Place figs in a large shallow container; sprinkle with soda. Cover with boiling water, and let stand 5 minutes. Rinse and drain in 2 baths of clean, cold water. Set aside.
Combine sugar and 2 quarts water in a flat-bottomed kettle; bring to a boil over medium heat, stirring constantly until sugar dissolves. Add reserved figs; return to a boil. Boil, stirring frequently, 25 minutes or until figs become tender and translucent.
Remove figs from syrup with a slotted spoon; boil syrup an additional 10 minutes or until desired consistency. Return figs to syrup. Remove from heat, and skim off foam with a metal spoon.
Quickly ladle preserves into hot sterilized jars, leaving 1/4- inch headspace. Cover at once with metal lids, and screw bands tight. Process preserves in boiling-water bath 15 minutes.