Wash and rinse the jars and place them in a 200°F oven to stay hot until ready to fill.  Place the lids of the jars in a saucepan of simmering water set on a back burner.  Fill a canner pot with water and heat to the boiling, then reduce the heat to low until ready to use.

Peel, pit, and chop the peaches.

Measure 4 cups of fruit into a large saucepan and mash with a potato masher to get a chunky texture. 

Stir in the lemon juice, pectin, salt, and butter. Bring the mixture to a full rolling boil over high heat while stirring constantly. 

Add the sugar and return to a full, rolling boil. Boil the mixture for 1 minute while stirring constantly. Remove from the heat and spoon off any foam. Stir in the almond extract if desired.

Ladle the preserves into the hot jars, wipe the rim of the jars with a damp cloth, and place a lid and jar ring on each jar. 

Place the filled jars into the basket of the canner. If necessary, add additional hot water so the top of the jars are covered by at least 1 inch of water.  Bring the pot to a boil over high heat, cover the pot and boil for 10 minutes.  

Lift the jars from the hot water and set them in a draft-free area to cool at room temperature.