Kr. cistoidea Hook, a plant scarcely to be distinguished from Kr. triandra, affords in Chili a rhatany very much like that of Peru. Its root was contributed to the Paris Exhibition of 1867.
Microscopic Structure—The chief portion of the bark is formed of liber, which in transverse section exhibits numerous bundles of yellow fibres separated by parenchymatous tissue and traversed by narrow brown medullary rays. The small layer of the primary bark is made up of large cells, the surface of the root of large suberous cells imbued with red matter. The latter also occurs in the inner cortical tissue, and ought to be removed by means of ammonia in order to get a clear idea of the structure. Many of the parenchymatous cells are loaded with starch granules; oxalate of calcium occurs in the neighbourhood of the liber bundles. The woody portion exhibits no structure of particular interest.
Chemical Composition—Wittstein (1854) found in the bark of rhatany (the only part of the drug having active properties) about 20 per cent. of a form of tannin called Ratanhia-tannic Acid, closely related to catechu-tannic acid. It is an amorphous powder, the solution of which is not affected by emetic tartar, but yields with ferric chloride a dark greenish precipitate. By distillation Eissfeldt (1854) obtained pyrocatechin as a product of the decomposition of ratanhia-tannic acid. The latter is also decomposed by dilute acids which convert it into crystallizable sugar and Ratanhia-red, a substance nearly insoluble in water, also occurring in abundance ready formed in the bark.
Grabowski (1867) showed that by fusing ratanhia-red with caustic potash, protocatechuic acid and phloroglucin[331] are obtained. Ratanhia-red has the composition C₂₆H₂₂O₁₁, the same, according to Grabowski, as an analogous product of the decomposition of the peculiar tannic acid occurring (as shown by Rochleder in 1866) in the horse-chestnut. The same red substance may also be obtained, as stated by Rembold (1868), from the tannic acid of the root of tormentil (Potentilla Tormentilla L.).
As to rhatany root, Wittstein also found it to contain wax, gum and uncrystallizable sugar (even in the wood! according to Cotton[332]). Cotton further pointed out the presence in very minute quantity of an odorous, volatile, solid body, obtainable by means of ether or bisulphide of carbon; it occurs in a somewhat more considerable amount in the other sorts of rhatany. The root contains no gallic acid.
A dry extract of rhatany resembling kino used formerly to be imported from South America, but how and where manufactured we know not. It is however of some interest as containing a crystalline body which Wittstein who discovered it (1854) regards as Tyrosin, C₉H₁₁O₃, previously supposed to be exclusively of animal origin.[333] Städeler and Ruge (1862) assigned to it a slightly different composition, C₁₀H₁₃NO₃, and gave it the name of Ratanhin. It dissolves in hot water which is acidulated by a little nitric acid; the solution on boiling turns red, blue, and lastly green, and becomes at the same time fluorescent. Kreitmair (1875) extracted 0·7 per cent, of ratanhin from an old specimen of commercial extract of rhatany; but he did not succeed in obtaining it from other specimens. He also showed that ratanhin is not a constituent of the roots of Krameria. The same substance has been abundantly found by Gintl (1868) in the natural exudation called Resina d’Angelim pedra[334] which is met with in the alburnum of Ferreirea spectabilis Allem., a large Brazilian tree of the order Leguminosæ (tribe Sophoreæ). Peckolt, who first extracted it, named it Angelin; it forms colourless, neutral crystals yielding compounds both with alkalis and acids, which have been investigated by Gintl in 1869 and 1870.
Uses—Rhatany is a valuable astringent, but is not much employed in Great Britain.
Other sorts of Rhatany—Of the 20 to 25 other species of Krameria, all of them belonging to America, several have astringent roots which have been collected and used in the place of the rhatany of Peru. The most important of these drugs is that known as—
Para Rhatany,—so called from having been shipped from Pará in Brazil. Berg who described it in 1865 termed it Brazilian Rhatany, Cotton in 1868, Ratanhia des Antilles. It is a drug nearly resembling the following, but of a darker and less purple hue; it is also in longer sticks which are remarkably flexible, and covered with a thick bark having numerous transverse cracks.[335] It is apparently derived from the Krameria argentea of Martius,[336] the root of which is collected in the dry districts of the provinces of Bahia and Minas Geraes, that plant growing throughout north-eastern Brazil. It is also called Rhatany from Ceará.
Savanilla or New Granada Rhatany. The plant yielding it is Krameria tomentosa St. Hil. (Kr. Ixina var. β granatensis Triana, Kr. grandifolia Berg), a shrub 4 to 6 feet high covering large arid tracts in the valley of Jiron between Pamplona and the Magdalena in New Granada, in which locality the collection of the root was observed by Weir in 1864.[337] According to Triana it also grows at Socorro, south of Jiron. The same plant is found near Santa Marta and Rio Hacha in north-eastern New Granada, in British Guiana, and in the Brazilian provinces of Pernambuco and Goyaz.