Re: FO sensitizer studies


Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Sat, 30 Oct 1999 00:44:21 -0400


After consideration of a communication from Vicente Vizcay Castro I am
recanting the position as to the 95% ferric oxalate composition of his
FO powder. Vicente makes a convincing argument that his FO powder is
between 98% to 99.5% ferric oxalate. The information in my Guide has
been changed to reflect a 98% FO composition as originally estimated.

I now suspect that there may be some error in Dick Stevens' approach to
calculating the FO concentration from the specific gravity. This may be
due to his use of an impure or undefined ferric oxalate.

Now this does bring about a dilemma as to the ferric oxalate itself.
Some say ferric oxalate is a known compound, while others claim it is
not well defined. I have observed it to have a color of yellow and to
have a color of green. I thought it was supposed to be green, but both
produce identical prints. Some say it requires ligand bonds of oxalic
acid while other ligands may work just as effectively.

Hopefully some of us (with the scientific urge) can dig in and do some
serious analytical and experiment work to understand this beast.

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/



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