Phillip Murphy (pmurf@bellsouth.net)
Tue, 06 Apr 1999 19:44:39 -0700
At 10:06 AM 4/6/99 -0400, you wrote:
> I've always wondered why someone would think of mercury in the early 1800s
>to use for photography. Was mercury known for fine droplets, and therefore
>a good choice for fine detail? Was mercury one of few chemicals that would
>stick to exposed silver nitrate?
>Dick
>
Helmut and Alison Gernsheim's "L.J.M. Daguerre" has many insights into this
question.
Daguerre approached the goal step by step in a long series of experiments
over a span of more than eleven years. Much of what Daguerre learned of
chemistry probably came from Berzelius's "Traite de Chemie" where
Berzelius refers to over one hundred light-sensitive substances. He says
of calomel that "solar light blackens it".
Of course, there's the cute story of the cupboard for the tourists.
However, Gernsheim sites from Mayer and Pierson : "he went on to explain by
what processes he had eventually achieved success step by step.' I first
tried corrosive sublimate ( bichloride of mercury); it marked the images a
little, but coarsely. I then tried sweet mercury or calomel (subchloride of
mercury); this was already better. That day, hope returned to me more
than ever, and brought back my old zeal. From this, it was only a short
step to the vapours of metallic mercury, and good fortune led me to take it'.
Apologies to the list for the PhotoHst response.
-Phillip
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:39:30