ABSTRACT
Volatile essential oils, fixed oils and hydrosols are extracted from a wide variety of plants and form the main tools used in aromatherapy practice. This chapter focuses on the science underlying the dermo-therapeutic use of essential oils; a more detailed discussion of fixed oils and hydrosols can be found. An essential oil is the volatile odoriferous oil extracted from aromatic vegetable plant material by physical means. The physical methods used are distillation or expression, which refers to the mechanical cold-pressing of the citrus fruit pericarp. An essential oil is not a solvent-extracted product. Essential oils are present in the plant within distinctive oil cells or secretory glands either on the surface of the plant or within plant tissue. Monoterpene hydrocarbons such as a- and ß-pinenes, limonene, d-3-carene, a-phellandrene and myrcene are found as complex mixtures in most essential oils, particularly plant leaf oils, while seed and flower oils contain more specialised monoterpenes.
