COBALTOUS

Co‐balt″ous (?), a. (Chem.) Pertaining to, derived from, or containing, cobalt; — said esp. of cobalt compounds in which the metal has its lower valence. Cobaltous chloride, a crystalline compound, CoCl2, of a pale rose color when hydrous, blue when dehydrated. Its solution is used for a sympathetic ink, the writing being nearly colorless when dried in the air, owing to absorbed moisture, and becoming bright blue when warmed.