3 pounds lemons
8 to 10 cups granulated sugar
Slice the lemons as thinly as possible and discard the ends. Remove and discard all the seeds. Place the lemon slices in a nonreactive bowl and add enough water to cover. Let stand overnight.
Measure the lemons and water into a wide, shallow, nonreactive pan. Add an equal volume of sugar and cook over low heat until sugar is dissolved. Raise heat to medium-high and cook, stirring frequently and skimming off the foam as it rises, until temperature reaches 220 degrees F, about 1/2 hour.
Remove marmalade from heat. To test for consistency, drop a little marmalade on a saucer and put the saucer into the freezer until marmalade is cold, about 5 minutes.
Tip the saucer. The marmalade should just barely run. If too thin, return the marmalade to medium-high heat and cook, testing often, until it has reached the right consistency. Put marmalade into hot, sterilized pint or half-pint jars. Store in refrigerator up to 1 month or, for longer storage, seal according to reliable canning instructions.
Makes about 4 pints.