Collecting, precipitating and then handling the finished product may not be
desirable either.   You still have to handle toxic mercury compounds,
including any filter papers used to collect the mercury pptd by another
compound. I guess it comes down to how much work you want to do, cost and
time effectiveness, which may turn out to be more than just having it
collected for controlled proper disposal.   

All this is an additional risk to handlers, potential spills, etc.  It may
be easier to bite the bullet and just have the solution collected, better
yet, not use mercury based fixatives, and go to another.  True, B5 is
excellent, but pathologists CAN learn to read tissues fixed with a mercury
fixative substitutes, since some complain about cells not looking a good. 

We opted to not use any mercury compounds because of all the extra work,
have it collected. 




Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303