Spiced Tomato Jam with Powdered Pectin

(about 5 half-pint jars). Wash firm-ripe tomatoes. Scald, peel, and chop tomatoes. Cover and simmer 10 minutes, stirring constantly. Measure 3 cups tomatoes into a saucepot. Add lemon rind, allspice, cinnamon and cloves. Sterilize canning jars. Place prepared fruit into a saucepot. Add lemon juice. Measure sugar and set aside. Stir powdered pectin into prepared fruit. Bring to a boil over high heat, stirring constantly. At once, stir in sugar. Stir and bring to a full rolling boil that cannot be stirred down. Then boil hard for 1 minute, stirring constantly. Remove from heat. Skim off foam. Pour hot jam into hot jars, leaving 1/4-inch head space. Wipe jar rims and adjust lids. Process 5 minutes in a boiling water bath.