[NHCOLL-L:1289] RE: testing fluid solutions

[Panza, Robin]

>>>Julian.Carter at nmgw.ac.uk> 01-10-16 4:27:00 am
...found using the Paar density meter of more benefit. The density readings
Robin gave are similar to my own results. <<<

What bothers me is that we put specimens in ethanol-water after fixing in
formalin.  Even after soaking, there's some formalin leaking into the
storage solution, so it's ethanol-water-formalin.  If formalin is heavier
than water and ethanol is lighter, how can a densitometer measure proof?
When the density reads 70%, is the ethanol concentration actually higher
because the water-formalin is denser?  How much formalin contamination is
"ok"?  

Ideally, we'd periodically replace the solution, rather than just "topping
off", so we'd be removing trace formalin and accurately measuring the
ethanol content, but who can afford to do that frequently?

Robin K Panza                         panzar at carnegiemuseums.org
Collection Manager, Section of Birds          ph:  412-622-3255
Carnegie Museum of Natural History       fax: 412-622-8837
4400 Forbes Ave.
Pittsburgh  PA  15213-4008  USA