When I first saw these items, "mercury glass" was something that immediatly came to mind.
I collect antique kerosene lamps, and with some of these, the inside of the base (not the font where the fuel was placed or inside the glass chimney) is "silvered" with mercury. Depending on the age, quality of the silvering, how the lamp has been stored and cared for, this silvering can hold up fairly well or deteriorate.
Mercury was also used in gold plating items - it was one of the best ways of applying a smooth uniform layer of gold over the surface of an object, such as jewelry.
The problem is, of course, that mercury is highly toxic, particularly in the heat processes used for this "silvering" and gold plating. The mercury is turned into a vapor and driven off to leave the gold behind, or turned into a vapor to cover the glass item with a fine coat of the red powder mercury turns into when heated, then heated again to turn it back into a coating of silver colored mercury.
Basically, due to the lack of filtration and recovery systems way back when, anyone who worked around mercury ended up being poisoned by it and dying a horrible death. The old master goldsmiths who were best at this mercury plating all died from it, and their experience and knowledge was lost.
This is also why many of the famous "lost gold mines" of the Old West became lost - people would find rich deposits of placer gold in sand/gravel/soil, use mercury to trap and extract the gold (high content gold ore in rock would be pulverised with sledge hammers or a primitive chain and rock "arrastra" grinding mill), then the gold/mercury amalgam would be packed into potatoe skins and placed in the glowing coals of a fire. The heat would vaporize the mercury, leaving a solid egg-shaped lump of gold. Of course, all these "Miner '49er" types would stand around in a circle going "Is it gold yet?" waiting to recover their little ingots, and would be poisoned by the mercury. Sometimes one would survive long enough to make it back to the nearest thing that passed for civilization with a saddle bag full of these gold lumps, give a vague description or draw a sketchy map, then die.
So what I am wondering here is, when the use of mercury for silvering decorative glassware like lamp pedestals and Christmas ornaments was discontinued or went out of general use in Germany, and if there is any non-destructive way to determine if the silvering in an object uses mercury - (not tarot cards, a lava lamp, and a double-barrle rectal thermometer, that only works on German helmet paint)
For instance, if the use of mercury was discontinued or forbidden in 1933 (I'm just using this date as an example, not attaching any real significance to it here and now), objects containing mercury silvering could be reasonably dated to that period and maybe a couple years afterward as existing supplies were used up.
Same with the manganese that made glass clear, but absorbed UV rays fron the sun and later turned purple. Most of the manganese came from Germany, and the supply was cut off in WW1 in 1914, due to both the British blockade of German shipping and the German's own embargo on selling it because they needed it for their aircraft engines. There was also limited manganese mining in the U.S. that continued to be used in glass up to the early 1920's and earlier manganese glass items were sometimes used for years after 1914, but with the cut-off of cheap and plentiful manganese from Germany, other processes for making glass clear were developed. So when you find an old homestead, mining, etc. site out in the desert, the presence of sun purpled glass fragments is helpful in dating the site. Lots of purple glass means generally a 1914 or earlier used site, lower quantities or the absence of it points to a later date.
