Phillip Murphy (email@example.com)
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?
Helmut and Alison Gernsheim's "L.J.M. Daguerre" has many insights into this
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.
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:39:30