Calcium Subiodide, CaI or Ca₂I₂

Wohler and Rodewald, applying to the production of the subiodide the method already described under the subfluoride and the subchloride, heated together atomic proportions of calcium and iodine in a steel tube at 800° C. When the product was rapidly cooled in solid carbon dioxide and washed with carbon disulphide, brown hygroscopic crystals of CaCa₂I or Ca₂I₂, were obtained. Slow cooling resulted in the formation of a mixture of calcium iodide and metallic calcium.