1930's Pet Milk Plain Cake

Ingredients:
2 cups pastry flour
3 teaspoons baking powder
1/2 cup shortening
1 cup sugar
2 eggs, seperated
3/4 cups Pet Milk
1 teaspoon vanilla

Sift flour once, measure, add baking powder and sift together 3 times. Cream shortening thoroly, add sugar gradually, and cream together until light and fluffy. Add egg yplks, well beaten, then flour alternately with milk, a small amount at a time. Beat with each addition till smooth. Add vanilla, fold in stiffly beaten egg whites. Bake in 2 greased 9 inch layer pans in moderate oven (375) for 20 minutes.