[L. Accrus calamus.] The Sweet-Flag, a plant found in ditches and by the side of ponds in Asia, Europe, and North America. The root-stock yields an aromatic stimulant and tonic, much used as a medicine in the East. It is also made into confections and used in liquors in Germany. Some persons chew it to clear the voice and sweeten the breath. Cal'cium. One of the metallic elements, whose oxide is the abundant and very useful lime. It occurs abundantly as limestone, and in its crystallized form as marble. Calcium carbonate is so abundant in nature that it is found in most natural waters, in which it is dissolved and carried to the sea. Sulphate of lime is a common constituent in what is known as hard water, and is found in sea water. In its solid state it is known as Gypsum, or Plaster of Paris.