Absinthe "the holy trinity." Many other herbs may be used as well, such as petite wormwood ("Artemisia pontica" or Roman wormwood), hyssop, melissa, star anise, angelica, peppermint, coriander, and veronica. Adding to absinthe's negative reputation in the late 19th and early 20th centuries, unscrupulous makers of the drink omitted the traditional colouring phase of production in favour of adding toxic copper salts to artificially induce a green tint. This practice may be responsible for some of the alleged toxicity historically associated with this beverage. Many modern day producers resort to similar (but non-deadly) shortcuts, including the use of artificial food colouring
Liqueur distilled from aromatic or flavoring agents. Anise and Rakı liqueurs have the property of turning from transparent to cloudy when added to water: the oil of anise remains in solution in the presence of a high concentration of alcohol, but crystallizes when the alcohol concentration is reduced; this is known as the ouzo effect. Liqueurs are sometimes mixed into cocktails to provide flavor. Layered drinks are made by floating different-colored liqueurs in separate layers. Each liqueur is poured slowly into a glass over the back of a spoon or down a glass rod, so that the liquids of different densities