Wash the kumquats thoroughly and drain.
Slice as thin as possible and discard the seed.
Cut the orange in eighths, discarding the seed, then chop.
Measure the kumquats and orange and add 3 cups water per cup fruit.
Let stand overnight in a cool place.
Bring to a boil and reduce the heat.
Simmer until the peel is tender.
Measure the kumquat mixture and add the lemon juice and 1 cup sugar for each cup mixture.
Boil until the liquid sheets from a spoon, then pour into hot sterilized jars and seal.