Soak ham overnight. Wash and scrub off mold with stiff brush. Saw off about 2 inches of the hock bone and put ham in roaster. Add 6 or 7 cups cold water. Put top of roaster tightly with all vents closed. Preheat oven to 500 degrees. Put ham in oven and cook 1 minute per pound at 500 degrees. Then cut off heat for 3 hours. Leave ham in oven. Then turn the heat on again at 500 degrees for 1 minute per pound. Turn off the heat. Let ham remain in oven for 3 or more hours at which time it is done. It can be left in oven overnight. Do not open oven while cooking.