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
Lavandula oil, and its major constituent linalyl acetate, are toxic to human skin cells "in vitro," contact dermatitis to lavender oil appears to occur at only a very low frequency." There are two reports on a total of six cases of gynecomastia in prepubertal boys who were exposed to topical lavender essential oil. A 2007 study examined the relationship between various fragrances and photosensitivity, stating that lavender is known "to elicit cutaneous photo-toxic reactions", but does not induce photohaemolysis. Flower spikes are used for dried flower arrangements. The fragrant, pale purple flowers and flower buds are used in potpourris. Lavender is