My “Matter” column this week at the New York Times My “Matter” column this week at the New York Times is a biography of the element chlorine. You may know it from roles in such classics as The Swimming Pool or Table Salt. But chlorine has had a long, weird history on Earth. Recent studies suggest that chlorine levels were ten times higher on our planet when it formed. If it still had that much chlorine today, we probably never would have existed. Check out my column for the full story.