Orange Marmalade

Combine oranges, lemon and water in a large wide saucepan or Dutch oven. Cover and bring to a simmer. Simmer very gently over low heat for 2 hours. Remove from the heat. Transfer the fruit with a slotted spoon to a cutting board and let cool 5 minutes. (Do not discard the liquid in the pan.) Cut the oranges and lemon in half; scoop out pulp, pith and seeds and add to the pan. Reserve the orange shells and discard the lemon shells. Bring the fruit mixture to a boil and boil for 5 minutes. Strain the fruit mixture through a colander lined with dampened cheesecloth into a bowl. Gather the ends of the cheesecloth and twist out any remaining juice. Add water, if necessary, to make 6 cups. Return the juice to the pan. Slice the reserved orange shells into thin strips and add to the fruit mixture. Stir in sugar and cook over low heat, stirring, until sugar dissolves. Increase the heat to medium and boil, stirring occasionally to prevent scorching, until the jelling point is reached, about 25 minutes. (To test for jelling, place a spoonful of the mixture on a chilled plate and refrigerate for 2 minutes. The jelling point has been reached if the marmalade is firm enough to remain divided when a finger is drawn through it and there is no watery edge. Continue cooking and testing as necessary.) Remove the marmalade from the heat and stir for 5 minutes, skimming off any foam. Ladle into hot jars, leaving 1/4 inch of headspace. Seal with canning lids and process 5 minutes in a boiling-water bath. Store in a cool, dry place.