Sponge Cake
["5 egg whites, beaten stiffly", "5 egg yolks, beaten", "2 c. granulated sugar", "2 c. sifted flour", "2 1/2 tsp. baking powder", "1 c. boiling water", "1 tsp. vanilla"]
["Add beaten egg yolks to beaten egg whites.", "Gradually add sugar and beat 5 minutes.", "Blend in 1 cup flour.", "Slowly add 1 cup boiling water.", "Blend in remainder of the flour, baking powder and vanilla until smooth.", "Pour into ungreased angel food pan.", "Bake 45 minutes at 350\u00b0."]
["egg whites", "egg yolks", "sugar", "flour", "baking powder", "boiling water", "vanilla"]