Source, Etc

Balsam of Peru is a balsam exuded from the trunk of Myroxylon Pereiroe, Klotsch (N.O. Leguminosoe), after the bark has been beaten and scorched.

The tree grows in the forests of that part of San Salvador (Central America), near the Pacific Ocean, and known as the Balsam Coast, and probably also in other parts of Central America, as, for instance, in Honduras (Dieterich), the drug having received the name ' Peruvian ' from the fact that it was originally sent from San Salvador to Callao, the port of Lima, and thence to Spain.

As in the case of Myroxylon Toluifera, the bark of young twigs contains secretion-ducts which, however, are soon thrown off, after which no fresh ones are formed. The formation of the balsam is induced by certain treatment to which the bark is subjected, and it is, therefore, not a normal secretion of the tree, but a pathological product. Of the exact nature of the changes induced we have no knowledge, but probably, as has been proved for colophony and for storax, schizogenous secretion-ducts are formed in the new wood after the infliction of injury.

The following is a brief account of the production of balsam of Peru. The bark of the tree is first beaten with the handle of an axe or with a stone over a space about 25 X 15 cm. and the cork removed. After five days a little balsam exudes, which is soaked off by rags. Now the wounded place is heated by torches and after about a week a more abundant flow takes place which is again absorbed by rags. The place is subsequently again cut and scorched and finally the scorched bark is itself detached. The wood thus laid bare is subjected to similar treatment lasting in all about six weeks. When the secretion of balsam ceases the bark immediately above the exhausted spot is treated.

The rags are collected and when sufficient have accumulated the balsam is pressed out and boiled with water which is poured off carrying impurities with it. The bark removed from the trees is also boiled with water and the balsam thus extracted mixed with the rag-balsam. The balsam is then filled into tin canisters with screw openings holding about 27 kilos each; these are conveyed on mules to Acajutla and Belize, whence the balsam is shipped to Hamburg, etc.

Description

Balsam of Peru, as seen in commerce, is a rather yiscid, oily liquid, resembling common black treacle, but rather thinner, and not of an adhesive or glutinous nature; it appears black in bulk, but in thin layers it is dark reddish brown and transparent. It has a fragrant, balsamic odour, and although it has no marked taste it produces, when swallowed, a burning sensation in the throat.

Balsam of Peru is heavier than water, its specific gravity varying within narrow limits - viz. from 1.137 to 1.158, being usually between 1.140 and 1.158, and this forms a valuable means by which adulteration can be detected, for many liquids that might be used for that purpose are lighter than water, and would appreciably depress the gravity. It is soluble in chloroform, and also in an equal volume of 90 per cent. alcohol, but with a larger proportion of the latter the mixture becomes turbid. It is practically insoluble in water, that liquid removing from it only a little cinnamic acid.

Its physical characters are so well marked, especially the odour and taste, that the drug is easy to recognise, but the detection of adulteration, especially with inferior qualities of the drug, which appears to be more or less regularly practised, is a more difficult problem.

Constituents

Balsam of Peru consists essentially of an oily fluid portion mixed with a dark resin. The fluid portion (cinnamein) constitutes from 56 to 66 per cent. of the commercial drug, and consists of benzyl benzoate and benzyl cinnamate in the proportion of about three of the former to two of the latter, although this varies. Both esters are colourless, crystalline aromatic bodies which readily liquefy on heating.

The resinous portion, amounting to about 28 per cent. of the commercial drug, is composed of an alcohol, peruresinotannol, combined with cinnamic and a little benzoic acid.

The drug also contains an alcohol, peruviol (= nerolidol) which possesses a sweet odour and taste, traces of vanillin, and free cinnamic acid.

Uses

Balsam of Peru is antiseptic and disinfectant. It is chiefly used as an external application in certain skin diseases and for bed sores. It has also been employed as a stimulant and disinfectant expectorant in bronchitis.

Adulterants

Balsam of Peru is, from its nature and high price, liable to adulteration, chiefly with such liquids as alcohol, fixed oils, turpentine, copaiba, gurjun balsam, and the like. Any such admixture lowers the specific gravity, and can generally be detected by this means. Alcohol can be removed from the balsam by shaking it with water, which with the genuine drug should cause no appreciable diminution in volume. The presence of copaiba and of gurjun balsam can be detected by taking advantage of the insolubility of the resin of balsam of Peru in carbon disulphide. One part of carbon disulphide makes a clear mixture with three parts of balsam of Peru, but on the further addition of nine parts of carbon disulphide the resin should separate leaving a clear yellow non-fluorescent liquid which on evaporating should leave a yellowish brown oil, and this warmed to 150° should not evolve an odour foreign to balsam of Peru.

The assay of the balsam may be effected by dissolving 1 gm. of the balsam in ether, removing the resin by shaking this solution with N/2 solution of sodium hydroxide, evaporating the ethereal solution, and drying and weighing the residue; it should amount to not less than 57 per cent. Each gramme of this residue (cinnamein) should require not less than 42 c.c. N/10 alcoholic solution of potassium hydroxide for saponification, corresponding to a saponification value of at least 235 (the saponification value of benzyl benzoate being 264.3, and of benzyl cinnamate 234.0). Full details of the test will be found in the British Pharmacopoeia (1914), p. 61.

Recently a factitious substitute, 'perugen,' has been made by mixing synthetically prepared benzyl benzoate ('peruscabin') with storax, benzoin, and balsam of Tolu. It has an odour quite distinct from that of genuine balsam.