or VOLATILE OILS, are mostly obtained from odoriferous vegetable substances, although some of the principles are found in animal matters. They are usually obtained by distillation, but in some instances by simple expression. They differ much in their physical properties. The greater number are yellow, others are colourless, while some again are red, brown, or green, and some few are bluish. Instead of being greasy to the touch, like fat oils, on evaporation they leave the skin dry and hard. Among the principal of the essential or volatile oils, are those of turpentine, aniseed, lavender, nutmeg, cloves, caraway, peppermint, spearmint, sassafras, camomile, and citron. See OILS.