Sorry, in my haste I seem to have forgotten to finish a couple of
sentences:
>
> Katharine Thayer wrote:
> >
>
But yes, if you had a situation like this, where
> there is still soluble dichromate that hasn't been completely washed
> out, then the basic chemistry Alberto has described here with regards
> to Cr(VI) and sulfite/bisulfite should apply, and combining this stain
> with bisulfite should form a green product,
and combining it with sulfite shouldn't.
>
> 2. A yellow dichromate stain (an actual stain that can't be washed out
> no matter how long the soak) which I have seen only a few times: once
> while testing papers I found that certain papers and sizes in
> combination with each other would hang onto the dichromate and not let
> go of it, and several times when I have dripped dichromate onto the
> glass of the coating surface and not noticed it, and the dichromate
> makes a spot on the back of the paper. This kind of stain I daresay
> would behave chemically the same as the "stain" in (1), since it is
obviously still Cr(VI).
kt
Received on Fri Oct 15 12:06:34 2004
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