To freshen or aid the fermentation of stale yeast.— Yeast may be made to ferment much more easily and quickly after it has become stale by mixing with it first a small quantity of sugar in powder, and then a few spoonfuls of warm water, and setting it in a warm place to rise. A teaspoonful of sugar will be sufficient for two tablespoonfuls of solid yeast: a little warm flour will further help the fermentation. The whole may be mixed into a thin batter.