Those principally obtained from tropical shrubs and plants are citronella, oil of oranges and lemons, from the rind of the fruit oil of cinnamon and cloves, croton oil, &c.

The oil of Sandal or Sanders wood (Santalum album), grown on the Malabar coast, is much esteemed as a perfume.  Keora oil, from Pandanus odoratissimus, in Bengal.  Oil of spikenard, so highly prized, on account of its perfume, by the ancients, may be procured in Sagur, Nepaul, and the mountains of the Himalaya.

956 lbs. of essential oils were imported into Hull in 1850.  There were exported from Ceylon in 1842, 902 cases; in 1843, 138; in 1844, 20; in 1845, 25 cases of essential oils, and in the last two years as follows:—­

1852.     1851.
cases.    cases. 
Cinnamon oil        17        23
Citronella oil     110        87
Essential oil       72        35

Of chemical, essential, and perfumed oils imported from France, the quantity is about 35,000 lbs. annually, worth L10,000.  The duty is 1s. per lb.  We also imported from France, in 1851, 9,596 cwt. of oil or spirit of turpentine, worth L14,197, on which a duty of 5s. 3d. per cwt. is levied.

From Western Australia some distilled oil of the Liptospermum was shown at the Exhibition, which it is stated may be obtained in any quantity, and a similar oil produced, by distillation, from the Eucalyptus piperita, a powerful solvent of caoutchouc, evidently very similar, if not altogether identical, with the oil of cajeput.  The characters of these two oils are much alike and without some care it is difficult to distinguish them from one another by the odor; the liptospermum oil has a slight tinge of yellow, its specific gravity is 0.9035; the eucalyptus oil is colorless, and has a density of 0.9145.  It is probable that these oils might be used with great advantage in the manufacture of varnish, they readily dissolve copal, and when its solution is spread over any surface the oil soon evaporates, and leaves a hard, brilliant and uniform coating of the resin.  These oils, according to Prof.  Solly, are specially worthy of attention.

Dr. Bennett, in his “Wanderings in New South Wales,” states that a large quantity of camphorated oil, which closely resembles the cajeputi, is produced from the foliage of several species of Eucalyptus.  Some of the leaves, which are of a bluish green, contain it in such abundance as to cover the hand with oil when one of the leaves is gently rubbed against it.

From the odorous leaves of the Arbor alba is extracted a portion of the aromatic cajeput oil.  This celebrated medicinal oil is principally made in the island of Borneo, one of the Moluccas.

The leaf of the Melaleuca minor yields, by distillation, the volatile oil of cajeputi, well known as a powerful sudorific, and a useful external application in chronic rheumatism.  It is an evergreen shrub, with white flowers like a myrtle, native of the East Indies, principally flourishing on the sea coasts of the Moluccas and other Indian islands.  Two sacks full of the leaves yield scarcely three drachms of the oil, which is limpid, pellucid, and of a green color.