Wash half ripe grapes and remove stems. Put in saucepan and add 1 cup of water to each quart of grapes. Boil until pulp is soft. Strain juice through jelly bag or double cheesecloth. Boil 10 minutes. Add 1 cup of sugar to each cup of juice. Boil rapidly until jelly sheets from spoon. While hot, fill No. 2 cans. Seal with Home Can Sealer. Cool quickly. Dry, label and store.