Blackberry Nectarine Jam

1/2 lb. blackberries
3 lbs nectarines, not too ripe
2 apples
1 lemon
1 1/2 c. water
6 cups sugar

Wash the blackberries and set aside to drain dry. Wash and peel the nectarines; cut into pieces, discarding the pits. Peel, quarter, and core the apples. Reserve the apple peel, tying it up in a muslin bag, and chop the flesh. Put the nectarines and apples in a saucepan with the water and the apple peel. Bring to a boil, cover, and cook until the fruit is very tender, about 20 minutes. Remove the muslin bag and mash the fruit with a wooden spoon. Add the lemon juice and sugar, a cup at a time, stirring until dissolved. Return to a boil; cook briskly until nearly set (about 15 minutes) before adding the blackberries. Continue to cook until set, stirring carefully from time to time. When ready to set, ladle the jam into hot sterilized jars, leaving 1/4 inch headspace. Wipe the rims clean, put the lids in place, and tighten down. Invert the jars for a few minutes, then return to the upright and let cool completely. Check the seals, label, and store in a cool, dry place.

Yield: about 4 cups