Sterilize 5 half-pint jars (see Directions for Sterilizing).
Peel tomatoes; chop coarsely.
Place in 3-quart saucepan; add lemon and ginger.
Bring to boiling; reduce heat, and simmer, uncovered, 1 hour.
Stir in sugar; boil, uncovered and stirring fre- quently, until thick—25 to 30 minutes, or until candy thermometer registers 22IF.
Ladle marmalade into hot jars.
Immediately cover with 1/8 inch hot paraffin.
Makes 5 half pints.