Crush berries and add tartaric acid to fruit.
Let stand 36 hours in a crock.
Strain berries through a thin bag, and then let drip through a thick bag.
Measure juice, add same amount of sugar, and place in saucepan.
Bring to a boil and let boil 5 minutes.
Seal in jars.
To serve, dilute with water to taste and serve with lemon slices.
