Plums are delicious bottled or canned, but of all the fruits they are the most difficult to get perfect in appearance, as their skins are so apt to crack. They are also very apt to rise in the jars, owing to shrinkage, and for that reason must be packed very firmly. Therefore it is necessary to select fruit that is rather under-ripe and prick with a darning needle. Pack into clean jars, fill up with a medium or heavy syrup, adjust the rubber rings, and screw down the lids slightly, then put into steriliser or saucepan, fill up with water to come to about the necks of jars, and bring gradually to simmering point - it should take about 1 1/4 hours to reach that point, then allow to simmer gently for 12 to 15 minutes. Remove from the water, screw down the lids tightly, or clamp down the spring, then return to the water to cool, or if the saucepan is needed, put them somewhere out of a draught and cover up warmly, so that the jars can cool down slowly in order to effect proper suction.