Raspberry Sauce

Set a saucepan on the stove with 1½ cups raspberry juice, ½ cup water, the juice and peel of 1 lemon, sugar to taste, 1 teaspoonful cornstarch and the yolks of 3 eggs; beat constantly with an egg beater until it comes to a boil; quickly remove it from the fire; beat for a few minutes longer; beat the whites of the 3 eggs to a stiff froth and stir them into the sauce.