In small mixer bowl combine 1 1/2 cups of the unbleached flour and the yeast.
Heat 1 cup water, molasses, butter, and 2 teaspoons salt till warm (115-120°), stirring constantly.
Add to dry mixture; add egg.
Beat at low speed with electric mixer for 1/2 minute, scraping bowl.
Beat 3 minutes at high speed.
By hand, stir in barley flour and enough remaining white flour to make soft dough.
Cover; let rise till double (45 to 60 minutes).
Spread in greased 9x5x3-inch loaf pan; smooth top.
Cover; let rise till double (30 to 45 minutes).
Bake at 375° for 25 to 30 minutes.
Cover with foil last 15 minutes.
Remove from pan; cool.