Boysenberry or dewberries may be substituted. Crush 2 1/2 quarts blackberries (in small amount). Measure: 5 c. sugar (level each cup)

Set aside in bowl.

Add 1 box Sure Jell and 1/2 teaspoon butter to juice. Bring to full rolling boil over high heat, stirring constantly. Quickly add sugar to juice. Bring to full rolling boil, stirring constantly, then continue boiling for 1 minute, stirring constantly. Remove from heat. Skim off any foam with large metal spoon. Fill jars immediately to 1/8" of tops. Wipe jar rims and cover quickly with lids. Screw bans tightly. Invert jars for 5 minutes then turn upright. After 1 hour check seals. Yield: 5 1/2 cups.