Mercury Glass

Mercury glass is the common term for silvered glass, which describes glass that was blown double walled, then silvered between the layers with a liquid silvering solution, and sealed. Silvered glass was free-blown, then silvered with a solution containing silver nitrate and grape sugar in solution, heated, then closed. Sealing methods include metal discs covered with a glass round (England) or a cork inserted into the unpolished pontil scar (American). "Mercury" silvered glass was produced originally from around 1840 Bohemia, now the Czech Republic, Germany, and was also manufactured in England from 1849-55.
Mercury glass is the common term for silvered glass, which describes glass that was blown double walled, then silvered between the layers with a liquid silvering solution, and sealed.
Silvered Glass is a layer of glass which is coated with a special compound of silver nitrate and sugar water. This is commonly done on the inside of blown glass ornaments to make them shiny. Decorative paint is then also applied to the outside of the glass. This process was invented in Lausha, Germany and copied widely.
The most commonly found glass ornaments are silvered glass and not double walled mercury glass which is quite heavy and unmistakable.