Put the apricots in a pot, barely cover with cold water, and cook until soft. Drain, reserving the juice. Chop the fruit and return to the juice. Add the canned pineapple with its juices and measure. Put in a large pot and bring to a boil. Measure the sugar, using about two-thirds as much sugar as fruit, and stir in. Boil rapidly, stirring to prevent sticking, until thick. Test for the jellying point, using a thermometer, the sheet test, or the freezer test. Pour into hot, sterilized jars and seal.