9 c. (about 4 lbs.) crushed blackberries
6 c. sugar

Combine blackberries and sugar in a large Dutch oven; slowly bring to a boil, stirring occasionally until sugar dissolves. Boil 30 to 40 minutes, stirring frequently, until jam reaches desired consistency. Skim off foam with a metal spoon.

Quickly ladle jam into hot sterilized jars, leaving 1/4 inch headspace; cover at once with metal lids and screw bands tight. Process in boiling water bath 15 minutes. Yield: 3 pints.