>From my text database (InfoSelect which I highly recommend BTW) with no
attributions:
>Dissolving freshly precipitated ferric hydroxide in a solution 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.
I snagged it of the net, probably here from the list, so its author may be
lurking.
My guess is that the green variety in precipitated out of a strong ammonia
hydroxide solution. I'd try (but don't do this at home kids) putting ferric
sufate in ammonium hydroxide it will hydrate, add the ammonium citrate and
it may form a green precipitate, which could then be filtered removing the
sulfur compounds. Just a guess and guessing in chemistry is dangerous.
Most people would not get beyond the strong ammonia part with out serious
equipmen t however.
Dick Sullivan