Preheat oven to 350°
Grease one 9x13 inch pan.
Dissolve baking soda in boiling water. Set aside
Mix together four, brown sugar, salt, and vegetable oil to form a crumb like mixture
Reserve 1 cup of crumbs
Mix the remaining crumbs with water and soda mixture.
Pour batter into prepared pan
Sprinkle the reserved crumbs on top
Bake for 45 minutes or until done