Seller: heirloomsforhospice (426) 99.3%, Location: Grand Junction, Colorado, Ships to: Worldwide, Item: 371778542315 Condition: Considering the age, these knobs are in very good condition!, Material: Mercury Glass, Details: Five Antique Mercury Glass Door KnobsLarge: has design, 3 1/2 inches diameter, 4 1/4 inches deep (from end of screw to top)Medium: gold tone with bubbles, 2 7/8 inches diameter, 4 1/4 inches deepMedium: plain, 2 3/4 inches diameter, 3 inches deepSmall: plain with some bubbling, 2 1/2 inches diameter, 4 inches deepSmall: has design, 2 1/2 inches diameter, 3 1/2 inches deep Mercury glass (or silvered glass) is glass that was blown double walled, then silvered between the layers with a liquid silvering solution, and sealed. Although mercury was originally used to provide the reflective coating for mirrors, elemental mercury was never used to create tableware. 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 or a cork inserted into the unpolished pontil scar. "Mercury" silvered glass was produced originally from around 1840 until at least 1930 in Bohemia (now the Czech Republic), Germany and also manufactured in England from 1849 to 1855. Edward Varnish and Frederick Hale Thomson patented the technique for silvering glass vessels in 1849. The English examples were often cased with a layer of colored glass then cut to silver as illustrated in the photograph.Companies in the United States, including the Boston and Sandwich Glass Company, New England Glass Company, Union Glass Co., and the Boston Silver Glass Company, made silvered glass from about 1852–1880. The New England Glass Company displayed a variety of silvered glass articles including copper wheel engraved goblets, vases and other tableware at the 1853 New Crystal Palace Exhibition. Proceeds from this sale go to Heirlooms for Hospice, which is a non-profit upscale resale shop, that supports HopeWest Hospice. HopeWest is dedicated to profoundly changing the way our community experiences serious illness and grief - one family at a time. Please consider the pictures part of the description and examine them carefully using zoom. Items Sold "AS IS." All sales are final....no returns. Be sure to add Heirlooms for Hospice to your favorites list!Check out our other items.