Klaus
I was a chemist and I'm not sure I understand either. It looks as if the
author of this didn't to me
>
> 2 K2Cr2O7 -> h*v -> 2 K2Cr2O4+ CrO2 +O2 (The h*v should be over the
arrow)
>
> another aproach is::
>
> 6 h*v + 3 K2Cr2O7 + 6 H -> (CrO2)CrO4 + 6 KOH
>
> It is not clear yet, which compound has the tanning effect. On one hand
the
> Chromichromate with the formula Cr2O3*CrO3 or CrO2 is considered, but on
the
> other hand the reaction product CrO2 or (CrO)2CrO4 is discussed.
I think these things above are just sort of formal ways of looking at the
reaction (also there are some things missing from them) which probably have
little relation to what is going on. I suspect the real bit is what follows:
>
> Newer research shows, that stable Cr(III)-compounds are creating a
crosslinking
> of the gelatin.
In other words it doesn't really add anything to the brief comments made on
the subject last week.
Peter Marshall
petermarshall@cix.compulink.co.uk