Re: ferro vs ferri
From: Trevor Cunningham <tr_cunningham@yahoo.com> Subject: Re: ferro vs ferri Date: Thu, 30 Aug 2007 22:05:36 -0700 (PDT) > The local company stocks what they call potassium > hexacyanoferrate, but when I ask them about the (III) > portion of the nomenclature I begin to loose clarity. That's plain unacceptable. But if the chemical dealer sells the same stuff as ferrocyanide, then that just gives you the info ... it's (II). You could also ask for the CAS number. Another way is to demand a sample and test it yourself. You can make a solution of the stuff, hook up two steel nails with a 9V battery, and immerse the nails into the solution. If you see the anode forming prussian blue pigment around it, it's (II). Or you can mix it with ferric chloride or something and see if it makes the pigment. If you immerse processed b&w print into the solution and if the image becomes lighter, it's (III). > Did you happen to write how to make K-Ferricyanide from > scratch? I didn't and I wouldn't. The thing is that you must have a serious safety facility and willing to go through the steps to make it. However, if what you need is K-HCF (III) you can make it from a solution of K-HCF (II) by completely oxidizing it with moderately strong oxidizing agents, such as ozone or peroxide, and then removing excess ozone or peroxide by evaporating the solution in vacuum or something. This is a bit safER than making it from scratch, but the process is involved and again, it's probably more than what you are willing to do. Simply, in this case, no amount of help I can give you here can substitute for a competent chemical dealer. -- Ryuji Suzuki http://silvergrain.org
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