Botanical Origin—Arachis hypogæa L., a diffuse herbaceous annual plant, having stems a foot or two long, and solitary axillary flowers with an extremely long filiform calyx-tube. After the flower withers, the torus supporting the ovary becomes elongated as a rigid stalk, which bends down to the ground and forces into it the young pod, which matures its seeds some inches below the surface. The ripe pod is oblong, cylindrical, about an inch in length, indehiscent, reticulated, and contains one or two, or exceptionally even four irregularly ovoid seeds.

The plant is cultivated for the sake of its nutritious oily seeds in all tropical and subtropical countries, but especially on the west coast of Africa. It is unknown in the wild state. De Candolle[738] regards it as a native of Brazil, to which region the other species of the genus exclusively belong. But the opinion of one of us[739] is strongly in favour of the plant being indigenous to Tropical Africa, and so is that also of Schweinfurth. Arachis is one of the most universally cultivated plants throughout Tropical Africa, from Senegambia to lake Tanganyika. In Europe it has not proved remunerative.

History—The first writer to notice Ground-Nut appears to be Fernandez de Oviedo y Valdes, who lived in Hayti from a.d. 1513 to 1525; he mentions in his Cronica de las Indias[740] that the Indians cultivated very much the fruit Mani, a name still used for Arachis in Cuba and in South America. A little later, Monardes,[741] described a nameless subterraneous fruit, found about the river Maranon and held in great esteem by both Indians and Spaniards. But before, the French colonists sent in 1555 by Admiral Coligny to the Brazilian coast had become acquainted with the “Mandobi,” which Jean de Léry[742] described quite unmistakably. Good accounts and figures of it were given in the following century by Johannes de Laet (1625),[743] and by Marcgraf,[744] who calls it by its Brazilian name of Mundubi. It is enumerated by Stisser among the rare plants cultivated by him at Helmstedt (Brunswick), about the year 1697.[745]

It is only in very recent times that the value of the Ground-Nut has been recognized in Europe. Jaubert, a French colonist at Gorée near Cape Verde, first suggested about 1840 its importation as an oil-seed into Marseilles, where it now constitutes one of the most important articles of trade.[746]

Description—The fat oil of Arachis, as obtained by pressure without heat, is almost colourless, of an agreeable faint odour and a bland taste resembling that of olive oil. An inferior oil is obtained by warming the seeds before pressing them. The best oil has a sp. gr. of about 0·918; it becomes turbid at 3° C., concretes at -3° to -4°, and hardens at -7°. On exposure to air it is but slowly altered, being one of the non-drying oils. At length it thickens considerably, and assumes even in closed vessels a disagreeable rancid smell and taste.

Chemical Composition—The oil consists of the glycerides of four different fatty acids. The common Oleic Acid, C₁₈H₃₄O₂, that is to say its glycerin compound, is the chief constituent of Arachis oil. Hypogæic Acid, C₁₆H₃₀O₂, has been pointed out by Gössmann and Scheven (1854) as a new acid, whereas it is thought by other chemists to agree with one of the fatty acids obtained from whale oil. The melting point of this acid from Arachis oil is 34-35° C. The third acid afforded by the oil is ordinary Palmitic Acid, C₁₆H₃₂O₂, with a fusing point of 62° C. Arachic Acid, C₂₀H₄₀O₂, the fourth constituent, has also been met with among the fatty acids of butter and olive oil, and, according to Oudemans (1866), in the tallow of Nephelium lappaceum L., an Indian plant of the order Sapindaceæ.

When ground-nut oil is treated with hyponitric acid, which may be most conveniently evolved by heating nitric acid with a little starch, a solid mass is obtained, which yields by crystallization from alcohol Elaïdic and Gæidinic acids, the former isomeric with oleic, the latter with hypogæic acid.

Production and Commerce—The pods are exported on an immense and ever increasing scale from the West Coast of Africa. From this region, not less than 66 millions of kilogrammes, value 26 millions of francs (£1,040,000), were imported in 1867, almost exclusively into Marseilles. From the French possessions on the Senegal, 24 millions of kilogr. were exported in 1876.

The oil is exported from India where the ground-nut is also cultivated, though not on so large a scale as in Western Africa. In Europe it is manufactured chiefly at Marseilles, London, Hamburg and Berlin. The yield of the seeds varies from 42 to nearly 50 per cent. The softness of the seeds greatly facilitates their exhaustion, whether by mechanical power or by the action of bisulphide of carbon or other solvent.

Uses—Good arachis oil may be employed in pharmacy in the same way as olive oil, for which it is a valuable substitute, though more prone to rancidity. It has been introduced into the Pharmacopœia of India, and is generally used instead of olive oil in the Indian Government establishments. Its largest application is for industrial purposes, especially in soap-making.

RADIX ABRI.

Indian Liquorice; F. Liane à réglisse, Réglisse d’Amérique.

Botanical Origin—Abrus precatorius L., a twining woody shrub[747] indigenous to India, but now found in all tropical countries.

History—The plant is mentioned in the Sanskrit medical writings of Susruta, whence we may infer that it has long been employed in India. Its resemblance to liquorice was remarked by Sloane (1700), who called it Phaseolus glycyrrhites. As a substitute for liquorice, the root has been often employed by residents in the tropical countries of both hemispheres. It was introduced into the Bengal Pharmacopœia of 1844, and into the Pharmacopœia of India of 1868.

The seeds, of the size of a small pea, well known for their polish and beautiful black and red colours, have given their name of Retti to a weight (= 2³/₁₆ grains) used by Hindu jewellers and druggists.

Description—The root is long, woody, tortuous and branching. The stoutest piece in our possession is as thick as a man’s finger, but most of it is much more slender. The cortical layer is extremely thin and of a light brown or almost reddish hue. The woody part breaks with a short fibrous fracture exhibiting a light yellow interior. The root has a peculiar, disagreeable odour, and a bitterish acrid flavour leaving a faintly sweet after-taste. When cut into short lengths it has a slight resemblance to liquorice, but may easily be distinguished by means of the microscope.

Mr. Moodeen Sheriff,[748] who says he has often examined the root of Abrus both fresh and dried, remarks that it is far from abounding in sugar as generally considered;—that it does not possess any sweetness at all until it attains a certain size, and that even then its sweet taste is not always well marked. As it is often mixed in the Indian bazaars with true liquorice, he thinks the latter may have sometimes been mistaken for it.

Microscopic Structure—On a transverse section the bark exhibits some layers of cork-cells, loaded with brown colouring matter, and then, within the middle zone of the bark, a comparatively thick layer of sclerenchymatous tissue. Strong liber-fibres are scattered through the interior of the cortical tissue, but are not distributed so as to form wedge-shaped rays as met with in liquorice. In the latter the sclerenchyme (thick-walled cells) is wanting. These differences are sufficient to distinguish the two roots.

Chemical Composition—The concentrated aqueous infusion of the root of Abrus has a dark brown colour and a somewhat acrid taste accompanied by a faint sweetness. When it is mixed with an alkaline solution of tartrate of copper, red cuprous oxide is deposited after a short time: hence we may infer that the root contains sugar. One drop of hydrochloric or other mineral acid mixed with the infusion produces a very abundant flocculent precipitate, which is soluble in alcohol. If the infusion of Abrus root is mixed with a very little acetic acid, an abundant precipitate is likewise obtained, but is dissolved by an excess. This behaviour is similar to that of glycyrrhizin (see p. 181).

Berzelius observed, so long ago as 1827, that the leaves of Abrus contain a sweet principle similar to that of liquorice.

Uses—The root has been used in the place of liquorice, for which it is in our opinion a very bad substitute.

SETÆ MUCUNÆ.

Botanical Origin—Mucuna pruriens DC. (Dolichos pruriens L., Stizolobium pruriens Pers., Mucuna prurita Hook.), a lofty climbing plant[750] with large, dark purple papilionaceous flowers, and downy legumes in size and shape not unlike those of a sweet pea, common throughout the tropical regions of both Africa, India and America.

History—The earliest notice we have found of this plant is that of Parkinson, who in his Theater of Plants, published in 1640, names it “Phaseolus siliquâ hirsutâ, the Hairy Kidney-Beane called in Zurrate [Surat] where it groweth, Couhage” It was subsequently described by Ray (1686), who saw the plant raised from West Indian seeds, in the garden of the Hatton family in Holborn.[751] Rheede figured it in the Hortus Malabaricus,[752] and it was also known to Rumphius and the other older botanists. We find it even in the pharmaceutical tariff of the county of Nürnberg, a.d. 1714.[753]

The employment of cowhage as a vermifuge originated in the West Indies, and is quite unknown in the East. In England the drug began to attract attention in the latter part of the last century, when it was strongly recommended by Bancroft in his Natural History of Guiana (1769), and by Chamberlaine, a surgeon of London, who published an essay[754] descriptive of its effects which went through many editions. It was introduced into the Edinburgh Pharmacopœia of 1783, and into the London Pharmacopœia of 1809. At the present day it has been almost discarded from European medicine, but has been allowed a place in the Pharmacopœia of India (1868).

The name Cowhage is Hindustani, and in the modern way is written Kiwânch, which is generally derived from the Sanskrit Kapi-Kachchu, monkey’s itch (Dr. Rice); the corruption into Cow-itch is absurd. Mucuna is the Brazilian name of another species mentioned in 1648 by Marcgraf.[755]

Description—The pods are 2 to 4 inches long, about ⁴/₁₀ of an inch wide, and contain 4 to 6 seeds; they are slightly compressed and of a dark blackish brown. Each valve is furnished with a prominent ridge running from the apex nearly to the base, and is densely covered with rigid, pointed, brown hairs, measuring about ⅒ of an inch in length. The hairs are perfectly straight and easily detached from the valves, out of the epidermis of which they rise. If incautiously touched, they enter the skin and occasion an intolerable itching.

Microscopic Structure—Under the microscope the hairs are seen to consist of a single, sharply pointed, conical cell, about ¹/₄₀ of an inch in diameter at the base, with uniform brownish walls 5 mkm. thick, which towards the apex are slightly barbed. Occasionally a hair shows one or two transverse walls. Most of the hairs contain only air; others show a little granular matter which acquires a greenish hue on addition of alcoholic solution of perchloride of iron. If moistened with chromic acid, no structural peculiarity is revealed that calls for remark. The walls however are somewhat separated into indistinct layers, the presence of which is confirmed by the refractive power displayed by the hairs in polarized light.

Chemical Composition—The hairs when treated with sulphuric acid and iodine assume a dark brown colour. Boiling solution of potash does not considerably swell or alter them. They are completely decolorized by concentrated nitric acid.

Uses—Cowhage is administered for the expulsion of intestinal worms, especially Ascaris lumbricoides and A. vermicularis, which it effects by reason of its mechanical structure. It is given mixed with syrup or honey in the form of an electuary.

The root and seeds are reputed medicinal by the natives of some part of India. The pods when young and tender may be cooked and eaten.

SEMEN PHYSOSTIGMATIS.

Botanical Origin—Physostigma venenosum Balfour, a perennial plant resembling the common Scarlet Runner (Phaseolus multiflorus Lam.) of our gardens, but having a woody stem often an inch or two thick, climbing to a height of 50 feet or more. It grows near the mouths of the Niger and the Old Calabar River in the Gulf of Guinea.

The imported seeds germinate freely, but the plant, though it thrives vigorously in a hothouse, has not yet, we believe, flowered in Europe. It has already been introduced into India and Brazil. In the latter country Dr. Peckolt, late of Cantagallo, has raised plants which have blossomed abundantly, producing racemes of about 30 flowers each, pendent from the axils of the ternate leaves.

The flower, which is fully an inch across and of a purplish colour, has the form of Phaseolus, but is distinguished from that genus by two special characters, namely that it has the style developed beyond the stigma backwards as a broad, flat, hooked appendage,[756] and the seeds half surrounded by a deeply grooved hilum.

History—The pagan tribes of Tropical Western Africa compel persons accused of witchcraft to undergo the ordeal of swallowing some vegetable poison. One of the substances employed in this horrid custom is the seed under notice, which is administered in substance or in the form of emulsion, or even as a clyster. It was first made known in England by Dr. W. F. Daniell about the year 1840, and subsequently alluded to in a paper read by him before the Ethnological Society in 1846.[757] The highly poisonous effects of the bean were observed in 1855 by Christison[758] in his own person, and in 1858 by Sharpey, who administered it to frogs.

Before the seed became an object of commerce, it was regarded by the natives with some mystery and was reluctantly parted with to Europeans. It was moreover customary in Old Calabar to destroy the plant whenever found, a few only being reserved to supply seeds for judicial purposes, and of these seeds the store was kept in the custody of the native chief. In 1859, the Rev. W. C. Thomson, a missionary on the West Coast of Africa, forwarded the plant to Professor Balfour of Edinburgh, who figured and described it as a type of a new genus.[759]

Fraser of Edinburgh (about 1863 or earlier) discovered the specific power of the seed in contracting the pupil, when the alcoholic extract is applied to the eye. These myotic effects, counteracting those of atropine and hyoscyamine, were further examined by many other experimenters on mammals or birds. The action of the poison when taken internally was found rapidly to affect the cardiac contractions and finally to paralyze the heart.

Description—The fruit of Physostigma is a dehiscent, oblong legume about 7 inches in length, containing 2 or 3 seeds. The latter, commonly known as Calabar Beans, are 1 to 1⅜ inches long, about ⁶/₈ of an inch broad, and ⁴/₈ to ⅝ of an inch in thickness, weighing on an average twenty seeds, 67 grains each.

They have an oblong, subreniform outline, one side being straight or but slightly incurved, the other boldly arched. The latter is marked by a broad furrow, ⅛ of an inch wide, bordered with raised edges, and running from the micropyle, which is a small funnel-shaped depression, quite round the opposite end of the seed. In the middle of this remarkable furrow the raphe is seen as a long raised suture running from end to end. The surface of the seed is somewhat rough, but has a dull polish; it is of a deep chocolate-brown, passing into a lighter tint on the ridges bordering the furrow. The latter is black, dull, and finely rugose.

When the seed is broken the cotyledons are found adherent to the testa, with a large cavity between them. The air thus included causes the seeds to float on water, but they sink immediately when broken. After digestion for some hours in warm water, the testa having been previously cracked, the whole seed softens and swells so that its structure may be easily studied. Each cotyledon is then seen to be marked on the hilum-side by a long shallow furrow, at one end of which, just below the micropyle, lies the plumule and radicle. A dark brown inner membrane, constituting part of the testa, surrounds the cotyledons.

The seeds have scarcely any taste, or not more than an ordinary bean; nor in the dry state have they any odour. After being boiled, or when their alcoholic tincture is evaporated, an odour suggesting cantharides is developed.

Microscopic Structure—The cotyledons are built up of large globular or ovoid cells, those of the outermost layer being smaller and of rather cubic form. This parenchyme is loaded with starch granules, frequently as much as 50 mkm. in diameter. Their interior part is less distinctly stratified than the outer; the hollow centre radiates in various directions around the axis of the ovate granule. Polarized light does not show a cross as in other more globular starch granules, but two elliptic curves approaching one another near the axis of the granule. Similar starch granules are commonly met with in the seeds of Leguminosæ.

In the Calabar seeds the starch is accompanied by numerous particles of albuminous matter becoming distinctly perceptible by addition of iodine, which imparts to them an orange colouration.

The shell of the seed is built up of four different layers; the prevailing layer consists of very long, simply cylindrical cells, densely packed so as to form only one radial row. Tison[760] has endeavoured to ascertain in what region of the seed the active principle is lodged; and he has arrived at the conclusion that its seat is the granular protoplasmic particles, which alone acquire an orange tint by the action of weak caustic alkalis.

Chemical Composition—Jobst and Hesse[761] proved in 1863 that the poisonous nature of Calabar bean depends upon an alkaloid, to which they gave the name Physostigmine. It is obtained by the method generally adopted for extracting analogous substances, that is, by precipitating one of its salts from an aqueous solution by bicarbonate of sodium, and dissolving out the base with ether or benzol. As extracted by these chemists, physostigmine is an amorphous mass of decidedly alkaline reaction, soluble in much water and in acids. On exposure to the air the solution soon becomes red, or sometimes intensely blue, a partial decomposition of the alkaloid taking place. The red coloration may even be observed in the aqueous infusion of a few cotyledons. It disappears by sulphuretted hydrogen or sulphurous acid, but returns if these reducing agents are allowed to evaporate.

Hesse[762] ascertained (1867) that physostigmine consists of C₃₀H₂₁N₃O₄; he now obtained it perfectly colourless and tasteless, softening at 40° C., fusing at 45°, but not supporting a heat of 100° C., without decomposition, which is manifested by a red coloration.

In 1865 Vée and Leven,[763] by treating the powdered unpeeled seed in nearly the same way, prepared an alkaloid which they called Eserine. It differs from Hesse’s physostigmine in that it forms colourless, rhomboidal, tabular crystals of a bitter taste, melting at 90° C. It dissolves easily in ether, alcohol, or chloroform, but very sparingly in water. The last named solution is alkaline, and reddens by exposure to the air.

It is assumed by some writers, as Tison,[764] that eserine is only the pure form of physostigmine; but at present we feel hardly warranted in admitting the identity of the two substances.

Harnack and Witkowski in 1876 ascertained the presence of another alkaloid in the seed, which they called Calabarine. It is nearly insoluble in ether and also very different from physostigmine in its physiological action, but somewhat similar to strychnine. Calabarine is consequently not to be found in those preparations of calabar bean which have been obtained or purified by means of ether.

Hesse (1878) exhausted the cotyledons of Physostigma with petroleum ether, and obtained crystals of a new indifferent substance C₂₆H₄₄+OH₂, which he called Phytosterin. It is closely allied to Cholesterin, but, in its solution in chloroform, devoid of rotatory power and melting at 133°. Cholesterin melts at 145°, and deviates, in its ethereal solution, the ray of polarized light to the left. Phytosterin also occurs in peas; Hesse suggests that the crystallized appearance of alkaloids as prepared by former observers was perhaps due to phytosterin.

From the cotyledons per se, cold water extracts mucilage, precipitable by neutral acetate of lead. The watery infusion contains also albumin, which may be coagulated by heat or by alcohol. The infusion is colourless, does not redden litmus, nor does it contain sugar in appreciable proportion; a few drops of solution of potash cause it to assume an orange colour. An infusion of the shell of the seed is already of this colour, but the tint is intensified by caustic alkali.

The cotyledons yield to boiling ether ½ to ⅓ per cent. of fatty oil, and after exhaustion by ether and alcohol, afford to cold water 12 per cent. of albuminous and mucilaginous constituents. The proportion of starch according to Teich[765] amounts to 48 per cent., the albuminous matter to 23 per cent. The entire seed furnishes 3 per cent. of ash, chiefly phosphate of potash. These constituents do not widely differ in proportion from those found in the common bean, which yields 23 to 25 per cent. of albuminous matters, and 32 to 38 per cent. of starch, besides 1 to 3 per cent. of oil.

The shells of Calabar bean are stated by Fraser to be by no means devoid of active principle.

Vée asserts that if to a solution of eserine, a little potash, lime, or carbonate of sodium be added, there is developed a red colour which rapidly increases in intensity. This colour is transient, passing into yellow, green and blue. If chloroform is shaken with such coloured solution, it takes up the colour; ether on the other hand remains uncoloured.

Uses—Calabar has been hitherto chiefly employed as an ophthalmic medicine, for the purpose of contracting the pupil. It has however been occasionally administered in tetanus and in neuralgic, rheumatic, and other diseases.

Adulteration—Other seeds are sometimes fraudulently mixed with Calabar beans. We have noticed in particular those of a Mucuna and of the Oil Palm, Elæis guineensis Jacq. The slightest examination suffices for their detection.

KINO.

Kino, Gum Kino, East Indian Kino; F. and G. Kino.

Botanical Origin—Pterocarpus Marsupium Roxb., a handsome tree 40 to 80 feet high, frequent in the central and southern parts of the Indian Peninsula and also in Ceylon, and affording a valuable timber. In the Government forests of the Madras Presidency, it is one of the reserved trees, the felling of which is placed under restrictions.

Pt. indicus Willd., a tree of Southern India, the Malayan Peninsula and the Indian and Philippine Islands, is capable of yielding kino, and is the source of the small supplies of that drug that were formerly shipped from Moulmein.

Several other plants afford substances bearing the name of Kino, which will be noticed at the conclusion of the present article.

History—The introduction of kino into European medicine is due to Fothergill, an eminent physician and patron of economic botany of the last century. The drug which Fothergill examined was brought from the river Gambia in West Africa as a rare sort of Dragon’s Blood, and was described by him in 1757[766] under the name of Gummi rubrum astringens Gambiense. It had been noticed at least twenty years before as a production of the Gambia, by Moore, factor to the Royal African Company, who says that the tree yielding it is called in the Mandingo language Kano.[767] Specimens of this tree were sent to England in 1805 by the celebrated traveller Mungo Park, and recognized some years later as identical with the Pterocarpus erinaceus of Poiret.

It seems probable that African kino continued to reach England for some years, for we find “Gummi rubrum astringens” regularly valued in the stock of a London druggist[768] from 1776 to 1792.

Duncan in the Edinburgh Dispensatory of 1803, while asserting that “kino is brought to us from Africa,” admits that some, not distinguishable from it, is imported from Jamaica. In a later edition of the same work (1811), he says that the African drug is no longer to be met with, and alludes to its place being supplied by other kinds, as that of Jamaica, that imported by the East India Company, and that of New South Wales derived from Eucalyptus resinifera Sm. It will thus be seen that at the commencement of the present century several substances, produced in widely distant regions, bore the name of Kino. That however which was principally used in the place of the old African drug, was East Indian Kino, the botanical origin of which was shown by Wight and by Royle[769] (1844-46) to be Pterocarpus Marsupium Roxb.,—a tree which, curiously enough, is closely allied to the kino tree of Tropical Africa.

This is the drug which is recognized as legitimate kino in all the principal pharmacopœias of Europe. It appears to have been first prepared for the European market in the early part of the present century, on a plantation of the East India Company called Anjarakandy, a few miles from Tellicherry on the Malabar Coast; but as we learn from our friend Dr. Cleghorn, it was not grown there but on the ghats a short distance inland.

Extraction—Kino is the juice of the tree, dried without artificial heat.[770] As it exudes, it has the appearance of red currant jelly, but hardens in a few hours after exposure to the air. In the Government forests of the Malabar Coast whence the supplies are obtained, permission to collect the drug is granted on payment of a small fee, and on the understanding that the tapping is performed skilfully and without damage to the timber. The method pursued is this:—A perpendicular incision with lateral ones leading into it, is made in the trunk, at the foot of which is placed a vessel to receive the outflowing juice. This juice soon thickens, and when sufficiently dried by exposure to the sun and air, is packed into wooden boxes for exportation.

Description—Malabar kino[771] consists of dark, blackish-red, angular fragments rarely larger than a pea, easily splitting into still smaller pieces, which are seen to be perfectly transparent, of a bright garnet hue, and amorphous under the microscope. In cold water they sink, but partially dissolve by agitation, forming a solution of very astringent taste, and a pale flocky residue. The latter is taken up when the liquid is made to boil, and deposited on cooling in a more voluminous form. Kino dissolves almost entirely in spirit of wine (·838), affording a dark reddish solution, acid to litmus paper, which by long keeping sometimes assumes a gelatinous condition. It is readily soluble in solution of caustic alkali, and to a large extent in a saturated solution of sugar.

Chemical Composition—Cold water forms with kino a reddish solution, which is at first not altered if a fragment of ferrous sulphate is added. But a violet colour is produced as soon as the liquid is cautiously neutralized. This can be done by diluting it with common water (containing bicarbonate of calcium) or by adding a drop of solution of acetate of potassium. Yet the fact of kino developing an intense violet colour in presence of a proto-salt of iron, may most evidently be shown by shaking it with water, and iron reduced by hydrogen. The filtered liquid is of a brilliant violet, and may be evaporated at 100° without turning green; the dried residue even again forms a violet solution with water. By long keeping the violet liquid gelatinizes. It is decolorized by acids, and turns red on addition of an alkali, whether caustic or bicarbonated. Catechu, as well as crystallized catechin, show the same behaviour, but these solutions quickly turn green on exposure to air.

Solutions of acids, of metallic salts, or of chromates produce copious precipitates in an aqueous solution of kino. Ferric chloride forms a dirty green precipitate, and is at the same time reduced to a ferrous salt. Dilute mineral acids or alkalis do not occasion any decided change of colour, but the former give rise to light brownish-red precipitates of Kino-tannic Acid. By boiling for some time an aqueous solution of kino-tannic acid, a red precipitate, Kino-red, is separated.

Kino in its general behaviour is closely allied to Pegu catechu, and yields by similar treatment the same products, that is to say, it affords Pyrocatechin when submitted to dry distillation, and Protocatechuic Acid together with Phloroglucin when melted with caustic soda or potash.

Yet in catechu the tannic acid is accompanied by a considerable amount of catechin, which may be removed directly by exhaustion with ether. Kino, on the other hand, yields to ether only a minute percentage of a substance, whose scaly crystals display under the microscope the character of Pyrocatechin, rather than that of catechin, which crystallizes in prisms. The crystals extracted from kino dissolve freely in cold water, which is not the case with catechin, and this solution assumes a fine green if a very dilute solution of ferric chloride is added, and turns red on addition of an alkali. This is the behaviour of catechin as well as of pyrocatechin; but the difference in solubility speaks in favour of the crystals afforded by kino being pyrocatechin rather than catechin.

We thought pyrocatechin must also occur in the mother plant of kino, but this does not prove to be the case, no indication of its presence being perceptible either in the fresh bark or wood.[772]

Etti (1878) extracted from kino colourless prisms of Kinoïn by boiling the drug with twice its weight of hydrochloric acid, about 1·03 sp. gr. On cooling, kino-red separates, very little of it remaining in solution together with kinoïn. The latter is extracted by exhausting the liquid with ether, which by evaporation affords crystals of kinoïn. They should be recrystallized from boiling water; they agree with the formula C₁₄H₁₂O₆, which is to be regarded as that of a methylated gallic ether of pyrocatechin, viz., C₆H₄ (OCH₃) C₇H₅O₅.

Kinoïn by heating it to 130° C. gives off water and turns red:

2 C₁₄H₁₂O₆ = OH₂ · C₂₈H₂₂O₁₁.

The latter product is an amorphous mass agreeing with kino-red; by heating it at 160-170° it again loses water, thus affording another anhydride.

Etti succeeded in preparing methylic chloride, pyrocatechin CH₄(OH)₂ as well as gallic acid C₇H₆O₅, by decomposing kinoïn.

We have prepared kinoïn from Australian kino (see page 198), but failed in obtaining it from Malabar kino, which however Etti states to have used. Kino affords about 1½ per cent. of kinoïn.

The solutions of kinoïn turn red on addition of ferric salts.

Commercial kino yielded us 1·3 per cent. of ash.

Commerce—The quantity of true kino collected in the Madras forests is comparatively small, probably not exceeding a ton or two annually. The drug is often shipped from Cochin.

Uses—Kino is administered as an astringent. It is said to be used in the manufacture of wines, and it might be employed if cheap enough in tanning and dyeing.

Other sorts of Kino.

1. Butea Kino, Butea Gum, Bengal Kino, Palas or Pulas Kino, Gum of the Palas or Dhak Tree.

This is an exudation from Butea frondosa Roxb. (Leguminosæ), a tree of India and Burma, well known under the name of Palas or Dhak, and conspicuous for its splendid, large, orange, papilionaceous flowers.[773] According to Roxburgh it flows during the hot season from natural fissures or from wounds made in the bark, as a red juice which soon hardens into a ruby-coloured, brittle, astringent gum.

Authentic specimens of this kino have been placed at our disposal by Mr. Moodeen Sheriff of Madras and by Dr. J. Newton of Bellary. That received from the first-named gentleman consists of flattish, angular fragments (the largest about ½ an inch across) and small drops or tears of a very dark, ruby-coloured gum, which when held to the light is seen to be perfectly transparent. The flat pieces have been mostly dried on leaves, an impression of the veins of which they retain on one side, while the other is smooth and shining. The substance has a pure astringent taste, but no odour. It yielded us 1·8 per cent. of ash and contained 13·5 per cent. of water. Ether removes from it a small quantity of pyrocatechin. Boiling alcohol dissolves this kino to the extent of 46 per cent.; the solution which is but little coloured, produces an abundant greyish-green precipitate with perchloride of iron, and a white one with acetate of lead. It may be hence inferred that a tannic acid, probably kino-tannic acid, constitutes about half the weight of the drug, the remainder of which is formed of a soluble mucilaginous substance which we have not isolated in a state of purity. By submitting the Butea kino of Mr. Moodeen Sheriff to dry distillation we obtained pyrocatechin.

The sample from Dr. Newton is wholly in transparent drops and stalactitic pieces, considerably paler than that just described, but of the same beautiful ruby tint. The fragments dissolve freely and almost completely in cold water, the solution being neutral and exhibiting the same reactions as the former sample.

Butea kino, which in India is used in the place of Malabar kino, was long confounded with the latter by European pharmacologists, though the Indian names of the two substances are quite different. It is not obtained exclusively from B. frondosa, the allied B. superba Roxb. and B. parviflora Roxb. affording a similar exudation.

2. African or Gambia Kino.—Of this substance we have a specimen collected by Daniell[774] in the very locality whence it was obtained by Moore in 1733 (see p. 195), and by Park at the commencement of the present century. The tree yielding it, which still bears the Mandingo name Kano, and grows to a height of 40 to 50 feet, is Pterocarpus erinaceus Poiret, a native of Tropical Western Africa from Senegambia to Angola. The juices exude naturally from crevices in the bark, but much more plentifully by incisions; it soon coagulates, becoming deep blood-red and remarkably brittle. That in our possession is in very small, shining, angular fragments, which in a proper light appear transparent and of a deep ruby colour. In solubility and chemical characters, we can trace no difference between it and the kino of the allied Pt. Marsupium Roxb. This kino does not now find its way to England as a regular article of trade. From the statement of Welwitsch, it appears that the Portuguese of Angola employ it under the name of Sangue de Drago.[775]

3. Australian, Botany Bay, or Eucalyptus Kino.—For some years past, the London drug market has been supplied with considerable quantities of kino from Australia; in fact at one period this kino was the only sort to be purchased.

As it is the produce of numerous species of Eucalyptus, it is not surprising that it presents considerable diversity of appearance. The better qualities closely agree with Pterocarpus kino. They are in dark reddish-brown masses or grains, which when in thin fragments are seen to be transparent, of a garnet red hue and quite amorphous. The substance is mostly collected by the sawyers and wood-splitters. It is found within the trunks of trees of all sizes, in flattened cavities of the otherwise solid wood which are often parallel to the annual rings. In such place the kino, which is at first a viscid liquid, becomes inspissated and subsequently hard and brittle. It may also be obtained in a liquid state by incisions in the stems of growing trees: such liquid kino has occasionally been brought into the London market; it is a viscid treacle-like fluid, yielding by evaporation about 35 per cent. of solid kino.[776]

Authentic specimens of the kino of 16 species of Eucalyptus sent from Australia by F. von Müller, have been examined by Wiesner of Vienna.[777] He found the drug to be in most cases readily soluble in water or in spirit of wine, the solution being of a very astringent taste. The solution gave with sulphuric acid a pale red, flocculent precipitate of Kino-tannic Acid; with perchloride of iron (as in common kino) a dusky greenish precipitate,—except in the case of the kino of E. obliqua L’Hér. (Stringy-bark Tree), the solution of which was coloured dark violet.

Wiesner further states, that Eucalyptus kino affords a little Catechin[778] and Pyrocatechin. It contains no pectinous matter, but in some varieties a gum-like that of Acacia. In one sort, the kino of E. gigantea Hook,[779] gum is so abundant that the drug is nearly insoluble in spirit of wine.

By Etti’s process, as given at page 197, we obtained kinoïn from an Australian Kino, which contained numerous fragments of the wood. We noticed that both Australian and Malabar kino emitted a somewhat balsamic odour, when they were treated with hydrochloric acid.

From this examination, it is evident that the better varieties of Eucalyptus kino, such for instance as those derived from E. rostrata Schlecht. (Red or White Gum, or Flooded Gum of the colonists), E. corymbosa Sm. (Blood-wood) and E. citriodora Hook., possess the properties of Pterocarpus kino and might with no disadvantage be substituted for it.

LIGNUM PTEROCARPI.