Lemon Coconut Cake

Sift flour once, measure, add baking powder and salt, sift together three times. Cream butter thoroughly, add sugar gradually, and cream together until light and fluffy. Add flour, altemately with milk, a small amount at a time, beating after each addtion until smooth. Add lemon extract. Fold in egg whites quickly and thoroughly. Bake in three greased 9-inch layer pans in moderate oven 375 degrees F.) 25 to 30 minutes. Spread Coconut Lemon Filling (see recipe) 1/2-inch thick on top of layers and let stand until filling is set then adjust layers and spread remaining filling on sides of