6 c. crushed blackberries (about 3 qt. boxes berries)
1 pkg. powdered pectin
8 1/2 c. sugar

Sort and wash fully ripe berries; remove any stems or caps. Crush berries. If they are very seedy, put part or all of them through a sieve or food mill. Measure crushed berries into a kettle. Add pectin and stir well. Place on high heat and, stirring constantly, bring quickly to a full boil with bubbles over the entire surface. Add sugar, continue stirring, and heat again to a full bubbly boil. Boil hard for 1 minute, stirring constantly. Remove from heat; skim. Fill and seal containers. Process 5 minutes in boiling water bath. Makes 11 or 12 half-pint jars.