RESINS AND BALSAMS.

The term resins is applied to certain organic substances which are very closely related to volatile oils, in so far as many of them are formed from the latter by oxidation. As previously mentioned, by exposure to the atmospheric air all volatile oils undergo a change, whereby they thicken and are finally converted into substances possessing the character of resins. In nature most resins also occur mixed with volatile oils.

The elementary constituents of resins are carbon, hydrogen, and oxygen; but, generally speaking, they are poor in oxygen and rich in carbon. Chemically they behave like weak acids, their solutions frequently reddening litmus and sometimes expelling, on boiling, the carbonic acid from alkaline carbonates.

Independent of a possible content of volatile oil, every naturally occurring resin consists of several resins which, however, can, as a rule, be separated only with difficulty.

The resins are generally divided into hard resins, soft resins or balsams, and gum-resins. The hard resins are, at the ordinary temperature, solid, hard, and brittle, can be readily pulverized, and contain little or no volatile oil. The soft resins or balsams are kneadable, and sometimes even semi-fluid; they represent solutions of resins in volatile oils, or a mixture of volatile oil and resin. On exposure to the air they are changed by the volatile oil suffering oxidation, they becoming then more or less hard, and may be converted into actual resins. The gum-resins are mixtures of vegetable gum, resin, and volatile oils, and are obtained by inspissation of the milky juice of several plants. When triturated with water they yield a milky, turbid fluid, and dissolve only partially in alcohol.

The resins are widely diffused in the vegetable kingdom, there being scarcely a plant which does not contain resin in one form or another. Some families of plants and organs of plants are, however, distinguished by their special wealth of resins. The resins are, as a rule, secreted simultaneously with volatile oils in special reservoirs, from which they flow out naturally at certain periods, or are obtained by incisions made in the plants. A few bodies of the character of resins also occur in the animal kingdom, and a series of them, the fossil resins, are generally classed in the mineral kingdom, though most of them are very likely derived from plants. Some resins, such as the aldehyde resins, etc., are purely artificial products.

Of the hard resins, benzoin alone is used in perfumery; of the balsams, Peru balsam, Tolu balsam, and storax balsam; and of the gum-resins, the myrrh.

Benzoin is exclusively obtained from Styrax benzoÏn, Dryand (BenzoÏne officinale, Hayne), a tree which grows in Java, Sumatra, and Siam. The bark of the tree is slit to allow a fluid to flow out, which concretes on the trunk in the form of grains, or is collected in vessels in which it congeals and assumes the form of lumps ("tampangs"). Older trees which have been frequently tapped for resin yield a product of a lower quality; the grains ("tears") forming, as a rule, the better varieties. When the benzoin collects in large masses it always shows an amygdaloid structure, the grains ("almonds") of a roundish form, smooth termination, homogeneous structure, and paler color, appearing imbedded in a dark, porous, or resiniform mass.

According to the appearance of the product three varieties are distinguished: Benzoin in tears (B. in lacrimis), amygdaloid benzoin (B. amygdaloides), and lump benzoin (B. in sortis, B. in massis). The benzoin in tears forms loose, smoothly terminated, longish, homogeneously appearing masses of an opal-like lustre, and first of a whitish, and later on, of a yellowish, reddish, or brownish color. The separate pieces are up to 3 millimeters in diameter, though the Siam benzoin in tears frequently consists of still larger and generally decidedly flattened pieces.

Amygdaloid benzoin consists chiefly of white pieces, becoming, later on, brownish, of a waxy lustre and imbedded in a lustrous brown-red resinous mass. The lump benzoin or ordinary benzoin has also an amygdaloid structure but is not so rich in almonds as the preceding variety and possesses either a fine granular or colophony-like ground-mass and is frequently contaminated by parts of plants. The exterior of the variety occurring in commerce in large lumps shows, according to the mode of packing, the imprint of leaves or of coarse pack-cloth.

Benzoin generally consists of cinnamic and benzoic acids which occur in a crystalline state in the grains as well as the ground-mass; further, of several amorphous resins soluble in alcohol, and coloring matter. The content of cinnamic and benzoic acids amounts to from 12 to 20 per cent. The best varieties from Sumatra and Singapore contain no benzoic acid, and those from Siam no cinnamic acid.

All varieties of benzoin possess a peculiar odor, that of the better varieties being agreeable, and a sweet, aromatic, but pungent taste. The melting point generally lies between 176° and 203° F., that of the tears and of the almonds being lower than that of the ground-mass. A low melting-point is accepted as a mark of quality, Siam benzoin, which is considered the best, melting at 167° F. Some varieties, for instance, those recently imported from Singapore, have a pronounced vanilla-like odor; the presence of vanillin has been established in them. The Sumatra benzoin has a storax-like odor.

Benzoin is sparingly soluble in chloroform, only partially so in ether, and completely in alcohol. On mixing the alcoholic solution with water, the resin is separated. Petroleum-ether and benzine withdraw only benzoic acid from the dry, powdered benzoin. All varieties of benzoin dissolve in concentrated sulphuric acid to a beautiful purple colored fluid, from which benzoic acid, if present, is separated in crystals by the gradual addition of water. The establishment of the presence of cinnamic acid is best effected as follows: Boil the sample in milk of lime, filter, and treat the solution with hydrochloric acid. The precipitate thereby separated is thoroughly washed, triturated with potassium permanganate and water, and heated, whereby in the presence of cinnamic acid, oil of bitter almonds is formed from the latter, which is readily recognized by the odor.

If benzoin containing benzoic acid be heated, white vapors are emitted which, on cold surfaces, deposit in very delicate, lustrous, acicular, or foliated crystals of benzoic acid, the so-called benzoin flowers (Floris benzoes.) Benzoic acid thus prepared possesses an agreeable, vanilla-like odor, since by heating the benzoin the greater portion of the odoriferous substance contained in it escapes. Benzoic acid separated by the wet method is odorless.

Benzoin is especially used for fumigating pastilles. It is also of great importance on account of its property of preventing fats from becoming rancid, if added to them in small quantities.

Peru balsam (Balsamum Peruvianum) is the produce of the Balsam Coast, San Salvador, Central America, where Sansonate forms the central point of the industry. In the mountain forests, back of the coast, grows the balsam tree (Myroxylon PereirÆ, Klotzch; ToluiferÆ PereirÆ, Baillon), natural order, PapilionaceÆ. The gaining of balsam commences when the tree is five years old, the collecting time beginning in the dry season in the first days of November. The trunks of the trees are belabored with hammers on four places (according to other statements, on twenty to thirty), so that the bark is detached in strips. After a few days the bark thus loosened is burnt off by means of torches, whereupon a balsamic fluid oozes from the young wood, which is absorbed by pieces of cloth or rags, placed upon the denuded places. When the rags are thoroughly saturated with balsam, they are squeezed out and then thrown into an earthen pot filled with boiling water, whereby the balsam is detached and collects on the bottom of the vessel. By this process the Balsamo de trapÓ is obtained. By boiling the bark, which falls off, a small quantity of a poorer quality of balsam, called tacuasonte, is obtained, which, it would seem, is frequently added to the better quality. Crude Peruvian balsam is a gray-green to dirty-yellow fluid, of the consistency of syrup. The process of purification in use on the Balsamic Coast is as follows: The crude balsam is brought into large iron vessels, holding from 1300 to 1500 lbs. each, and allowed to clarify by quietly standing from 8 to 14 days, the heavy impurities settling on the bottom, while the light dirt, together with the water, appears as foam on the surface. After 8 to 14 days the balsam is drawn off through a cock, located about 4¾ inches above the bottom of the vessel, into a tinned iron boiler, and boiled over an open fire at a moderate heat for 2 to 3 hours. The foam which forms is skinned off, and boiling continued until no more foam appears.

The collection of balsam continues until the first rain falls in April or May, when the work ceases. A vigorous tree, well treated, yields balsam for 30 years in succession, and if then allowed to rest 5 or 6 years can be used several years longer. The annual yield of balsam from 100 trees is said to be about 550 lbs.

From the very odoriferous flowers of the balsam tree or, according to others, by expressing the fruits, a white Peruvian balsam is obtained, which is, however, seldom found in commerce. It is of the consistency of honey, pale-yellow, smells of vanilla and melilot, and has an aromatic bitter taste. On standing for some time it deposits crystals of myroxocarpin.

Ordinary (black) Peruvian balsam is a black-brown fluid, transparent and dark (honey-yellow in thin layers), which retains its consistency even after being kept for years and deposits no crystals. It shows a slight acid reaction, has an agreeable odor reminding one of gum benzoin and vanilla, and at first a mild, but, later on, a sharp and pungent taste.

The specific gravity of pure Peru balsam formerly varied between 1.14 and 1.16, but at present between 1.135 and 1.145, this change in the specific gravity being very likely due to a different process of purification.

Peru balsam is miscible in every proportion with absolute alcohol, while ether leaves behind undissolved a black, smeary residue, and hot oils of turpentine or almonds dissolve only about one-half. It is miscible with acetone, chloroform, amyl alcohol. By digesting the balsam with aqueous potash lye, Peru balsam oil, which constitutes about 60 per cent. of the balsam, separates on the surface. In an undecomposed state the oil is, according to Kachler, chiefly benzyl, cinnamate, or cinnamein. The potash solution separated from the Peru balsam oil, contains cinnamic acid, benzoic acid, and resin. The latter, according to Stotze, can be separated into two portions, one soluble, and the other insoluble, in aqueous alcohol.

Benzine and petroleum-ether dissolve from the Peru balsam only the nearly colorless cinnamein of which it contains up to 45 per cent. The behavior of Peru balsam towards bisulphide of carbon is very characteristic, 3 parts of it giving, according to FlÜckiger, a clear solution with 1 part of bisulphide of carbon; if, however, 8 parts more of the latter be added, up to 30 per cent. of a dark resin is separated, while the bisulphide of carbon is but slightly colored.

From San Salvador 11,000 to 13,000 lbs. of Peru balsam are annually brought to Europe, it being generally imported in tin cans, and more rarely in earthen jars surrounded by a kind of plaited matting. According to whether the product comes by way of England, New York, Bremen, or Hamburg, it is distinguished as English, American, Bremen, or Hamburg Peru balsam. The supply being frequently insufficient, the balsam is subjected to many adulterations. A cheap, so-called London Peru balsam always contained colophony and had a specific gravity of 1.133. There can be no doubt that pure unadulterated Peru balsam is difficult to obtain.

As adulterants, are used: Alcohol, volatile oils, fat oil, especially castor oil; further, copaiba balsam, Canada balsam, gurjun balsam, storax, benzoin, and asphaltum. The establishment of these adulterants is connected with difficulties; but the properties of Peru balsam are so characteristic that it is quite easy to detect whether it is genuine and pure, or not, the specific gravity and proportions of solubility deserving especial attention in this respect. The test by the specific gravity is available, since most of the adulterants render the balsam specifically lighter, especially alcohol, but also copaiba balsam (specific gravity, O.95), castor oil (0.96), oil of turpentine (0.87), gurjun (0.96), etc. The customary procedure is as follows: Prepare a common salt solution of 1.25 specific gravity, by dissolving 1 part of dried sodium chloride in 5 parts of distilled water; drop the balsam into the solution; every drop of pure Peru balsam sinks in a roundish form to the bottom; but if the drop again comes to the surface and spreads out upon it, it is a sure sign of some kind of adulteration. However, the change in the specific gravity by the admixture of fat oils is but very slight, since the balsam can only be mixed with them to a conformable fluid in the proportion of from 7 to 10 to 1. Castor oil forms an exception in this respect, it being miscible also in other proportions.

Petroleum-ether is an excellent testing agent. Bring into a test-tube about 2.5 grammes of Peru balsam, and 6 to 7 centimeters of petroleum-ether, close the tube with the finger and shake vigorously; a brown, thickly-fluid mass adheres in unequal layers to the sides of the tube, and before running together remains in this position 1 to 2 minutes after the petroleum-ether has been poured into a porcelain saucer. If, however, the mass is thinly-fluid, and does not, in the above-mentioned manner, adhere to the sides of the tube, but, after shaking, collects below the petroleum-ether, the balsam is adulterated. After shaking, immediately pour off the petroleum-ether; if the latter is almost colorless, or but slightly colored yellowish, the balsam is pure; if, however, it is turbid, and soon forms a sediment, or if it is yellow or brownish, or brown, the balsam is adulterated.

Alcohol is added either by itself or in the form of saturated solution of storax, benzoin, or Canada balsam, by which means the specific gravity of the balsam is but slightly changed. Bring the above-mentioned common salt solution, together with 20 grammes of the Peru balsam to be examined, into a small flask, and distil off about 5 grammes; gradually mix the distillate with 5 drops of caustic potash lye and potassium iodide solution saturated with iodine, shaking gently until the mixture acquires a slightly yellow-brownish coloration. If this coloration does not disappear in one minute, add drop by drop more of the potash lye until discoloration appears. In the presence of alcohol, yellow crystals of iodoform, which are readily recognized under the microscope by their form, collect on the bottom of the fluid. Adulteration with a volatile oil is recognized in the distillate by odor and taste.

Fat oil, Canada balsam, copaiba balsam, gurjun balsam, and volatile oil may be recognized by the following tests: If pure Peru balsam in a porcelain saucer is thoroughly mixed with an equal volume of pure concentrated sulphuric acid, the mixture thereby becomes heated, vapors of a pungent odor being emitted, and if then set aside to cool, it congeals. In the presence of fat or volatile oils, copaiba balsam, gurjun balsam, or Canada balsam, it remains, however, more or less thickly fluid or more or less soft-smeary. If the balsam be pure, the cold mixture, after washing with water, should yield a hardish or soft-friable mass, which, when kneaded with the fingers, should not prove smeary or sticky.

Fat oils are also very readily recognized by the use of warm petroleum-ether. The extract is evaporated, saponified with potash lye, extracted with alcohol, evaporated and decomposed with hydrochloric acid. A mixture of cinnamic acid and any of the fatty acids present in the Peru balsam is thereby obtained, which, after treatment with water, remains in the residue.

Of copaiba balsam, Peru balsam can take up as much as 25 per cent. From such adulterated balsam benzine dissolves the copaiba balsam, together with cinnamein, and the adulteration can then be recognized by the odor. Cinnamein treated with sulphuric acid acquires a cherry-red color, while in the presence of copaiba balsam or gurjun balsam, a yellow-brown coloration appears. The detection of an adulteration of Peru balsam with storax is, according to Denner, effected as follows: Shake in a test-tube 5 parts of the balsam to be examined with 5 parts of a 15 per cent. soda solution (soda lye of 1.60 specific gravity) and 10 parts of water. Then shake with 15 parts of ether, and after settling pour off the ether as much as possible. Repeat the shaking with 15 parts of fresh ether. Now heat the aqueous residue to boiling, acidulate with hydrochloric acid, add cold water, remove the resin separated thereby from the fluids, dissolve it in about 3 parts of soda lye of the above-mentioned strength, dilute with 20 parts of water, heat to boiling, and precipitate with barium chloride solution. Bring the precipitate upon the filter, and, after allowing it to drain off, dry it in the water-bath. Then extract it with alcohol, evaporate the alcoholic extract, take it up with concentrated sulphuric acid, add chloroform, and shake. In the presence of gum benzoin or storax, the chloroform acquires a violet to blue color. This method is a sure test for the recognition of even very small admixtures.

A content of asphaltum is readily detected by mixing the Peru balsam with ether compounded with about ? alcohol. Any asphaltum present remains undissolved, and may be collected upon a filter.

In perfumery Peru balsam is chiefly used for pomades and fumigating pastilles, but also for cosmetics and soaps.

Tolu balsam is the produce of Myroxylon toluiferum, Humb., Bonpl. et Kunth, Toluifera balsamum, L., a tree of the natural order PapilionaceÆ, growing in Northwestern South America. It exudes during the heat of the day, and is collected in gourds. It soon hardens, by which it is distinguished from Peru balsam. In commerce two varieties of Tolu balsam are found, one of the consistency of turpentine and the other solid. The first variety, Brazilian balsam, forms a semi-fluid, turpentine-like, sticky mass, of the color of copaiba balsam. By long storage it becomes hard and brownish. The solid variety, Tolu, or Carthagena balsam, is a brittle, more or less translucent yellow-brown or red-brown resin of a granular or crystalline appearance. It softens at about 86° F., and melts between 140° and 149° F. Viewed under the microscope, it appears rich in crystals of separated ciannamic and benzoic acids. Its specific gravity varies between 1 and 2. Both varieties of Tolu balsam have an aromatic, slightly pungent and sourish taste, resembling somewhat that of Peru balsam. They are readily soluble in ordinary spirit of wine, alcohol, acetone, chloroform, and potash lye, but insoluble in petroleum-ether and bisulphide of carbon. In Tolu balsam have been found toluene, cinnamic and benzoic acids, and several resins not yet sufficiently examined. According to Scharling, toluene constitutes about 1 per cent. of the Tolu balsam. It forms a colorless, limp oil, boils, according to Deville, at 338° F., and according to E. Kopp, at between 309° and 320° F., and has a specific gravity of 0.858. It has a sharp, pungent, pepper-like taste, and an odor resembling that of elemi. In the air, it is gradually converted by oxidation into a soft resin, without, however, becoming colored.

On boiling Tolu balsam with water, cinnamic and benzoic acids are separated from the solution. When treated with potash lye the resinous acids are fixed, and the toluene floats upon the fluid.

Commercial Tolu balsam is frequently more or less mixed with vegetable remains, which, however, can be readily detected with the microscope, especially after the solution of the resinous constituents. It is frequently adulterated with turpentine or pine resin. Such adulterations may be detected by bisulphide of carbon, which completely dissolves these substances, but not the Tolu balsam. When pure Tolu balsam is triturated with concentrated sulphuric acid, a cherry-red fluid is, according to Ulex, obtained, which does not evolve sulphurous acid, as is the case in the presence of turpentine-resins.

Tolu balsam is chiefly used for fumigating pastilles. The tincture prepared from it is also frequently used with advantage to give durability to the scent of handkerchief perfumes.

According to Holmes and Nalor, a Tolu balsam differing in its chemical behavior is found in the English wholesale trade. In thick layers it is yellow-brown, but perfectly transparent and gold-yellow in thin layers and extraordinarily sticky. By storage it hardens but slightly, and does not become brittle even if exposed for several days to a temperature of 212° F. Its odor reminds one somewhat of glue, and it develops a pungent, sharp taste only after chewing it for a few seconds. Its melting point lies at 136.4° F., being lower than that of ordinary Tolu balsam, from which it also differs in that it completely dissolves in ether as well as in benzine, while it is only partially dissolved by potash lye. The balsam contains no toluene, nor a hydrocarbon, boiling at 320° F. Further investigations have shown it actually to be a natural product, the derivation of which, however, could not be ascertained.

Storax is the produce of Liquid ambar orientale, Mill, a plantain-like tree which reaches a height of about 32 feet. In Southern Asia Minor, especially in Cyprus, the tree forms handsome, dense forests. According to FlÜckiger, the balsam is extracted from the peeled-off bark, with the assistance of warm water. The mass thus melted out sinks down in the water, and is later on combined with the substance obtained by expressing the boiled bark while still warm. This mixture forms the liquid storax (Storax liquidus). The residue remaining after expression is dried in the sun and forms, under the name of Cortex thymiamatis, an article of commerce, which is used for fumigating purpose, for the preparation of ordinary storax, etc. The crude storax is brought to Smyrna, Syra, and Kos, and comes into the European market almost exclusively from Trieste.

Liquid storax is a sticky, opaque substance of the consistency of turpentine. It has a mouse-gray color, which by contact with the air becomes brown on the surface, an agreeable benzoin-like odor, and a sharp, pungent, aromatic taste. It is heavier than water, its specific gravity being 1.112 to 1.115. On losing its content of moisture (by drying out when heated) it becomes brown and clear. When exposed to the air in a thick layer it does not completely dry, and in a thin layer only after considerable time; but when pressed with the finger always shows a certain stickiness. It is partially soluble in spirits of wine, yielding with it a more or less turbid solution. It is also incompletely soluble in oil of turpentine, benzine, petroleum-ether, and chloroform. Viewed under the microscope liquid storax appears as a colorless thickish fluid, intermingled with larger and smaller drops, fragments of bark tissue, and now and then, perhaps, with crystals of styracin and cinnamic acid.

Liquid storax contains styrol (10 to 15 per cent.), styracin, and cinnamic acid (10 to 15 per cent.). Styrol or cinnamol seems to be the most important carrier of the odor and taste of liquid storax. If 20 parts of liquid storax are subjected to distillation together with 15 parts of crystallized soda and 200 parts of water, the cinnamol collects in the form of a yellowish, very mobile liquid upon the distillate. By rectification it can be obtained colorless, but is thereby partially converted into metastyrol, an isomeric, amorphous, odorless, and tasteless substance which is solid at an ordinary temperature. By exposure for some time to a heat of 608° F. it is reconverted into styrol. Styrol (C₈H₈) forms a clear, colorless, mobile liquid having an odor of benzine and naphthalene. Its specific gravity is 0.924 and its boiling point lies at 294.8° F. In water it is but sparingly soluble, but is miscible in all proportions with anhydrous spirit of wine, chloroform, benzine, ether, and oils. It stands in the same relation to cinnamic acid as benzol to benzoic acid, and is formed by distilling a mixture of cinnamic acid and barium oxide.

Styracin is cinnyl cinnamate. On distilling liquid storax with water, styrol passes over. If now from the residue the cinnamic acid be withdrawn by means of soda-solution, and the resin, which remains behind, be treated with cold spirit of wine, styracin is left, which crystallizes from ether, hot alcohol, or benzol. It forms colorless, odorless, and tasteless crystals which melt at 113° F. and remain for a long time fluid after melting. It is insoluble in water, but soluble in 25 parts cold, and 2 parts boiling, spirit of wine, as well as in 5 parts ether. By oxidizing substances it is converted into bitter almond oil and benzoic acid, and by the action of potassium hydroxide it is decomposed to cinnyl alcohol and cinnamic acid.

Good liquid storax should yield to 90 per cent. alcohol at least so much soluble matter that the dried residue of the filtered alcoholic solution amounts to 65 per cent. of the quantity of storax.

Ordinary liquid storax, which has not been stored too long, contains 10 to 20 per cent. of water and about the same quantity of impurities (fragments of plant tissue) which remain behind on treatment with the above-mentioned solvents.

Liquid storax is said to be adulterated with the turpentines of some species of larch and pine. Such adulteration is primarily detected, according to Hager, by the specific gravity. Take up a drop of the balsam with a knitting-needle, and by heating the needle make it fall into a cold solution of 1 part common salt and 8 parts water. On stirring, the drop must sink, otherwise adulteration with turpentine is very likely. Next bring 5 grammes of the storax into a test-tube, melt it in the water-bath, add ½ volume of absolute alcohol, and mix by shaking; then compound the mixture with several times its volume of petroleum-ether, shake vigorously, allow to settle, and decant the layer of petroleum-ether. Repeat twice this shaking with petroleum-ether; then evaporate the petroleum-ether solution in a tared flask in the water-bath. The residue remaining after evaporation is colorless, bluish opalescent, and of an agreeable odor; in the presence of turpentine it is yellowish and has the, not to be mistaken, odor of turpentine.

Storax in grains consists of round, longish grains of a brown-black color and smooth, lustrous surface, which soften by the warmth of the hand. It is nothing but liquid storax brought into a granular form and by storing freed more or less from impurities.

Ordinary storax (Styrax calamitus or St. vulgaris) is an artificial product prepared by mixing liquid storax with various comminuted vegetable substances. Formerly the above-mentioned bark of the storax tree (Cortex thymiamatis) was only used for this purpose, but at present sawdust and exhausted cinnamon are also taken. This storax forms a reddish or brown-black, humus-like mass, which is generally moist. When dried it is very friable and has a storax-like odor distinctly calling to mind that of cinnamon. Good qualities are abundantly covered with crystalline efflorescences (of cinnamic acid and styracin); poorer qualities prepared with the addition of sawdust have a musty odor. The admixed vegetable tissue can, according to Wiesner, be readily recognized by boiling the storax with alcohol, and after washing treating with dilute chromic acid, to which a small quantity of sulphuric acid has been added.

Liquid storax was already used for fumigating purposes by the ancient Greeks and Jews, and it forms to-day a constituent of fumigating pastilles, essences, etc. Storax tincture furthermore possesses the property of giving more constancy to scents resembling it. Piesse says, in regard to the odor of liquid storax, that it combines the agreeable with the disagreeable, it possessing partially an odor similar to that of the tuberose and partially one reminding of coal-tar oil. However, it possesses this disagreeable odor only in a concentrated state; when finely divided or diluted, it diffuses a very agreeable perfume.

Under the name American storax, white Peru balsam, white Indian balsam or liquid ambar is found in commerce a product similar to storax, which is derived from Liquidambar styraciflua, L., a tree indigenous to Mexico and Louisiana. This balsam forms a clear, transparent, brownish-yellow, semi-fluid mass. It has a storax-like odor, and a sharp and pungent taste. It is only partially soluble in alcohol, specifically lighter than water, and shows an acid reaction. It is said to consist of 24 per cent. styracin, 1 per cent. benzoic acid, volatile oil, etc. It is sometimes used for fumigating purposes, but chiefly serves for the adulteration of Tolu balsam.

Myrrh (Gummi-resina myrrha, Gummi myrrha) is a gum resin, the produce of Balsamodendron Ehrenbergianum, Berg, and, perhaps, also of Balsamodendron Myrrha, Nees. The first-named tree is found in the countries bordering on the Red Sea, and extends into Africa to the Somali Coast, where the principal supply of myrrh is collected. The gum-resin exudes naturally as a white oil-like mass, which, after hardening, whereby it becomes considerably darker, is collected by the natives and brought chiefly to Berbera, a small seaport opposite Aden, to be exchanged for English and Indian goods. From there, by way of Aden and Bombay, it reaches the European market. In Bombay the first sorting takes place, which is, however, superficial, and hence has to be repeated in Europe (London). According to Parker, ten different resins are admixed with myrrh, especially bdellium resins.

In commerce Myrrha electa and Myrrha vulgaris or in sortis are distinguished. Myrrha electa, the best quality, occurs in pieces of irregular form and variable sizes, consisting of tears—either distinct or agglomerated—usually covered with a fine powder or dust. The surface is seldom smooth, but generally rough or granular. The color varies, being pale reddish-yellow, red, or reddish-brown. The fracture is conchoidal, seldom smooth, but rather granular, rough, of a fatty lustre, and sometimes shows whitish striÆ or veins, or opalesces like flint. The fractured edges are more or less translucent; thin disks or splinters are translucent or transparent. The specific gravity is, according to Hager, 1.195 to 1.205, and according to Ruickholdt, 1.12 to 1.18. A Myrrha electa is the better, the more fragile, friable, and paler in color it is, and the more rapidly it ignites and burns with a yellow, sooty flame. Poorer qualities may be recognized by the dark-brown color and dirty appearance. Myrrh is with difficulty rubbed to a fine powder, this being possible only after drying, which must, however, be done at a very moderate heat in order to prevent loss of volatile oil.

According to Hager, myrrh consists in 100 parts of about 2.5 parts volatile oil (myrrhol), 25 to 35 parts resin (myrrhin), 55 to 65 parts gum soluble in water, 3 to 8 parts salts, impurities, and water. Water forms with myrrh an emulsion, and dissolves the gum. The resinous constituents are dissolved by spirit of wine.

The gum, which forms the portion of the myrrh soluble in water, but insoluble in alcohol, and amounts to from 57 to 59 per cent., is, according to Oscar Koehler, a hydrocarbon of the formula C₆H₁₀O₅. The portion soluble in alcohol is, according to the same chemist, a mixture of various resins, an indifferent soft resin of the formula C₂₆H₃₄O₅, soluble in alcohol and ether, forming the greater portion of it. There are further present two resin acids, one of which has to be considered a bibasic acid of composition C₁₂H₁₆O₈, and the other as a monobasic acid of the formula C₂₆H₃₂O₉. The principal constituent of the volatile oil of which, according to Koehler, 7 to 8 per cent. is present, while Ruickholdt formerly found only 2.18 per cent. corresponds to the formula C₁₀H₁₄O. The volatile oil is laevorotatory, and when diluted with bisulphide of carbon becomes, according to FlÜckiger, violet by the action of bromine. An extract of myrrh, prepared with bisulphide of carbon, gives the same reaction with bromine vapor. Hydrochloric or nitric acid also colors myrrh violet, which also applies to the volatile oil.

Petroleum-ether should, at the utmost, take up 6 per cent. of the myrrh, and the extract must be colorless.

Myrrh is frequently contaminated with bark, which forms either a film of cork as thick as paper or a crust of a fibrous and, at the same time, brittle nature. Sand or small pebbles are also frequently mixed with the myrrh. Other varieties of gum or gum-resin, which considerably decrease the value of the product, are often found in the commercial article, the inferior qualities especially being adulterated and mixed with dark pieces of Suakim gum, gum of the plum or cherry tree, bdellium, and similar substances, which are partially moistened with myrrh tincture, and scattered over with myrrh powder. Adulteration with gum-arabic, gum of the plum or cherry tree, which are coated with alcoholic myrrh solution, is recognized by the paler lustre, greater transparency, and mucilaginous taste. Pieces of resin melt on heating, while myrrh only swells up. Bdellium is detected by the dark or black-brown color, toughness, less bitter taste, and by crackling and spitting when held in the flame of a candle, as well as by the reaction of myrrh with nitric acid discovered by Bonastre. By mixing 5 cubic centimeters of alcoholic myrrh tincture with 5 to 10 drops of fuming nitric acid, a rose-color coloration passing into red results. Parker gives the following method for testing myrrh: Prepare a tincture of 1 part myrrh and 6 parts spirit of wine. Saturate with this tincture white filtering paper, allow it to drain off, and then wrap it around a glass rod moistened with nitric acid of 1.42 specific gravity. With genuine myrrh the paper immediately becomes deep yellow-brown and then black, while the edges of the paper strip appear dark purple-red. When a few drops of the tincture of myrrh are allowed to dry in, a transparent residue remains behind. The tinctures of spurious articles (with the exception of bissabol) give turbid residues.

Myrrh was already in Moses's time an article used in the sacrifices of the Israelites. It seems to have been made use of by Democrates. Dioscorides enumerates eight varieties of it, and Pliny seven, which he obtained from Abyssinia. Herodotus and Diodorus Siculus mention Arabia as the home of the myrrh tree.

In perfumery, myrrh is chiefly used for dentifrices and fumigating pastilles and essences.

Opopanax is the inspissated juice of the root of Opoponax Chironium, Koch, or Ferula Opoponax, L. It forms grains or lumps of a red-yellow or brown color, and has a fracture of a waxy lustre. It can be rubbed to a gold-yellow powder. It has a strong and peculiar odor, and a very bitter and balsamic taste. With water it forms an emulsion, while it is only partially soluble in spirit of wine. It contains very little volatile oil, and a resin which melts at 212° F., and is soluble in ether and aqueous alkalies. It further contains gum, organic and inorganic salts, and foreign admixtures. Opopanax is but little used in perfumery. For Extraits the opopanax oil is better adapted than the tincture prepared from the gum, the latter coloring the Extrait dark.

Olibanum or Frankincense is the inspissated juice of various varieties of Boswellia, partially indigenous to Africa and partially to Asia. The pure pieces are pale yellow, seldom reddish, transparent, or opaque, brittle, covered with a mealy coating and of a splintery fracture. The specific gravity of olibanum is 1.22; its odor is slightly balsamic, and its taste bitter and pungent. It melts only incompletely when exposed to heat, diffusing an agreeable odor. It consists in 100 parts of 5 to 7 parts of a clear volatile oil, boiling at 323.6° F., and of specific gravity 0.86, 56 parts of acid resin, and 30 to 36 parts gum, which corresponds with gum-arabic. With water it forms a milky fluid, and is mostly dissolved by spirit of wine. Selected olibanum (Olibanum electum) is the best commercial variety, while Olibanum naturale, O. in lacrymis, and O. in sortis, form darker pieces intermingled with separate paler grains, and contaminated by pieces of bark, and wood and sand.

Olibanum is only adulterated with sandarac and naturally exuded pine resin, inspissated to tears by exposure to the air. The former is recognized by the fracture being glassy and transparent, and the latter by completely dissolving to a clear solution in spirit of wine.

Olibanum serves as an addition to fumigating pastilles, etc.

Sandarac is the resin exuding from the bark of Thuja articulata, Desf., or Callitris quadrivalvis, Vent., which grows in Barbary. It forms pale yellow, transparent, brittle grains with a glassy fracture, which have a specific gravity of 1.06 to 1.09 and fuse readily. Its odor is slightly balsamic and its taste somewhat bitter. Sandarac softens at 212° F. and melts at 275° F. It dissolves in hot absolute alcohol, ether, and amyl alcohol, is less soluble in chloroform, petroleum-ether, and volatile oils, and insoluble in benzol. In 90 per cent. alcohol ? of it dissolve; the term sandaracin has been applied to the insoluble portion. According to Unverdorben, sandarac consists of three different resins. It is sometimes employed in fumigating pastilles.