Re: was Bone Marrow (now rather long ...)
RSRICHMOND@aol.com wrote to Cliff and to Histonet:
> Pathologists need saws, and what they want varies ...
> ... Satterlee saw is over $70 ... double-bladed ... $500 ...
> ... Good Management, so I routinely go to a hardware store
> and buy a five dollar hacksaw.
Good on yer, Bob! But why do you _routinely_ buy hacksaws?
I've had the same one for about 25 years. I don't use it a
lot, and only on wood, plastic and the occasional bit of
metal, but this week it's still doing well on its second
blade. Are femora so tough that they wear out the frame?
Otherwise, concerning bis-chloromethylether:
> Uh, Cliff, you left something out here - do
> Decal and Decal-Stat contain hydrochloric acid? - I've
> heard the bis-chloromethylether story and I've also heard
> it's an urban legend. John Kiernan, do you know the answer
> to this? I don't.
My understanding of this is based on Walker's big 1964 book
called "Formaldehyde," a prized possession that has been cited
in many of my Histonet utterances concerning formaldehyde,
paraformaldehyde, formalin etc. The bibliographic data will
be in the archives at www.histosearch.com many times, so I
won't repeat them again. The reaction that generates
bis(chloromethyl)ether, (ClCH2)2O, occure between two
gases - formaldehyde and HCl. The hydrochloric acid we
use as a liquid is a solution of the gas in water. It does
not contain any HCl molecules, only hydrogen ions and
chloride ions. There is a low concentration of HCl molecules
in the air above concentrated hydrochloric acid, which is
a near-saturated solution. The air above dilute hydrochloric
acid contains no HCl molecules. Formaldehyde (HCHO) is also a
gas, but in aqueous solutions it present as an addition
compound with water called methylene hydrate. There is a
low concentration of formaldehyde in the air above any
solution of formaldehyde in water.
The reaction that generates bis(chloromethyl)ether could
occur if fumes from concentrated hydrochloric acid were to
mix with formaldehyde fumes from a fixative. With diluted
hydrochloric acid this is not a risk. Mixing dilute
hydrochloric acid with a formaldehyde solution will not
generate the dreaded bis(chloromethyl)ether. Walker's
book was published nearly 10 years before the hoo-ha
about bis(chloromethyl)ether was brought up. In the 1970s
the safety people were saying, "don't pour formaldehyde
and hydrochloric acid into the sink at the same time."
This was reasonable advice, even if it erred on the side
of caution. I've not seen any bis(chloromethyl)ether doom
predictions since about 1978. If I've missed out in a
big way, I hope someone will come to the rescue, and
provide suggestions for reading up in this field.
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London, Canada N6A 5C1
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