Cut the oranges in half and squeeze out the juice. Put the pips into a muslin bag. Cut the fruit into thick shreds. Put into the pan with juice, the juice of the lemon, water and the bag of pips. Simmer for about two hours until the peel is tender. Take out the bag of pips, and squeeze out the liquid. Stir in the sugar and black treacle until dissolved and boil quickly to setting point. Cool slightly, stir well, pour into hot jars and cover. If liked, four tablespoons rum or whisky can be added just before pouring into pots.