Silver Nitrate Spray is a silver nitrate gas used by humans to determine if someone is a Lycan. In the case that a Lycan is found, the spray can be used to weaken them, and, in some cases, to kill the Lycan. On contact, the spray burns the skin of the Lycan and, if breathed in, it will burn them internally. In the 15-minute anime, Underworld: Endless War. Endless War depicts two IPU agents spraying people caught in a roadblock with the gas to see how they react.