Makes about 6 half-pints. Wash and remove the seeds of the limes and lemons and put fruits through a food chopper or cut in small pieces. Measure the pulp and add 3 cups of water for each cup of pulp; let stand overnight. The next morning, boil the mixture, uncovered, in a preserving kettle about 20 minutes. Remove mixture to a bowl, cover and let stand again overnight The next morning, measure citrus mixture. Cooking batches of only 4 to 6 cups of fruit at a time, measure out 3/4 cup of sugar for each cup of fruit and combine fruit and sugar in a preserving kettle. Bring mixture slowly to a boil, stirring frequently until sugar has dissolved. Then boil rapidly for about 20 minutes until jellying point is reached. Test for jellying point with a jelly thermometer which should read 200 to 222 F, or with a spoon which, when dipped into mixture, has 2 drops form along the edge, come together and fall as 1 drop. Ladle into hot, sterilized jars and seal immediately.
To seal: Fill to within 1/2-inch head room, being sure to first wipe the rim and threads of the jars with a hot damp cloth to remove all particles of food, seeds or spices. While contents are hot, cover with a 1/8-inch layer of paraffin. When paraffin has set, add another layer of melted paraffin, tilting and rotating the jar to sea/l completely. Jams and Jellies - 1975