_Camphor_,[1879] _Common Camphor_, _Laurel Camphor_; F. _Camphre_; G.
_Campher_.
=Botanical Origin=—_Cinnamomum Camphora_ Fr. Nees et Ebermaier (_Laurus
Camphora_ L., _Camphora officinarum_ C. Bauh.), the Camphor tree or
Camphor Laurel is widely diffused, being found throughout Central China
and in the Japanese Islands. In China it abounds principally in the
eastern and central provinces, as in Chekiang, Fokien and Kiangsi; but
it is wanting, according to Garnier (1868), in Yünnan and Szechuen.
It is plentiful, on the other hand, in the island of Formosa, where
it covers the whole line of mountains from north to south, up to an
elevation of 2000 feet above the level of the sea. It flourishes in
tropical and subtropical countries, and forms a large and handsome
tree in sheltered spots in Italy as far north as the Lago Maggiore.
The leaves are small, shining, and glaucous beneath, and have long
petioles; the stem affords excellent timber, much prized on account of
its odour for making clothes’ chests and drawers of cabinets.
_Dryobalanops aromatica_, the camphor tree of Borneo and Sumatra,
yields a peculiar camphor, which we shall describe further on.
=History=—The two kinds of Camphor afforded by the two trees just
named have always been regarded by the Chinese as perfectly distinct
substances, and in considering the history of camphor this fact must be
borne in mind.
On perusing the accounts of Laurel Camphor given by Chinese
writers,[1880] the remarkable fact becomes apparent, that although the
tree was evidently well known in the 6th century, and probably even
earlier, and is specially noticed on account of its valuable timber, no
mention is made in connexion with it of any such substance as _camphor_.
Le-she-chin, the author of the celebrated herbal _Pun-tsao-kang-muh_,
written in the middle of the 16th century, was well acquainted with the
two sorts of camphor,—the one produced by the camphor laurel of his own
country, the other imported from the Malay islands; and he narrates how
the former was prepared by boiling the wood, and refined by repeated
dry sublimations.
Marco Polo, towards the end of the 13th century, saw the forests of
Fokien in South-eastern China, in which, says he, are many of the trees
which give camphor.[1881] It would thus appear that Laurel Camphor was
known as early as the time of Marco Polo, yet it is certain that the
more ancient notices which we shall now quote have reference to the
much valued Malay Camphor, which remains up to the present day one of
the most precious substances of its class.
[1879] The word _Camphor_, generally written by old Latin authors
_Caphura_, and by English _Camphire_, is derived from the Arabic
_Káfúr_, which in turn is supposed to come from the Sanskrit _Karpūra_,
signifying _white_.
[1880] Passages from several have been translated and kindly placed
at our disposal by Mr. A. Wylie. Dr. Bretschneider of Pekin and Mr.
Pauthier of Paris (see p. 494, note 7,) have also been good enough to
aid us in the same manner.
[1881] Yule, _Book of Ser Marco Polo_, ii. (1871) 185.
There is no evidence that camphor reached Europe during the classical
period of Greece and Rome. The first mention of it known to us
occurs in one of the most ancient monuments of the Arabic language,
the poems of Imru-l-Kais,[1882] a prince of the Kindah dynasty, who
lived in Hadramaut in the beginning of the 6th century. Nearly at
the same period, Aëtius of Amida (the modern Diarbekir) used camphor
medicinally, but from the manner in which he speaks of it, it was
evidently a substance of some rarity.[1883]
In fact, for many centuries subsequent to this period, camphor was
regarded as one of the most rare and precious of perfumes. Thus, it is
mentioned in A.D. 636, with musk, ambergris, and snadal-wood, among the
treasures of Chosroes II., of the Sassanian dynasty of kings of Persia,
in the palace at Madain on the Tigris, north of Babylon.[1884]
Among the immense mass of valuables dispersed at Cairo on the downfall
of the Fatimite Khalif Mostanser in the 11th century, the Arabian
historians[1885] enumerate with astonishment, besides vast quantities
of musk, aloes wood, snadal-wood, amber, large stores of _Camphor of
Kaisur_, and hundreds of figures of _melons in camphor_, adorned with
gold and jewels, which were contained in precious vessels of gold and
porcelain. One grain (crystal?) of camphor is mentioned as weighing
5 mithkals, one melon of the weight of 70 mithkals, was contained
in a golden box weighing no less than 3,000 mithkals (1 mithkal =
71·49 gr. Troy = 4·63 grammes). It is also on record that about A.D.
642, Indian princes sent camphor as tribute or a gift to the Chinese
Emperors;[1886]—further, that in the Teenpaou period (A.D. 742-755),
the Cochinchinese brought to the Chinese court a tribute of Barus
camphor, said by the envoy to be found in the trunks of old trees, the
like of which for fragrance was never seen again.[1887] Masudi,[1888]
four centuries later, mentions a similar present from an Indian to
a Chinese potentate, when 1,000 _menn_[1889] of aloes-wood were
accompanied by 10 _menn_ of camphor, the choice quality of the latter
being indicated by the remark that it was in pieces as large or larger
than a pistachio-nut.
Again, between A.D. 1342 and 1352, an embassy left Pekin bearing a
letter from the Great Khan to Pope Benedict XII., accompanied by
presents of silk, precious stones, _camphor_, musk, and spices.[1890]
Ibn Batuta, the celebrated traveller, relates that after having visited
the King of Sumatra, he was presented on leaving (a.d. 1347) with
aloes-wood, _camphor_, cloves, and sandal-wood, besides provisions.
[1882] In the description of Arabia by Ibn Hagik el Hamdany, fol. 170
of the MS. at Aden (Prof. Sprenger).
[1883] He directs two ounces of camphor to be added to a certain
preparation, provided camphor is sufficiently abundant.—Tetr. iv. sermo
4. c. 114
[1884] G. Weil, _Geschichte der Chalifen_, i. (Mannheim, 1846) 75.
[1885] Quatremère, _Mém. sur l’Egypte_, ii. (1811) 366-375.—It is
interesting to find that _Káfúre-kaisúri_, i.e., _Kaisur Camphor_, is a
term still known in the Indian bazaars.
[1886] Käuffer, _Geschichte von Ostasien_, ii. (1859) 491.
[1887] Translation from the Chinese communicated by Mr. A. Wylie.
[1888] _Les Prairies d’or_, i. (Paris, 1861) 200.
[1889] The Arabian _menâ_ or _menn_ is equal to 2⅕ pounds Troy, or 933
grammes.
[1890] Yule, _Cathay and the way thither_, ii. 357.
Ishâk ibn Amrân, an Arabian physician living towards the end of the
9th century, and Ibn Khurdádbah, a geographer of the same period, were
among the first to point out that camphor is an export of the Malayan
Archipelago; and their statements are repeated by the Arabian writers
of the middle ages, who all assert that the best camphor is produced
in Fansúr. This place, also called Kansúr or Kaisúr, was visited in
the 13th century by Marco Polo, who speaks of its camphor as selling
for its weight in gold; Yule[1891] believes it to be the same spot as
Barus, a town on the western coast of Sumatra, still giving a name to
the camphor produced in that island.
From all these facts and many others that might be adduced,[1892] it
undoubtedly follows that the camphor first in use was that found native
in the trunk of the Sumatran _Dryobalanops aromatica_, and not that of
the Camphor Laurel. At what period and at whose instigation the Chinese
began to manufacture camphor from the latter tree is not known.
Camphor was known in Europe as a medicine as early as the 12th century,
as is evident from the mention of it by the abbess Hildegard[1893]
(who calls it _ganphora_), Otho of Cremona,[1894] and the Danish canon
Harpestreng (_ob._ A.D. 1244).
Garcia de Orta states (1563) that it is the camphor of China which
alone is exported to Europe, that of Borneo and Sumatra being a hundred
times more costly, and all consumed by eastern nations. They partly
devoted the latter to ritual purposes, as for instance embalming,
partly to “eating,” _i.e._ for the preparation of the betel-leaves for
chewing. Neuhof[1895] states that the other ingredients used in China
for that purpose are: Areca nuts (see article Semen Arecæ) and lime
or Lycium (see page 35), _Caphur de Burneo_, aloë (_i.e._ Aloë-wood,
see Aloë), and musk. Kämpfer,[1896] who resided in Japan in 1690-92,
and who figured the Japanese camphor tree under the name _Laurus
camphorifera_, expressly declares the latter to be entirely different
from the camphor tree of the Indian Archipelago. He further states
that the camphor of Borneo was among the more profitable commodities
imported into Japan by the Dutch, whose homeward cargoes included
Japanese camphor to the extent of 6,000 to 12,000 lb. annually.[1897]
This camphor was refined in Holland by a process long kept secret,
and was then introduced into the market. In Pomet’s time (1694 and
earlier), crude camphor was common in France, but it had to be sent to
Holland for purification.
It is doubtful whether at that period, or even much later, any camphor
was obtained from Formosa. Du Halde[1898] makes no allusion to it as a
production of that island; nor does he mention it among the commodities
of Emouy (Amoy), which was the Chinese port then in most active
communication with Formosa.
[1891] _The Book of Ser Marco Polo_, ii. (1874) 282, 285.
[1892] For further historical details, compare my paper in the
_Schweizerische Wochenschrift für Pharmacie_, 27 Sept., 4 and 11 Oct.
1867, or in Buchner’s _Repertorium f. Pharmacie_, xvii. (1868) 28.—F.
A. F.
[1893] S. Hildegardis _Opera Omnia_, accurante J. P. Migne, Paris,
1855. 1145.
[1894] Choulant, _Macer Floridus_, Lips. 1832. 161.
[1895] _Gesantschaft, etc._ Amsterdam, 1666. 363.
[1896] _Amœnitates exoticæ_ (1712) 770.
[1897] _Hist. of Japan_, translated by Scheuchzer, i. (1727) 353. 370.
[1898] _Description de la Chine_, i. (1735) 161.
=Production=—The camphor of European commerce is produced in the island
of Formosa and in Japan. We have no evidence that any is manufactured
at the present day in China, although very large trees, often from 8 to
9 feet in diameter, are common, for instance in Kiangsi, and camphor
wood is an important timber of the Hankow market.
In Formosa, the camphor-producing districts lie in the narrow belt of
debateable ground, which separates the border Chinese settlements from
the territory still occupied by the aboriginal tribes. The camphor is
prepared from the wood, which is cut into small chips from the trees,
by means of a gouge with a long handle. In this process there is
great waste, many trees being cut and then left with a large portion
of valuable timber to perish. The next operation is to expose the
wood to the vapour of boiling water, and to collect the camphor which
volatilizes with the steam. For this purpose, stills are constructed
thus:—a long wooden trough, frequently a hollowed trunk, is fixed over
a furnace and protected by a coating of clay. Water is poured into it,
and a board perforated with numerous small holes is luted over it.
Above these holes the chips are placed and covered with earthen pots.
A fire having been lighted in the furnace, the water becomes heated,
and the steam passing through the chips, carries with it the camphor,
which condenses in minute white crystals in the upper part of the pots.
From these it is scraped out every few days, and is then very pure
and clean. Four stills, each having ten pots placed in a row over one
trough, are generally arranged under one shed. These stills are moved
from time to time, according as the gradual exhaustion of timber in the
locality renders such transfer desirable. A considerable quantity of
camphor is however manufactured in the towns, the chips being conveyed
thither from the country. A model of a much better still, which was
contributed from Formosa to the Paris Exhibition in 1878, is perhaps
referring to a town manufacture.
Camphor is brought from the interior to Tamsui, the chief port of
Formosa, the baskets holding about half a pecul each (1 pecul = 133⅓
lbs.), lined and covered with large leaves. Upon arrival, it is stored
in vats holding from 50 to 60 peculs each, or it is packed at once
in the tubs, or lead-lined boxes, in which it is exported. From the
vats or tubs there drains out a yellowish essential oil known as
_Camphor Oil_, which is used by the Chinese in rheumatism.[1899] In
1877 hydraulic pressure has been established for the separation of the
oil and moisture; the raw camphor loses about 20 per cent. of these
admixtures.
Kämpfer in his account[1900] of the manufacture of camphor in the
Japanese province of Satzuma and in the islands of Gotho, describes
the boiling of the chips in an iron pot covered with an earthen head
containing straw in which the camphor collects. In the province of
Tosa, island of Sikok, there is now a still in use, which is quite
conveniently combined with a cooling apparatus consisting of a wooden
trough, over which cold water is flowing.[1901]
[1899] The foregoing particulars are chiefly extracted from the _Trade
Report of Tamsui_ by E. C. Taintor, Acting Commissioner of Customs,
published in the _Reports on Trade at the Treaty Ports in China_ for
1869, Shanghai, 1870, and from James Morrison’s _Description of the
island of Formosa_, in the _Geogr. Magazine_, 1877, 263 and 319.
[1900] _op. cit._ p. 772.
[1901] Both of the above mentioned stills from Sikok and Formosa
are figured in my “_Account of the Paris Exhibition_,” _Archiv der
Pharmacie_, 214 (1879) 12.—F. A. F..
=Purification=—Camphor as it is exported from Japan and Formosa
requires to be purified by sublimation. The crude drug consists of
small crystalline grains, which cohere into irregular friable masses,
of a greyish-white or pinkish hue. Dissolved in spirit of wine, it
leaves from 2 to 10 per cent. of impurities consisting of gypsum,
common salt, sulphur, or vegetable fragments.
In Europe, crude camphor is sublimed from a little charcoal or sand,
iron filings or quicklime, and sent into the market as _Refined
Camphor_ in the form of large bowls or concave cakes, about 10
inches in diameter, 3 inches in thickness, and weighing from 9 to 12
lb.[1902] Each bowl has a large round hole at the bottom, corresponding
to the aperture of the vessel in which the sublimation has been
conducted. This operation is performed in peculiar glass flasks termed
_bomboloes_, in the upper half of which the pure camphor concretes.
These flasks having been charged and placed in a sand-bath, are rapidly
heated to about 120°-190° C. in order to remove the water. Afterwards
the temperature is slowly increased to about 204° C., and maintained
during 24 hours. The flasks are finally broken.
As camphor is a neutral substance, the addition of lime probably serves
merely to retain traces of resin or empyreumatic oil. Iron would keep
back sulphur were any present.
In the United States the refiners use iron vessels; their product is in
flat disks, about 16 inches in diameter by one inch in thickness.
The refining of camphor is carried on to a large extent in England,
Holland, Hamburg, Paris, Bohemia (Aussig), in New York and
Philadelphia. It is a process requiring great care on account of the
inflammability of the product. The temperature must also be nicely
regulated, so that the sublimate may be deposited not merely in loose
crystals, but in compact cakes. In India where the consumption of
camphor is very large, the natives effect the sublimation in a copper
vessel, the charge of which is 1½ maunds (42 lb.): fire is applied to
the lower part, the upper being kept cool.[1903]
=Description=—Purified Camphor forms a colourless crystalline,
translucent mass, traversed by numerous fissures, so that
notwithstanding a certain toughness, a mass can readily be broken
by repeated blows. By spontaneous and extremely slow evaporation at
ordinary temperatures, camphor sublimes in lustrous hexagonal plates or
prisms, having but little hardness. If triturated in a mortar, camphor
adheres to the pestle, so that it cannot be powdered _per se_. But if
moistened with spirit of wine, ether, chloroform, methylic alcohol,
glycerin, or an essential or fatty oil, pulverization is effected
without difficulty. By keeping a short time, the powder acquires a
crystalline form. With an equal weight of sugar, camphor may also be
easily powdered.
Camphor melts at 175° C., boils at 204°, and volatilizes somewhat
rapidly even at ordinary temperatures. To this latter property,
combined with slight solubility, must be attributed the curious
rotatory motion which small lumps of camphor (as well as barium
butyrate, stannic bromide, chloral hydrate, and a few other substances)
exhibit when thrown on to water.
[1902] These are the dimensions of the cakes manufactured in the
laboratory of Messrs. Howards of Stratford, but it is obvious that they
may vary with different makers.
[1903] Mattheson, _England to Delhi_, Lond. 1870, 474.
The solubility of camphor in water is very small, 1300 parts dissolving
about one; but even this small quantity is partially separated on
addition of some alkaline or earthy salt, as sulphate of magnesium.
Alcohols, ethers, chloroform, carbon bisulphide, volatile and fixed
oils and liquid hydrocarbons, dissolve camphor abundantly.
The sp. gr. of camphor at 0° C. and up to 6° is the same as that of
water; yet at a somewhat higher temperature, camphor expands more
quickly, so that at 10° to 12° C. its sp. gr. is only 0·992.
In concentrated solution or in a state of fusion, camphor turns the
plane of polarization strongly to the right. Officinal solution of
camphor (_Spiritus Camphoræ_) is too weak, and does not deviate the ray
of light to a considerable amount.[1904] Crystals of camphor are devoid
of rotatory power.
The taste and odour of camphor are _sui generis_, or at least are
common only to a group of nearly allied substances. Camphor is not
altered by exposure to air or light. It burns easily, affording a
brilliant smoky flame.
=Chemical Composition=—Camphor, C₁₀H₁₆O, by treatment with various
reagents, yields a number of interesting products: thus when repeatedly
distilled with chloride of zinc or anhydrous phosphoric acid, it is
converted into _Cymene_ or _Cymol_, C₁₀H₁₄, a body contained in many
essential oils, or obtainable therefrom.
Camphor, and also camphor oil, when subjected to powerful oxidizing
agents, absorbs oxygen, passing gradually into crystallized _Camphoric
Acid_, C₁₀H₁₆O₄ or C₈H₁₄(COOH)₂, water and carbonic acid being at
the same time eliminated. Many essential oils, resins and gum-resins
likewise yield these acids when similarly treated.
By means of less energetic oxidizers, camphor may be converted into
_Oxy-Camphor_, C₁₀H₁₆O₂, still retaining its original odour and taste
(Wheeler, 1868).
=Commerce=—Two kinds of crude camphor are known in the English market,
namely:
1. _Formosa_ or _China Camphor_, imported in chests lined with lead or
tinned iron, and weighing about 1 cwt. each; it is of a light brown,
small in grain, and always wet, as the merchants cause water to be
poured into the cases before shipment, with a view, it is pretended,
of lessening the loss by evaporation. The exports of this camphor from
Tamsui in Formosa[1905] were in peculs (one pecul = 13·33 lb. avdp. =
60·479 kilogrammes) as follows:
1870 1871 1872 1875 1876 1877
14,481 9691 10,281 7139 8794 13,178
The shipments of camphor from Takow, the other open port of Formosa,
are of insignificant amount. Planks of camphor wood are now exported in
some quantity from Tamsui.
2. _Japan Camphor_ is lighter in colour and occasionally of a pinkish
tint; it is also in larger grains. It arrives in double tubs (one
within the other) without metal lining, and hence is drier than the
previous sort; the tubs hold about 1 cwt. It fetches a somewhat higher
price than the Formosa camphor.
[1904] _Pharm. Journ._ 18 April 1874. 830.
[1905] _Returns of Trade at the Treaty Ports in China for 1872_, part.
2, p. 124.
Hiogo and Osaka exported in 1871, 7089 peculs (945,200 lb.), and
Nagasaki 745 peculs (99,333 lb.), the total value being 116,718
dollars.[1906] In 1877 the value of camphor exported from Japan was
stated to be equal to 240,000 dollars. The imports of _Unrefined
Camphor_ into the United Kingdom amounted in 1870 to 12,368 cwt.
(1,385,216 lb.); of _Refined Camphor_ in the same year to 2361
cwt.[1907]
Camphor is largely consumed by the natives of India; the quantity
of the crude drug imported into Bombay in the year 1872-73 was 3801
cwt.[1908]
=Uses=—Camphor has stimulant properties and is frequently used in
medicine both internally and externally. It is largely consumed in
India.
Other kinds of Camphor; Camphor Oils.
Camphor, as stated above at page 512, was the name originally applied
to the product of Dryobalanops; it was then also given to that of
Camphor Laurel, and in 1725 Caspar Neumann, of Berlin, first pointed
out that many essential oils afford crystals (“stearoptenes” of later
chemists), for which he proposed the general name of camphor. Many of
them are agreeing with the formula C₁₀H₁₆O, and there are also numerous
liquids of the same composition. It would appear, however, that no
stearoptene of any other plant is absolutely identical with common
camphor; Lallemand’s statement (see p. 479), that oil of spike affords
the latter, requires further examination.
Many other liquid and solid constituents of essential oils, or
substances afforded by treating them with alcoholic potash, answer to
the formula C₁₀H₁₇(OH). Among them we may point out the two following:
they are the only substances of the class of “camphors,” besides common
camphor, which are of some practical importance.
_Barus Camphor, Borneo Camphor, Malayan Camphor, Dryobalanops
Camphor_—This, as already explained, is the substance to which
the earliest notices of camphor refer. The tree which affords it
is _Dryobalanops aromatica_ Gärtn. (_D. Camphora_ Colebrooke), of
the order _Dipterocarpeæ_, one of the most majestic objects of the
vegetable kingdom.[1909] The trunk is very tall, round, and straight,
furnished near the base with huge buttresses; it rises 100 to 150 feet
without a branch, then producing a dense crown of shining foliage, 50
to 70 feet in diameter, on which are scattered beautiful white flowers
of delicious fragrance. The tree is indigenous to the Dutch Residencies
on the north-west coast of Sumatra, between 0° and 3° N. lat., from
Ayer Bangis to Barus and Singkel, and to the northern part of Borneo,
and the small British island of Labuan.
[1906] _Commercial Reports from H. M. Consuls in Japan_, No. 1,
1872.—The returns for Hiogo and Osaka are upon the authority of the
Chamber of Commerce.
[1907] _Statement of the Trade and Navigation of the United Kingdom_
for 1870. p. 61—no later returns accessible.
[1908] _Statement of the Trade and Navigation of Bombay for 1872-73._
ii. 27.
[1909] For a full account and figure of it, see W. H. de Vriese’s
excellent _Mémoire sur le Camphrier de Sumatra et de Bornéo_, Leide,
1857. 23 p. 4°. and 2 plates.
The camphor is obtained from the trunk, in longitudinal fissures of
which it is found in a solid crystalline state, and extracted by
laboriously splitting the wood. It can only be got by the destruction
of the entire tree;—in fact, many trees afford none, so that to avoid
the toil of useless felling, it is now customary to try them by cutting
a hole in the side of the trunk, but the observation so made is often
fallacious. Spenser St. John, British Consul in Borneo, was told that
trees in a state of decay often contain the finest camphor.[1910] The
camphor when collected is carefully picked over, washed and cleaned,
and then separated into three qualities, the best being formed of
the largest and purest crystals, while the lowest is greyish and
pulverulent.
Dryobalanops attaining more than 150 feet in height, the quantity of
camphor which it yields must necessarily be greatly variable. The
statements are from about 3 to 11 lb.
A good proportion of the small quantity produced is consumed in the
funeral rites of the Batta princes, whose families are often ruined by
the lavish expense of providing the camphor and buffaloes which the
custom of their obsequies requires. The camphor which is exported is
eagerly bought for the China market, but some is also sent to Japan,
Laos, Cochin China, Cambodia, and Siam.
The quantity annually shipped from Borneo was reckoned by Motley in
1851 to be about 7 peculs (933 lbs.). The export from Sumatra was
estimated by De Vriese at 10 to 15 quintals per annum.[1911] The
quantity imported into Canton in 1872 was returned as 23⁷/₁₀ peculs
(3,159 lb.), value 42,326 taels, equivalent to about 80_s._ per
lb.[1912] In the _Annual Statement of the Trade of Bombay_ for the year
1872-3, 2 cwt. of _Malayan Camphor_ is stated to have been imported;
it was valued at 9,141 Rs. (£914). In the “Indian tariff,” 1875, the
duty is fixed _per cwt._ at 40 rupees for crude camphor, 65 rupees
for refined camphor, and 80 rupees _per pound_ for Baros camphor
(“Bhemsaini camphor”). The price in Borneo in 1851 of camphor of fine
quality was 30 dollars per catty, or about 95_s._ per lb.: consequently
the drug never finds its way into European commerce.
[1910] _Life in the Forests of the Far East_, ii. (1862) 272.
[1911] In Milburn’s time (_Oriental Commerce_, ii. 1813. 308), Sumatra
was reckoned to export 50 peculs, and Borneo 30 peculs a year. Rondot’s
statement (see Cassia Buds) that China imports of Barus camphor about
800 peculs annually is plainly erroneous.
[1912] _Returns of Trade at the Treaty Ports in China for 1872_, p. 30.
Borneo Camphor, also termed by chemists _Borneol_ or _Camphyl Alcohol_,
is somewhat harder than common camphor, also a little heavier so that
it sinks in water. It is less volatile, and does not crystallize on the
interior of the bottle in which it is kept; and it requires for fusion
a higher temperature, namely 198° C. It has a somewhat different odour,
resembling that of common camphor with the addition of patchouli or
ambergris. The composition of borneol is represented by the formula
C₁₀H₁₇(OH). It may be converted by the action of nitric acid into
common camphor, which it nearly resembles in most of its physical
properties. Conversely, borneol may also be prepared from common
camphor. By continued oxydation borneol yields camphoric acid.
_Camphor Oil of Borneo_—Besides camphor, the _Dryobalanops_ furnishes
another product, a liquid termed _Camphor Oil_, which must not be
confounded with the camphor oil that drains out of crude laurel
camphor. This Bornean or Sumatran _Camphor Oil_ is obtained by
tapping the trees, or in felling them (see also p. 229). In the latter
way, Motley in cutting down a tree in Labuan in May, 1851, pierced a
reservoir in the trunk from which about five gallons of camphor oil
were obtained, though much could not be caught.[1913] The liquid was
a volatile oil holding in solution a resin, which after a few days’
exposure to the air, was left in a syrupy state. This camphor oil,
which is termed _Borneene_, is isomeric with oil of turpentine, C₁₀H₁₆,
yet in the crude state holding in solution borneol and resin. By
fractional distillation, it may be separated into two portions, the one
more volatile than the other but not differing in composition.
_Camphor Oil of Formosa_, which has been already referred to as
draining out of the crude camphor of _Cinnamomum Camphora_, is a brown
liquid holding in solution an abundance of common camphor, which it
speedily deposits in crystals when the temperature is slightly reduced.
From Borneo Camphor Oil it may be distinguished by its _odour of
sassafras_. We find no optical difference in the rotatory power of the
oils; both are dextrogyre to the same extent, which is still the case
if the camphor from the lauraceous camphor oil is separated by cooling.
Borneo camphor oil, for a sample of which we are indebted to Prof. de
Vriese, deposits no camphor even when kept at -15° C.
_Ngai Camphor, Blumea Camphor_—It has been known for many years that
the Chinese are in the habit of using a third variety of camphor,
having a pecuniary value intermediate between that of common camphor
and of Borneo camphor. This substance is manufactured at Canton and
in the island of Hainan, the plant from which it is obtained being
_Blumea balsamifera_ DC., a tall herbaceous _Composita_, of the tribe
_Inuloideæ_, called in Chinese _Ngai_, abundant in Tropical Eastern
Asia.
The drug has been supplied to us[1914] in two forms,—crude and
pure,—the first being in crystalline grains of a dirty white,
contaminated with vegetable remains; the second in colourless crystals
as much as an inch in length. By sublimation the substance may be
obtained in distinct, brilliant crystals, agreeing precisely with those
of Borneo camphor, which they also resemble in odour and hardness, as
well as in being a little heavier than water and not so volatile as
common camphor.
The chemical examination of Ngai camphor, performed by Plowman,[1915]
under the direction of Prof. Attfield, has proved that it has the
composition C₁₀H₁₈O, like Borneo camphor. But the two substances differ
in optical properties,[1916] an alcoholic solution of Ngai camphor
being _levogyre_ in about the same degree that one of Borneo camphor
is _dextrogyre_. By boiling nitric acid, Borneo camphor is transformed
into common (_dextrogyre_) camphor, whereas Ngai camphor affords a
similar yet _levogyre_ camphor, in all probability identical with the
stearoptene of _Chrysanthemum Parthenium_ Pers.
As Ngai camphor is about ten times the price of Formosa camphor, it
never finds its way to Europe as an article of trade. In China it is
consumed partly in medicine and partly in perfuming the fine kinds of
Chinese ink. The export of this camphor by sea from Canton is valued at
about £3,000 a year; it is also exported from Kiung-chow, in the island
of Hainan.
[1913] Ibn Khurdádbah in the 9th century mentions it as being obtained
in this way.
[1914] Through the courtesy of Mr. F. H. Ewer, of the Imperial Maritime
Customs, Canton.—Hanbury, _Science Papers_, 189. 393.
[1915] _Pharm. Journ._ March 7, 1874. 710.
[1916] Flückiger in _Pharm. Journ._ April 18, 1874. 829.