The term hydrosol is derived from the Latin words hydro and sol, meaning "water solution." When plant material, such as the roots, barks, flowers, leaves, stems and seeds, is steam distilled to obtain an essential oil, certain chemical constituents of the plant first build up in the water. Only after they reach their maximum solubility in water, do they start to collect in a separate layer on the surface of the water (the essential oil). Many of the water-soluble plant compounds and some of the oil-soluble compounds wind up in the distillation water.
A hydrosol is the pure, distillate water that remains after essential oils are steam distilled from the original plant material. Hydrosols are usually clear and have the appearance and consistency of water. Their aroma is generally, but not always, similar to that of the essential oil, but the aroma is usually much more subtle. Hydrosols contain small amounts of essential oil. They also contain water-soluble components of the plant material that may not be present in the essential oil. The aroma, therefore, may differ somewhat from the plant's essential oil. Some hydrosols do smell surprisingly different from the essential oil.
Cosmetic Uses: Chamomile has been used for centuries in a variety of skin care formulations including lotions, creams, and soaps.