Pick up the lemons and remove the seeds after halving them and in a cheesecloth bag, tie the seeds. Take one lemon at a time and quarter it thinly slice and half. Take a heavy pot and combine bag of seeds and water along with the lemons. Let the mixture stand for a while and cover it in room temperature for about 24 hours.
Heat up the lemon mixture over moderate heat and let it come to a boil. After that, reduce the heat and simmer for about 45 minutes. Make sure that you let it remain uncover and stir in sugar later on. Let it come to a boil again and keep stirring to skim off any foam. Wait for another 15 to 20 minutes.
Now ladle that hot marmalade into jars but do not fill more than 1/4 inch off top. Use dampened cloth to wipe rims and use lids in order to seal the jars. Take a water-bath canner or you can even choose to use a rack set for the next step.
Take all the jars that have marmalade in them and carefully put them in either a water-bath canner or rack set in a deep pot. Once you have done putting jars there, add hot water to the pot about an inch and let it bring to a boil. Now you need to boil the jars and use tongs to transfer them to a rack. Let them stay there for a while and cool the jars completely.
Let the jars cool down on room temperature and you cannot use refrigerator for this purpose. Once they are cooled down, you can pick them up and your yummy and tasty lemon marmalade is ready to serve.