[wordup] Why didn't the Romans invent Photography?

[Adam Shand]

This is just kinda cool, see the web site for pictures of it all in action ...

From: The Eristocracy <Eristocracy at merrymeet.com>
URL:  http://www.grand-illusions.com/roman.htm

Why didn't the Romans invent Photography?
Or how to bend nature to your will 

The word photography comes from the Greek "photos", meaning light, and
"graphos" meaning drawing, but the ancient Greeks didn't invent
photography. The word camera comes from the Latin "camera", meaning room,
and "obscura", meaning dark. It's not surprising the Ancient Greeks didn't
invent photography, after all, they never liked to get their hands dirty,
but the Romans, who would have been at home in the "Dark Room", could have
invented photography, but never did. Why?

Nowadays, most people take photographs. Remove the modern cameras and
film, and many homes still contain the things needed to produce a
photograph, things which the Romans could have had access to as well.

What do we need to produce photographs?

 * A dark room or box 
 * Lots of light 
 * Something which is sensitive to light 
 * A way to focus the light 
 * Chemicals that will reveal and fix the image 

Until the recent development of digital cameras, most photography involved
the use of films coated with various light sensitive compounds of silver.
The sensitivity of certain silver salts to light was known from about
1727, when Johann Heinrich Schulze published his findings in the Nuremburg
Academy of Natural Philosophers. But many natural things are sensitive to
light. Long ago people noticed the effect of light on green plants, or how
it made coloured fabrics fade. It is the effect of light on plants that
makes Roman Photography possible.

This is what you need:

 * One healthy geranium plant with large leaves 
 * A dark room or large box 
 * A slide projector 
 * A slide of a high contrast negative image 
 * Methylated spirits or other strong alcohol 
 * Tincture of Iodine from a pharmnacist 
 * Various pots, jars, trays and small boxes 

How it all works:

The chlorophyll in healthy green leaves captures light and uses its energy
to join together carbon dioxide and water. The result is the organic
compound we call starch. It is the basis of much of the food we eat.
Starch is white, but if you drop a small amount of a solution of iodine on
it, the starch turns black. So that's it really. All you have to do is get
a plant to produce lots of starch in the right place, then stain the
starch with iodine. Don't let a few details prevent you starting straight
away.

Keep the geranium in a dark room or box for two days.  During this time
the plant will use up all the existing starch in the leaves. Snip off one
leaf, leaving plenty of stalk attached. Fix the leaf flat against the
outside wall of a small box, gently push the stalk through a hole in the
box.

Arrange for the cut end of the stalk to rest in a dish of water, to keep
the leaf fresh. You can use sticky tape to keep the leaf reasonably flat.
In a dimly lit room project a small but very bright image onto the leaf.
Leave it to expose for about four or five hours, depending on the
brightness of the projected image. After the exposure you should be able
to see the effect of the light on the leaf, in the form of a faint, pearly
image.

Now comes the violent bit. You have to kill the leaf, for the good of your
art, you understand. Drop it in boiling hot water. After a minute or two,
remove the now very limp leaf and place it in a bowl of cold water. Allow
the leaf to fan out to a mere remnant of its former self. It should look
like a fragile translucent pale brown thing, floating on the water.

Place a few drops of Tincture of Iodine on the surface of the leaf; after
twenty or thirty seconds rock the bowl gently to spread the iodine.  
Slowly the positive image should appear, your first, and possibly last,
photo on a geranium leaf. You have to keep the leaf in water, and after a
few hours the image may fade, but you can restore it any time with a
little more iodine.

Our portrait of a man has come out slightly dark, but hey - this is
experimental science! If you know of any improveents to this method, we
would be very pleased to hear about them.