For the candied peels:
For this recipe, the peels include not only the colored parts of the skin but the pith as well. Cut wedges through the skin of the citrus fruits, pull the skin off the fruit, and dice it into pieces about 3/8 inch thick—you will have about 2¼ cups of diced peel. (The flesh of the fruit can be used for juice or in salads.) You may also collect and use the peels left over from squeezing oranges or grapefruits in the morning.
Put the diced fruit peel in a saucepan with 6 cups of cold water, bring to a boil, and cook over high heat for about 1 minute, then drain in a colander. Wash the pieces for a few seconds under cold tap water. Rinse the saucepan with cold water, return the diced fruit peel to the pan, and add another 6 cups of water. Repeat the boiling, draining, and washing procedure, and wash the saucepan again. This blanching process removes the bitterness from the peel. Finally, return the diced peel to the saucepan with the sugar and 1½ cups water, and bring to a boil. Reduce the heat to medium, and boil gently for 15 to 20 minutes, until reduced to a very syrupy liquid.
Add the dried apricots, dried pears, dried peaches, and raisins to the candied peels and syrup. Mix in the rum, Armagnac, or cognac. At this point, the mixture can be placed in a jar and kept, refrigerated, almost indefinitely.
To make the cake:
Preheat the oven to 350 degrees. Beat the soft butter and sugar for 1 minute in the bowl of a mixer fitted with a flat beater. Add the eggs, and beat for 30 seconds. Add the orange juice, salt, and flour, and beat for 10 to 20 seconds, just enough to incorporate. Using a spatula, fold in the candied and dried fruits.
Cut a strip of parchment paper long enough to fit the length of a 6-to-8-cup loaf pan and extend 1½ inches beyond it at either end. (This makes it easy to unmold the cake after baking.) Butter the paper and the mold, bottom and sides, and position the paper in the mold, buttered side up, pressing to make it adhere to the bottom and sides at either end. Pour the batter into the prepared pan, and smooth the top with a spatula.
Place the loaf pan on a cookie sheet, and bake in the 350-degree oven for approximately 45 minutes. Reduce the heat to 325 degrees, and cook for another 60 to 70 minutes, until completely set inside.
Allow the cake to cool in the pan on a rack. When cool, unmold, wrap in plastic wrap and/or aluminum foil, and keep either frozen or in the refrigerator, where it will keep for a couple of weeks.
Cut into ½-inch slices, and serve. This cake is a nice accompaniment to cream custard but can be served alone or with fresh fruit and nuts.