Chiffon Cake

2 cups flour

1 1/2 cups sugar

1 tablespoon baking powder

1 teaspoon salt

1/2 cup oil

7 eggs -- separated

3/4 cup cold water

2 teaspoons vanilla

1/2 teaspoon cream of tartar

Preheat oven to 325 degrees. Prepare tube pan. Beat egg whites with cream of tartar, set aside. Combine flour, sugar, powder, and salt. Make a well and add yolks, oil, water a nd vanilla. Beat 2 minutes medium speed. Fold in egg whites. Pour into pan, bake 55 minutes. Increase temperature to 350 and bake 10 minutes more. Invert pan and cool completely. Frosting follows.