Pour juices into a 6-8 quart kettle. Measure sugar into a separate bowl. Add the Sure-Jell and butter to juices. Bring mixture to a full rolling boil over high heat, stirring constantly. Quickly stir sugar into juices and bring the mixture back to a full rolling boil-boil for 1 minute while stirring constantly. Mixture will rise to within 2 inches of the top of the pan so make sure you stir continuosly.
Remove from the heat and skim off foam with a spoon. Fill jars to 1/8th inch from top. Wipe jar rims then cover with flat lids. Screw lids on tightly. Use a water bath to finish sealing.
