Add chopped fruit, with juice, and 1 c of the sugar into peel mixture. Cover and simmer 20 minutes longer.
Measure 3 1/2 c of the fruit/peel mixture into a 6-8 qt (non reactive) pot. Stir in (use wooden spoon) remaining sugar and add the butter (it keeps the foam to a minimum, and won't spoil the canning process due to small amount). Bring to a full rolling boil, stirring constantly.
QUICKLY stir in pectin. Return to a full rolling boil, stirring constantly, for 1 minute.
Remove from heat and skim off any foam (I didn't have any!). (Add color, if desired.)
Ladle quickly into sterilized jars, leaving 1/8 inch head space. Wipe rims, cover with lids and bands, and BWB 10 minutes. Yields @ 4 pints. (Note: The marmalade will look runny at first. After about 12-24 hours canned, it will really thicken up!)
(originally posted by Tammi, modified by Elizabeth)