Dissolve two drachms and a half of bicarbonate of potassium in four fluidounces of water. To make a draught, pour out a tablespoonful of this solution, and add to it a tablespoonful of water. Then pour into these a tablespoonful of fresh lemon-juice. It will effervesce, and should be drunk at once. If lemon-juice cannot be had, an apothecary may furnish instead a solution containing two drachms of citric acid in four fluidounces of water. A tablespoonful of this, with one of water, may take the place of lemon-juice.