Re: Foxlee Gum Process

> This is simply incorrect. When maximum insolubility of the colloid is
> reached, there is still plenty of unreacted dichromate; Duncalf and Dunn
> for example found 42% dichromate remaining at the point of complete
> insolubility. And as I've already said, Galinsky followed Marion's
> procedure except for the mechanical pressure.

I know, but we are talking about practical use. If they remaining dichromate
trapped in hardened gelatin is enough to produce any reaction, certainly the
total/original amount of dichromate trapped in unhardened gelatine is going
to be more effective.

> And besides, Marion's conclusion wasn't about a dark reaction, it was
> about insoluble gelatin transferring its solubility somehow to soluble
> gelatin. Galinsky concludes, reasonably I think, that the effect was the
> result of mechanical pressure, not of the soluble gelatin becoming
> insoluble as a result of being in contact with the insoluble gelatin.
>

We can believe in anything, but I think we need to take what is more
reasonable. There are other processes where you pour the gelatin on the
matrix (I forgot what the process is called), but the pressure is not a
factor. Again, we can certainly argue that different process is different
process, so one does not correlate with the other, but I think that would be
argument for arguement sake. What is happening in the hardening of gelatin
by dichromate is a chemical process but not a mechanical process (of course
certain mechanical aspects have to be there).

I do not have any favoritism toward Marion or Gallinsky. To me they are just
two names. But my explanation seems to fit *their* data better. I am not
discounting their contributions either, but these are *early* research but
might not have reached maturity yet. If Gallinsky had truly duplicated
Marion's result and then tested it under different situation and couldn't
get an image, I think the conclusion that we can make *today* is still
probably due to humidity difference rather than squeezee.

I do agree that Marion probably made the wrong inference as I mentioned in
my previous email.

I guess I will have to check the original papers. I think Univ. of Michigan
has Biochemical Journal, but I am not sure about Phot News, especially when
it went back so far.

Dave S
Received on Thu Jun 24 13:25:49 2004