It would probably help others on the list if you kept matters such as Tetris 
out of it - already there will be some thinking it is some new trick that 
you have for producing gums. What is tetris and where can we buy it?.... Judy 
will be fomenting over yet another brit conspiracy.
Keith may get something from me at some time - whether he wants it or no. 
I have one or two points to sort out on something I wrote at Christmas.
To dichromate/colloid reactions. First the redox must involve something 
other than the chromium compound - this gets reduced so something must get 
oxidised. Dichromate is not too fussy about what it chews up, and this is 
likely to be part of the colloid. The likely fate of most of the oxygen in 
the dichromate is as water. I don't have any books that deal with 
these reactions in detail, but assume that the gum becomes insoluble 
through the presence of the chromium(III) ions (as in hardening using chrome 
alum) rather than by the oxidation reaction.
I think I have read something about the chemistry involved in this hardening 
on this list.
A Ph.D in Chemistry only evidences that one has spent 3 years or so scratting head 
down in a peculiar corner of the backyard (I speak from experience). I think I 
blinked while colloid chemistry was being dealt with in my undergrad course. 
Of course we chemists (or ex-chemists in my case) are generally in favour of a quiet 
life and are likely to nod politely when confronted with chemical ignorance on a 
grand (or even king-like) scale:-) I'm sure that I or even others more qualified 
would be willing to suitably doctor anything chemical you care to write on the 
subject.
Peter 
petermarshall@cix.compulink.co.uk
PS. To save _further_ unnecessary comments: Tetris is a game. Netris is an even 
smoother version of it, suitable for multiple players on a single Windows PC or over 
a network. Inetris lets you play it against others over the Internet.  If really 
desperate, got to: 
http://www.dur.ac.uk/~d405ua/             * fiction, art, links and...
>> s0ftware f0rge programs * entertainment : MIDI utilities * Win 3.1/95
>> latest feature * iNETRiS 2.0 internet tetris release! * req. Win 3.1+