=BALSAMUM DIPTEROCARPI.=
_Balsamun Gurjunæ; Gurjun Balsam, Wood Oil._
=Botanical Origin=—This drug is yielded by several trees of the genus
_Dipterocarpus_, namely—
_D. turbinatus_ Gärtn. f. (_D. lævis_ Ham., _D. indicus_ Bedd), a
native of Eastern Bengal, Chittagong and Pegu to Singapore, and French
Cochin China.
_D. incanus_ Roxb., a tree of Chittagong and Pegu.
_D. alatus_ Roxb., growing in Chittagong, Burma, Tenasserim, the
Andaman Islands, Siam, and French Cochin China.
_D. zeylanicus_ Thw. and _D. hispidus_ Thw., indigenous to Ceylon.
_D. crispalatus_ ... abounding, together with _D. turbinatus_ and _D.
alatus_, in French Cochin China.
_D. trinervis_ Bl., a native of Java and the Philippines, and _D.
gracilis_ Bl., _D. littoralis_ Bl., _D. retusus_ Bl. (_D. Spanoghei_
Bl.), trees of Java supply a similar useful product which as yet
appears to be of less commercial importance.[360]
The Gurjun trees are said by Hooker[361] to be among the most
magnificent of the forests of Chittagong. They are conspicuous for
their gigantic size, and for the straightness and graceful form of
their tall unbranched trunk, and small symmetrical crown of broad
glossy leaves. Many individuals are upwards of 200 feet high and 15
feet in girth.
=History=—Gurjun balsam was enumerated as one of the productions of
Ava by Francklin[362] in 1811, and in 1813 it was briefly noticed by
Ainslie.[363] Its botanical origin was first made known by Roxburgh,
who also described the method by which it is extracted.
[359] _Comptes Rendus_, xliv. (1857) 1355.
[360] That of _D. trinervis_ is especially used in Java. Filet,
_Plantkundig Woordenboek voor Nederlandsch Indië_, Leiden, 1876, No.
6157.
[361] _Himalayan Journal_, ed. 2, ii. (1855) 332.
[362] _Tracts on the Dominions of Ava_, Lond. 1811. 26.
[363] In the _Catalogue des Produits des_ _Colonies françaises,
Exposition Universelle de 1878_, p. 175, it is stated that the balsam
of _D. alatus_ in French Cochin China is preferred, being a “_huile
b’anche_.”
The medicinal properties of Gurjun balsam were pointed out by
O’Shaughnessy[364] as entirely analogous to those of copaiba; and his
observations were confirmed by many practitioners in India. This has
obtained for the drug a place in the _Pharmacopœia of India_ (1868).
=Extraction=—A recent account of the production of this drug is found
in the _Reports of the Jury of the Madras Exhibition of 1855_. It is
there stated that _Wood Oil_, as the balsam is commonly called, is
obtained for the most part from the coast of Burma and the Straits,
and is procured by tapping the trees about the end of the dry season.
Several deep incisions are made with an axe into the trunk of the
tree and a good-sized cavity scooped out. In this, fire is placed,
and kept burning until the wood is somewhat scorched, when the balsam
begins to exude, and is then led away into a vessel of bamboo. It is
afterwards allowed to settle, when a clear liquid separates from a
thick portion called the “_guad_.” The oil is extracted year after
year, and sometimes there are two or three holes in the same tree. It
is produced in extraordinary abundance; from 30 to 40 gallons according
to Roxburgh may sometimes be obtained from a single tree in the course
of a season, during which it is necessary to remove from time to time
the old charred surface of the wood and burn afresh.
If a growing tree is felled and cut into piece, the oleo-resin exudes
and concretes on the wood, very much, it is said, _resembling camphor_
(?) and having an aromatic smell.
=Description=—As Gurjun balsam is the produce of different trees as
well as of different countries, it is not surprising to find that it
varies considerably in its properties.
The following observations refer to a balsam of which 400 lb. were
recently imported from Moulmein for a London drug firm. It is a thick
and viscid fluid, exhibiting a remarkable fluorescence, so that when
seen by reflected light it appears opaque and of dingy greenish grey;
yet when placed between the observer and strong daylight it is seen to
be perfectly transparent and of a dark reddish-brown.[365] It has a
weak aromatic copaiba-like odour and a bitterish aromatic taste without
the persistent acridity of copaiba. Its sp. gr. at 16·9° C. is 0·964.
[364] _Mat. Med. of Hindoostan_, Madras, 1813. 186.
[365] _Bengal Dispensatory_, 1842. 22.
With the following liquids Gurjun affords perfectly clear solutions
which are more or less fluorescent, namely pure benzol (from benzoate
of calcium), cumol, chloroform, sulphide of carbon, essential oils. On
the other hand, it is not entirely soluble in methylic, ethylic, or
amylic alcohol; in ether, acetic ether, glacial acetic acid, acetone,
phenol (carbolic acid), or in caustic potash dissolved in absolute
alcohol. Many samples of commercial benzin also are not capable of
dissolving the oleo-resin perfectly, but we have not ascertained on
what constituent of such benzin this depends. We have further noticed
that that portion of petroleum which is known as _Petroleum Ether_,
containing the most volatile hydrocarbons, does not wholly dissolve the
oleo-resin. One hundred parts of the balsam warmed and shaken with
1000 parts of absolute alcohol yielded on cooling a precipitate of
resin amounting when dried to 18·5 parts. All concentrated solutions of
the balsam are precipitated by amylic alcohol.
If the balsam is kept for a long time in a stoppered vessel at 100° C.
it simply becomes a little turbid; but about 130° C. it is transformed
into a jelly, and on cooling does not resume its former fluidity.
Balsam of copaiba heated in a closed glass tube to 220° C. does not at
all lose its fluidity, whereas Gurjun balsam becomes an almost solid
mass.
=Chemical Composition=—Of the balsam 6·99 grammes dissolved in
benzol and kept in a water bath until the residue ceased to lose
weight, yielded 3·80 grammes of a dry, transparent, semi-fluid resin,
corresponding to 54·44 per cent., and 45·56 of volatile matters
expelled by evaporation. But another sample afforded us much less
residue. By submitting larger quantities of the above balsam to the
usual process of distillation with water in a large copper still, 37
per cent. of volatile oil were easily obtained. The water passing over
at the same time did not redden litmus paper. A dark, viscid, liquid
resin remained in the still.
The essential oil is of a pale straw-colour and less odorous than
most other volatile oils. Treated with chloride of calcium and again
distilled, it begins to boil at 210° C. and passes over at 255°-260°
C., acquiring a somewhat empyreumatic smell and light yellowish tint.
The purified oil has a sp. gr. of 0·915;[366] it is but sparingly
soluble in absolute alcohol or glacial acetic acid, but mixes readily
with amylic alcohol.
According to Werner (1862) this oil has the composition C₂₀H₃₂ like
that of copaiba. He says it deviates the ray of polarized light to the
left, but that prepared by one of us deviated strongly to the _right_,
the residual resin dissolved in benzol being wholly inactive. The
oil does not form a crystalline compound with dry hydrochloric acid,
which colours it of a beautiful blue.[367] De Vry[368] states that the
essential oil after this treatment deviates the ray to the right.
The resin contains, like that of copaiba, a small proportion of a
crystallizable acid which may be removed by warming it with ammonia
in weak alcohol. That part of the resin which is insoluble even in
absolute alcohol,[369] we found to be uncrystallizable. The _Gurgunic
Acid_, as the crystallized resinous acid is called by Werner,[370]
but which it is more correct to write _Gurjunic_, may consequently
be prepared by extracting the resin with alcohol (·838) and mixing
the solution with ammonia. From the ammoniacal solution gurjunic acid
is precipitated on addition of a mineral acid, and if it is again
dissolved in ether and alcohol it may be procured in the form of small
crystalline crusts. From the specimen under examination we were not
successful in obtaining indubitable crystals.
[366] 0·944 according to Werner; 0·931 O’Shaughnessy; 0·928 De Vry
(1857).
[367] This magnificent colouring matter is not dissolved by ether.
[368] _Pharm. Journ._ xvi. (1857) 374.
[369] The sample of gurjun balsam examined by Werner as well as the
resin it contained were entirely soluble in boiling potash lye.
[370] Gmelin, _Chemistry_, xvii. 545.
Gurjunic acid, C₄₄H₆₈O₈ according to Werner, melts at 220° C., and
concretes again at 180° C.; it begins to boil at 260° C., yet at the
same time decomposition takes place. By assigning to this acid the
formula C₄₄H₆₄O₅ + 3H₂O, which agrees well with Werner’s analytical
results, we may regard it as a hydrate of abietinic acid, the chemical
behaviour of which is perfectly analogous. Gurjunic acid is soluble in
alcohol 0·838, but not in weak alcohol; it is dissolved also by ether,
benzol, or sulphide of carbon (Werner).
In copaiba from Maracaibo, Strauss (1865) discovered _Metacopaivic
Acid_ which is probably identical with gurjunic; the former, however,
fuses at 206° C.
The amorphous resin forming the chief bulk of the residue of the
distillation of the balsam, has not yet been submitted to exact
analysis. We find that after complete desiccation it is not soluble
in absolute alcohol. A crystallized constituent of Gurjun, which
we obtained from a balsam of unknown origin, has been shown[371]
to answer to the formula C₂₈H₄₆O₂. Its crystals, belonging to the
asymmetric system, melt at 126°-130°C.; they are entirely devoid of
acid character. A comparative examination of the product of each of the
above named species of Dipterocarpus would be highly desirable.
=Commerce=—Gurjun balsam is exported from Singapore, Moulmein, Akyab
and the Malayan Peninsula, and is a common article of trade in Siam. It
is likewise produced in Canara in Southern India. It is occasionally
shipped to Europe. More than 2000 lb. were offered for sale in London
under the name of _East India Balsam Capivi_, 4th October 1855; and
in October 1858, a no less quantity than 45 casks appeared in the
catalogue of a London drug-broker. It is now not unfrequent in the
London drug sales.
=Uses=—In medicine it has hitherto been employed only as a substitute
for copaiba, and chiefly in the hospitals of India.
In the East its great use is as a natural varnish, either alone
or combined with pigments; and also as a substitute for tar as an
application to the seams of boats, and for preserving timber from the
attacks of the white ant. To the first application it is often made
better appropriated[372] by boiling it, so that the essential oil is
evaporated.
_Wood Oil of China_—The oleo-resin of Dipterocarpus must not be
confounded with the so-called _Wood Oil_ of China, which is of a
totally different nature. The latter is a fatty oil expressed from
the seeds of _Aleurites cordata_ Müll. Arg. (_Dryandra cordata_
Thunb. _Elaeococca Vernicia_ Sprgl. Prodromus xv. part 2, p. 724),
the well-known _Tung_ tree of the Chinese. It is a large tree of the
order _Euphorbiaceæ_, found in China and Japan. The oil is an article
of enormous consumption among the Chinese, who use it in the caulking
and painting of junks and boats, for preserving woodwork, varnishing
furniture, and also in medicine. In the commercial reports of H.M.
Consuls in China (No. 5, 1875, p. 3, 26) we find that this oil is
largely exported from Hankow: 199·654 peculs in 1874, and forms an
article of import at Ningpo: 15·123 peculs in 1874 (pecul = 133·33 lb.
avoirdupois). It is, however, not shipped to foreign countries. The
oil of the Tung tree is also extremely remarkable on account of its
chemical properties as shown by Cloëz (1875-1877).
[371] Flückiger, _Pharm. Journ._ (1878) 725, with fig.
[372] _Catalogue of the French Colonies_, _Paris Exhibition_, 1878,
101, quoted above.