Re: Van Dyke precip. A Cure

Richard Sullivan (richsul@roadrunner.com)
Mon, 08 Sep 1997 09:19:07 -0600

At 03:02 AM 9/8/97 -0400, you wrote:
>Message text written by Richard Sullivan
>>
>>The reason is that ferric ammonium citrate is an ill defined compound. If
>you look in your Merk Index you will see that it does not have a chemical
>formula. Every batch may be different. I suspect that the manufacturers are
>getting *better* at making it.
><
>
>How does one make it ?
>
>
>Terry King
>

Terry,

Notes from my text database say:
>Dissolving freshly precipitated ferric hydroxide in a soln of ammonium
>citrate in the correct proportions, then evaporating is supposed to
>produce the brown version. Perhaps the green version could be produced
>by using an excess of ammonium citrate.

Sorry I can't quote the source for this statement but it was likely from
the List.

As Mike Ware has said about ferric oxalate it is ill defined. I think that
the molecules join hands in different was each time and do a different
dance. I dunno. I do know that it works after adding the extra tartaric acid.

Cheerio.

Dick
Bostick & Sullivan
PO Box 16639, Santa Fe
NM 87506
505-474-0890 FAX 505-474-2857
http://www.bostick-sullivan.com