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

Mon Nov 25 11:27:10 EST 2024

Hey Tom,
The “floating around” was more of a casual figure of speech than a technical description. The beads were initially noticed adhering to the cotton cheesecloth bags which hold the soft bodies of individually numbered specimens, and upon shaking the jar these droplets/beads fall to the bottom and coalesce. They are certainly denser than the surrounding ethanol.

John Simmons sent me a copy of his article on mercury in wet specimens from the NHMW in Vienna [Collection Forum 2007; 22(1-2):32-36]. In that paper, the authors indicate that the only metal that would be liquid at slightly below room temperature is mercury. The temp of one jar in our collection this morning is 20.1º C. At that temperature, gallium or a gallium alloy would be solid (though some reading suggests there are some gallium alloys that have lower melting points, I don’t have any reason to think these would be present in the sample).

The evidence from the preparator’s dissertation that mercuric chloride was used to prep the specimens in question points to the substance being mercury that fell out of solution. The questions are – what reaction took place, and what are the potentially harmful products of that or subsequent reactions?

-Nate
-
Nathaniel F. Shoobs, Curator of Mollusks
College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology, The Ohio State University
Museum of Biological Diversity
1315 Kinnear Rd, Columbus, OH 43212
614-688-1342 (Office)
mbd.osu.edu<http://mbd.osu.edu/>
________________________________
From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> on behalf of Tom Schiøtte <tschioette at snm.ku.dk>
Sent: Monday, November 25, 2024 4:01:34 AM
To: nhcoll-l at mailman.yale.edu <nhcoll-l at mailman.yale.edu>
Subject: Re: [Nhcoll-l] Safely rehousing specimens contaminated with mercury / mystery Mercuric chloride reaction

Hi Nate, I am no chemist, but I wonder about your initial statement that the silvery beads were ‘floating around in the alcohol’. Do you mean on the bottom of the jar? Mercury weighs 13. 5 g/cm3. Best Tom Tom Schiøtte Collection manager,

Hi Nate,

I am no chemist, but I wonder about your initial statement that the silvery beads were ‘floating around in the alcohol’. Do you mean on the bottom of the jar? Mercury weighs 13.5 g/cm3.

Best

Tom

Tom Schiøtte

Collection manager, Echinodermata & Mollusca

Natural History Museum of Denmark (Zoology)

Universitetsparken 15

DK 2100 Copenhagen OE

+45 35 32 10 48

TSchioette at snm.ku.dk<mailto:TSchioette at snm.ku.dk>

From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Shoobs, Nate
Sent: 22. november 2024 20:30
To: nhcoll-l at mailman.yale.edu
Subject: [Nhcoll-l] Safely rehousing specimens contaminated with mercury / mystery Mercuric chloride reaction

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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