Distilling Essential Oils
Today, the most commonly used essential oils -- from lavender to lemon to eucalyptus -- are distilled. Plant matter is placed in a distillation apparatus (or alembic) above water which is heated, causing the volatile materials to vaporize. The vapor flows into a cooling tank and the essential oils rise to the top. The remaining water, or plant water essence, is also used; the most common types of these are orange blossom, lavender, and rose water.
Pressing Essential Oils
Before the discovery of distillation, the method of pressing was used to extract oils. This is still common in Egypt, where traditionally, the plant material is pressed and buried in an unglazed ceramic vessel and left for months in the desert to expel the water. Because water has a smaller molecular size than the ceramic vessels, it diffuses through the sides, leaving behind the essential oil of the plant. This method was used to press the lotus oil found in Tutankhamun's tomb, which after 3000 years retained its scent.
Common Essential Oils
Some of the more common essential oils are basil, which is used in perfumeries for its mildly spicy and sweet aroma. It is also used in aromatherapy for sharpening the mind and lifting one's mood. Bergamot is both an effective insect repellent, a flavor in Earl Grey tea, is used for the urinary and digestive tract and is one of the most popular oils in perfumery.
Black pepper has a sharp, spicy aroma. It is often used to stimulate circulation and relieving muscular discomfort. Its stimulating properties make it good for bruises. Citronella is often found in insect repellent, and lavender, tea tree, eucalyptus and sandalwood are effective antiseptics.
Specialists advise people to use essential oils with care, as they can have adverse effects on people with health problems, or pregnant women.
