[Nhcoll-l] Safely rehousing specimens contaminated with mercury / mystery Mercuric chloride reaction

[Shoobs, Nate]

A question for the chemists in the room:

In examining a jar of freshwater bivalves from our wet collection, a student and I noticed that there were small silvery beads floating around in the alcohol. Upon closer inspection, we realized that these beads were actually liquid – to my eye, it looks and acts like elemental mercury (the droplets readily coalesce and break apart, are silvery white, and denser than the surrounding alcohol).

Here’s what we know about the contents of the jar:

  *   I figured the fixative used on these specimens contained a mercury compound, and found this information, in the doctoral dissertation of the preparator of the sample:
     *   “ The entire body of each animal was fixed whole, usually in FSA fixative (40 g mercuric chloride, 50 ml glacial acetic acid, 200 ml. commercial formalin, 800 ml distilled water) (Movat, 1953). After 24 hours In this fixative, the soft parts were rinsed In tap water and dehydrated in 50%, 70%, and 80% ethanol. They were stored In 80% ethanol until needed.”
  *   The specimens are currently, to the best of my knowledge, stored in a solution of “AGW”: (75% nondenatured ethanol, 3% glycerine, 22% distilled water).
  *   There is a metal tag, either steel or aluminum, in the jar, which is disintegrating, turning green, and forming many small grey tube-shaped tendrils of precipitate.
     *   The tag is not magnetic, but I don’t know if that’s because it has completely reacted, or because it is aluminum. I know that aluminum + water in the presence of ethanol tends to form Aluminum hydroxide, but this precipitate does not appear to be. It was curatorial practice from 1960-2019 to include a metal embossed tag with the cat number in wet lots, but I abolished this practice because of the tendency of metal to react with the preservatives.

  *   It seems evident that because there is free mercury in the jar, the mercuric chloride reacted with something in the jar. The green tinge in the alcohol makes me think that that reaction yielded some amount of chlorine gas, as well.


These are important voucher specimens, and ideally I’d like to figure out a way to safely rehouse them and keep them long term, but if there is no way to ensure they aren’t a health hazard going forward, I will contact our EHS department to coordinate disposal. Does anyone have any experience with a situation like this?

Obviously I am not opening the jars or letting anyone else near them until I can figure out what reaction(s) took place in the jar. And unfortunately, this is one jar of a few dozen 1~3 liter Le Parfait bail top jars prepared by this researcher.

-Nate
--

[The Ohio State University]
Nathaniel F. Shoobs
Curator of Mollusks
College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology
Museum of Biological Diversity, 1315 Kinnear Rd, Columbus, OH 43212
614-688-1342 (Office)
mbd.osu.edu<http://mbd.osu.edu>
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