Slip skins off grapes, set aside. Place pulp in a kettle with just enough water to keep it from burning. After a few minutes simmering, the seeds will come away quite easily, after which the pulp may be put through a colander or sieve. Add finely chopped skins to pulp; add juice from oranges. Add raisins; mix all together and bring to boiling point. Simmer gently for about 25 minutes. Measure pulp, alloting 3/4 cup of sugar to each cup of pulp. Boil until mixture shows jelly test (with wooden spoon dip in mixture and let drip. When it only drips 2 or 3 times and then sets it is done). Bottle in sterile jars, store in a cool dark place.