Ammonia

Ammonia was a pungent gas. It was deadly to some species, including humans. Other races, including the Rills, who could not breathe oxygen, breathed ammonia. (TV: Galaxy 4)

Ammonia was also used as a liquid cleaning agent. Phil Tyson carried a bucket filled with ammonia while he cleaned Cheeky Chicken. When the Bailiffs almost consumed the Ninth Doctor and Rose on board the Vandosian ship, Phil threw his bucket at them. The ammonia burned the Baliffs and caused them to drop the Doctor and Rose. (COMIC: Mr Nobody)