Boston Brown Bread III

Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x5 inch loaf pan, knocking out excess flour. In a large bowl, whisk together whole wheat flour, all-purpose flour, baking soda, and brown sugar. Mix in molasses and buttermilk until just combined. Pour batter into prepared pan. Bake for one hour, or until done. Cool on a wire rack for 5 minutes, and then remove from pan. Cool completely before slicing.