Sift flour, baking powder and salt together 3 times.
Beat egg whites stiff and set aside.
Cream butter and shortening with sugar and add yolks, beating well. Add dry ingredients
alternately with milk. Fold in whites and lemon juice. Gently fold in berries. Pour
into greased 9-inch tube pan; sprinkle with sugar.
Bake 350 degrees F for 30 minutes.
Sprinkle with sugar, again, immediately upon removing from oven.