Sodium selenite (Na2SeO3) is a toxic inorganic salt that is highly soluble in water and insoluble in organic solvents. The crystal structure of the anhydrous salt has been variously reported as tetragonal or monoclinic.
In 1889, Irish chemists Sir Charles A. Cameron* and John Macallan produced Na2SeO3 and the previously unknown selenium oxychloride1 (SeOCl2) by heating selenium oxide (SeO2) with sodium chloride.