Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.

Combine prepared apricots with lemon juice and sugar in a 6- or 8-quart saucepan. Add up to 1/2 tsp butter or margarine to reduce foaming, if desired. Bring mixture to a full rolling boil that cannot be stirred down, over high heat, stirring frequently.

Add pectin, immediately squeezing entire contents from pouch. Continue hard boil for 1 minute, stirring constantly. Remove from heat. Skim foam if necessary.

Ladle hot jam into hot jars leaving 1/4 inch headspace. Wipe rim. Center lid on jar. Apply band and adjust until fit is fingertip tight. Place jar in boiling water canner. Repeat until all jars are filled.

Process jars 10 minutes, adjusting for altitude. Turn off heat, remove lid, let jars stand 5 minutes. Remove jars and cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.