Re: Foxlee Gum Process

Dave Soemarko wrote:
>
> I probably should not say too much, but if I only read from the information
> below, I think in the case mentioned, Gallinsky probably just misunderstood
> Marion's writing, and she subsequently did a wrong test and so she couldn't
> duplicate Marion's observation (though from Marion's writing sounds like
> s/he probably didn't quite understand what was really happening either).
>
> What Marion did was to exposed the dicrhomated gelatin *UNDER A NEGATIVE*,
> so the exposed parts get hardened, but there are unexposed parts with
> unhardened gelatin and dichromate left.

Which is also what Galinsky did. If you are assuming that Marion stopped
short of insolubulizing the gelatin, you are assuming something that I
don't see that I have any right to assume from the information I have.

When another piece of undichromated
> gelatin is placed in closed contact with the exposed gelatin, the leftover
> dichromate hardened the undichromated gelatin.

When Galinsky did this, following Marion's procedure except for the
mechanical pressure, she found that this hardening did not occur.

The amount of leftover
> dichromate is proportional to the exposure, which is inverse proportional to
> density of the negative, so Marion got an image. I think humidity would help
> here, but we don't know the condition of Marion's lab.
>
> In Gallinsky test, she exposed dichromated gelatin until maximum
> insolubility! The is no leftover dicrhomate, no unhardened gelatin which to
> retain some moisture.

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.

 No wonder she didn't get any image. But then her
> conclusion is about squeezee!

Her conclusiion is about squeeze because the squeeze was the only
difference between her experimental conditions and Marion's.

That is an example of how we sometimes make
> "logical" conclusion but might not be right because not all the parameters
> or information is known.

And I think that Marion's conclusion was incorrect and Galinksky's was
probably closer.

What it seems to me you are arguing is that Marion got a dark reaction
and Galinksy didn't, because Galinsky didn't have enough dichromate and
moisture left to produce a dark reaction. But since Galinsky had already
demonstrated quite conclusively in another experiment, that with
purified gelatin she could get no dark reaction whatever, the fact that
she didn't get a dark reaction here doesn't prove anything.

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.

Katharine

 
>
> Dave S
>
> ----- Original Message -----
> From: "Katharine Thayer" <kthayer@pacifier.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Thursday, June 24, 2004 6:30 AM
> Subject: Re: Foxlee Gum Process
>
> > Chris,
> > This is quite similar to Marion's 1873 (Phot News 17:242) observation.
> > described by Galinsky in 1930 (Biochemical Journal 24: 1706-1715) that
> > "if a dichromated gelatin film which had become insoluble by exposure to
> > light under a negative were placed in contact with a similar but
> > unexposed film and the two were squeezed together under pressure, the
> > gelatin in contact with the exposed gelatin became insoluble after 8-10
> > hours and a print of the image was obtained. It was concluded that once
> > action was set up by light in a dichromated gelatin film, this could
> > induce the same change in gelatin placed in contact with it, without
> > exposure to light.... The present writer attempted to reproduce this
> > change in the absence of any mechanical influence, and found that no
> > such alteration occurred."
> >
> > She exposed dichromated gelatin until maximum insolubility had been
> > produced, and then added a gelatin coating and left the whole in the
> > dark for 24 hours, then for two weeks, and then four weeks, and found
> > by analysis that there was no change in the added gelatin regardless of
> > the length of time it stayed in contact with the exposed gelatin. She
> > concluded that a more probable explanation for Marion's observation was
> > that the squeezing caused the insoluble material to impregnate the
> > soluble gelatin in contact with it, thus making it more difficult to
> > dissolve, although there was no actual change in the added gelatin
> > itself.
> >
> > Katharine
> >
> > Christina Z. Anderson wrote:
> > >
> > > This list has been so darn quiet this week I figured I might as well
> post
> > > another historical gum blurb!
> > >
> > > This is the oddest process, so just a point of interest that maybe
> > > relates to nothing, or maybe something. It is the "indirect pigment
> image".
> > > Sized paper, gelatin.
> > > paper sensitized with a 2.5% pot bi.
> > > Paper exposed.
> > > Paper developed so nothing remains except a faint positive.
> > > Paper is dried, and can be pigmented right away as per below, or saved
> for
> > > weeks later.
> > > To pigment: 5 parts 40% gum to 1 part glycerin to 2 parts acetic acid
> to
> > > 8-10 grains dry pigment.
> > > Coat and dry the paper, leave under pressure for 30-36 hr, like under
> books,
> > > and then cold water develop, no exposure. It'll automatically develop in
> an
> > > hour.
> > > Based on, get this, Foxlee's idea that the action of light set up in one
> > > colloid is transferred to, and continued in, another which is not
> exposed to
> > > light at all. (mind you, no bichromate has been supposedly washed out
> in
> > > the water). Foxlee prefers to use starch as the sizing colloid, but
> Griffin
> > > prefers gelatin.
> > > Advantages: no rush to develop. Pigmented coat not printed thru so it
> > > doesn't need to be carefully applied. Hardening from bottom up, so it
> is
> > > more durable.
> > > Weird
> > > Chris
> >
Received on Thu Jun 24 12:53:44 2004