This chilled Christmas beverage consists of a homogeneous blend of milk or cream, beaten eggs, sugar, nutmeg and usually liquor of some kind. Rum was the spirit noted in early references to the drink, but brandy and whiskey are also common additions. Liquor-free eggnog has long been served to convalescents and growing children. Some eggnogs are made by separating the eggs and stiffly beating the whites before adding them to the milk mixture; this produces an airier brew. Commercial eggnog is sans liquor and must contain 1 percent egg-yolk solids by weight. It's available in cartons beginning around mid-October. Canned eggnog can be found year-round in some locations, though some think its flavor takes on a metallic quality.