Here is Canadian Livings' Recipe for Marmalade
2 lb Seville Oranges
7 cups sugar
Scrub the oranges and lemon; cut off both ends and any blemishes. Cut in half crosswise and squeeze out juices, reserving pulp and seeds, and strain into Dutch oven.
Pull membranes from peels and place with reserved pulp and seeds onto a 15 inch square doubled piece of cheesecloth, bring up sides, tie with kitchen twine and add to pan.
Half orange and lemon peels and cut crosswise into paper-thin strips. Add to pan
Add 8 cups of water. Bring to a simmer over medium heat and simmer, stirring often and pressing bag to realease pectin, until peel turns to mush when pressed between fingers, 2-2 1/2 hours.
Remove bag and let cool; squeeze juice into pan. Mixture should measure 7 cups. If not, add water or boil until reduced. In clean Dutch oven, bring sugar and fruit mixture to full rolling boil, stirring. Boil vigorously, stirring constantly until free of foam, thickened and at gel stage, 12-15 minutes. (Now this took me about 45 minutes)
Using sterilized jars, lids and utensils, fill 1 cup jars leaving 1/2 inch head space. Cover with prepared lids and screw on bands.
Place in boiling water canner for 10 minutes.