Observing the world - The chemistry of almost everything (24/31)

Uploaded by OUlearn on 03.09.2009

It was just a hobby like so many others,
a bit of an expressive outlet.
And I followed the usual course, going to clubs and so on,
meeting other fellow practitioners.
Then by pure chance in my reading,
I discovered that there were other ways of doing it.
And being a chemist these other ways which had long gone out of use,
aroused my curiosity.
In the same way a composer might choose a key for a piece of music,
I could choose a colour or a surface texture for a particular image.
I believe that we do have a common route, science and art,
which is the observation of the world.
It isn't widely appreciated that there is a strong visual element
in chemical understanding.
A chemist thinks in terms of shape and form,
spatial relationships, filling space.
These, after all, are ideas which are quite common to the artist
and the architect and the designer.
The difference being that the chemist
is thinking about matter at the sub microscopic or atomic level.
In the earliest days of photography it was by no means obvious
to the experts who were then investigating it
which metal exactly was going to provide the royal road to success.
Talbot, on the one hand, was working with silver
and we know that that is now what has come down to us
and he's acknowledged as the inventor of photography on paper.
But Sir John Herschel at the same time and in collaboration with Talbot
was working with gold, platinum, Prussian blue, with plant juices,
a whole host of other ways of making photographic images.
The iron compound that goes into the sensitiser
is inherently unstable but it doesn't decompose
except when light falls on it and quite energetic light, at that,
the ultraviolet light that those tubes emit.
So the light supplies the energy to lift that compound over the barrier
and it decomposes.
Then what is left, the decomposition products
react with the precious metal compound to precipitate metal
as the image.
So you see where the light has come through the negative
it's caused a chemical reaction
which has precipitated platinum and paladium.