Lemon Lime Marmalade

Combine lime and lemon slices and water in large kettle. Bring to boil and boil 20 minutes, or until peels are tender. Drain and measure liquid. Add enough water to make 3 quarts liquid, then combine liquid, fruit and sugar in kettle. Bring to boil and cook rapidly until mixture sheets off spoon or to 221 degrees on candy thermometer. Pour boiling hot into hot sterilized jars and seal.