Pare and cut in strips the rind of ripe melons. Soak in alum water to cover, allowing two teaspoons powdered alum to each quart of water. Heat gradually to boiling-point and cook slowly ten minutes. Drain, cover with ice-water, and let stand two hours; again drain, and dry between towels. Weigh, allow one pound sugar to each pound of fruit, and one cup water to each pound of sugar. Boil sugar and water ten minutes. Add melon rind, and cook until tender. Remove rind to a stone jar, and cover with syrup. Two lemons cut in slices may be cooked ten minutes in the syrup.