Hollandaise sauce mayonnaise and Béarnaise, the egg does not coagulate as in a custard; rather, the lecithin in the eggs serves as an emulsifier, allowing the mixture of the normally immiscible butter and lemon juice to form a stable emulsion. To make hollandaise sauce, beaten egg yolks are combined with butter, lemon juice, salt, and water, and heated gently while being mixed. Some cooks use a double boiler in order to control the temperature. Some recipes add melted butter to warmed yolks; others call for unmelted butter and the yolks to be heated together; still others combine warm butter and eggs in
French opera Classical "Pénélope" (1913) and Paul Dukas's colourful Symbolist drama, "Ariane et Barbe-Bleue" (1907). The more frivolous genres of operetta and opéra comique still thrived in the hands of composers like André Messager and Reynaldo Hahn. Indeed, for many people, light and elegant works like this represented the true French tradition as opposed to the "Teutonic heaviness" of Wagner. This was the opinion of Maurice Ravel, who wrote only two short but ingenious operas: "L'heure espagnole" (1911), a farce set in Spain; and "L'enfant et les sortilèges" (1925), a fantasy set in the world of childhood in which various animals and