Calcium Iodate, Ca(IO₃)₂

Calcium Iodate, Ca(IO₃)₂, occurs naturally in the nitre beds of Chili and in sea-water. It can be obtained either by the action of calcium carbonate or hydroxide on iodic acid, or, since calcium iodate is not very soluble in water, by precipitating a boiling solution of calcium nitrate with an alkaline iodate. The salt crystallises with 4 or 6 molecules of water according to circumstances. The hexahydrate belongs to the rhombic system. On drying at 100° C. a monohydrate is left, but it is only at a considerably higher temperature, about 200° C., that the anhydrous salt is obtained. On further heating, oxygen and iodine are given off and a mixture of iodide and oxide remains.