Essential oil which is then collected in the receiving vessel. Most oils are distilled in a single process. One exception is "ylang-ylang" ("Cananga odorata") which is purifed through a fractional distillation. The recondensed water is referred to as a hydrosol, hydrolat, herbal distillate, or plant water essence, which may be sold as another fragrant product. Hydrosols include rose water, lavender water, lemon balm, clary sage, and orange blossom water. The use of herbal distillates in cosmetics is increasing. Most citrus peel oils are expressed mechanically or cold-pressed (similar to olive oil extraction). Due to the relatively large quantities of oil in citrus
Essential oil Estimates of total production of essential oils are difficult to obtain. One estimate, compiled from data in 1989, 1990, and 1994 from various sources, gives the following total production, in tonnes, of essential oils for which more than 1,000 tonnes were produced. The medical value of essential oils is the subject of ongoing research, and varies among species, presence or absence of active compound(s), route of administration, potency, and dosage. Some may be inappropriate for persons with certain medical conditions or who take certain prescriptions or over-the-counter (OTC) medications. Taken by mouth, many essential oils can be dangerous in high