short explanation of Silvered or Mercury Glass:
Mercury glass or Silvered Glass, as it was sometimes called,
is double-walled glass with a coating of silver-colouring
on the inside. This gives it the appearance of silver
and in the 19th century this was a much cheaper product
than real silver, for such things as church candlesticks.
Hence the name "Poor Man's Silver".
reason it is sometimes called Mercury Glass is because
in the early days the internal coating was sometimes
mercury or a mercury product. However mercury proved
unsuitable and very little silvered glass has mercury
on the inside. Silver nitrate was used instead.
hole on the bottom which allowed access for pouring
in the silver coating, was sealed with either a metal
or glass disc, in theory to keep the silvered surface
from tarnishing. Whether or not the silvered surface
is damaged when the disc has been missing for some time,
seems to vary. It is easily damaged if water is allowed
into the hollow space between the inner and outer layers
vase below is etched with ferns and foliage and has
a gold coloured interior. It is German from around 1880.
kind of glass was first made in the 1840s, and patented
in England in 1849 and in the USA in 1855. The English patented
pieces are sometimes marked E. Varnish & Co. or F. Hale
Thomson; the USA pieces are sometimes marked with the New
England Glass mark. Its popularity waned about 1885.