small amounts as flavouring. Medicinal Angostura bitters are alleged to have restorative properties. Angostura brand bitters is often incorrectly believed to have poisonous qualities because it is associated with angostura bark (which it does not contain), which, although not toxic, during its use as a medicine was often adulterated by unscrupulous sellers, who padded out the sacks of bark with cheaper, poisonous Strychnos nux-vomica or copalchi bark. Angostura is still often used by Trinidadians to treat digestive problems, under the assumption that the ingredient gentian may aid indigestion. Cocktails Angostura bitters are a key ingredient in many cocktails. Originally used to help with upset stomachs of the soldiers in Simón Bolívar's army, it later became popular in soda water and was usually served with gin. The mix stuck in the form of a pink gin, and is also used in many other cocktails such as long vodka, consisting of vodka, bitters, and lemonade. In the United States, it is best known for its use in whiskey cocktails: old fashioneds, made with whiskey, bitters, sugar, and water, and Manhattans, made usually with rye whiskey and red vermouth. In a pisco sour, a few drops are sprinkled on top of the foam, both for aroma and decoration. In a champagne cocktail, a few drops of bitters are added to a sugar cube. In Hong Kong, Angostura bitters are included in the local gunner cocktail. Though not in the classic recipe, bartenders sometimes add more flavour to the mojito cocktail by sprinkling a few drops of Angostura bitters on top. Bitters can also be used in "soft" drinks; a common drink served in Australian and New Zealand pubs is lemon, lime and bitters. In Malawi, and many other countries, bitters are added to a mix of crushed ice, ginger ale, and Sprite to make a rock shandy. Among certain bartending communities (especially in Malaysia), shots of Angostura are taken as the "bartender's handshake" either during or after the shift is done. The largest purveyor of Angostura bitters in the world is Nelsen's Hall Bitters Pub on Washington Island off the northeast tip of Door Peninsula in Door County, Wisconsin. The pub began selling shots of bitters as a "stomach tonic for medicinal purposes" under a pharmaceutical license during Prohibition in the United States. The practice, which helped the pub to become the oldest continuously operating tavern in Wisconsin, remained a tradition after the