The so-called root beers are aqueous or alcoholic extracts of certain aromatic bitter principles, some of which have medicinal properties and are included in the Pharmacopoeia of the United States. Among the materials which are used for flavoring in this way are juniper berries, pipsissewa, sarsaparilla, spikenard, wintergreen, vanilla, various barks and roots, bitter principles such as tannin, and other allied bodies. These materials are sometimes furnished together with the necessary quantity of yeast so that the fermentation of the beers may be made at the home.