Re: Daguerreotypes again-mercury

Ryuji,

This repeated tale is strictly for the tourists.

The discovery of the Daguerreotype process
was made with considered and methodical experimentation.
A major contributor to this discovery was his partner
Niepce who's goal was to create a new form of lithography.
Unfortunately, Niepce died unexpectedly and the research
which they had shared became the groundwork for the experiments
that led to the discovery of the Daguerreotype.

-Phillip

Ryuji Suzuki wrote:

> From: Etienne Garbaux <photographeur@softhome.net>
> Subject: RE: Daguerreotypes again-mercury
> Date: Mon, 23 Aug 2004 22:50:31 -0400
>
> > Indeed! It was known at the time that silver halides were light sensitive,
> > but what leap of logic made him ask, "What would happen if you suspended an
> > exposed silver iodide plate in mercury vapor?"
>
> Discovery of development in Daguerreotype is said to be accidental,
> when he left an insufficiently exposed plate in his chemical cabinet
> and found images was visualized later. He repeated the same
> experiment, but by removing some of the chemicals each time, and
> finally identified mercury vapor was responsible for development of
> the image.
>
> On the other hand, Calotype used acid pyrogallol solution fortified
> with silver nitrate, which is a physical developer, more similar to
> "silver intensifier" solution (like Kodak IN-5) than commonly used
> chemical developers. It took many years to realize alkaline pyrogallol
> without silver nitrate was a better (chemical) developer, which was
> after silver gelatinobromide plates. But then, a race was started to
> search for a new, better developing agent.
>
> --
> Ryuji Suzuki
> "You have to realize that junk is not the problem in and of itself.
> Junk is the symptom, not the problem."
> (Bob Dylan 1971; source: No Direction Home by Robert Shelton)
Received on Wed Aug 25 05:41:49 2004