This is probably the weirdest thing I've ever heard about the
jewelery trade. I'm sure nobody does this now, but is there any
truth to this ever having been done in the past? I can't even
fathom how one could dissolve gold in mercury to begin with, let
alone how you could get it back out again to use it...
I’d agree that jewelers don’t store their gold dissolved in mercury,
simply because a good safe is so much easier and safer. But gold does
indeed dissolve in mercury. That behavior is the basis of the old
style method of gilding silver with gold, as well as ancient methods
of refining gold, still tragically used today in many primative gold
mining operations, especially in latin america, where it’s use not
only poisons the people doing it, but terribly pollutes the rivers
and waterways downstream. All you do to dissolve gold in mercury is
simply put it in. Like solid silver added to molten gold, the gold
dissolves in the molten mercury (liquid at room temperature, but
still a molten metal, after all). In primative refining, the ore is
mixed with mercury, where gold in the ore dissolves in the liquid.
That’s then seperated from the remaining solid ore (sands, etc) and
the mercury is heated to vaporize it, leaving the gold. At best, this
is done in some version of a primative still so as to recondense and
recover the mercury, but usually that’s only partially efficient,
resulting in mercury contamination of the area, and slow poisoning of
the people doing it. In fire gilding, the same method is used. An
amalgam (liquid to pasty mix of mercury and gold) is spread out on
the silver item to be gilded, and it’s then heated to drive off the
mercury, leaving the gold as a layer on the surface. Similar
unfortunate consequences (short lifespans, early death, neurological
damage, etc) as with the refining operations doing this, are why
fire gilding is not generally done much today…
As to hiding or disguising gold items with mercury, though I’ve not
heard of it being specifically done, it might have been. Coating a
gold item with mercury causes the mercury to diffuse into the gold
surface. If there’s enough, this results in a fairly white metal
color, rather than a gold color, with some surface degredation, such
as to the polish, but not necessarily all that much (a good polishing
would be required later. Again, heating to a low red heat would
vaporize the mercury again at a later date. I can see how such a
plan might have been used in some desperate wartime situations, but
certainly not as any sort of routine practice. Probably, I’d guess
painting the object would have been easier… In both cases, the
obvious density / weight of the object might still easily give away
the deception. Imbedding the object in a ceramic covering (the gold
could withstand low temp firing of the clay) might work better, since
then the larger ceramic might not be quite so obviously too heavy…
Peter Rowe