SIFT flour once, measure, add baking powder, soda, and salt, and sift together three times. Sift 1 cup of flour mixture over fruits and nuts; mix thoroughly.
CREAM shortening thoroughly, add sugar gradually and cream together until light and fluffy. Add remaining flour mixture to creamed, a small amount at a time. Beat after each addition until smooth. Add lemon juice, fruits, and nuts. Fold in egg whites.
POUR into paper-lined tube pan or small bread pans, 2 x 2 ¾ x 4 ½ inches. Bake in slow oven (250 degrees) 2 ½ hours, then increase to 300 degrees for 15 minutes. Sprinkle with powdered sugar and decorate. Make 6 pounds fruit cake.