Quicksilver is the compound secreted by the biosynthetic quicksilver gland in The Invisible Man (2000-2002 - SciFi).
By bending the visible light spectrum around the object coated in quicksilver, the object is rendered completely invisible to the naked eye. However, quicksilver does not completely bend other wavelengths of light, making it possible to see while 'quicksilvered', and also making it possible to see something that has been quicksilvered. Additionally, since light does not reach the surface of the quicksilver, and is simply refracted around it, the object's surface temperature drops to a very low temperature (approximately –10°C), rendering quicksilvered items visible to thermal systems such as thermal night-vision goggles.
Quicksilver acts as a neuroinhibitor, causing the host implanted with the gland to eventually go insane and become afflicted with quicksilver madness unless they receive regular injections of a counteragent to the effects of the quicksilver. This neutralises the excess quicksilver in the host’s bloodstream, curing them of quicksilver madness.