Lewisite is nasty stuff - it's a compound of arsenic with two labile chlorines. As I mentioned yesterday, BAL is its antidote.
Lewisite is a chemical weapon from a particularly brutal era in this regard, and you hear about it a lot less these days. However, there's still plenty floating around...
Have a good weekend.
If you are interested in learning more about lewisite pleae see my book: Dew of Death: The Story of Lewisite, America's World War I Weapon of Mass Destruction