Cream shortening: add sugar slowly, blend well. Add egg whites one at a time; beat well after each addition. Add vanilla. Sift together dry ingredients; add alternately with milk. (Be sure that the baking powder is Royal! It is made with wholesome cream of tartar-never leaves a bitter taste. And Royal's steady action gives batters continuous, even expansion-to help make your cake velvety fine in crumb, even in grain.) Bake in 3 greased 9-inch layer pans in moderate oven, 375 degrees F. about 25 minutes. Cool before frosting.