Sift flour with 1 c sugar four times. Set aside. Beat whites with salt till foamy, then add cream of tartar and beat till stiff. Add the 3/4 c sugar 1 T at a time, beating into egg whites. Add vanilla. Sift flour and sugar mixture over top of whites a little at a time and fold in. Bake in an ungreased 10" tube pan at 325 for 65-75 minutes. Invert pan to cool. Serves 12.