Nectarine-Orange Marmalade

3 pounds nectarines
3 medium-size oranges
4 1/2 cups granulated sugar

Wash, blanch, peel and pit nectarines; wash the oranges. Remove the peel from 1 1/2 of the oranges and discard it. Put the nectarines and the peeled and unpeeled oranges through a meat grinder. There should be about 4 1/2 cups. Place the fruit in a preserving kettle; add 4 1/2 cups of sugar and bring slowly to a boil. Boil rapidly, uncovered, for about 30 minutes, stirring frequently. Skim off foam with a metal spoon. Ladle into hot, sterilized jars and seal immediately.

To seal: Fill to within 1/2-inch head room, being sure to first wipe the rim and threads of the jars with a hot damp cloth to remove all particles of food, seeds or spices. While contents are hot, cover with a 1/8-inch layer of paraffin. When paraffin has set, add another layer of melted paraffin, tilting and rotating the jar to seal completely.

Makes about 4 half-pints.