Re: Ferric Oxalate Solution?

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From: Joe Portale (jportale@gci-net.com)
Date: 12/23/00-10:35:56 PM Z


Yes, there is a simple test. You need a 5% solution of potassium
ferricyanide (sp?). Take a piece of filter paper or a white coffee filter
and place a couple of drops of your ferric solution on it. Wait a couple of
seconds for the solution to soak in. Then add a drop or two of the cyanide
solution. If your oxalate is good, you will have no or only very pale blue
coloring. If the more ferric present, the darker the blue. If you are
getting anything more than a pale blue, you are in trouble. You may be able
to salvage you ferric oxalate solution by adding, drop by drop, small
amounts of hydrogen peroxide. There will be some fizzing and heat
generated, so go slow. Add the peroxide until there is little or no fizzing
and retest. Hope this helped.

One more thing. Even with heating it will take a bit of time to get all the
oxalate into solution. If by tomorrow morning you still have some sediment,
give the bottle a good shake every couple of hours. It will eventually all
go into solution. I believe the saturation point of ferric oxalate in around
55 to 60%.

Joe

----- Original Message -----
From: Sandy King <sanking@hubcap.clemson.edu>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, December 27, 2000 8:59 PM
Subject: Re: Ferric Oxalate Solution?

>
> Joe,
>
> I heated the solution, but violently in the microwave, maybe up to
> 170F in about a minute. Any way to know if this turned the ferric to
> ferrous? Most of the oxalate, but not all, went into solution after
> the above plus some agitation.
>
> Sandy
>


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