Remove any pinfeathers from bird.
Wash bird under cold water tap, inside as thoroughly as outside, and make sure all traces of red, spongy lungs near ribs are removed.
Pat as dry as possible, using clean cloth or paper towels.
Sprinkle inside with a little salt.
Stuff with dressing, placing a little against upper breast meat under neck skin and filling body cavity from rear vent.
Do not pack dressing, as it swells during cooking.
Using small poultry skewers, pin vent closed, and hold together with twine laced round, or sew up with heavy thread and darning needle.
Truss bird for roasting by tucking wing tips under back and pressing legs close to body.
Loop middle of yard-long piece of twine over tail; bring ends up tightly to loop legs and hold them securely against the body; then carry each length along side to wing and up over wing joint; tie together over neck skin at back.
This method avoids marks across breast.Rub softened butter or margarine over entire bird.
Place breast up on rack in open roasting pan.
Use no water in pan; do not cover and do not sear.
Place in oven preheated to 325°F.
Dip small square of clean, dry cheesecloth in melted fat and place over bird for self-basting.
Cook at low-to-medium temperature, allowing 35 minutes to the pound or about 3-3 1/2 hours for 5-pound capon.
Salt bird midway in the cooking-Remove basting cloth about 45 minutes before end of cooking time, for nice browning of skin.
When bird is done, allow it to stand in warm place for 5 minutes before serving.
This period allows for absorption of juices and easier carving.