1. Peel, pit, and chop the peaches (you should have about 6 cups). In an 8-quart stainless steel or enameled stockpot, cook the peaches, uncovered, over moderate heat for 8 minutes, or until they are soft, stirring and mashing them constantly. While the peaches cook, tie up the cinnamon stick and cloves in a piece of cheesecloth.
2. Stir in the sugar and lemon juice, add the spice bag, and bring to a full rolling boil. Continue to boil, uncovered, stirring and skimming the surface often, for 25 to 30 minutes, or until a candy thermometer registers 218° to 220°F. and the preserves have thickened slightly and appear golden and glossy.
3. While the preserves cook, sterilize 8 half-pint jelly jars. Spoon in the preserves, leaving a 1/2-inch head space in each; wipe the rims 'well and seal. Process in a boiling water bath for 10 minutes, then let cool thoroughly and check the seals. Store in a cool, dark, dry place for up to 6 months.