Scald one quart of milk, add to it two tablespoonfuls of sugar, a teaspoonful of salt, and when lukewarm, half an ounce of compressed yeast, moistened in two tablespoonfuls of warm water. Now add sufficient flour, about one pint and a half to make a batter. Beat thoroughly and stand in a pan of warm water, cover the whole and keep warm for four hours. When light add sufficient flour to make a dough, knead lightly until soft and elastic. Put it back in the bowl and when it has doubled its bulk and is very light, pinch off bits of the dough, form them into round biscuits, stand in greased pans, cover and stand in a warm place (750 Fahr.) for one hour or until very light. Brush the tops with water and bake in a quick oven twenty minutes. Stand aside until cold and they are ready for making into zweiback.