Sprinkle the soda over the figs and cover with 6 quarts boiling water and let stand for 10 minutes.
Drain off the soda solution and rinse the figs well in clear cold water.
Mix the sugar and 4 quarts water and boil for 10 minutes.
Skim and add the figs gradually.
Cook rapidly for 2 hours or until the figs are clear and tender.
Lift the figs out carefully and place in a shallow pan.
Boil the syrup until thick as honey.
Cover the figs with the syrup.
Let stand overnight.
Pack cold figs in sterilized jars and fill jars with syrup.
Seal and process in boiling water in a waterbath canner for 10 minutes.