Homemade Blackberry Jam

Carefully measure out the berries, put them into a very large pot (8qt).
Carefully measure sugar in a lg bowl.
Add the pectin to the berries a little at a time, stirring constantly.
Heat on hi, stirring constantly until mixture comes to a FULL boil.
Add sugar ALL at once, stirring.
Bring mixture back to a full hard boil, stirring constantly.
Boil for 1 minute.
Remove from heat and ladle into clean, hot 8oz jars, leaving 1/4 inch space at the top.
Wipe the rim of the jar and put canning lids and rings on fingertip tight.
Place in canner with very hot water, make sure water is 1 inch above jars.
Process in boiling water bath for 10 minutes.
Remove and set them upright on a towel to set for 12 hours.