2 1/4 c. sifted flour
1 tbsp. baking powder
1/2 tsp. salt
1 1/2 c. sugar
1/2 c. vegetable oil
5 egg yolks
3/4 c. orange juice
1 tsp. vanilla extract
2 tsp. grated orange rind
8 egg whites
1/2 tsp. cream of tartar

Combine first 4 ingredients in a mixing bowl. Make a well in the center; add oil, egg yolks, orange juice, vanilla, and orange rind. Beat at medium speed with mixer until smooth. Beat egg whites and cream of tartar in a large bowl at high speed until soft peaks form. Pour egg yolk mixture over the egg whites in a thin steady stream and gently fold yolks into whites. Pour batter into an ungreased 10 inch tube pan, spreading evenly. Bake at 325 degrees for 1 hour or until cake springs back when lightly touched. Invert pan and cool 40 minutes. Loosen cake form sides of pan and remove.