Soak lemons in water overnight. Pour the lemons and water into an enameled, tinned or stainless steel kettle and cook gently for about 20 minutes, or until the peel is tender. Add the apples and cook until they are tender, aproximatly 20 minutes. Stir in the sugar and boil until jelling point is reached. Pour into jars and cover. Process, if desired 10 minutes. Makes about 7 pints