Squeeze juice from fruits. Save the pips and tie in a muslin bag. In a food processor (or a meat grinder) grind the fruit peels and pulp. Measure juice and ground fruit together; add 1 1/2 times its volume in water. Bring fruit and water to a boil in a non-reactive (enamel or stainless steel) pan and boil until mixture is reduced to half its original volume. Add to this mixture 3/4 cup of sugar for each cup of fruit. Stir and bring to a rolling boil (i.e. a boil which cannot be stopped by stirring). Reduce heat to maintain a fast simmer. Stir occasionally and test for doneness after 20 minutes. Marmalade is done when a skin forms on the test after five minutes. If you are in doubt, turn up the heat and bring to a fast boil for 5 minutes. Test again. Ladle mixture into preheated, sterilized jars. Cover with melted paraffin was.