The main active ingredient of commercial products called bleaching powder, chlorine powder, or chlorinated lime, used for water treatment and as a bleaching agents. This compound is relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach). It is a white solid, although commercial samples appear yellow. It strongly smells of chlorine, owing to its slow decompositionin moist air. It is not highly soluble in hard water, and is more preferably used in soft to medium-hard water. It has two forms: dry (anhydrous); and hydrated(hydrous).