We have an old copy of Putting Food By and it has a good recipe for orange marmalade. 2 lbs of oranges, 2 lemons, 8 cups of water and 8 cups of sugar(4 lbs) will yield about 6 pints of wonderfully fragrant orange marmalade.
Starting this morning, we washed the oranges and lemons and removed the 'buttons' on the ends of the fruit. The fruit was placed in a large pot and enough water to cover them was added. The fruit boiled for 90 minutes, until the fruit is fork-tender. At that point, we remove the fruit from the pot to cool. Once cooled, the fruit is sliced and any seeds or pith removed and placed in the pot of juices to boil for an additional 10 minutes. The juice in the pot is strained, returned to the pot along with the fruit. Now we are ready to make marmalade.
Bring the fruit and juices to a boil, then add the sugar and boil stirring occasionally to prevent scorching. Do this until the fruit temperature reaches 9 degrees beyond the boiling point in your kitchen(at least 220F). Remove the pot from the heat, skim off any foam and spoon the jam into hot sterilized pint jars, leaving 1/2 inch of head room. Seal the jars with the canning lids and place in a hot water bath in a canning pot for 10 minutes. Each batch makes 5-6 pints of marmalade.