RUST, the flower or calx of any metal, procured by corroding and dissolving its superficial parts by some menstruum. Water is the great instrument or agent in producing rust: and hence oils, and other fatty bodies, secure metals from rust; water being no menstruum for oil, and therefore not able to make its way through it. All metals except gold are liable to rust; and even this also if exposed to the fumes of sea-salt. For remedies against rust, see IRON, par. ult.