Cinchona. Peruvian Bark.
Nat. Ord. — Cinchonaceae. Sex. Syst. — Pentandria Monogynia.
Description. — Cinchona Calisaya according to Weddell, is a lofty tree, with a trunk two or more feet in diameter, and a summit usually rising above the other trees of the forest. The leaves are oblong, or lanceolate-obovate, petiolate, obtuse, acute or slightly attenuated at the base, softish, from three to six inches long, and one or two in breadth, above smooth, of a velvety aspect and obscurely green, beneath smooth, and of a pale emerald hue, with scrobiculi at the axils of the veins, but scarcely visible on the upper surface. The stipules are about as long as the petioles, or somewhat longer, oblong, very obtuse, and very smooth. The flowers are in ovate or subcorymbose panicles. The calyx is pubescent, with a cup-shaped limb, and short triangular teeth ; the corolla is rose-colored, with a cylindrical tube about one-third of an inch long, and a laciniate limb fringed at the edges ; the stamina are concealed in the tube, and have anthers more than twice as long as the filaments. The fruit is an ovate capsule scarcely as long as the flower, inclosing elliptical lanceolate seeds, the margin of which is irregularly toothed, so as to have a fimbriated appearance. This tree grows in forests upon the Andes several thousand feet above the ocean, also in the hottest valleys of Bolivia, and in the south of Peru. From it the Calisaya or Yellow Bark is obtained, but, as stated by Weddell, who met with considerable difficulty before he could obtain a sight of the tree in its full vigor, it is rapidly disappearing, on account of the careless manner in which the bark-collectors attend to it. The discovery of this species has settled the inquiry concerning the true source of the Calisaya bark.
The Cinchona Boliviana, discovered and named by Weddell, inhabits Peru and Bolivia, but is found further to the north than the C. Calisaya; and in the northern parts of Bolivia the two species frequently grow together. The bark of the C. Boliviana is frequently mixed with the Calisaya, and it is not easy to distinguish them ; this, however, is unimportant, as the two barks do not essentially differ in their properties.
Cinchona Condaminea is a tree attaining the hight of eighteen feet, with a stem a foot in diameter. The branches are opposite, the lower horizontal, the upper rising at their extremities ; the bark of the trunk is ash-gray, with clefts or fissures, and yields when wounded a bitter astringent juice ; that of the small branches is greenish, smooth, glossy and easily separable from the wood. The leaves are quite smooth at all periods of growth, usually ovate-lanceolate, sometimes narrower and only lanceolate, occasionally ovate ; about four inches long and less than two broad, rather thin, not shining on the upper surface, or but little so in some specimens ; mostly with a pit or scrobicula at the axils of the veins beneath, when full-grown ; this scrobicula is either naked or ciliated, but the young leaves are indistinctly or not at all scrobiculate. Petioles smooth, about one-fourth the length of the leaves ; stipules oblong, obtuse, membranous, smooth. The flowers are in corymbose panicles, pedunculated, and forming a loose, large, very downy thyrsus in the axils of the upper leaves. Tube of the calyx tomentose, limb shortly urceolate, five-toothed, pubescent, not shining ; the teeth acute, roundish, triangular. Tube of the corolla slender, about four times as long as that of the calyx, tomentose; limb very shaggy within. This tree inhabits the mountains near Loxa, and several other places in Peru, always in micaceous schist, and occupies a zone of 1800 feet, growing at elevations between 5700 and 7500 feet. It furnishes the Crown, or Loxa bark.
Cinchona Micrantha is a large tree attaining the hight of forty feet, with quadrangular branches, smooth, except among the inflorescence. The leaves are from four to twelve inches long, and from two to six broad, oblong, obtuse, or hardly acute, rather membranous, very large, quite smooth on both sides, shining on the upper surface, and distinctly pitted at the axils of veins beneath, and either smooth or hairy there ; those near the base of the inflorescence, shorter and blunter. The flowers are smaller than those of any other species, except C. Lancifolia, and are in terminal, loose, leafless panicles. Calyx tomentose, with a short five-toothed limb, scarcely changed in the fruit. Corolla tomentose, woolly inside the limb. This tree grows on the high, cool, and wooded mountains of Peru, and furnishes the pale bark, or the gray or silver bark of British commerce, frequently called Huanuco bark.
Cinchona Lancifolia has quadrangular branches, except when very young, when they are covered with short spreading hairs. Leaves oblong-lanceolate, very acute at both ends, revolute at the edge ; somewhat coriaceous, not shining, smooth above, thinly beset with hairs on the veins beneath, not scrobiculate. Peduncles axillary, hairy, trifid, shorter than the leaves, and not forming a panicle or thyrsus ; the divisions cymose and about five-flowered. Tube of calyx tomentose ; limb smooth, campanulate, three to five-toothed, teeth revolute at the apex. Corolla hairy, the smallest in the genus, with a tube about three times as long as the cup of the calyx ; the limb on each side smooth, surmounted by an enlarged calyx. This tree is a native of New Grenada, and the bark which it affords was supposed by Lindley to be the best pale bark; but according to Pereira it is the spongy Carthagena bark of Guibort, a new spurious yellow bark. Mutis, the discoverer of this species, termed it Orange bark.
Cinchona Cordifolia is a spreading tree, fifteen or twenty feet high, with a single, erect, round stem, covered with a smooth bark, of a brownish-gray color. Its branches are smooth and quadrangular. Leaves roundish, obtuse at both ends, especially at base, or roundish-oblong and tapering to the base, strongly-veined, thin, smooth above, downy beneath, and hairy at the veins and axils when young, becoming nearly smooth when old ; never pitted. Panicle contracted, thyrsoid, leafy at base, or formed of corymbose peduncles, axillary to the upper leaves, with the ramifications tomentose. Calyx tomentose, with a large, smooth, campanulate, five-toothed cup, the lobes of which become quadrate and cuspidate ; the tube subglobose when it first begins to enlarge after the fall of the corolla, afterward becoming longer. Corolla tomentose, with a thick tube whose diameter is equal to the length of the shaggy lobes. This tree inhabits the mountains about Santa Fe de Bogota in New Grenada, at an elevation of from 5000 to 9500 feet. It was at one time supposed to afford the officinal yellow bark. The Quina Amarilla, or Yellow bark of Santa Fe is supposed to be derived from this tree, and which has been ascertained by Bergen and Guibort, to be identical with Hard Carthagena Bark.
Cinchona Magnifolia, described by Mutis as the C. Oblongifolia, has oblong leaves, sometimes narrowed toward the base, obtuse, often a foot long, coriaceous, strongly-ribbed, shining on both sides, perfectly free from hairiness, except when very young, unless on the principal veins, and at their axils. Flowers in a large terminal, leafless thyrsus, with erect branches, merely downy, not woolly. Calyx-tube clothed with a very short, dense tomentum ; limb pubescent, smooth at the edges, with oval, obtuse, imbricating teeth. Corolla externally tomentose, with a tube hardly four times as long as that of the calyx ; limb quite smooth inside, except at the edges, which are tomentose. Fruit smooth, narrower at the base than at the apex, slightly ribbed. This tree is found in abundance on the mountains Panatahuas, in low land near torrents, in situations fully exposed to the sun, but badly ventilated. It was formerly supposed to be the source of the officinal red bark, which, however, is incorrect. The bark afforded by the tree is red, but it is the red Carthagena bark, a worthless variety, and identical with the Quina Nova or New bark of European commerce. Weddell has transferred this tree to his new genus Cascarilla, which differs from the true Cinchona or Peruvian bark trees, in not yielding any cinchonia or quinia.
The first three species above described, are regarded as officinal by the Pharmacopeias of the United States and Great Britain ; the others have contributed more or less to furnish the bark of commerce, but are not viewed as officinal. There are many other species which yield barks possessing febrifuge properties, and which we will merely name, as :
— the C. Nitida, found in cold situations, in lofty mountains of the Andes, and furnishing a bark, which, though unknown as a distinct variety in commerce, is yet very highly esteemed in Huanuco, Huamalies, etc., bringing a veiy high price.
— The C. Lucumaefolia, growing near Loxa in Peru, and probably contributing to the Loxa barks.
— C. Lanceolata, inhabiting cold elevated situations in the Andes ; its bark is yellow, and resembles the calisaya in its flavor.
— C. Ovalifolia, a shrub from seven to ten feet high, and growing in the province of Cuenca ; its bark is of an inferior quality, and according to Pereira, it is the White cinchona of Mutis.
— C. Ovata, growing in close, badly ventilated woods, in the hottest parts at the foot of the Andes, about ten leagues from Huanuco. The bark from this tree varies in character according to its situation, the finer kinds passing for Calisaya bark, and in some sections it is employed to adulterate the true Calisaya. Weddell states that this species is widely diffused in Peru and Bolivia. Ruiz calls its bark Cascarilla Pallida or Pale bark, and states that an extract is prepared from it at Panao.
— C. Pubescens inhabits the lower parts of the Andes in the provinces of Loxa, Jaen, Panatahuas, etc., and is likewise found in New Grenada. It is a large tree with purple flowers, and leaves violet-tinted. It yields an inferior bark, which, it is said, is employed to adulterate the better kinds. Reichel considers it the Huamalies bark of commerce, and Weddell states it to be the Cusco bark of French commerce.
— C. Hirsuta, occurring in high and cold situations on the Andes, yields a good bark, formerly called Quina Delgadilla or Delgada, but which is seldom collected at present.
— C. Glandulifera, a shrub of about twelve feet, with very fragrant blossoms, and found on the high mountains N. W. of Huanuco. It yields an excellent bark, not met with in commerce, called by the inhabitants Cascarilla Negrilla from its blackish epidermis.
— C. Acutifolia, growing in the Peruvian Andes, and yielding a worthless bark, called according to Ruiz and Pavon, Cascarilla de hoja aguda ; Weddell has placed this species in his new genus Cascarilla. C. Macrocarpa, a shrub about eight feet high, found in the provinces of Loxa and Cuenca, and in New Grenada. Its bark is called Quina Blanca, or White Bark, and is not much esteemed ; Weddell has transferred it to his Cascarilla.
— C. Villosa, growing at Jaen of Loxa.
— C. Rotundifolia, of Loxa.
— C. Oblongifolia, of St. Jaen de Loxa, of which three nothing is known respecting their barks.
— C. Cadiiciflora, growing near the town of Jaen de Bracomoris ; the trunk yields considerable resin, and the bark is called Cascarilla bora. C Scrobiculata, growing in the Peruvian provinces of Jaen, Cuzco, and Carabaya ; the bark of the young branches has been placed with the pale or gray barks in quality ; that of the larger branches and stem probably among the red.
— C Stenocarpa, occurring in the mountains of Loxa, placed among the Cascarillas by Weddell.
— C. Cava, found in Quito, and placed by Weddell in the genus Cascarilla. To these may be added, C. Amygdalifolia, C. Purpurascens, C. Australia, C. Chomeliana, C. Asperifolia, C. Carabayensis, all of which were discovered and described by Weddell ; and as imperfectly known species, C. Dichotoma, C. Macrocalyx, C. Crassifolia, C. Pelaba, and C. Muzonensis.
History. — Peruvian Bark was introduced into Europe in 1640, but the first account of the plant was given by Dr. Arrott in 1737. About the same time La Condamine, and in 1740 the elder Jussieu obtained specimens from near Loxa. In 1772, Mutis, a Spanish botanist, having official charge of the Cinchona forests, became a leading authority among Botanists, but, unfortunately, he committed many errors, and misled them, causing much difficulty in determining the correct botanical history of the trees which yielded the Peruvian bark. Since then Ruiz, Pavon, Humboldt, and Bonpland, with many others, have furnished more or less accurate information relative to this subject. The latest investigations have been made by Weddell, whose valuable researches have settled the hitherto vexatious question relative to the Calisaya bark, he having discovered its true source.
The name, Cinchona, was bestowed upon the plant by Linnaeus, in compliment to the Countess of Cinchon, the wife of the then Viceroy of Peru, who was cured of an ague by it, and brought some of it to Europe in 1640. The history of its discovery is involved in much obscurity. The genuine Cinchonas are found on the Andes, principally in Columbia, Bolivia, and Peru, or from 11° N. to 20° S. latitude. They are found in the greatest abundance west of the Andes, and at elevations varying from 1200 to 10,000 feet ; how far they extend eastward has not been thoroughly ascertained. The best kinds are found in dry situations, at a temperature about 68° F., and situated at elevations between 6000 and 8000 feet. Much confusion has resulted from the too great importance attached to the study of particular species, and to the attempt to divide the genus into numerous species, from very slight differences. It is now well known that the same tree may vary in its foliage, as well as in the chemical character of its bark, depending on peculiarities of situation or growth, severity or mildness of climate, degree of mountainous elevation, nature of the soil, and various other circumstances. Humboldt considers all those trees with hairy and woolly blossoms, as the true Cinchonas, possessing febrifuge virtues, and Weddell has transferred all those with smooth corollas into his new genus, Cascarilla.
The gathering of the bark is performed by persons called Cascarilleros, who, in order to be properly qualified for the business, must be well acquainted with the trees, the proper period for collection, and other circumstances necessary for obtaining good bark. They usually commence operations in May, when the dry season sets in, more generally cutting down the tree, and then stripping off the bark; sometimes they decorticate the tree while standing. The former plan is viewed as the best, as the stump pushes up shoots which eventually become fit for decortication, while, in the latter instance, deprived of its bark, the whole plant perishes. After the bark has been removed, it must be speedily dried in the sun, or else it becomes impaired. In the process of drying, the bark rolls itself up, becoming quilled, and is then sent to the coast for exportation, and is packed in chests, called seroons, formed of hides and coarse cloth, each package weighing from fifty to one hundred and fifty pounds, and usually containing several sorts in the same seroon.
The Cinchona forests occupy regions which never can be applied to agricultural purposes, and which extend over thirty degrees of latitude, thus almost precluding the idea of even their remote extinction. The bitterness of the tree is not confined to its bark, but exists in its leaves, flowers, and root-bark. In the leaves it is associated with an acid, and in the flowers with a delightful fragrance which diffuses itself throughout the air in the vicinity of the trees.
Cinchona is divided into three varieties, the Pale, the Yellow, and the Red — the extra-officinal or inferior kinds are termed Carthagena Barks. This division is founded on the physical characters of the bark, which appear to be very distinct in the officinal varieties above alluded to, and which is, prohahly, the best division that could be made in the present state of our knowledge.
The Pale Bark is so termed, on account of the color of its powder, which is pale or grayish-fawn, and of a deeper hue in the inferior sorts. It is moderately bitter and somewhat astringent, with a feeble, agreeably aromatic odor. The bark as received in this country is in cylindrical pieces, varying from a few inches to two feet in length, singly or doubly quilled, from two lines to an inch in diameter, and from half a line, to three or four lines in thickness. The best kinds are about the size of a goosequill. They have a rough exterior, with circular or longitudinal fibers, and a grayish, dull-brown, or grayish-fawn color, owing to adhering lichens. The interior or internal surface is smooth in the finer kinds, but rough and somewhat ligneous in the coarser ; its color is a brownish-orange, sometimes inclining to red, sometimes to yellow, and in the poorer specimens of a dusky hue. The fracture of the bark is generally smooth, with some short filaments on the internal part only ; it is more fibrous in the coarser barks. The pale bark is collected, probably, from C. Condaminea and C. Micrantha, and its appearance indicates it to have been taken from the smaller branches. All the pale barks contain a much greater quantity of cinchonia than quinia.; and solution of sulphate of soda is not precipitated with their infusion. In this country it is but little employed, in consequence of the little quinia which it yields. There are several varieties of pale bark, differing more or less in their properties, as the Crown or Loza, the Gray, Silver, Lima, or Huanuco, the Ash or Jaen, and the White Loxa, among which the first named is esteemed the finest.
Yellow Bark, is the term applied to those barks of this color only, which possess the valuable chemical properties of the drug, and which are known by the name of Calisaya ; they are arranged into two divisions, the quilled and the flat. The quilled Calisaya is in pieces varying from a few inches to two feet in length, from a quarter of an inch to three inches in diameter, and of equally variable thickness. The epidermis is of a brownish color, diversified or concealed by whitish or yellowish lichens, rough, being much traversed by longitudinal wrinkles and transverse fissures, and is generally easily separable from the proper bark. It yields a dark-red, tasteless, and inactive powder, and should, therefore, always be removed before the bark is powdered. When the epidermis is removed, the bark is one or two lines in thickness, compact, of a short-fibrous texture, and when broken presents shining points, apparently the termination of small fibers running longitudinally, which, examined by the microscope, are found, when freed from a salmon-colored powder that surrounds them, to be yellow and transparent. They readily separate, when the bark is powdered, in the form of spiculae, which, like those of cowhage, insinuate themselves into the skin, and produce a disagreeable itching and irritation. The color of the bark is brownish-yellow, with a tinge of orange, the taste less astringent than that of the pale bark, but much more bitter. The external portion of the proper bark is more powerful in medicinal virtue than the internal ; probably from the longer exposure of the latter to the action of the air and moisture ; the odor is faint, but resembles that of the pale varieties, when the bark is boiled in water.
The Flat Calisaya bark is obtained from the large branches and trunk; it is in pieces of various lengths, either quite flat, or but slightly curved, generally stripped of their epidermis, on which account they are preferable to the quilled pieces. Their inner surface is like that of the quilled pieces ; the outer is irregular, marked with confluent longitudinal furrows and ridges, and somewhat darker-colored than the inner, being of a brownish-fawn, frequently diversified with darker stains. The bark is of uniform fracture throughout, generally thicker than the quilled, more fibrous in its texture, less compact, less bitter, and possessed of less medicinal power. The best yellow bark is very bitter, with a slight astringency, of a brownish-yellow color with a tinge of orange, which is still brighter in the powder, and contains a much greater quantity of quinia than cinchonia ; the salts of quinia and lime are so abundant in its composition, that a strong infusion of it instantly precipitates a solution of sulphate of soda. This variety of bark is principally derived from the Cinchona Calisaya, and a portion from the C. Boliviano,, both of which species have been recently described by Weddell. It is produced exclusively in Bolivia, and in the southern part of the province of Carabaya, and is imported principally from the ports on the Pacific Ocean.
The Red Bark, always comes to this country in quilled or flat pieces, and packed in chests. The quills are from two lines to an inch and a quarter in diameter, from one-third of a line to two lines thick, and from two to twelve inches or more in length. The flat pieces, which are the more common of the two, are seldom absolutely flat, but are somewhat curved ; they are from two inches to two feet in length, from one to five inches in breadth, and from three to nine lines in thickness. They are generally covered with the epidermis, which is rough, wrinkled longitudinally, often warty, little fissured, of a reddish-brown color, with a grayish efflorescence in the hollows from adhering lichens. Beneath the epidermis is a dark-red, brittle, and compact layer, possessing some bitterness and astringency, but much less so than the fibrous and woody interior parts, which have a lively brownish -red color, and the odor of other good barks. Its powder is of a reddish-brown color, and contains considerable quantities both of quinia and of cinchonia. Its decoction is of a turbid salmon color. The species of Cinchona which yields the red bark is unknown, although supposed to be taken from the same trees which furnish the pale bark. Weddell observed that the pale barks are almost constantly nothing else than the young barks of the same trees which yield the yellow and red barks. The red and yellow barks are preferred in medicine to the pale variety.
The Carthagena Barks are all those barks brought from the northern Atlantic ports of South America, and known as Carthagena, Maracaybo, and Santa Martha barks. They all have a soft, whitish, micaceous epidermis, which may be readily removed by the nail, and some contain small quantities of quinia and cinchonia ; there are several varieties of them, as, — 1. Hard-yellow Carthagena Bark, the China flava dura of Von Bergen, supposed to be derived from the Cinchona Cordifolia, and imported from Carthagena. It is obtained generally in quilled pieces, or in sections of cylinders, and often in fiat pieces. It may be known from the true yellow bark, by having scarcely any transverse fissures, and by presenting uniformly a velvety, grayish-white, or pale-yellowish-white, glistening epidermis, except in places where it has been rubbed, and which color is essential and not dependent upon lichens, as with the true bark. Its fracture is abrupt and splintery. Its taste is bitter and nauseous, but not so bitter as in the officinal article.
2. Fibrous, or Woody-yellow Carthagena Bark, the China flava fibrosa of Von Bergen ; its botanical source is not positively known. It generally occurs in flat or slightly-curved pieces, sometimes in quills. Its epidermis is generally wanting in part or altogether, but when present, resembles in consistence that of the former variety. Its color is rather brighter than in the preceding kind, it is less compact, its fracture is more fibrous, causing it to exhibit long splinters when broken transversely, and often to hang together by connecting fibers when broken longitudinally, and its taste is more feebly bitter and slowly developed.
The powder of these Yellow barks is of a yellowish-cinnamon color, with less of the reddish tint than the calisaya, for which it is not unfrequently sold. It may be detected by its feeble bitterness, but with still more certainty by a solution of sulphate of soda, which causes no precipitate with its infusion.
3. The Red Carthagena Bark, the Quinquina Nova or New Bark of Guibort, and the Red Bark of Santa Fe of Mutis ; said to be derived from the Cinchona Magnifolia. It is widely different from every other true cinchona bark, and has no resemblance whatever to the true officinal red bark ; and is seldom seen, except as an adulteration of this latter article. When large the bark is flat or open, when small and cylindrical, quilled ; its epidermis is whitish, micaceous, thin, uniform, with a very few transverse rents, apparently caused by drying. The bark, stripped of its epidermis, is of a pale reddish-brown color, becoming deeper externally where it is exposed to the air, thick, spongy, of a flat astringent taste with scarcely any bitterness ; its fracture is foliaceous externally, and short-fibrous internally ; its powder is fibrous and red, and said to contain neither quinia nor cinchonia.
4. The Orange Carthagena Bark, the Spongy Carthagena Bark of Guibourt, and the Orange Cinchona of Santa Fe, of Mutis, derived from the Cinchona Lancifolia. It occurs in quills, flat and semicylindrical pieces of various sizes, covered with a velvety, pale grayish-white, micaceous surface, marked with longitudinal and sometimes transverse fissures. The substance of the bark is orange-colored, fibrous externally, light, spongy under the teeth, feebly bitter, and of but little value. Its powder is of a beautiful orange color. This bark is seldom met with in commerce.
5. Guibourt has described a Brown Carthagena Bark, which is thick, of an orange-brown color when freshly cut, and a chocolate color on its inner surface, very bitter and disagreeable, but sometimes spongy and nearly tasteless ; its epidermis is soft, velvety, white, and micaceous. Its origin is unknown, and it is worthless.
Several barks have occasionally been found in commerce, possessing none of the physical characteristics of the officinal varieties, and which are termed False Barks. Among them are, the Caribwan Bark from the Exostemma Caribaea ; the St. Lucia Bark from the Exostemma Floribunda, and the Pitaya Bark of uncertain origin. This last only is known in this country ; it is in quills, the bark being hard, compact, thin, and with a short, rough fracture. The outer surface is of a dull grayish-olive color, with irregular lighter or whitish spots ; the internal surface is deep-brown or blackish ; the fresh fracture, brownish-red or orange. It has a very bitter taste, and is inodorous. It contains a new crystallizable alkaline, tasteless salt, forming bitter salts with the acids, termed Pitania. The bark has cured ague in the quantity of half an ounce. Neither quinia nor cinchonia exist in the false barks.
The Cinchona barks have often been analysed, and with various results. Dr. Westring was the first who attempted the discovery of an active, febrifuge principle in the bark ; subsequently Seguin, Deschamps, Vauquelin, Duncan, Gomez, Lambert, and others pursued a similar undertaking, but the honor of first making the great discovery of the alkaloid principles termed Cinchonia and Quinia was reserved to Pelletier and Caventou, who announced it in the year 1820. According to their analysis, the several barks contain, as follows : —
Pale Loxa Bark contains a fatty matter, a red coloring matter, very slightly soluble, identical with the cinchonic red of Reuss, a yellow coloring matter, soluble in water and alcohol, and capable of being precipitated by the subacetate of lead, tannin, gum, starch, lignin, kinate of lime, kinate of cinchonia, and a minute quantity of kinate of quinia.
Yellow Calisaya Bark contains the same as the above, with the exception of gum, and a larger proportion of kinate of quinia, and much less kinate of cinchonia.
Red Bark also contains the same as the Pale Loxa, with the exception of gum, and a large proportion both of kinate of quinia, and of kinate of cinchonia.
The only appreciable difference therefore in the officinal barks, is in the proportions they contain of quinia and cinchonia. The odor of the bark depends upon a thick, bitterish acrid, volatile oil, which is present in minute quantity.
The fatty matter existing in the bark is of a greenish color when obtained from the pale bark, and orange-yellow from the yellow. Boiling alcohol dissolves it, but deposits a portion of it on cooling ; ether dissolves it readily ; alkalies form soaps with it, and in water it is insoluble. The red coloring matter is a reddish-brown, amorphous substance, insipid, inodorous, soluble in alcohol, alkaline solutions, or their carbonates, and insoluble in ether or water, though slightly soluble in the latter at the boiling point. Its solubility in water is augmented by the addition of acids. It precipitates tartar emetic, but not gelatin ; if treated with a cold solution of potassa or soda, or by ammonia, lime, or baryta with heat, and precipitated, from the solution thus formed, by acids, it is converted into a species of tannin, and forms an insoluble compound with gelatin. Subacetate of lead precipitates it. The red bark contains the greatest proportion of it, the pale the least. The yellow coloring matter has little taste, is soluble in water, alcohol, and ether, does not precipitate gelatin nor tartar-emetic, and is itself precipitated by subacetate of lead.
The Tannin or Soluble red coloring matter of Pelletier and Caventou, has a brownish-red color, and austere taste, is soluble in water or alcohol, combines with metallic oxides, like the tannin in catechu, produces precipitates with the salts of iron, which are deep-green with the pale bark, blackish-brown with the yellow, and reddish-brown with the red. With gelatin and tartar-emetic it forms white precipitates, and readily absorbs the atmospheric oxygen, becoming red and insoluble. Although considered to possess all the properties of tannic acid, yet it must differ materially from that found in galls, which forms insoluble compounds with quinia and cinchonia.
Kinic acid, likewise called Quinic, or Cinchonic acid, may be obtained by evaporating the infusion of bark to a solid consistence, and then treating the solid extract with alcohol, which gives a residue consisting of mucilage with kinate of lime, which is insoluble in alcohol. Dissolve this residue in water, and evaporate with a moderate heat, and crystals of the kinate will be deposited, which may be purified by a second solution and crystallization. The salt thus obtained, being dissolved in water, is decomposed by means of oxalic acid, which precipitates the lime, and leaves the kink acid in solution. This may be procured in the crystalline state by spontaneous evaporation, though as usually prepared, it is in the form of a thick, syrupy liquid. The crystals are transparent, colorless, acid, and readily soluble in alcohol, and in water. The kinates of cinchonia and quinia may be obtained either by the direct combination of their constituents, or by the mutual decomposition of the sulphates of those alkaloids and the kinate of lime. Kinate of cinchonia crystallizes with difficulty, is very soluble in water, soluble in alcohol, and has a bitter and astringent taste. Kinate of quinia crystallizes in opake or translucent crusts of a mammillated form ; it is soluble in water, less so in rectified alcohol, and has a very bitter taste.
The most important constituents of Cinchona bark are the Cinchonia and Quinia, the mode of preparing which, with their history, etc., will be found under their appropriate heads.
The different kinds of Cinchona bark, yield their active constituents to boiling water, rectified spirit, proof spirit, and diluted acids. In preparing a decoction or infusion of bark, the addition of muriatic or sulphuric acid in small quantity would be advantageous in retaining the alkaloids in the solution ; because, without the infusion is thus acidulated, the cinchonic-red unites with the alkaloids, producing compounds not readily soluble in hot water, and still less soluble when cold, so that as the infusion cools, the active constituents are thrown partly down insoluble, forming part of a deposit of a reddish powder. Proof spirit, from its ready solubility of the principal constituents, is a much better solvent than water, and should be used in preparing officinal tinctures. Percolation exhausts more of the alkaloid principles than maceration; and the extract prepared from the tincture is vastly superior to that obtained from the aqueous decoction.
Water acidulated with muriatic, sulphuric, nitric, acetic, or tartaric acid, but especially with the first-named acid, effects exhaustion completely, either by decoction or by percolation. Diluted alkalies, as well as their carbonates, do not act on the alkaloids, but decompose their natural salts, leaving the bases undissolved, and dissolving cinchonic-red, cinchonic-yellow, tannin and fatty matter.
In infusions of the true barks, ammonia and potassa precipitate chiefly the alkaloids; bichloride of mercury, and neutral chloride of platinum produce insoluble double salts of the alkaloids ; astringent solutions produce insoluble tannates of the alkaloids; tartar emetic, sulphate of iron, and gelatin, owing to the presence of tannin, precipitate tannates of antimony, iron, and of gelatin, and sometimes throw down cinchonic-red also ; oxalate of ammonia, and in strong infusions sulphate of soda, throw down oxalate or sulphate of lime; and iodide of potassium causes precipitates of a complex nature.
In order to determine the genuineness of Peruvian bark, or to detect adulterations, many druggists judge of the color of the powder, which is the form in which they more usually obtain it, its pure, strong, aromatic, evanescent bitterness, and the peculiarity and strength of its aroma ; but this method is extremely fallacious. The best methods of testing it are by chemical reactions, among which ammonia, iodide of potassium, infusion of galls, and solution of isinglass are the best. Ammonia causes a more or less abundant precipitate with the true bark, soluble in an excess of the reagent, but throws down no precipitate with the infusions of the Carthagena and of the false barks. Iodide of potassium causes sooner or later a yellowish-white or yellowish-red precipitate with the true barks, but not with the others. Infusion of galls causes no precipitate, except with the true barks; hence, no bark can be considered good which does not afford a precipitate with the infusion of this substance. Gelatin causes a precipitate only with the Carthagena barks. It must be remembered that all the substances which precipitate the infusion of bark, do not by any means, necessarily impair its virtues, as it contains several inert ingredients which form insoluble compounds with bodies that do not disturb its active principles.
In preparing a decoction of Cinchona, it should be boiled for ten minutes in a covered vessel, and strained while hot; long boiling, or the action of atmospheric oxygen, or both combined materially impair its virtues. By acidulating the water employed, say a fluidrachm of muriatic or sulphuric acid to a pint of the water, we will be able to extract all the virtues of the bark. Tannic, gallic, oxalic and tartaric acids, or substances containing them should be excluded from the decoction, as they form insoluble, or nearly insoluble salts with the alkaline principles of the bark. The alkalies, alkaline earths, and salifiable bases generally should also be excluded, because, uniting with the Kinic acid, they precipitate the quiuia and cinchonia.
The following mode of estimating the value of bark by the quantity of alkaline matter it contains, we copy from a communication of M. Tilloy of Dijon, published in the 13th vol. of the Journ. de Pharmacie, p. 530. "Take an ounce of the bark coarsely powdered, introduce it into about 12 ounces of alcohol of 30° B. (sp. gr. 0.8748), expose the mixture for half an hour to a temperature of from 105° to 120° F., draw off the alcohol, add a fresh portion, and act as before ; unite the liquors, and throw into them a sufficient quantity of acetate or subacetate of lead to precipitate the coloring matter and kinic acid, then allow the insoluble matter to subside, and filter. Add to the filtered liquor a few drops of sulphuric acid to separate the excess of acetate of lead, filter, and distil off the alcohol. There remains an acetate or sulphate of quinia, according to the quantity of sulphuric acid employed, together with a fatty matter which will adhere to the vessel. Decant the liquor, and add ammonia, which will instantaneously precipitate the quinia. Too much ammonia will retain it in solution ; but in this case a few drops of sulphuric acid will cause it to precipitate. The quinia washed with warm water, and then treated with sulphuric acid, water, and a little animal charcoal, yields very white sulphate of quinia. I have thus obtained in six hours nine grains of the sulphate from an ounce of bark [576 grains French], which is a large proportion when allowances are made for the loss during the process."
The Edinburgh Pharmacopoeia gives the following mode of testing the value of yellow bark: "A filtered decoction of one hundred grains of the powder in two fluidounces of distilled water, gives, with a fluidounce of concentrated solution of carbonate of soda, a precipitate, which, when heated in the fluid becomes a fused mass, weighing when cold two grains, or more, and easily soluble in solution of oxalic acid."
Properties and Uses. — Cinchona bark is tonic, antiperiodic, slightly astringent, and topically antiseptic. When received into the stomach it generally causes a sense .of heat, which often diffuses itself gradually over the whole trunk ; occasionally it causes gastric and intestinal irritation, and even nausea and vomiting, particularly if the stomach is in an irritable or inflamed condition. The circulation finally becomes influenced by it, as manifested in the increased frequency of the pulse, with a slight excitement of all the functions of the system, especially when given in large doses. In many persons its action upon the nervous system is accompanied with a sense of tension, fullness, or slight pain in the head, tinnitus aurium or singing in the ears, and partial deafness. It is valuable in functional derangements of the stomach, improving digestion, and invigorating the nervous and muscular systems in diseases of general debility, and in convalescence from exhausting diseases. As a tonic, it will be found of advantage in the latter stages of typhus gravior, also in measles, small-pox, malignant scarlatina, during the absence of fever or inflammation ; likewise in carbuncle, gangrenous erysipelas, and in all cases in which the system is exhausted under large purulent discharges, and where there is a tendency to recovery, supporting the powers of the constitution until all abnormal action is removed. It may likewise be used in all chronic diseases attended with debility, as in scrofula, dropsy, passive hemorrhages, certain forms of dyspepsia, obstinate cutaneous affections, amenorrhea, chorea, and hysteria. Its use is contra-indicated where any local irritation or inflammation is present ; profuse sweats during sleep may be considered one indication for its employment.
Cinchona bark, however, exhibits its most important therapeutical powers, as an antiperiodic, and in the consequent influence it exerts in almost invariably curing remittent and intermittent fevers, and the generality of diseases which are accompanied by symptoms of marked periodicity, as neuralgia, hemicrania, epilepsy, diarrhea and dysentery when epidemic, etc. Its use should in most cases be preceded by a laxative, after the action of which the powder may be given in doses of from ten to sixty grains, and repeated according to circumstances, every one, two or four hours, until one or two ounces have been taken during the periods of intermission, and continue thus until a cure is effected, or the remedy is found insufficient for the cure of the disease. In the use of the barks, to obtain their antiperiodic influence, the red and yellow are considered superior to the pale, and of which the red is preferred. The pale bark is preferable as a tonic, being less apt to offend the stomach, or irritate the bowels. Quinia, or its salts, especially the sulphate, is usually employed as a tonic and antiperiodic in place of the bark itself, but there have been many instances in which the bark in powder has succeeded in effecting a cure, when its alkaloidal salts failed; the cause of this is not well understood. In such cases, when the powder from its bulk or otherwise, offends the stomach, the infusion, decoction, tincture, or extract may be administered. Sometimes bark or its preparations occasions purging, which may be obviated by small portions of opium or laudanum.
Externally, a poultice of the bark has been found an excellent application to felons, fetid and gangrenous ulcers, etc., also as an injection with opium, when the stomach rejects it; and quilted between two pieces of muslin or flannel, and made into jackets, it has been of utility in obstinate intermittents, to be worn next the skin. Dose of Cinchona as an antiperiodic, from half a drachm to a drachm; as a tonic, from ten to sixty grains ; of the infusion or decoction two fluidounces, to be repeated two or three times a day; of the extract from five to thirty grains.
Off. Prep. — Cinchonia; Decoctum Cinchonae; Extractum Cinchonae; Extractum Cinchonae Fluidum; Infusum Cinchonae; Quiniae Sulphas; Tinctura Cinchonae; Vinum Cinchonae Compositum.