Of doubtful or uncertain efficacy, provenance, etc.; dodgy.
Fraught with danger.
Of uncertain, risky outcome.
Nauseating, rank.
Unpredictable, erratic or fickle; mercurial.
To overlay with quicksilver.
To treat with quicksilver.
The metal mercury.
An amalgam of mercury and tin applied to the backs of mirrors, quicksilvering.