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Essential Oils (General Directions)
General Directions.
The quantity of volatile oil yielded by a plant will depend upon the part employed, the season, and the period of growth. The drier the season and the warmer the climate, the richer are the plants in oils. They should be gathered, as a general rule, immediately after blossoming, and distilled, if possible, while fresh.
It is better to macerate the plants for one day before distilling. Roots, barks, etc., should be coarsely powdered. Parts which yield no oil, as the stems of mint, sage, etc., should be detached.
The larger the quantity operated on the better; the quantity of water should be sufficient to thoroughly cover the plant; too much water causes loss by dissolving a portion of the oil. When the plants are abundant the distillate should be returned to a fresh portion of the plant in a retort. It is a good plan to use the water of a previous distillation for the same plant, as it is already saturated with the oil.
If the oil is heavier than water, use a saturated solution of salt. If lighter, the Florentine receiver. Solutions for the Water-bath.
Various salts dissolved in water materially raise the boiling point, and thus afford the means of obtaining a steady temperature at different degrees above 212°. The following are some of the most useful: A saturated solution of nitrate of soda boils at 246°; Rochelle salts at 240°; nitre at 238°; muriate of soda at 224°; sulphate of magnesia at 222°. Oil of Aniseed.
One lb. of the seeds will yield 2 drs. It is congealed, except in warm weather; this oil is carminative, and poisonous to pigeons, if rubbed on their bills or head.
Oil of Ben, or Behen, Is obtained by expression from the seeds of Mohringa aptera. It is insipid, inodorous, and does not become rancid. It is used in perfumery. Hazel-nut oil is sometimes substituted for it. Birch Oil.
Obtained by distilling 20 parts of birch bark and 1 of ledum palustre, crammed in layers into an earthen pot, with a handful of tripoli between each layer; the mouth of the pot is closed with a perforated oak plug, and being inverted, it is luted to the mouth of another pot sunk in the ground; the pot being then surrounded with fire, a brown empyreumatic oil distills per descensum into the lower jar; an 8 gall. pot, properly filled, yields about 2 lbs. or 2 lbs. of oil. In Siberia it is prepared without the ledum. This oil is liquid when fresh, but grows thick in time. It is used in Russia for currying leather, to which it gives a very peculiar smell, much disliked by insects.
Oil of Gum-benzoin.
Obtained by distilling the residuum left after making flowers of benjamin, by a strong fire. It is used instead of birch oil in making an imitation of Russia leather. Cajeput Oil.
This is obtained from the leaves, which are imported from the East Indies, generally in large copper flasks; it is cooler than that of peppermint, but smells of turpentine. It is used externally in rheumatism. Oil of Caraway.
This is obtained from the seeds; it is carminative; 2 lbs. will yield more than 1 oz., and 4 cwt. 83 oz.
Oil of Cloves.
This is obtained from a spice of that name; it is very heavy, acrimonious, and supposed to contain some part of the resin of the clove. One lb. of cloves will yield from 1 to 24 oz.; 7 lbs. will yield 1 lb. of oil. It is also expressed from the cloves when ripe. Muller, by digesting oz. of cloves in ether, and then mixing it with water, obtained 7 scruples of oil, greenish yellow, swimming upon water. Oil of cloves is imported from the spice islands; it is stimulant, and added to purgative pills to prevent griping; it is externally applied to aching teeth.
Oil of Cassia.
This is a common oil of cinnamon, and is obtained from the bark of inferior cinnamon, imported under the name of cassia. One lb. will yield from 1 to 1½ drs. It is stimulant and stonachic. Another oil is obtained from cassia buds. Oil of Chamomile.
This is obtained from the flowers, and is stomachic. One lb. will yield a dr.; 82 lbs. will yield from 13 to 18 drs. It is of a fine blue, even if distilled in glass vessels.
Oil of Cinnamon.
This is obtained from the fresh bark, which is imported from Ceylon. De Guignes says the cinnamon from Cochin China is so full of essential oil that it may be pressed out by the fingers.
Essence of Cedrat:
This is obtained from the flowers of the citron tree; it is amber-colored and slightly fragrant; 60 lbs. yield 1 oz. It is also obtained from the yellow part of citron-peel; it is colorless, very thin, and fragrant. The second oil is obtained by the distillation of the yellow part of citron-peel, and is greenish; 100 citrons will yield 1 oz. of the white essence, and oz. of this. It is likewise obtained from the yellow part of citron-peel by expression between two glass plates; also, from the cake left on squeezing citron-peel, by distillation with water. It is thick. Common Essence of Cedrat.
This is obtained from the fæces left in the casks of citron-juice; clear, fragrant, greenish; 50 lbs. of fæces will yield, by distillation, 3 lbs. of essence. Oil of Calamus.
The rhizoma of the acorus calamus, or swell flag, yields about 1 per cent. of oil. It is carminative, but little used. It is also employed in perfumery. Oil of Cedar.
Obtained by distillation; is sometimes used in perfumery.
Camphor.
This is obtained from the roots and shoots of the laurus camphora and laurus cinnamomum, as also the capura curundu, by distillation with water. This crude camphor is refined by sublimation with one-sixteenth of its weight of lime in a very gentle heat.
Camphor from Essential Oils.
Obtained from the oils of the labiate plants by a careful distillation, without addition of of the oil; the residuum will be found to contain crystals of camphor, on separating which and re-distilling the remaining oil 2 or 3 times, the whole of the camphor may be obtained. Oil of rosemary or of sweet marjoram yields about 1 oz. of camphor from 10 of oil; of the sage 1 oz. from 8, and of lavender 1 oz. from 4, or even less of oil; that from oil of marjoram is not volatile, and although it takes fire, it soon goes out. This resin, like the others from essential oils, may be obtained in a larger proportion if the oil is kept in slightly stopped bottles in a cool place.