Gomme syrup (or gum syrup; gomme is French for "gum") is an almost forgotten ingredient of the Absinthe culture of the 19th century. It was used for Absinthe based cocktails and as a popular alternative to using crystalized sugar. You ordered then "une absinthe gommée" instead of "une absinthe au sucre". Like bar syrups, Sirop de Gomme is a sugar and water mixture, but has an added ingredient of gum arabic, the hardened sap of the acacia tree, which acts as an emulsifier. Gum syrup is made with the highest percentage of sugar to water possible. The gum arabic prevents the sugar from crystallizing and adds a smooth texture. Sirop de Gomme is a must have for traditionalists who enjoy the allure of nostalgia!