Blueberry or huckleberry jam recipe

Blueberry or Huckleberry Jam
4 1/2 c Berries
1 Bottle fruit pectin
7 c Sugar
1 Lemon
Wash fruit thoroughly. Crush. Add lemon juice. Add grated rind of 1/2 lemon. Add sugar. Mix thoroughly. Heat rapidly to full rolling boil. Stir constantly before and while boiling. Boil hard 2 minutes. Remove from fire and stir in fruit pectin. Skim.