Grapefruit Marmalade

Peel grapefruit and lemon; cut away inner white part of peel, leaving rind and white pith. Cut rind into slivers 3.4 inch long and 1/8 inch wide. Chop frit coarsely, reserving juice. In an 8-quart non-reactive heavy kettle over moderately high heat, simmer rind, chopped fruit, reserved juice and water, uncovered, 10 minutes.

Pour into a large heatproof glass bowl and let stand, covered, in a cool place overnight.

Return mixture to kettle. Add sugar and set over moderate heat. Insert a candy thermometer and bring to a boil, stirring until sugar dissolves. Continue boiling, stirring occasionally, until thermometer registers 218 degrees F to 220 degrees F.

Remove from heat, skim off foam and ladle into sterilized half-pint canning jars, leaving 1/4-inch head space. Wipe rims, seal jars and process in a boiling water bath for 10 minutes (15 minutes for altitudes above 6000 feet).

Remove jars from water bath, let cool for 12 hours and test for airtight seals. Label and store in a cool, dark place. If you decide not to sterilize and process jars, refrigerate marmalade and serve within three weeks.

Makes 4 half-pints