[Nhcoll-l] Crystal Formation From Evaporated Holding Fluid

[Simon Moore]

Hi Joanna,

Given the tiny amount of fluid left in the jar, I would extract a few drops and test them with a drop or two of either Schiff or Feulgen reagent.  These are used to test for the presence of aldehydes (as in formaldehyde)  and which turn magenta, rapidly and deeply if the formaldehyde concentration is strong and proportionally weakly for more dilute solutions.  If this is formalin (I suspect that it may well be so) then the crystals are very likely a buffering salt such as sodium phosphate mix - NaH2PO4 and Na2HPO4 or sodium b-glycerophosphate.  If the test is Schiff negative (no colour change) thenI regret to say you’re back to stage 1.

If you wish to rehydrate the lizard then some Decon-90 diluted to 5% in warm water works well but beware as this process can harm DNA. However, if the specimen has been in formalin for that long then the DNA sequence will have altered in the long immersion in formalin.

Always use gloves but never when handling wet jars (slippery) and extract the specimen under water if it’s a tight-ish squeeze, through the neck of the jar.

Hope that this helps.

With all good wishes, Simon.

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian, 



www.natural-history-conservation.com 




> On 6 Jul 2018, at 00:15, Joanna Chu <jchu at csumb.edu> wrote:
> 
> I came across a horned lizard specimen while going through jars from an old donated collection. Its holding fluid has totally evaporated and there has been a lot of large crystal formation (see photos). I do not have any information on how this specimen was fixed or what was in the holding fluid. I'm concerned about potential hazards with handling this specimen due to the crystallization (reactivity, explosive, etc.). Any information on what these crystals might be and how to safely handle the specimen would be greatly appreciated. 
> 
> Thanks,
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