Stir all ingredients in a medium saucepan. Bring to a boil over high heat; then reduce heat to medium and continue cooking. Skim off the resulting foam. Continue cooking until the preserve is set when tested on a chilled plate. Remove from heat and ladle hot jam into a jar, leaving ¼-inch headspace. Using a non-metallic utensil, remove air bubbles and adjust headspace by adding more jam. Wipe jar rim to remove any food residue. Centre hot sealing disc on clean jar rim. Screw band down until resistance is met; then increase to fingertip tight. Return filled jar to rack in canner. Repeat for remaining jam. When canner is full, ensure that water covers all jars by at least one inch. Cover canner and bring water to full, rolling boil before starting to count processing time. Boil for 10 minutes. Turn off stove, remove canner lid, and wait five minutes. Remove jars without tilting; place them upright on a protected work surface. Cool upright, undisturbed for 24 hours. Do not retighten screw bands. After cooling, check jar seals. Sealed discs curve downward and do not move when pressed. Remove screw bands; wipe and dry bands and jars. Store screw bands separately or replace loosely on jars. Label and store jars in a cool, dark place. For best quality, use within one year. Yields approximately two litres jam; four medium-sized jars or eight 250-millilitre jars.