Preheat oven to 200 °F (95 °C).
Place a saucepan filled with hot water on bottom rack.
Butter a 9 x 5 inch (23 x 13 cm) loaf pan.
Set aside.
In a cup, dissolve yeast in 1/2 cup (125 mL) lukewarm water.
Set aside.
In a second cup, pour remaining lukewarm water.
Dissolve sugar and salt.
Set aside.
In a bowl, lightly mix both kinds of flour, bran and butter.
Fold in 2 liquid mixtures.
Knead dough until lukewarm.
Add a little flour.
Let rise in oven 20 minutes.
Remove dough from bowl.
Punch down.
Place in loaf pan.
Return to oven until dough doubles in size.
Remove bread and water filled saucepan from oven.
Increase temperature to 375 °F (190 °C).
Return bread to oven.
Bake on top rack 30 minutes.