Why didn't the Romans invent Photography?
see:
http://www.grand-illusions.com/roman.htm for an explanation with pictures as to how this was done.
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.
