Choose fine yellow quinces; pare, quarter and core them, or cut in circular slices an inch thick; pare and dig the core from each so as to leave the slice ring-shaped. Save all the perfect cores and skins. Put the quinces over the fire with just water enough to cover them and simmer until they are soft enough to pierce with a yellow straw. Take out carefully with a skimmer and spread upon broad dishes to cool. Add the cores and parings to the water in which the quinces were boiled, and stew, closely covered, for an hour. Strain through a jelly-bag, and to every pint of the liquid or to every pound of the fruit, add 1 pound of sugar before it heats; stir in the beaten white of an egg to clarify it; let boil up two or three times and skim each time. Put the fruit in the syrup and let boil until a rich red color. Remove the fruit and boil syrup down until it begins to jelly on the sides. Pack the quinces in jars and pour the syrup over them.