I am an PhD student (emphasis in inorganic). I am currently working with a local high school chemistry teacher to put together lessons and go through all the stuff left behind by the very old chemistry teacher who retired. We found a large, sealed test tube (ampule) with mercury and some blue crystals in it (the crystals resemble pieces of cobalt glass). I've seen this before, but it was red crystals last time (I don't think they were cinnabar, but maybe.) I think it's used to demonstrate some chemical or physical properties. Beyond that, I'm clueless. Also, the old chemistry teacher, who was there for over 30 years, said that the tube was purchased by some teacher before she taught there. So, it's a very old demo, and I can't find it in any science teacher supply catalogs. Anybody have any idea? I have a pic, but I don't know how to post it here. Thanks for any help.