_Oleum Graminis Indici_; _Indian Grass Oil_.
=Botanical Origin=—Among the numerous species of _Andropogon_[2703]
which have foliage abounding in essential oil, the following furnish
the fragrant _Grass Oils_ of commerce:—
1. _Andropogon Nardus_ L.,[2704]—a noble-looking plant, rising when in
flower to a height of 6 or more feet, extensively cultivated in Ceylon
and Singapore for the production of _Citronella Oil_.
2. _A. citratus_ D.C.,[2705] Lemon Grass,—a large coarse glaucous
grass, known only in a cultivated state, and very rarely producing
flowers. It is grown in Ceylon and Singapore for the sake of its
essential oil, which is called _Lemon Grass Oil_, _Oil of Verbena_
or _Indian Melissa Oil_; it is also commonly met with in gardens
throughout India and is not unfrequent in English hothouses. In Java it
is called _Sireh_.
3. _A. Schœnanthus_ L.,[2706] a grass of Northern and Central India,
having leaves rounded or slightly cordate at the base, yielding by
distillation the oil known as _Rúsa Oil_, _Oil of Ginger Grass_ or _of
Geranium_.
[2703] Major-General Munro has at our request investigated the
botanical characters of the fragrant species of _Andropogon_, and
examined a numerous suite of specimens in our possession. The synonyms
in foot-notes are given upon his authority.
[2704] _A. Martini_ Thwaites, _Enum. Plantarum Zeylaniæ_ nec
aliorum.—Fig. in Bentley and Trimen’s _Med. Plants_, part 28 (1878).
[2705] _A. citratum_ A.P. De Candolle, _Catalogus Plantarum Horti
Botanici Monspeliensis_, 1813; _A. Schœnanthus_ Wallich, _Plant. Asiat.
rariores_, iii. (1832) tab. 280; Roxburgh, _Flora Indica_, i. (1820)
278, quoad observationes, sed non quoad diagnosis.
[2706] Ventenat, _Jardin de Cels_, 1803. tab. 89; _A. Martini_ Roxb.
_Flor. Ind._ i. (1820) 280; _A. pachnodes_ Trinius, _Species Graminum_,
iii. (1836) tab. 327; _A. Calamus aromaticus_ Royle, _Illustrations of
Bot. of Himalayan Mountains_, 1839. tab. 97.
=History=—The aromatic properties of certain species of _Andropogon_
were well known to Rheede, Rumphius, and other early writers on Indian
natural history; and an oil distilled from the _Sireh_ grass in Amboyna
was known as a curiosity as early as 1717.[2707]
But it is only in very recent times that the volatile oils of these
plants have become objects of commerce with Europe. Lemon grass oil
is mentioned by Roxburgh in 1820 as being distilled in the Moluccas;
and it was first imported into London about the year 1832. Citronella
oil is of much more recent introduction. Ginger grass oil, called in
Hindustani _Rúsa ka tel_, is stated by Waring[2708] to have been first
brought to notice by Dr. N. Maxwell in 1825.
=Production=—Citronella and Lemon grass are cultivated about Galle and
at Singapore, the same estate often producing both. The grasses are
distilled separately, the essential oils being regarded as entirely
distinct, and having different market values. In Ceylon they are cut
for distillation at any time of year, but mostly in December and
January.
On the Perseverance Estate at Gaylang, Singapore, belonging to Mr. John
Fisher, an area of 950 acres is cultivated with aromatic grasses and
other plants, for the production of essential oils. The manufacture
was tried on a small scale in 1865, and has been so successful that an
aggregate of 200 lb. of various essential oils is now produced _daily_.
These oils are stated to be Citronella, Lemon Grass, Patchouly, Nutmeg,
Mace, Pepper, and Oman (p. 302): and mint is now being cultivated.[2709]
Ginger grass oil is distilled in the collectorate of Khandesh in the
Bombay Presidency. That produced in the district of Namár in the valley
of the Nerbudda, is sometimes called _Grass Oil of Namar_. We have
no particulars of the distillation, which however must be carried on
extensively.
=Description=—The Indian grass oils are lighter than water, devoid
of rotatory power when examined by polarized light, and do not alter
litmus paper. They are all extremely fragrant, having an odour like
a mixture of lemon and rose. Lemon grass, which in colour is a deep
golden brown, has an odour resembling that of the sweet-scented verbena
of the gardens, _Lippia citriodora_ H.B.K. Ginger grass oil, the
colour of which varies from pale greenish yellow to yellowish-brown,
has the odour of _Pelargonium Radula_ Aiton. The colour of citronella
oil is a light greenish yellow. The manufacture of Winter of Ceylon,
and of Fisher of Singapore, have a reputation for excellence, and are
generally indicated by name in drug sale catalogues.
=Chemical Composition=—Stenhouse[2710] examined in 1844 oil of ginger
grass given to him by Christison as _Oil of Namur_ (or _Nimar_). The
sample was of deep yellow, and apparently old, for when mixed with
water and subjected to distillation, it left nearly one half its bulk
of a fluid resin, the oil which passed over being colourless. After
rectification from chloride of calcium, it was shown to consist of a
hydrocarbon mixed with a small proportion of an oxygenated oil. The
latter having been decomposed by sodium, and the oil again rectified,
a second analysis was made which proved it isomeric with oil of
turpentine.
[2707] _Ephemerides Naturæ Curiosorum_, cent. v.-vi. (1717), appendix
157.
[2708] _Pharmacopœia of India_, 1868. 465.
[2709] _Straits Settlements Blue Book for 1872_, Singapore, 1873. 465.
[2710] _Mem. of Chem. Soc._ ii. (1845) 122.
A genuine grass oil from Khandesh, derived as we suppose from the
same species, which was examined by one of us (F.), yielded nothing
crystalline when saturated with dry hydrochloric acid; but when the
liquid was afterwards treated with fuming nitric acid, crystals of the
compound, C₁₀H₁₆, HCl, sublimed into the upper part of the vessel. We
have observed that the oils both of lemon grass and citronella yield
solid compounds, if shaken with a saturated solution of bisulphite of
sodium.
Citronella oil was found by Gladstone (1872) to be composed chiefly of
an oxidized oil, which he called _Citronellol_, and which he separated
by fractional distillation into two portions, the one boiling at
202-205° C., the other 199-202° C. The composition of each portion is
indicated by the formula C₁₀H₁₆O.
Wright’s researches (1874) tend rather to show the prevailing part of
citronella oil to consist of the liquid C₁₀H₁₈O, boiling near 210°,
which he calls _Citronellol_. It unites with bromine, and the resulting
compound, upon heating, breaks up according to the following equation:—
C₁₀H₁₈OBr₂ = OH₂ · 2 HBr · C₁₀H₁₄.
Cymene.
=Commerce=—The growing trade in grass oil is exemplified in a striking
manner by the following statistics. The export of _Citronella Oil_ from
Ceylon in 1864 was 622,000 ounces, valued at £8230. In the _Ceylon Blue
Book_, the exports for 1872 are returned thus:—
To the United Kingdom 1,163,074 ounces}
British India 5,713 ” } 1,595,257
United States of North America 426,470 ” } ounces.[2711]
In 1875 the oil shipped from Ceylon to the United Kingdom was valued at
42,871 rupees, that sent to other foreign countries at 45,871 rupees,
to British possessions 660 rupees (one rupee equal to about 2_s._).
_Oil of Lemon Grass_, which is a more costly article and less
extensively produced, was exported from Ceylon during the same year
to the extent of 13,515 ounces, more than half of which quantity was
shipped to the United States. There are no analogous statistics for
these two oils from Singapore, where, as stated at p. 726, they are now
largely manufactured.
By the official _Report on the External Commerce of Bombay_, published
in 1867, we find that during the year ending 31 March, 1867, _Grass
Oil_ [i.e. _Ginger Grass_ or _Rúsa Oil_] was exported thence to the
amount of 41,643 lb. This oil is shipped to England and to the ports of
the Red Sea.
=Uses=—Grass oils are much esteemed in India as an external application
in rheumatism. Rúsa oil is said to stimulate the growth of the hair.
Internally, grass oil is sometimes administered as a carminative in
colic; and an infusion of the leaves of lemon grass is prescribed as
a diaphoretic and stimulant. In Europe and America the oils are used
almost exclusively by the soapmakers and perfumers.[2712]
[2711] In addition to which, there were “_842 dozens and 33 packages_”
of the same oil shipped to the United States. One ounce equal to 31·1
grammes.
[2712] The foliage of the large odoriferous species of _Andropogon_ is
used in India for thatching. It is eaten voraciously by cattle, whose
flesh and milk become flavoured with its strong aroma.
But the most remarkable use made of any grass oil is that for
adulterating _Attar of Rose_ in European Turkey. The oil thus employed
is that of _Andropogon Schœnanthus_ L. (see p. 725); and it is a
curious fact that its Hindustani name is closely similar in sound to
the word _rose_. Thus under the designation _Rusa_, _Rowsah_, _Rosa_,
_Rosé_, _Roshé_,[2713] it is exported in large quantities from Bombay
to the ports of Arabia, probably chiefly to Jidda, whence it is carried
to Turkey by the Mahommedan pilgrims. In Arabia and Turkey, it appears
under the name _Idris yàghi_, while in the attar-producing districts
of the Balkan it is known, at least to Europeans, as _Geranium Oil_ or
_Palmarosa Oil_. Before being mixed with attar, the oil is subjected to
a certain preparation, which is accomplished by shaking it with water
acidulated with lemon juice, and then exposing it to the sun and air.
By this process, described by Baur,[2714] the oil loses a penetrating
after-smell, and acquires a pale straw-colour. The optical and chemical
differences between grass oil thus refined and attar of rose are slight
and do not indicate a small admixture of the former. If grass oil is
added largely to attar, it will prevent its congealing.
=Adulteration=—The grass oil prepared by the natives of India is not
unfrequently contaminated with fatty oil.
Other Products of the genus Andropogon.
=Herba Schœnanthi vel Squinanthi=, _Juncus odoratus_, _Fœnum Camelorum_.
The drug bearing these names has had a place in pharmacy from the days
of Dioscorides down to the middle of the last century, and is still
met with in the East. The plant which affords it, formerly confounded
with other species, is now known to be _Andropogon laniger_ Desf., a
grass of wide distribution, growing in hot dry regions in Northern
Africa (Algeria), Arabia, and North-western India, reaching Thibet,
where it is found up to an elevation of 11,000 feet. Mr. Tolbort has
sent us specimens under the name of _Kháví_, gathered by himself in
1869 between Multán and Kot Sultán, and quite agreeing with the drug of
pharmacy. The grass has an aromatic pungent taste, which is retained in
very old specimens. We are not aware that it is distilled for essential
oil.
=Cuscus or Vetti-ver=[2715]—This is the long fibrous root of
_Andropogon muricatus_ Retz, a large grass found abundantly in
rich moist ground in Southern India and Bengal. Inscriptions on
copper-plates lately discovered in the district of Etawah, south-east
of Agra, and dating from A.D. 1103 and 1174, record grants of villages
to Brahmins by the kings of Kanauj, and enumerate the imposts that were
to be levied. These include taxes on mines, salt pits and the trade
in precious metals, also on mahwah (_Bassia_) and mango trees, and on
_Cuscus Grass_.[2716]
[2713] 50 cases, containing about 2250 lb., imported from Bombay, were
offered as “_Rose Oil_” at public sale, by a London drug-broker, 31
July, 1873.
[2714] See p. 267.
[2715] _Cuscus_, otherwise written _Khus-khus_, a name adopted by the
English in India, is probably from the Persian _Khas_. _Vetti-ver_ is
the Malyalim name of the plant.
[2716] _Proc. of Asiat. Soc. of Bengal_, Aug. 1873. 161.
Cuscus, which appears occasionally in the London drug sales, is used
in England for laying in drawers as a perfume. In India it serves for
making _tatties_ or screens, which are placed in windows and doorways,
and when wetted, diffuse an agreeable odour and coolness. It is also
used for making ornamental baskets and many small articles, and has
some reputation as a medicine.