1Preheat oven to 350 degrees F (175 degrees C). Lightly grease two 9 inch layer cake pans.
2Cream the shortening, add the sugar gradually.
3Sift the flour, baking powder, cream of tartar, and salt. Add the flour mixture alternately with the milk to the creamed mixture.
4Beat the egg whites until stiff peaks are formed. Fold the beaten egg whites and the vanilla into the cake batter. Pour batter into the prepared pans.
5Bake at 350 degrees F (175 degrees C) for 30 minutes.