Re: Daguerreotypes again-mercury

From: Phillip Murphy ^lt;[email protected]>
Date: 08/25/04-05:41:35 AM Z
Message-id: <>


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.


Ryuji Suzuki wrote:

> From: Etienne Garbaux <>
> 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

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