Method. Pare off the green part of watermelon rind and scrape out all soft or pink pulp. Cut these strips of white rind into inch pieces and soak in boiling water to which a small piece of alum has been added. Let stand over night, then drain and soak an hour or more in cold water. Have ready a sirup as directed for Sweet Pickled Fruits, add a sliced lemon to every three cups of sirup, and a piece of ginger root or a little preserved ginger. Cover the watermelon rind well with the prepared sirup, and as it takes a long time for it to become tender, cover the kettle in order that it may steam, and prevent too rapid evaporation. When the rind begins to look clear, uncover and boil until every piece is clear and easily pierced with a silver fork. Put into glass jars, and if there is a surplus of sirup, or if it does not seem rich enough, boil the sirup for a while, and then pour over pickles.