Rinse your mixing bowl in hot water and dry completely to warm it. Dissolve the yeast in the 2 1/2 cups warm water in the bowl.
Add the salt, butter, and flour. Using the dough hook, mix at low speed for about 3 minutes.
Place dough in a grease bowl, turning once.Cover and allow to rise in a warm place about 1 hour or until doubled in size. Punch dough down and divide in half.
Place half of dough on a well-floured surface and roll into a rectangle (about 12 inches by 15 inches) and then roll the dough tightly from the longest side as if making a jelly roll. Tape towards the ends.
Dust baking sheets with cornmeal and place loaves on baking sheets. Cover and allow to rise again until doubled in size, about 1 hour.
Preheat oven to 450 degrees.
With a serrated knife, make slits diagonally across each loaf. Bake for 25 minutes. Remove from oven.
Mix together the egg white and cold water. Brush over the loaves and then return to oven for 5 minutes longer. Remove from baking sheets and cool on wired racks.