prepared fruit (buy about 2-1/4 lb. fully ripe peaches)
fresh lemon juice
sugar, measured into separate bowl
butter or margarine
Bring boiling-water canner, half full with water, to simmer. Wash jars and screw bands in hot soapy water; rinse with warm water. Pour boiling water over flat lids in saucepan off the heat. Let stand in hot water until ready to use. Drain well before filling.
Peel and pit peaches. Finely chop or grind fruit. Measure exactly 2-3/4 cups prepared fruit into 6- or 8-qt. saucepot. Add lemon juice; mix well.
Stir sugar into prepared fruit in saucepot. Add butter to reducing foaming. Bring to full rolling boil (a boil that doesn't stop bubbling when stirred) on high heat, stirring constantly. Stir in pectin. Return to full rolling boil; cook exactly 1 min., stirring constantly. Remove from heat. Skim off any foam with metal spoon.
Ladle immediately into prepared jars, filling to within 1/4 inch of tops. Wipe jar rims and threads. Cover with two-piece lids. Screw bands tightly. Place jars on elevated rack in canner. Lower rack into canner. (Water must cover jars by 1 to 2 inches. Add boiling water, if necessary.) Cover; bring water to gentle boil. Process 10 min. Remove jars and place upright on towel to cool completely. After jars cool, check seals by pressing middle of lids with finger. (If lids springs back, lids are not sealed and refrigeration is necessary.) Let prepared jars stand at room temperature 24 hours. Store unopened jams and jellies in cool, dry, dark place up to 1 year. Refrigerate opened jams and jellies up to 3 weeks.