Sift cake flour, sugar, and salt together. Stir in boiling water. Let cool. In separate bowl, beat egg whites and cream of tartar until stiff peaks form. Fold in baking powder, vanilla, and almond extract. Fold both mixtures together. Add to a greased and floured pan. Bake at 350F for 35 minutes. Lay a tea towel across the cake and invert the pan. Remove cake from pan when completely cool.