Sift flour and sugar separately nine times. Beat egg whites until foamy; add cream of tartar and beat until dry, then beat until soft. Add salt. Add sugar gradually, beat hard a few times and add flavors. Fold in flour gradually and gently until absorbed. Turn into angel food cake pan and bake at 350 degrees for 1 to 1 1/2 hours until it begins to pull away from edge of pan. Invert over plate and cool completely.