1Combine berries and sugar; bring slowly to boiling, stirring occasionally until sugar dissolves.
2Cook rapidly to, or almost to, jellying point, depending upon whether a firm or soft jam is desired.
3As mixture thickens, stir frequently to prevent sticking.
4Pour into hot jars, leaving 1/4 inch (6mm) head space.
6Process 15 minutes in boiling water bath.
7Yield: about 3 to 4 pints.
8Note: If seedless jam is preferred, crushed berries may be heated until soft and pressed through a sieve or food mill; then add sugar and proceed as above.
www.justberryrecipes.com, which has lots of blackberry and raspberry recipes.