Scald a pint of milk; add 1 teaspoon salt, 2 tablespoons sugar, 1 tablespoon butter. When lukewarm add 1/2 cake compressed yeast dissolved in 1/2 cup warm water, then stir in 2 1/2 cups white flour or enough to make a thick batter; beat it well; cover closely and set the bowl in a pan of water, hot, but not scalding. Place the pan where the water will keep hot or add more hot water occasionally. In an hour or less the batter will be full of bubbles; then stir in the whole wheat flour, using enough to make a dough that will keep its shape when you stop stirring. Mix and cut it through and through with a knife, until not a particle of flour can be seen. Work well from the bottom and edges to the center, scrape the bowl clean and smooth off the top; if it settles to a level it is too soft and a little more flour is needed, but add only a table-spoonful at a time lest it be too stiff. Cover and let it raise again; stir it down as soon as it cracks and seems light, After it raises again in the bowl, turn it out on the floured board, using only enough flour to prevent sticking. Shape into 4 round or 2 long loaves with as litle handling as possible; put in pans. Cover and let it raise until double its bulk, then bake about an hour. The oven should be a little cooler than for white bread and a little more time will be required for baking.