the kino from Coccoloba uvifera to be free from Etti's kinoin, but to contain a body acquiring, like kinoin, a red color with ferric chloride, which proved to be pyrocatechuic acid; this was present either alone or mixed with gallic acid. (A. J. P., 1883, 267.) Some doubt was also thrown upon the value of Etti's conclusions by White (P. J., 1903, p. 676), who failed to find several of the constituents reported by Etti. The true chemistry of kino may therefore be consider