Gold and mercury form an amalgam, so you would still have had something that looks like a big hunk of metal. I suppose you wouldn't have known whose gold that was, but the fact that you had a large chunk of gold-mercury amalgam in the lab would have been not so good.
Edit: Looking at some videos, it appears you could get something that looks like regular mercury. I'm wondering how much mercury you would have needed to solubilize a medal. They may also not have had that much on hand, HCl and nitric acid are way easier to find.
> They may also not have had that much on hand, HCl and nitric acid are way easier to find.
At the same time, Mercury use was way more widespread than now in laboratories, so it may have been readily available as well. A number of things were banned or heavily restricted for laboratory use in relatively recent history (80s~90s).
Sure, but if you have a sufficient amount of mercury, that amalgam will remain invisible to the eye as Mercury is not translucent - and you can just write "mercury" on the flash and you can be sure no-one will dare to touch it.
When I was at school (1980s) the teacher had us line up and put our fingers in a flask of mercury. It was a very peculiar sensation. I probably wouldn't want to repeat that "experiment" today.
Sure, I'm not saying the general knowledge of mercury poisoning was commonplace back then, but in the scientific community it was, I believe, well known already.
Mercury poisoning has been known for some time, however people in the general public knowing or caring about mercury poisoning is a pretty recent phenomenon.
Edit: Looking at some videos, it appears you could get something that looks like regular mercury. I'm wondering how much mercury you would have needed to solubilize a medal. They may also not have had that much on hand, HCl and nitric acid are way easier to find.