Boiled salad dressing

Into three well-beaten eggs stir a cupful of vinegar, a tablespoonful of sugar, two saltspoonfuls of salt, a dash of paprika, and a small teaspoonful of French mustard. Beat thoroughly, turn into a saucepan, stir steadily until the boil begins, and add a teaspoonful of butter. When this melts remove the dressing from the fire. Beat for two minutes and set aside to cool. When cold put in the ice-box, where it will keep a week or ten days.