Place boiling water into a large mixing bowl. Stir cornmeal slowly into boiling water to make mush, stirring constantly to eliminate large lumps. Add baking soda to molasses, and beat until light and foamy. Add molasses mixture to cornmeal mixture. Mix in butter or margarine and salt. Stir in cold water to make mixture lukewarm. Dissolve yeast in 1/4 cup warm water, and add to cornmeal mixture. Gradually add flour.
Turn dough out onto a lightly floured surface, and knead until smooth. Place in a large greased bowl. Grease the top of the dough. Cover with a damp cloth, and allow to rise until doubled.
Punch down dough, and divide into 6 parts. Shape 4 parts into loaves, and place in 9 x 5 inch loaf pans. Use the remaining dough to make into 2 dozen rolls. Allow to rise until doubled.
Bake at 350 degrees F (175 degrees C) for 35 to 40 minutes, or until brown.