Scientific Notices. On the coloring matter of the orange-leaved Morinda (Morinda citrifolia.)

The London Journal of Arts, Sciences, and Manufactures, and Repertory of Patent Inventions.

Conducted by Mr. W. Newton, of the Office for Patents, Chancery Lane. (Assisted by several Scientific Gentlemen.)

VOL. XXXVI. (Conjoined Series.)

London: Published by W. Newton, at the office for patents, 66, Chancerylane, and Manchester; t. and W. Piper, Paternoster Row; Simpkin, Marshall, and Co., Stationers' Court; J. McCombe, Buchanan St., Glasgow; and Galinani's Library, Rue Vivienne,

Paris. 1850

By Mr. T. Anderson.

The substance which forms the subject of this paper was introduced some time ago into Glasgow under the name of Sooranjee, as a substitute for madder in the operation of dyeing. Experiments were, immediately after its importation, made with it by some of the first cotton printers in Glasgow, and the uniform opinion formed was, that this substance was not a coloring matter, and, therefore, could not be of any utility. Professor Balfour having forwarded some samples of the root to Mr. Anderson, that gentleman subjected them to chemical analysis. The seeds of this plant seemed perfectly identical with those of the sooranjee or soorinjee,—a quantity of which Mr. Anderson had formerly received from Bombay. This plant appears to have been long known and employed by the natives for the production of coloring matter. Unfortunately Mr. Anderson did not succeed in causing these seeds to germinate, which prevented the possibility of his studying the native plant itself, and comparing its characteristics with those of the pretended mother plant.

The morinda citrifolia has been described by Rheede (Hortus Malabaricus I., 97) under the name of cada pilava and is known to botanists under the name of Bancutus latifolia Rumphi (Herbar Amboinense V., cap. 13). In these works, it is expressly stated that the roots of the species mentioned do not possess any dyeing properties; whilst those of the Bancutus angustifolia, or morinda citrifolia, of modern botanists (doubtless the wongkudu of the Japanese dyers) is employed for the production of a splendid scarlet color. An exact description of the cultivation of the morinda citrifolia, and its employment for dyeing, is given by Hunter (Asiatic Researches IV., 35). He also calls attention to the fact, that this plant is known in Malacca under the name of aal, and in Oude under that of atchy. It does not appear that any chemical analyses have yet been made of this root. Dr. Bancroft has, however, made some observations upon a root introduced from India under the name of aurtch, which resembles madder in appearance, and seems to belong to the morinda citrifolia. As to the name sooranjee, which it has received, no definite information could be arrived at as to its derivation. Sooranjee is the root of the plant; and, as imported, it consists of pieces from one to two inches in thickness, and varying in diameter from three to twelve-thirtieths of an inch. In the largest pieces, the bark is thick, and constitutes the greatest part of the root; but, in pieces of a smaller size, the bark is much thinner,—its outside color is of a pale yellowish-brown; but, when broken, it presents, in the interior, a color varying from a fine yellow to a reddish-brown. The wood itself is of a light yellow color, becoming deeper towards the centre, and scarcely perceptible near the bark. Alkalies cause it to assume a deep red color, which indicates the presence of a certain quantity of coloring matter. The bark or rind is easily removed, and presents, on its inner face, a peculiar silvery lustre, which is very evident in large pieces, but is scarcely discernible in the small pieces. On boiling in water, the inside furnishes a yellow color; and, if boiled with alcohol, a deep red is produced.

In order to prepare the coloring matter from sooranjee, which Mr. Anderson calls morindin, the treatment with boiling water was first adopted, —preliminary experiments having shewn that this substance was easily soluble in that liquid: it was soon as certained, however, that this method was not applicable, as the decoction contained a viscous matter, which presented an obstacle to filtration. The employment of alkalies, in which this substance is rapidly dissolved, appeared also to be impracticable; Mr. An derson was therefore obliged to have recourse to alcohol, which perfectly answered the purpose. The bark or rind, after being deprived of all its ligneous parts, and ground to a fine powder, was boiled with six times its weight of rectified alcohol. The solution, after having been filtered while hot, was of a deep brownish-red color; and, on cooling, deposited a brown flaky precipitate, containing the morindin, and other coloring matters found in the root, although in small proportion. A second decoction, with the same quantity of alcohol, furnished a paler solution, in which the morindin was deposited with a much less quantity of red coloring matter. The same treatment was repeated until, on the dyeing matter cooling, no further deposit was obtained. Each of these latter decoctions furnished a substance purer and purer,—so that, at last, it was deposited in the form of small yellow crystals. By means of repeated crystalliza tion in alcohol at 50°, the red substance was completely removed and a fine yellow color obtained; but still some impurity remained,—for, in one instance, a residuum of 0.47 per cent. of ash was left; and, in another, a residuum of 0.32 per cent. The elimination of these mineral matters could not be effected by crystallization in alcohol, but only in alcoholic solutions, sharpened with hydrochloric acid. In this liquor the morindin is crystallized in a perfectly pure state.

Morindin is separated from its solution in the form of small crystals, grouped in the same manner as those of the wavelite. These crystals are exceedingly delicate, and, when collected and dried on a filter, present the appearance of a sulphur-colored mass, having a silky lustre. These crystals are not very soluble in cold alcohol; but are dissolved, in large proportion, in boiling alcohol, especially when it is diluted. The solution, on cooling, is converted into a mass of crystals, which shrink very much on being dried, are but slightly soluble in alcohol, and almost in soluble in ether.

Morindin is dissolved, in very small proportion, by means of cold water; but sufficient to impart a yellow color to it. At the boiling point, it is dissolved in much greater abundance; and, on cooling, is precipitated from its solution in the form of a gelatinous mass, which presents no traces of crystallization. It obstructs the passages of the filter, and, consequently, cannot be separated from its mother liquor. Morindin is dissolved by alkalies, which impart to it a fine orange-red color. By concentrated sulphuric acid it is changed to a deep purple-red, which, in thin layers, appears of a violet color. After remaining in a state of repose for twenty-four hours, the solution, on being diluted, deposits yellow flakes of coloring matter, completely insoluble in cold water, and furnishing, with ammonia, a violet and not an orange-colored solution. Nitric acid, of sp. gr. 1-28, in the cold state, slowly dissolves morindin, and is thereby converted into a deep brownish-red color. In the hot state, the action is brisk, the brown color disappears, and nitrous vapours are disengaged in abundance. The liquor, on being submitted to continued ebullition, and neutralized by means of ammonia, furnished no precipitate with salts of lime.

Morindin in solution gives, with basic acetate of lead, a crimson-red precipitate, flaky, and extremely fugitive, and which cannot be washed without loss of coloring matter. Solutions of baryta, strontian, and lime, furnish an abundant red precipitate, slightly soluble in water. Chloride of iron produces a deep brown color, but does not give any precipitate. On adding alum to an ammoniacal solution of morindin, this latter is precipitated, together with the alumina, in the form of reddish-colored lac; and by the addition of chloride of iron, the precipitate becomes brown, and is not distinguishable from that of pure oxide of iron; it however contains the whole of the morindin,—the supernatant liquor being colorless. On heating the morindin in a close vessel, it melts into a deep brown liquid, which boils at a high temperature, and afterwards disengages vapors of a splendid orange-color, analogous to the nitrous vapors, and which are deposited upon cold bodies in the form of oblong red crystals;—a large quantity of carbonaceous residuum remaining in the vessel. An elementary analysis of morindin gave results which agree with the formula C28H15O15. From this formula it would appear, that a remarkable analogy exists between morindin and the coloring matter of madder. This circumstance is so much the more worthy of notice, that it indicates identity in the chemical nature of plants, which approach very nearly to each other in natural classification. Morinda, in fact, belongs to the natural family of chicoraceoe, which is considered by many botanists to be a subdivision of the rubiacece, of which madder (rubia tinctorum is the type. This analogy does not extend further than the coloring properties,—the two substances differing essentially from each other.

It has been stated above, that the experiments of several printers at Glasgow, to produce upon cotton fabrics a coloring matter from sooranjee, completely failed. This is quite confirmed as respects the ordinary methods of mordanting. Mr. Anderson digested some morindin for a considerable time, and at a gradually increasing temperature, with pieces of stuff which had been mordanted with alumina and iron; the coloring matter was not, however, fixed, and the mordants, after boiling for a few minutes with soap, did not undergo any alteration. With the root itself, the fabric, mordanted with alum, acquired a greyish-red color, and with iron a rather deeper color; there was, however, considerable difference on trying a fabric mordanted for dyeing Turkey-red.

Mr. Anderson procured from Glasgow specimens of cotton fabric, prepared for Turkey-red according to the old and also the new method, and found, that after the lapse of a few hours, both of them had acquired a deep red-brown color, which did not possess any beauty, but was perfectly fast. These observations agree with the remarks made by Hunter on the method employed by the Hindoos in dyeing with the morinda plant. According to his account, the fabric is first immersed in an imperfect soap, obtained by mixing oil of sesame with soda lye, and, after being washed and scoured, it is treated with a decoction of myrobolans (astringent fruits of the Terminalia chebula) and finally exposed, for four or five days, to the sun. After undergoing this treatment, it is immersed in an alum bath; it is then wrung dry and again exposed for four or five days.

By another method the morinda roots are pulverized, damped with sesame oil, and mixed with the flowers of the Lythrum fruticosum, or a corresponding quantity of Purwas (galls of a species of mimosa). This mixture is, with the cotton, introduced into a large quantity of water, and kept at the boiling point over a moderate fire for about three hours: a red color is thus obtained, which, according to Hunter, possesses great durability and beauty. This process is the one usually employed for dyeing Turkey-red; but Hunter further states, that with fabrics mordanted with iron a fixed purple-red or a chocolate color may be obtained; and that in that case the color is probably produced by the tannic acid of the astringent substance employed in the process.

It has been stated above, that morindin is decomposed by heat, and a carbonaceous residuum left in the vessel,—a crystallizable matter, totally different in its properties from the original substance, being sublimed. Mr. Anderson gives to this substance the name of morindon. It has the form of long crystals, which, when inspected through a microscope, present the appearance of six-sided prisms, with an oblique base, and have a red color of extraordinary brightness. These crystals are insoluble in water (either hot or cold), but will readily dissolve in either alcohol or ether. The morindon may be easily obtained from these solutions, in the form of crystals, by careful evaporation. This substance is dissolved by alkalies, and thereby acquires a rich violet color. Concentrated sulphuric acid also dissolves it, and imparts to it the same rich violet color: on evaporating the solution a precipitate is formed. By adding alum to an ammoniacal solution, a red lac is produced; and with barytawater a cobalt blue precipitate is formed. The small quantity of morindon obtained did not allow of its being brought to a perfect state of purity; Mr. Anderson, therefore, merely washed the sublimed crystals with ether, in order to deprive them of all empyreumatical matters, and dried them at the temperature of 100° Cent. On analysis they furnished a result agreeing with the formula C^H^Oi0. Morindon, therefore, appears to be produced from morindin by the elimination of water; and this is confirmed by the change morindin undergoes when brought into contact with sulphuric acid. As was above stated, morindin is insoluble in water, and furnishes, with alkalies, a violet color: this is also the case with morindon. Now, as the sulphuric acid acts in the ordinary manner, viz., by extracting the water, it appears very likely that the morindin loses five equivalents of water, and is thereby converted into morindon.

Supposing that further experiments should confirm the for mula given above for morindon, a strong analogy would be established between the coloring matter of this suhstance and that of madder,—the only difference between them being that of one equivalent of water. It appears, therefore, that morindon really is a coloring matter, and is capable of entering into combination with the ordinary mordants. With alumina it furnishes a deep lively red, and with iron a violet or black. These colors are, however, not fast, and moreover have the disadvantage of combining with the non-mordanted portions of the fabric, and of adhering to the parts desired to be left white. The morindon, when treated with sulphuric acid, will enter into combination with the ordinary mordants.

The discovery of a peculiar coloring matter, which only combines with a fabric which has been treated with oil, in the manner practised for Turkey-red dyeing, is so much the more interesting that it shews the existence of a peculiar class of substances which had not hitherto been noticed. The theory of Turkey-red dyeing, which has been for many years a secret in chemistry, may, perhaps, by this means, have some light thrown upon it; for, although this method of dyeing was imported into Europe some centuries ago, and many improvements have been made upon it, yet, during this lengthened period, no satisfactory explanation of the process has yet been arrived at.

It may be presumed, that by the action of the dung, which is employed in large quantity, the fabric becomes, as it were, animalized; by means of which it acquires the property of being charged with finer and brighter colors than when simply mordanted with mineral substances. Further researches have moreover proved, that the oil, which is employed in large quantity in Turkey-red dyeing, when brought into contact with the air and with decomposed animal matter, becomes also decomposed, and is converted into a sort of resinous matter, which constitutes the mordant for Turkey-red dyeing. M. Weissgerber, to whom we are indebted for some experiments on this subject (an account of which is given by M. Persoz in his Traité Théorique et Pratique de l'impression des Tissus, Vol. III., p. 174), found that fabrics treated with oil took a fine lively red; that, by means of acetone, the oil might be extracted, and that it would be found to have undergone no change; also, that after each successive application of the acetone, the fabric gradually lost the property of taking up the coloring matter of the madder, until at last (the whole of the oil having been extracted) the fabric would come out of the dyebath without taking up any color. The same chemist also found, that by employing the extract obtained by the acetone, as a mordant, a very fine color was produced with madder, without the necessity of adding any other substance. The observations of M. Weissgerber are confirmed by the experiments detailed in this memoir; there being no doubt that the deep red color obtained from morindin was produced in a manner totally independent of the alum, as this salt does not possess the property of fixing the coloring matter.

M. Persoz and Mr. Anderson both seem to be of opinion that the alum now used for Turkey-red dyeing will be completely abandoned, when Turkey-red dyers shall have become acquainted with the nature of the modification which the oil undergoes during the operation.

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