Combine raspberries and vinegar in a glass bowl or earthenware crock.
Cover with a cloth and tie up well to keep out insects.
Let stand for 4 days.
Drain into a jelly bag and let drip overnight into a glass container.
The next day measure the juice.
There should be about 3 cups.
Place in a saucepan and add 1 cup sugar for each cup of juice.
Bring to the boil.
Boil 20 minutes.
Pour into hot, sterilized sealers or bottles.