Volatile oils are little soluble in water, yet enough so as to impart to it by agita tion their characteristic smell and taste. The water which distils with any oil is in general a saturated solution of it and as such is used in medicine under the name of distilled water.
The principal volatile or essential oils are those of turpentine, aniseed, nutmeg, lavender, cloves, caraway, peppermint, spearmint, sassafras, camomile, and ci tron. The taste is acrid and burning ; and the odor very pungent, resembling the taste and smell of the vegetables. They boil at a temperature considerably above that of, boiling water; thus, oil of turpentine boils at 315°. They are solu ble in strong alcohol, but, on adding water, are precipitated. They are solu ble in ether in like manner, but do not form soaps with alkalies, by they are distinguished from the fixed oils. They are readily inflamed by strong ni tric acid ; especially if a little sulphuric acid be added, to render the acid more concentrated. Exposed to the action of the air, they undergo an alteration in consequence of the absorption of oxygen, become thickened, and gradually change into a solid matter, resembling resins.
When digested with sulphur, they unite with it, forming balsam of sulphur.
One of the most useful is that of tur pentine, called spirit of turpentine. It is obtained by distilling turpentine and water, in due proportions, in a copper alembic. It is the solvent employed in making a variety of varnishes, but it re quires to be rectified by a second distilla tion.
In general, volatile oils are used in pharmacy or as perfumes. Those ap plied to the latter use, are the essence of roses, of jasmine, violets, Jo., but re quire much care in preparation. This is best done by spreading upon white woql, impregnated with olive oil, the petals of the flowers, and leaving them for some time, covered over with a woollen cloth, upon which flowers are also scattered. The flowers are renewed from time to time, until the olive-oil employed appears to he saturated with the oil of the flowers, and this last is then separated by digest ing the wool in alcohol.
Essential oils, as previously mentioned, are obtained by distilling the basis with an equal weight of water to prevent them from adhering to the still, and the oil and water acquiring a burnt taste ; some, as those of the peels of fresh fruits, are ob tained by rasping them, and pressing the rasping ; a few by distilling the articles with twice their weight of water, adding 1 lb. of salt to each gallon of water, using a quick fire, and when half the water has come over, pouring it back again into the still, and thus cohobating it. When rec tified, for the purpose of rendering them finer, they are distilled without water in a retort, and one half the oil is drawn over. They are all stimulant, in doses of 2 to 10 drops upon sugar, but are mostly made into cordial waters, by distilling with spi rit of wine, or water. The following are some of the principal, for they consist of 2 or 300.
Oil of Wormwood-25 lbs. of green wormwood yielding from 6 to 10 drs. of this oil. Oil of Acorns-50 lbs. yield 2 oz. Essential oil of bitter Almonds—from ground almond cake, by distillation, with twice as much water and half as much salt, after having been left to soak for some days, and when half the water is come over, pouring it back into the still : 25 lbs. of cake yield 2 oz. and contains prussic acid ; when rectified, its strength is prodigiously increased. Oil of Anise seeds—from the seeds ; congeals at 62°. Oil of Star Anise-seeds—from the capsules, very fragrant. Oil of Dill-aeed—Carmi native. Essence of Berpamotte—from the peels of the Bergamotte orange • by pres sure, very fragrant. Ifuile d'orange- from orange-peel, by pressure ; very fra grant. (*Tut ail—from the leaves. Oil of Carui—from the seeds, carininative. Oil of Cloves—from cloves, soaked and distilled with salt-water, the distilled wa ter being returned two or three times into the still ; very heavy and acrimonious. Distilled oil of Camomile Rowers—from the flowers, stomachic. Oil of Cinnamon. —from the fresh bark, distilled with sea water. Rectified oil of Citrons—the press ed oil of the whole peels, distilled until 3 oz. out of 5 are come over, white, very fragrant. Oil of Curnmin-seed—Oil of lops—Collected during the boiling of hops in beer. Essences des Violettes—from the root of Florentine orris ; smells like violets. Essence of Jasmine—from the
flowers of Jasminium grandiflorum, high ly fragrant. Oil of Lavender—from the flowers of narrow-leaved lavender, very fine scented. Oil of Spike—from the flowers and seeds of French lavender. Rectd oil of Lavender—drawing off 3 oz. in 5 ; used for choice perfumery. Riga Balsam—from the shoots of Pinus eembra, previously bruised and macerated for a month in water • vulnerary, diuretic. Essence Lemons—from the fresh peels of lemons ; limpid, watery, fragrant; used in perfumery. Oil of Mace—from that spice. Oil of sweet Marjoram—Oil of Peppermint—from the dried plant, 4 lbs. of the fresh herb yielded 3 drs. ; used to flavor spirit. Rectified oil of Peppermint —used for peppermint lozenges and drops, very warm. Oil of Milfoil—1 8 baskets yield 4 oz. 4 drs. Essence of Myrtle— from the flowers and leaves ; fragrant. Essence of Jonquil—used in perfumery. Oil of Nutmeg—from that spice. Oil if Thyme—from the plant, 2 cwt. fresh yield 51 oz. stimulant, makes the hair grow, used in tooth-ache. Oil of Pimento— from allspice. Oil of Penny-royal—from the herb when in flower. Oil of Ravent sara—from the leaves ; sold for oil of cloves. Oil of 1?hodium—from Levant lignum rhodium : 80 lbs. yielded 9 drs. Oil (1 Roses—from the flowers of musk roses in the cups split open, soaked in twice their weight of salt-water for several days, then distilled, and the water eoho bated once or twice on them ; 1 cwt. yields from half an oz. to an oz. of oil. Attar of Roses—from the evergreen rose and the musk rose, the newly-distilled rose-water being exposed to the night air ; a highly esteemed perfume ; freezes at 60°, melts at 85°. Oil of Rosemary—from the flow ering tops ; sweet scented. 'Rectified oil of Roomnary—by redistilling until one half is come over, and used for fine per fumery. Oil Rue—from the dried plant, carminative, antispasmodic. Oil of Savine—from the dried plant, stimu lant and powerfully emmenagogue • ex ternally rubefacient. Oil of Sandalwood —1 lb. yields 2 drs. It is sold for oil of rhodium, and oil of roses. Oil of Sassa fras—from the root of sassafras, with salt-water, and cohobation. Oa of Lemon Thyme—used to scent soaps. Oil of Tan sey—from the herb. Oil of Thyme-2 cwt. fresh flowers yield 5* oz. Oil of Turpentine—from rough turpentine dis tilled with an equal weight of water. Om MILLS, or PRESSION Mims, are mov ed by horse, or water power, in Holland by wind, and in England often, and in this country almost always, by steam. The object is to unite weight pressure with percussion, and therefore obtain oil from seeds. The principle is that of the pile engine, the falling with acceleration of a heavy loaded beam on a bag of seed, so placed as that its oil will exude into receptacles beneath. A wheel called a walloper, provided with wipers, or pro jections, is turned by the spur and treadle, and the wipers catch and lift the beams, or pestles, which being unattach ed by the rotation of the wheel fidi with force on the seed, which has usually been rolled and expressed previously. The oil paste, or cakes, left after pressing, is ex cellent food for cattle. The French ve getable oils produce the whitest and clearest light known, equal to the best carburetted hydrogen gas.
The quantities of volatile oil, obtained from different vegetables, are : Aniseed 1 lb. 2 dr& .Assafcetida 4 oz. 1 dr.
Cajcput seeds 1 lb. 15 gra Camomile flowers, common 1 lb. 1 dr.
Caraway seeds 4 lbs. 2 oz.
Cardamum seeds 1 oz. 1 scr.
Carrot seeds 2 lbs. 11 dr.
Cinnamon 1 lb. 1 dr.
Cloves 1 lb. 11 oz.
Copaiba balsam 1 lb. 6 oz.
Cummin seed 1 lb. 5 drs.
Dill seed 4 lbs. 2 oz.
Juniper berries 8 lbs. 3 oz.
Lavender, in flower, fresh 48 lbs. 12 oz.
Mace 11b. 5 drs.
Marjoram, in flower, fresh..... • 85 lb& 31 oz.
Nutmegs 1 lb. 1 oz.
Roses 1 cwt. 1 oz.
Rosemary, in flower 1 cwt. 8 oz.
Sage leaves 84 lbs. 11 oz.
Sassafras w,od 6 lbs. 11 on Sevin bark 2 lbs. 5 oz.
Thyme, in flower, fresh 2 cwt. 51 oz.
According to experiments, the follow ing species of plants yield per cent. of oil:— Filberts 60 Garden cress 56 to 58 Olive 50 Walnut 50 Poppy 41 to 50 Almond 46 Navew 89 White Mustard 86 Tobacco seed 82 to 86 Kernels of plums 83 Winter rape 83 Summer rape 80 Woad 80 Cainelina Hemp seed 25 Fir 24 • • Linseed 22 Black mustard 18 Heliotrope 15 Beech masts 12 to 16 Grape stones 10 to 11