Blackberry Jam 1 cup sugar • ¼ teaspoon butter • 2 tablespoons lemon juice • 4 cups black berries Place all the ingredients in a heavy-bottom, non-aluminum saucepan. Let stand for 10 to 15 minutes to draw the juices. Bring to a boil then reduce heat and simmer for about 30. Skim the froth off the top, and stir frequently to prevent sticking. .