Liqueurs are sweetener] alcoholic liquors which have peculiar and characteristic flavours, owing to the presence of different aromatic compounds. Though giving the liqueur a decidedly pleasant taste, these compounds are, however, frequently of a deleterious nature. The liqueurs may be divided into three classes, viz. the crimes, the richest and finest varieties, as e.g. Maraschino, obtained from cherries, Chartreuse, etc.; the oils, as Curaqoa, obtained from the rinds of oranges, and the ratafias in which the alcohol and flavouring are in the smallest proportions, as in eau de Noyau, the flavour of which is due to the hydrocyanic or prussic acid present in the bitter almonds from which it is prepared.