Allow egg whites to stand at room temperature for 30 minutes.
Sift together powdered sugar and flour; set aside.
In a large mixing bowl, beat whites, cream of tartar, and salt until foamy.
Gradually add granulated sugar, 2 tablespoons at a time, beating on high speed until stiff peaks form.
Quickly beat in vanilla and almond extract. Sprinkle flour-sugar mixture, 1/4 cup at a time, over beaten egg whites, folding in gently just until flour-sugar mixture disappears.
Push batter into an ungreased 10-inch tube pan. Gently cut through batter with a knife or spatula to remove large air pockets.
Bake in a 375 degree F oven for 35 to 40 minutes or until top springs back when touched lightly with your finger. Invert cake in pan on a funnel and let the cake hang until completely cool. Loosen the sides of the cake with a narrow-bladed spatula or knife; remove cake from pan. Makes 12 servings.