Put six egg whites into a copper basin, with a light half saltspoon-ful of salt, and with a wire-whip begin beating slowly, but gradually increase until a stiff froth is obtained. Should it become grainy, beat briskly again, adding half an ounce of powdered sugar. (Eight minutes should suffice to a have proper froth.) Remove the whip. Have on a plate one pound of powdered sugar, and with a spatula drop the sugar slowly and carefully over the froth, mixing it in meanwhile with the spatula. This should take about two minutes. Flavor it with any desired flavoring, and it will be ready for use.