Balsamum Tolutanum. U. S., Br.
Balsam of Tolu. Bals. Tolu. [Tolu Balsam]
"A balsam obtained from Toluifera Balsamum Linne (Fam. Leguminosae)." U. S. "Balsam of Tolu is a solid balsam obtained from incisions made in the trunk of Myroxylon toluiferum, H. B. and K." Br.
Balsamum Americanum; Baume de Tolu, Baume de Carthagene, Fr.; Balsamum Tolutanum, P. G.; Tolubalsam, G.; Balsamo Tolutano, Balsamo del Tolu, It.; Balsamo de Tolu, Sp.
This balsam like balsam of Peru, has been the subject of much controversy. This is not only seen in the distinct sources above given by the U. S. and British Pharmacopoeias, but is rendered more confusing by the fact that the German Pharmacopoeia prescribes "the air hardened balsam of Myroxylon balsamum (L.) Harms var. genuinum Baillon." In addition to this Tschirch regards the tree yielding balsam of Tolu like that of the tree yielding balsam of Peru, merely physiological varieties of Toluifera Balsamum L. Schaer has recently reported on Myrocarpus Balsam (Cabureiba Balsam, of Piso; Baume du Perou en coques, of Guibourt), and concludes that it has intermediate properties between balsam of Tolu and balsam of Peru. It did not contain cinnamic acid an the benzoic acid which he obtained had a melting point from 3° to 4° higher than normal benzoic acid. (Arch. d. Pharm., 1909, p. 176.)
The balsam is said to be produced normally in the tree only in young growing tissues such as the young twigs and leaves, and to be formed in the older tissues only as the result of injuries received. It is procured by making V-shaped incisions in the trunk quite through the bark. The juice is received in small calabash cups, which are inserted in slight excavations beneath the point of the two vertical incisions meeting at the lower end; and Weir has seen as many as twenty cups at a time on one tree. The collectors go from tree to tree, emptying the cups into flasks of raw-hide. In these skin vessels the juice is taken to the different ports on the river, where it is transferred to tin cans. It is brought from Carthagena in calabashes or baked earthen jars, or in tin or glass vessels.
Properties.—As first imported, balsam of Tolu has a soft tenacious consistence, which varies considerably with the temperature. By age it becomes hard and brittle like rosin. It is shining, translucent, of a reddish or yellowish-brown color, a highly fragrant odor, and a warm, somewhat sweetish and pungent, but not disagreeable taste. Exposed to heat, it melts, inflames, and diffuses an agreeable odor while burning. It is entirely soluble in volatile oils. The official description is as follows: "Balsam of Tolu is a yellowish-brown, or brown, plastic solid, becoming brittle when old, dried, or exposed to cold. It is transparent in thin layers, has a pleasant, aromatic odor, resembling that of vanilla, and a mild aromatic taste. Balsam of Tolu is nearly insoluble in water and in petroleum benzin. It is soluble in alcohol, chloroform, and ether. It is dissolved by solutions of the fixed alkalies, usually leaving an insoluble residue. An alcoholic solution of the Balsam (1 in 20) is acid to litmus. Shake about 1 Gm. of the Balsam with 25 mils of carbon disulphide, allow it to stand for thirty minutes, filter the liquid and evaporate 15 mils of the nitrate to dryness. The residue thus obtained, when dissolved in glacial acetic acid, does not show a green color on the addition of a few drops of sulphuric acid (rosin). The remaining portion of the filtrate, when shaken with an equal volume of an aqueous solution of copper acetate (1 in 1000), does not acquire a green color (rosin or copaiba). Dissolve about 1 Gm. of the Balsam, accurately weighed, in 50 mils of alcohol, add 1 mil of phenolphthalein T.S. and titrate the solution with half-normal alcoholic potassium hydroxide V.S. The acid number thus obtained is not less than 112 nor more than 168. Now add sufficient half-normal alcoholic potassium hydroxide V.S. to the neutralized liquid to make the total amount of the volumetric alkali solution exactly 20 mils; heat the liquid on a water bath for half an hour, under a reflux condenser, and allow it to cool. Mix this liquid with 200 mils of distilled water, or more if necessary, and titrate the excess of potassium hydroxide with half-normal sulphuric acid V.S.; the total amount of half-normal potassium hydroxide V.S. consumed corresponds to a saponification value of not less than 154 nor more than 220 (see Part III, Test No. 10)." U. S.
"A soft, tenacious solid when first imported, becoming harder and finally brittle. Transparent and yellowish-brown in thin films. Pressed between pieces of glass with the aid of heat, and examined with a lens, it exhibits crystals of cinnamic acid. Odor fragrant, especially when warmed; taste aromatic and slightly acid. Soluble in alcohol (90 per cent.), the solution being acid to litmus. Acid value 107.4 to 147.2; saponification value 170 to 202. If 5 grammes are gently warmed with three successive portions of 25, 15, and 10 millilitres of carbon disulphide, the solution yields, when evaporated to dryness, a distinctly crystalline residue, which, when tested as described under 'Styrax Praeparatus' yields not less than 1.25 grammes of balsamic acids." Br.
The carbon disulphide test is based upon Braithwaite's researches upon spurious balsams of Tolu. (See P. J., 1895, 145; also 1897, 307.)
Boiling water extracts its acid. Distilled with water it affords a small proportion of volatile oil, and, if the heat be continued, an acid matter sublimes. Hatchett states that when dissolved in the smallest quantity of solution of potassium hydroxide it loses its own characteristic odor and acquires that of the clove pink. G. L. Ulex gives as a test of the purity of the balsam, that if heated in sulphuric acid it dissolves without disengagement of sulphurous acid, and yields a cherry-red liquid. (A. Pharm. Jan., 1853.) A modification of this test is that of R. A. Cripps (P. J., xix, 1888), who states that by a comparative test of the suspected balsam with a pure specimen 1 per cent. of storax or other resinous adulterant can be detected. Thirty grammes of the sample are digested in carbon disulphide for fifteen minutes with gentle warmth, the clear liquid decanted, evaporated to dryness, and dissolved in sulphuric acid. A bright red rose color is produced, remaining rose for a length of time if the balsam be pure, rapidly becoming brown if the balsam has been adulterated. The balsam is a mixture of volatile oil, free acid, and resin. The volatile oil is obtained by distilling the balsam with water, and may amount to a little over 1 per cent. This oil is chiefly tolene, C10H16, boiling at 170° C. (338° F.), and rapidly hardening by absorption of oxygen from the air. The free acid, according to Deville and Scharling, consists of benzoic and cinnamic acids, which statement has been confirmed by Flückiger. (Pharmacographia, 2d ed., 204.) Buse (Ber. d. Chem. Ges., 1876, 833) has shown that the benzylic esters of these two acids are present in the balsam, the benzyl cinnamate in larger amount.
Tschirch (Harze und Harzbehälter, 1900, p. 173) found that the ester mixture in Tolu balsam amounted to 7.5 per cent. against 62 to 64 per cent. in Peru balsam. Trommsdorff obtained 88 per cent. of resin, 12 of acid, and only 0.2 of volatile oil. According to Heaver, the balsam yields by distillation about one-eighth of its weight of pure cinnamic acid. The acid distills over in the form of a heavy oil, which condenses into a white crystalline mass. It may be freed from empyreumatic oil by pressure in bibulous paper, and subsequent solution in boiling water, which deposits it in minute colorless crystals upon cooling. (A. J. P., xv, 77.) A later investigation by Tschirch and Oberlander shows that the resinous portion of the balsam consists of tolu-resino-tannol in combination with cinnamic and benzoic acids, the latter in small proportions only. It contains, in addition, 7.5 per cent. of an aromatic, acid, oily liquid, composed mainly of benzyl benzoate, with a little benzyl cinnamate and a trace of vanillin. (A. Pharm., 1894, 599.) A factitious balsam described by R. V. Mattison (A. J. P., 1876, 51) contained 63 per cent. of storax.
Tolu balsam is sometimes adulterated with rosin and pine resins, both of which are readily detected, as they are soluble in carbon disulphide and benzol. The Balsam of Tolu of commerce is sometimes deficient in alcohol-soluble contents. Occasionally, the cans of shipment of tolu contain large pieces of red brick with enough melted balsam poured in to completely cover the bricks and fill the cans.
Uses.—Balsam of Tolu is a feeble stimulant expectorant; the syrup of Tolu is much used, on account of its agreeable flavor, as the basis of cough mixtures. Old and obstinate catarrhs are said to be sometimes greatly relieved by the inhalation of the vapor proceeding from an ethereal solution of this balsam. The best form of administration is that of emulsion, made by triturating the balsam with mucilage and loaf sugar, and afterwards with water.
Dose, ten to thirty grains (0.65-2.0 Gm.).
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.