Mercury glass, also known as silvered glass, does not contain mercury or silver. It's actually clear glass, blown into double-walled shapes and coated on the inside with a silvering formula, which is inserted though a small hole that is then sealed with a plug. A few manufacturers did, for a time, try to line their glass with a mercury solution; this practice was discontinued due to expense and toxicity. This vintage pair is in their original condition with brass hardware.