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Gums & Resins

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   Gums    Gum Arabic   Gum Tragacanth    Karaya Gum    Resins    Courbaril    Hard Resins    Copals    East African Copals

 

      West African Copals   Kauri Copal    Manila Copal    South American Copals    Damars    Amber    Lacquer    Shellac

 

    Acaroid Resins    Sandarac     Mastic    Dragon’s Blood    Kinos    Oleoresins    Turpentines    Canada Balsam    Spruce Gum

 

     Venetian Turpentine    Misc. Turpentines    Turpentines of Minor Importance   Balsams    Balsam of Peru    Balsam of Tolu

 

  Styrax     Benzoin    Copaiba    Elemi    Mecca Balsam    Gum Resins    Ammoniacum    Asafetida    Galbanum    Myrrh

 

      Frankincense   Opopanax / Bdellium    Misc. Resins

 

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          Many of the substances noted in the following discussion have synthetic counterparts that either practically eliminated or greatly reduced the production of the natural products.

 

Gums

 

          True gums are formed from the disintegration of internal plant tissues, mostly from the decomposition of cellulose in a process called gummosis.  Gums contain high amounts of sugar and are closely allied to the pectins.  They are colloidal and soluble in water, either dissolving entirely or swelling, but they are insoluble in alcohol and ether.  They exude naturally from the stems or in response to wounding of the plant.  Commercial gums arrive in the market in the form of dried exudations.  Gums are especially common in plants of dry regions.  They are used primarily as adhesives, and are also used in printing and finishing textiles, as a sizing for paper, in the paint and candy industries and as drugs.  Three important commercial plant gums are gum arabic, gum tragacanth and karaya gum.

 

     Gum Arabic

 

           A dried gummy exudate obtained from Acacia senegal and related acacias.  These are small native trees of arid northern Africa and are extensively cultivated in the Sudan.  The trees are tapped between February and May when the fruits are ripe.  Transverse incisions are made with a small ax and thin strips of the outer bark are torn off.  The gum slowly exudes as a viscous liquid, collects in a drop and hardens.  After 3-8 weeks these “tears” are collected.  The sun bleaches them, and the impurities are removed before marketing.  The Egyptians used gum arabic as early as 2,000 B.C.  Sudan gum has been an article of commerce since 100 A.D.  Several kinds reach world markets.  Kordofan or Hashab gum has been exported from the region around Cairo and Port Sudan, while Senegal gum originates north of the Senegal River.  Gum arabic is slowly and completely soluble in cold water and has a high degree of adhesiveness and viscosity.  Most has been used in textile, mucilage, paste, polish and confectionery industries and as a glaze in painting.  In medicine it has been used as an emulsifying agent and as a demulcent.

 

    Gum Tragacanth

 

          This is formed by a transformation of the pith and medullary-ray cells into a mucilaginous substance that exudes naturally or after the bark has been punctured or excised.  It comes from Astrangalus gummifer and other species of that genus.  They are thorny shrubs of the arid regions of Western Asia and Southeaster Europe.  The gum is allowed to dry on the bark before it is collected.  It reaches the market in one of three forms:  tears, which are the dried natural exudate; vermiform gum, which consists of narrow twisted coils or strings; and flakes, which are ribbonlike pieces.  Most of the commercial supply originates in Iran and Turkey.  Gum tragacanth has been used in calico printing and for other industrial purposes.  It is one of the oldest drugs and was known since 300 B.C.  In modern medicine it has served as an adhesive agent for pills and troches and for the suspension of insoluble powders.

 

    Karaya Gum

 

          Karaya gum has been used as a substitute for gum tragacanth, and several million pounds were imported annually from India by the mid 1900’s.  It is used in the textile, cosmetic, cigar, past and ice cream industries.  It is obtained from Sterculia urens, a large tree in central India.  Incisions are made into the heartwood and the gum oozes into these and accumulates as large irregular knobs.  They are then collected, sorted and graded.  The gum enters the trade in the

 

     Other Gums

 

          There are many other plants, which produce gums of some commercial importance.  Gum ghatti, obtained from Anogeissus latifolia, a large tree native to India and Ceylon, is used as a substitute for gum arabic.  The leaves are used for tanning.  Feronia limonia and Cochlospermum religiosum in India, Burma and Java yield gums that are also used in place of gum arabic.  The Asiatic Cycas ciccinalis is the source of cycas gum.  The carob, Ceratonia siliqua, produces tragasol, a mucilaginous hemi cellulose occurring in the pods.  Mesquite gum in North America is obtained fro Posopis juliflora, P. glandulosa and other species, while cherry gum is found in various species of Prunus.

 

Resins

 

          Resins are formed as oxidation products of various essential oils and are very complex and varied in chemical composition.  The resin is usually secreted in definite cavities or passages.  It frequently oozes out through the bark and hardens on exposure to air.  Tapping is usually necessary in order to obtain a sufficient amount to be of commercial value.  Commercial resins are also frequently collected from fossil material.  Resinous substances may occur alone or in combination with essential oils or gums.  Resins, unlike gums, are insoluble in water, but they dissolve in ether, alcohol and other solvents.  Resin production is widespread in nature, but only a few families are of commercial importance.  These include the Anacardiaceae, Burseraceae, Dipterocarpaceae, Guttiferae, Hammamelidaceae, Leguminosae, Liliaceae, Pinaceae, Styracaceae and Umbelliferae.  The exact botanical origin of a resin is often hard to trace, especially in the case of fossil and semi fossil types.

 

          Resins probably serve the plant by preventing decay, which is due to their high antiseptic qualities.  They may also lower the amount of water lost from the plant tissues.

 

          Resins have certain characteristics that render them important to industry.  Their ability to harden gradually, as the oil that they contain evaporates, makes possible commercial varnishes.  The resins are dissolved in solvents and surfaces are painted with the mixture.  As the solvents and oils evaporate, a thin waterproof layer of resin remains.  Resinous substances have been utilized for waterproof coatings, and also for decorative coatings for millennia.  Ancient Egyptians varnished their mummy cases and the utilization of lacquer in the arts has been practiced in China and Japan for centuries.  The Greeks and Romans were familiar with many of the same resinous materials that are used today (e.g., mastic, amber, sandarac).  Another property of resins that is of industrial importance is their ability to dissolve in alkalis to form soap.  Resins are also used in medicine; for sizing paper; as a stiffening material for mats; in the preparation of sealing wax, incense and perfumes; and for many other purposes as well.

 

          It is difficult to classify resins because the same term is often used for very diverse materials.  In commerce, resins are often referred to as gums, while such terms as varnish resins, hard resins, spirit varnishes, balsams, gum resins, damar resins, soft resins, and many others are used quite indiscriminately.  The chemical differences between the various groups are much more definite.  In this section three groups that will be distinguished are Hard Resins, Oleoresins and Gum Resins.

 

Hard Resins

 

          These contain only a little if any essential oil.  They are usually solid, quite transparent, brittle substances with no particular odor or taste.  They are readily fusible and burn in air with a smoky flame.  They are nonvolatile and very poor conductors of electricity.  They become negatively charged with friction.  The hard resins constitute the best source of varnishes, due to their low oil content and the readiness with which they dissolve in alcohol.  The most important commercial resins, such as the copals and damars, belong to this group.  Hard resins are also used in paints, inks, plastics, sizing, adhesives, fireworks and other products.

 

    Courbaril

 

<bot777>  Courbaril (Hymenea courbaril L.) (fruit, seed pulp; resin, treat lung infections; wood products) [Mexico-Cent. America]

 

Copals

 

          Copals comprise a considerable group of resins of recent, semi fossil and fossil origin that are found in many tropical and subtropical areas of the world.  The word “copal” is of Mexican origin.  Many of the harder copals are called animes, especially in northern Europe.  The copals insignificant quantities of oil and they yield a hard elastic varnish, which has been widely used for outdoor work.  Several types are know which are diverse in character and source

 

        East African Copals

 

          Zanzibar copal and the closely related Madagascar and Mozambique copals are derived from Trachylobium verrucosum.  Zanzibar copal is the hardest of all resins except amber and is very valuable.  The resin exudes naturally from the trunk, branches and fruit.  However, most of the commercial supply was obtained from semi fossil material derived from still living trees, and fossil material from trees that no longer exist.  Fossil copal when removed from the ground is covered with a crust of oxidized material.  After this has been removed, the copal shows a typical surface known as “goose skin,” which consists of large and small excrescences.  The interior is clear and transparent and varies from yellow to brownish red in color.

 

          Inhambane Copal is obtained from Copaifera conjugata, a valuable timber tree in coastal Southeast Africa; but it is of little commercial value. 

 

        West African Copals

 

          There are a large number of hard resins among the West African copals.  They are usually designated by the name of the region from which they were obtained.  The most important of these are the Congo, Angola, Sierra Leone, Acere and Benin copals.

 

          Congo copal is the most important because it is very hard and has been extensively exploited in the 20th Century.  It is derived from Copaifera demeusii and C. mapane, which are characteristic trees of the Congo Basin.   Although living trees have furnished some of the supply, the greater part was obtained from the ground or from watercourses, and was more or less fossil in nature.  The white and red Angola copals are derived from the same two species.

 

          Sierra Leone copal is a light-yellow, hard and brittle resin that is obtained from Copaifera copallifera and C. salikounda.  Live trees are wounded and the resin exudes and hardens in the form of globular tears.  Some fossil material is also obtained.  Because of the value of this copal, the Sierra Leone government has protected the trees.

 

          Accra and Benin copals are probably derived from Daniella ogea and related species.  These large trees are found in the coastal forests of Liberia, the Gold Coast and Nigeria.  The resinous exudation, known locally as ogea gum, has gained prominence as a varnish resin.     

 

        Kauri Copal

 

          This copal is one of the most valuable of the hard resins.  It is obtained from the kauri pine, Agathis australis, which is the largest and most important tree in New Zealand.  The copal is chiefly fossil in nature and is dug up on ridges and in swamps and bogs.  “Swamp gum” furnishes the bulk of the supply, and ranges in size from pieces that are 1-2 inches in diameter to lumps weighing 100 lbs.  “Range gum” yields the best grade of kauri.  Tapping living trees gets an inferior “Bush Gum”.  Kauri is yellow, transparent and very hard.  It is an exceedingly valuable varnish resin, especially for marine and outside work.  It was also used in making linoleum.  Kauri constituted one of the chief exports of New Zealand in the mid 20th Century.

 

        Manila Copal

 

          The first shipments of this important copal were made from Manila and the name persisted, although by mid 20th Century 75 percent of the product was shipped from Indonesia.  The source of all the East Indian, Philippine and Malayan copals, of which there are many different kinds, is Agathis alba.  This is a tall conifer reaching a height of 200 ft.  The resin exudes naturally, and is also obtained by systematic tapping.  Some of the supply was derived from fossil material and consisted of large, irregular, angular, milky pieces with a yellowish interior.  Hard, semi hard and soft copals are included among the many different kinds in the trade.  Pontianak copal, a semi fossil type from Borneo, is the hardest variety and was especially popular in the United States.  Manila copal varnishes are durable, but they do not adhere strongly to surfaces and they are not very brilliant.  They are used chiefly for interior work and enamels.  These copals are often erroneously called damars, although they are quite distinct from the true damars.

 

        South American Copals

 

          The tall locust tree in South America, Hymenaea courbaril, which is found in Brazil and other portions of Neotropical America, is the main source of this copal.  The stems, twigs and even the fruits exude a large amount of resin, which trickles to the ground.  The commercial resin is collected from the base of living trees, and former trees as well, and is marked as Demerara or Para Copal.  It is the softest of all copals and therefore the least valuable. 

 

        Damars

 

          There is confusion in the term “damar.”  The word is of Malayan origin and is used by the natives to indicate a torch made of decayed wood and bark, mixed with oil and powdered resin, wrapped in leaves and bound with strips of rattan.  At one time it did not refers to any specific tree or resin.  However, the word came to be a collective term for a great variety of hard resins of different origin, and included even kauri and manila copal.  In the commercial trade the term “damar” restricted to resins that re obtained from members of the Dipterocarpaceae.  A few resins from species of the Burseraceae are also included.  This distinction should be maintained for the true damars are very different chemically from the various coniferous resins.  Unlike Manila copal, damar is insoluble in chloral hydrate, but completely soluble in alcohol and turpentine.

 

          The trees that yield damars are characteristic of all Southeastern Asia, and are particularly abundant in Malaya and Sumatra.  Although all members of the Dipterocarpaceae secrete resin, only a few species are of commercial importance.  These are found mainly in the genera Balanocarpus, Hopea and Shorea.  Damars are especially important in Malaya and are obtained by tapping the trees.  The most important Malayan varieties are Damar Mata Kuching from Hopea micrantha and related species. Damar Penak from Balanocarpus heimii, and Damar Temak from Shorea hypochra.  The principal damars of India are saldamar from Shorea robusta, white damar from Vateria indica, and black damar from Canarium strictum.  Damars also come from Borneo, Java, Sumatra, Thailand and Cochin China. Batavian damar, a product of Shorea wiesneri, is the best commercial variety.

 

          The so-called East India resins are products of the same trees that yield damars.  They are older and harder and are often gathered from the ground or from watercourses.

 

          Damars were used principally in spirit varnishes and the manufacture of nitrocellulose lacquers.  Damar varnishes adhere better than Manila copal varnishes, but are softer and less durable.  They are particularly well adapted for varnishing paper because of their luster and light color.  They have also been used for indoor work and in histology.

 

        Amber

 

          Amber is a fossil resin found mainly along the shore of the Baltic Sea. and to a lesser extent in Mexico, Central America and Caribbean Islands.  The principal source of Baltic amber was the now extinct pine, Pinus succinifera that flourished on the shores of a former sea in the Eocene.  Amber is very hard and brittle.  It occurs in several forms, the most important of which is succinite.  Some of these forms are transparent and others are almost opaque.  The color varies from yellow to brown and even black.  Amber assumes a high polish and becomes negatively charged when rubbed.  It also gives off a characteristic aromatic odor.  This substance has been known for thousands of years.  The Swiss Lake Dwellers were familiar with it and it was highly prized by the Greeks and Romans.  It has always been used for beads and other ornamental purposes and is often carved.

 

          The chief use of amber is for the mouthpieces of pipes and cigarette and cigar holders.  The darker grades yield a valuable varnish, but this is too costly for general use.  Amber is also used to increase the elasticity of rayon fibers and as the source of an essential oil.  It is of scientific interest that there are often found imbedded in amber the remains of plants, insects and other objects that existed at the time the fresh resin was exuded from the pine trees.

 

        Lacquer

 

          Lacquer is a natural varnish that exudes from various trees in Asia, and great quantities of it are used in the Orient for ornamental purposes.  The principal source is the lacquer tree, Rhus verniciflua, native to China but cultivated in Japan.  The trees are systematically tapped.  The exudate is a milky liquid, which darkens and thickens rapidly on exposure to air.  However, it can remain unchanged for long periods by storage in closed containers.  It is filtered before use.  When applied as a varnish, the thin film rapidly hardens in a moist atmosphere, in part due to oxidation.  Lacquer impart5s a remarkable protection as it is unchanged by acids, alkalis, and alcohol or heat up to 160 deg. Fahrenheit.  Pigments may be mixed with the lacquer before drying.

 

          The lacquering process originated in China many centuries before Christ, and reached its highest development during the Ming dynasty (A.D. 1368-1644).  In Japan the first records are from the 4th Century, when lacquer was used for many purposes.  The earliest examples known belong to the 6th Century.  The art reached its height during the 17th Century, although much fine work was produced as late as the 19th Century.  In Japan the quality of lacquered goods is of the highest excellence.  Gold has often been used as a coloring.  The process of lacquering is very complicated and tedious.  Sometimes 300-400 coats are applied and the whole operation requires several years to complete.  This technique was kept secret for many years.

 

          In Burma lacquer is obtained from Melanorrhoea usitata.  It dries more slowly than Japanese lacquer, but has been used in an attempt to build an industry in Burma.  Natural lacquers are also obtained in Taiwan and Vietnam, with Rhus succedanea being the source in the latter.

 

        Shellac

 

          True shellac is not a direct plant product but deserves discussion here.  It is made from stick-lac, a resinous substance secreted on the twigs of many trees by an insect, Tachardia lacca.  The lack insect derives its food from the sap of the trees and secretes the resin as a kind of cocoon for its own protection and that of its offspring.  Although there are about 40 species that may serve as hosts for the insect, only seven are of importance.  These are often cultivated.  They include Butea monosperma, Schleichera oleosa, Zizyphus xylopyrus, Ficus religiosa, Acacia nilotica, Cajanus cajan, and Zizyphus jujuba.  Butea monosperma was used as a host as early as 250 A.D.  At first a valuable red dye, which was obtained from the insect, was the only sought after product.  However, since 1590 A.D. the resinous excretions have been more important.  Native workers prepare most of the shellac of industry.  India furnished over 97 percent of the total output by the mid 1950’s, the rest being from Burma, Thailand and Vietnam.  The crude stick-lac is removed from the twigs and soaked in water to extract the red dye.  It is then dried and powdered to a granular consistency.  This seed-lac is melted and thin sheets of it are hardened.  These are broken into the semitransparent, brittle, orange-red flakes which make-up shellac.  If the melted seed-lac is poured out in droplets, it hardens into the thick round pieces known as button-lac.  Shellac is often bleached.

 

          At one time shellac had many industrial uses, but synthetic substitutes made from petroleum have greatly competed with it.  True shellac can be molded readily and was the most satisfactory material for the manufacture of phonograph records.  It is an insulator of the highest grade and was once extensively used in the electrical industry.  It was the principal spirit-varnish resin yielding a tough film with a smooth finish, which is also capable of a high polish.  Shellac varnishes cannot be used out-of-doors because they are not water resistant.  Shellac was also used in making sealing wax, drawing inks, some watercolors and nitrocellulose lacquers; for sizing papers; for stiffening felt hats; and, in India, for many ornamental purposes.

 

        Acaroid Resins

 

          These are grass-tree resins obtained from Australian trees belonging to the genus Xanthorrhoea.  These plants are among the few monocotyledons, other than palms, which have an arboreal habit.  They consist of a short woody stem, composed of the old leaf bases, surmounted by a tuft of long rush like leaves.  The resin collects around the bases of the old leaves and is removed by beating the stem.  The yellow acaroid resins reach the market in the form of elongated or round reddish-brown pieces.  They are obtained chiefly from Xxanthorrhoea hastilis.  Red acaroid resins from X. tateana, X. australis, and related species are much more common.  They consist of uneven pieces of a brownish color.  The acaroid resins are used in the manufacture of sealing was, gold, size, and spirit varnishes for use in coating metals; as a substitute for rosin in paper sizing and inks; as a mahogany stain; as a source of picric acid; and in medicine.

 

<bot200>  Grass Trees (Xanthorrhoea preissil) & Eucalyptus spp., central New South Wales, Australia

 

        Sandarac

 

          This is a soft pale-yellow resin obtained mainly from Tetraclinis articulata (= Callistris quadrivalis), a small tree in Northern Africa.  Australian species of Callitris are also a source of sandarac.  The resin is formed between the inner and outer layers of the bark, and is excreted inn the form of small tears, which quickly become opaque.  Sandarac yields a hard, white, rather brittle spirit varnish that is especially useful for coating labels, negatives, cardboard, leather and metals.  It was once used in medicine and was well known to previous civilizations.

 

        Mastic

 

          This is a very old resin that was known at least as far back as 400 B.C.  The most useful variety is Chios mastic, derived from Pistacia lenticus, a small tree from the Mediterranean area.  Although the resin exudes naturally, removing strips of bark enhances the flow.  Some of the resin adheres to the trunk in the form of long, ovoid, pale-yellow, brittle tears, while the remainder falls to the ground.  Bombay mastic, which consists of large irregular pieces of a dull, milky color, is from P. cabulica.  Mastic yields a pale varnish used for coating metals and pictures, both oils and watercolors.  It is also used in lithographic work, in perfumery, in medicine, and as cement for dental work.  It is one of the most expensive and high-grade resins.

 

        Dragon’s Blood

 

          Included here are various deep red materials of a resinous nature.  Sumatra dragon’s blood is from Daemonorops draco, a climbing rattan palm of Eastern Asia.  The dark reddish-brown resin forms as small granules on scaly fruits.  It is used mainly in the manufacture of red spirit varnishes for metals and in making zinc line engravings.  During the 18th Century Italian violinmakers used dragon’s blood in their varnishes.  Socotra dragon's blood is a resin that exudes from the stem of Dracaena cinnabari of Western Asia.  It has been also used for varnishes, dyes and stains.  Dragon’s blood is sometimes secured from tropical American species of Dracaena and other Asiatic species of Daemonorops.

 

        Kinos

 

          Gum kinos are produced by several plant species.  Malabar kino is derived from the dried juice of Pterocarpus marsupium, a large tree in India.  Trees are tapped and the juice is boiled down.  It reaches the market in the form of small, brownish-red, brittle pieces.  West African kino is a red resin from P. erinaceus.  Bengal kino is from Butea monosperma.  Some Australian species of Eucalyptus are also sources of gum kino, but mainly Eucalyptus camaldulensis.  The kino is secreted in cavities between the wood and bark, and oozes out after incisions have been made.  In the air the resin hardens into a solid reddish mass.  Several tropical American trees, mainly Dipteryx odorata and Cocoloba uvifera, also yield kinos.  Kinos have found their main use in medicine for throat disorders, and are sometimes used in tanning.

 

        Oleoresins

 

          A considerable amount of essential oils are contained in oleoresins in addition to the resinous materials.  Thus, they are often liquid in nature.  They have a distinct aroma and flavor.  Among the oleoresins we find the turpentines, balsams and elemis.  There is only a very slight distinction between these groups and often a confusion of names.

 

Turpentines

 

          These are oleoresins that are obtained almost exclusively from coniferous trees.  They are viscous, honey like liquids or soft and brittle solids.  The resin is secreted and stored in ducts near the cambium layer and exudes naturally as a soft, sticky substance, often called pitch.  For commercial use crude turpentine is obtained by tapping the trees.  On distillation turpentines yield the essential oil or spirits of turpentine, and rosin, both of which are useful products around which an important industry had been built in the 20th Century.  The turpentine or navel-stores industry was one of the oldest of the forest industries.  The Trojans and Greeks were familiar with pitch and its uses, and it is mentioned in the Bible.  The industry was valued at 35-40 million US dollars annually by the mid 20th Century.  The United States led in production with over half of the total output.  Turpentine and rosin are also produced in Europe and India and Vietnam.

 

          Common Turpentine

 

     <bot400>  Turpentine from  Longleaf Yellow Pine, Pinus australis Michx. f.(= palustris Mill.)., in northern Florida

 

Turpentines of Minor Importance

 

          Turpentines from various species of conifers have been frequently used in their natural state for purposes other than the production of naval stores.  Some of them have been important in industry, in the arts and particularly in medicine for over five centuries.  Among the more common are the following:

 

        Canada Balsam

 

          This is actually turpentine rather than a balsam, as the name seems to indicate.  It is secreted by the balsam fir, Abies balsamea, of northeastern North America.  The resin collects in elongated blisters on the bark and only small amounts are obtainable.  It was estimated that a tree could yield from 8-10 oz. per year.  Collectors use a pot with a spout cut at an angle.  This is forced into the blisters and held in place while the balsam drains out.  The balsam is a viscid yellowish or greenish substance.  It main use has been as a mounting medium for microscopic work and as cement for optical lenses.  It is very transparent and has a high refractive index, which results in a minimum of dispersed light.  The medicinal value of Canada balsam was known as early as 1607.  It was used as an irritant, stimulant and antiseptic, and is a component of collodion and some plasters.  It has also been used as a fixative for soap and perfumes.

 

          Oregon Balsam is obtained from the Douglas fir and it has similar properties and uses.

 

        Spruce Gum

 

          This is the natural exudation of various species of spruce of North America, with Picea rubens being the main source.  It is usually the result of an injury to the sapwood.  The thin, clear, bitter, sticky oleoresin is secreted in blister like cavities in the bark or in longitudinal fissures in the wood.  It hardens on exposure to the air and is collected when hard or semi soft.  Before the advent of chewing gum about 500,000 lb. were used each year as a substitute.  The gum softens in the mouth and assumes a reddish color.  It has a pleasing resinous taste.

 

        Venetian Turpentine

 

          This turpentine is obtained from the European larch, Larix decidua, a widespread tree in the mountains of Central Europe.  Unlike other conifers, the resin ducts are located in the heart of the tree so that holes are bored in order to obtain the resin.  The trees are tapped in the spring.  Venetian turpentine has been an important product since the middle of the 18th Century.  It is a yellowish or greenish liquid with a typical odor and taste.  It has been used in varnishes, histology, lithographic work and veterinary medicine.

 

        Misc. Turpentines

 

          Turpentines of small importance include Bordeaux turpentine from Pinus pinaster, Strasbourg turpentine from Abies alba and Jura turpentine from Picea abies.  In he first two of these European turpentines, the crude exudation is used to some extent, but generally it is strained and filtered through cloth.  The residue, known as Burgundy pitch, is a stimulant and counterirritant, and has been used in plasters, ointments and other pharmaceutical preparations.

 

Balsams

 

          These are technically oleoresins that contain benzole or cinnamic acid and therefore are highly aromatic.  However, the term “balsam” is frequently applied in error to much different substances, such as Canada balsam, copaiba balsam, etc.  The true balsams contain much less oil than the turpentines and are more viscous.  They yield essential oils on distillation.  Balsams are used in medicines and as fixatives in the perfume industry.

 

        Balsam of Peru

 

          This balsam is from Myroxylon pereirae, a tall tree in Central America.  It is cultivated in many tropical and subtropical areas.  The wood resembles mahogany and is valuable.  The balsam is a dark, reddish-brown, thick, syrupy, viscous liquid, and is a pathological product formed as a result of wounding the tree.  The tree trunks are beaten with a blunt instrument and the injured bark is then charred.  It falls off naturally or is removed.  Sometimes small “windows” are cut in the bark.  The balsam exudes from the exposed surface of the wood and is collected on cloths.  These cloths are later boiled to free the purified balsam.  Balsam of Peru has been used in medicine for healing wounds and skin diseases.  During World War II it was used in field dressings for quick applications of a protective covering to the surface of wounds.  It has also been used in the treatment of coughs, bronchitis and similar ailments, because of its simulative and antiseptic effect on the mucous membranes.  It is utilized in perfumes as a fixative for the heavier odors and has served as a substitute for vanilla.  Its common name is a misnomer because the tree does not grow in Peru.  The main supply for the United States has been El Salvador.

 

        Balsam of Tolu

 

          This balsam is a pathological product obtained from Myroxylon balsamum, a tree of Venezuela, Colombia and Peru.  Incisions with a V-shape are made in the trunk and the balsam exudes slowly and is collected in gourds.  It is a brown or yellowish-brown plastic substance with a pleasant aromatic taste and odor.  It has been used for salves and ointments and as an expectorant and antiseptic in the treatment of coughs, colds and bronchitis.  It is sometimes used to flavor cough syrups.  Considerable amounts have been used as fixatives in the perfume and soap industries.

 

        Styrax

 

          Styrax, or storax, occurs in two forms.  The most important type, the styrax of antiquity, is known as Levant styrax.  This is obtained from Liquidambar orientalis, a small tree found along the coasts of southwestern Asia Minor.  The balsam issues as a pathological product from a wound.  The outer bark is bruised and soon the balsam exudes into the inner bark.  The outer layers are discarded and the balsam is recovered by boiling the inner layers in seawater.  The residual bark is dried and used for fumigation.  Styrax is a semi liquid, grayish-brown, sticky, opaque substance with a pronounced aromatic odor.  It has been used in soaps and cosmetics; as a fixative for the heavy oriental type of perfume; in adhesives, lacquers, and incense; as a flavoring for tobacco; and in medicine as a stimulant to the mucous membranes and for the treatment of scabies.

 

          American styrax is obtained from the sweet gum, Liquidambar styraciflua.

 

        Benzoin

 

          This is a solid balsam that is often classified as a resin or balsamic resin.  It is the pathological product obtained from several species of Styrax in Southeastern Asia and the East Indies.  The balsam oozes from incisions made in the trunk and branches.  Two varieties are known in commerce.  Siam benzoin is from Styrax tonkinense and S. benzoides and occurs as yellowish or brownish pebble like tears with a milky white center.  The tears are hard and brittle at room temperature and occur separately or adhere together slightly.  Sumatra benzoin, from Styrax benzoin, occurs in reddish or grayish-brown blocks or lumps, composed of masses of tears stuck together.  Benzoin is exceedingly aromatic with a vanilla like odor.  It is used in medicine as a stimulant and expectorant; and in the preparation of heavy sweet perfumes, soap, toilet waters, lotions, tooth powders, incense and fumigating materials.

 

Other Oleoresins

 

          Oleoresins that do not belong to either the turpentines or balsams are such products as copaiba, elemi and Mecca balsam.

 

        Copaiba

 

          Also known as copaiba balsam or copaiba, this product is a natural oleoresin obtained from several species of Copaifera from tropical South America.  The copaiba trees are small with strong, tough, durable wood, which contains resin ducts of a large size.  So much oleoresin is secreted and stored in cavities that sometimes the pressure causes the trunks to burst.  Copaiba is obtained by boring holes into the heartwood.  The secretion flows out very rapidly.  It is a thin, clear, colorless liquid at first, but turns yellow and becomes more viscid with age.  It has a peculiar aromatic odor and a persistent bitter taste.  Several commercial varieties occur, which differ in the amount of resins and essential oils present as well as inn the source.  The most important are Maracaibo copaiba from Venezuela, obtained from Copaifera officinalis, which contains much resin and is rather thick; and Para copaiba, a very fine grade from Brazil, obtained from C. reticulata.  Copaiba has been used in making varnishes, lacquers, and tracing paper, as a fixative in scenting soaps and perfumes, and in photography to emphasize half tones and shadows.  In medicine it was used as a disinfectant, laxative, diuretic, and mild stimulant.  Amerindians used it for its healing properties.  It became known in Europe early in the 16th Century.

 

          Substitutes for copaiba are Gurjun Balsam and Illurin Balsam.

 

          Gurjun Balsam is obtained from Dipterocarpus turbinatus and related species from India and the East Indies.  The thick, opaque, grayish oleoresin is obtained by cutting holes in the trunk.

 

          Illurin Balsam or African Copaiba is a very fragrant oleoresin with a thick pungent, pepperlike odor that originates from a West African tree, Daniella thurifera.  This species is sometimes called Sierra Leone Frankincense.  It is found in the drier open forests and savannahs of Upper Guinea.  The resin exudes in a copious flow from the base of the trees.  A similar product comes from D. oliveri, a species of the denser moist forests.  This oleoresin, under the name of wood oil, was once one of the chief products of Nigeria.

 

        Elemi

 

          This name is used as a collective for several oleoresins of different origin.  It is also used in error as a synonym for some of the soft copals.  Elemis differ considerably in their characteristics.  These oleoresins exude as clear pale liquids, but they tend to harden on exposure.  Some remain soft, while others become very hard.

 

          Manila Elemi is the most important and the best know of the elemis.  Its source is the pili tree, Canarium luzonicum, of the Philippines.  The oleoresin is secreted in the bark and oozes from the trunk in fragrant white masses.  Native people have used elemi for torches and for caulking their boats.  Manila elemi has been used in lithographic work and in the manufacture of inks, adhesives, and cements; in the varnish industry to give toughness and elasticity to the products; in perfumes; and in medicine in plasters and ointments.

 

          Of lesser importance is African Elemi from Boswellia frereana; Mexican Elemi from Amyris elemifera, A. balsamifera and other species; and Brazilian Elemi from Protium heptaphyllum, Bursera gummifera and other trees.

 

        Mecca Balsam

 

          This is a greenish turbid oleoresin with the odor of rosemary.  It is obtained from Commiphora opobalsamum, in Arabia.  This material has long been used in incense and for perfumes of an oriental type.  It has some medicinal value.  The supply of Mecca balsam has always been limited and thus is a rare and costly product.

 

Gum Resins

 

          Gum resins are mixtures of both true gums and resins and naturally combine the traits of both groups.  They often contain small amounts of essential oils and traces of coloring material.  Gum resins occur naturally as milky exudates and collect in the form of tears or irregular masses.  Injuring or tapping the plants also produces them.  They are mostly from plants of dry, arid regions, especially species of the Umbelliferae and Burseraceae.  Three of the umbelliferous species, the sources of ammoniacum, asafetida and galbanum, are very common in Iran and Afghanistan and furnish the characteristic aspects of the vegetation of the plains and steppes in those regions.  During the dry season these plains are barren, but shortly after the rains begin, these plants send up thick stems from their perennial rootstalks.  When fully grown the plants attain a height of 5-6 ft., and are so abundant that they from a kind of open forest.

 

        Ammoniacum

 

          This is obtained from Dorema ammonniacum, a tall, stout naked, hollow-stemmed perennial found in the deserts of Iran, southern Siberia and other parts of Western Asia.  It has a milky juice, which exudes from the stem and flowering branches and hardens into tears.  Insect injury often causes the exudation to occur.  The brownish-yellow tears are hard and brittle and occur singly or in masses.  Ammoniacum is used in medicine as a circulatory stimulant, and in perfumery.

 

        Asafetida

 

       This is derived from Ferula assafoetida and allied species, stout perennial herbs of Iran and Afghanistan.  The cortex of the thick fleshy roots exudes a milky juice during the rainy season.  The crown of the roots is cut off and protected from the sun.  The gum resin gradually collects on the surface in the form of tears, or masses of tears of varying colors imbedded in a thick, gummy, grayish or reddish matrix.  Asafetida has a powerful and foul odor and a bitter acrid taste, due to sulfur compounds present in the essential oil.  Despite this it has been used throughout the East for flavoring sauces, curries and other foods, and as a drug.  In Europe and America is used in perfumes and for flavoring only when exceedingly dilute and after certain impurities have been removed.  Asafetida has may valuable medicinal properties and is used in the treatment of coughs, asthma, and other nervous disorders and as an aid to digestion and metabolism.

 

        Galbanum

 

          Galbanum is a gum resin excreted from the lower part of the stems of Ferula galbaniflua, a stout herbaceous perennial of Northwestern Asia.  It occurs in the form of separate tears or brownish and yellowish-green masses.  It has been used for centuries in medicine.  Galbanum has a powerful tenacious aromatic odor.

 

        Myrrh

 

          This is one of the oldest and most valuable of the gum resins.  There has been some confusion regarding its source because two forms seem to occur.

 

          Herabol Myrrh is derived from Commiphora myrrha, a large shrub or small tree of Ethiopia, Somaliland and Arabia.  The gum resin oozes naturally from the stems or as a result of wounding.  The pale-yellow liquid gradually solidifies and becomes brown or even black in color.  Herabol myrrh is used in perfume manufacture and for medicinal purposes as a tonic, stimulant, and antiseptic and is often a constituent of mouthwashes and dentifrices.

 

          Bisabol Myrrh or Sweet Myrrh is from Commiphora erythraea, and Arabian species of similar appearance.  This is the myrrh of antiquity and has been used for centuries in incense, perfumes and embalming.  Myrrh was an important product in Biblical times, ranking with gold in value.  It is still used in perfumes and incense for religious ceremonies.  It is one of the constituents of Chinese joss sticks.

 

        Frankincense

 

       This is also known as Olibanum and is obtained from Boswellia carteri and related Asiatic and African species.  The clear yellow resin exudes from incisions made in the bark and hardens as small yellow grains.  Frankincense, like myrrh, has been a valuable material since Biblical times.  It is still an indispensable ingredient of incense for religious purposes, and is also used in perfumes, because of its excellent fixative properties, face powders, pastilles and fumigating powders.

 

        Opopanax / Bdellium

 

          These gum resins have been of much less importance.  Opopanax is derived from two very distinct plants, Commiphora kataf of the Burseraceae and Opopanax chironium of the Umbelliferae.  It is used in perfumery and was formerly of importance in medicine.

 

       Bdellium is a bitter aromatic gum resin obtained from Commiphora mukul of India and C. africana of Africa.  It has been used in the perfume industry.

 

Misc. Resins

 

          There are other resinous substances, which find no use in industry but are treated under “Medicinal Plants.”  These include aloes, guaiacum, jalap and podophyllum, and will be treated later.  Gamboge, a gum resin is discussed under “Dye Plants.”