Heat oven to 350°F. Line large cookie sheet with cooking parchment paper.
In 4-quart saucepan or Dutch oven, heat 10 cups water to boiling over medium-high heat. Reduce heat to medium-low.
Meanwhile, separate dough into 8 biscuits; cut each biscuit in half to make 16 pieces. Shape each biscuit half into a ball. Flatten balls slightly, and press a piece of cheese in center of each biscuit. Wrap around cheese to cover completely. Pinch seams to seal well. Gradually stir 1 tablespoon of the baking soda into boiling water (water will foam slightly). Add 4 biscuits at a time to water for 15 seconds. Using tongs or slotted spoon, turn biscuits over; simmer 15 seconds longer. Repeat with remaining biscuits, adding 1 tablespoon of the baking soda each time. Place biscuits 2 inches apart on cookie sheet. Sprinkle with salt.
Bake 15 to 22 minutes or until deep golden brown. Serve immediately with blackberry preserves for dipping.