|Table of Contents for Caveman Chemistry: 28 Projects, from the Creation of Fire to the Production of Plastics|
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It has already been observed, that when a solar spectrum falls upon paper covered over with chloride of silver, the chloride turns black in the more refrangible regions, and from this and similar experiments we have been lead to the knowledge that there exists in the sunbeam a principle which can bring about chemical changes.
This fact has been perceived from the beginning of the present century; but, of late, much attention has been given to these rays, and from a consideration of the phenomena they exhibit, I have endeavored to prove that they constitute a fourth imponderable principle of the same rank as heat, light, and electricity; and for the purpose of giving precision to this view, have proposed that they be called Tithonic rays, from the circumstance that they are always associated with light; drawing the allusion from the classical fable of Tithonus and Aurora. …
The process of the Daguerrotype depends on the action of the Tithonic rays. It is conducted as follows: A piece of silver plate is brought to a high polish by rubbing it with powders, such as Tripoli and rotten-stone, every care being taken that the surface shall be absolutely pure and clean, a condition obtained in various ways by different artists, as by the aid of alcohol, dilute nitric acid, &c. This plate is next exposed in a box to the vapor which rises from iodine at common temperatures, until it has acquired a golden yellow tarnish; it is next exposed, in the camera obscura, to the images of the objects it is designed to copy, for a suitable space of time. On being removed from the instrument, nothing is visible upon it; but on exposure to the fumes of mercury, the images slowly evolve themselves.
To prevent any further change, the tarnished aspect of the plate is removed by washing the plate in a solution of hyposulfite of soda, and finishing the washing with water; it can then be kept for any length of time. …
There are many other photogenetic processes now known; several have been invented by Mr. Talbot; among them may be mentioned the calotype. Sir J. Herschel, also, has discovered very beautiful ones, and these possess the great advantage over Daguerre's that they yield pictures upon paper. In minuteness of effect they can not, however, be compared to the Daguerrotype.
Well, where is the Figment? This is his chapter, is it not?
Looks like he's out of the picture.
Speaking of writing on the wall, I guess that photography really started with the invention of the camera obscura, which is basically just a dark little room with a hole at one end. Light from outside comes in through that hole and projects an image of the outside scenery on the wall. Folks had been using the camera obscura since the sixteenth century, tracing the projected image onto paper with a pencil.
All well and good, but you cannot consider a pencil drawing as a photograph. More fundamental to the birth of photography was my discovery in 1725, in the person of Johann Schulze, that silver nitrate darkens upon exposure to light. In modern photography it is from exposed silver salts that the photographic image is ultimately formed.
Formed, yes, as long as this image remains in the dark of the camera. But bring it out into the daylight and the whole shebang turns black. You are probably wondering how this image may be "fixed" permanently. I will tell you. In 1819 John Herschel discovered that aqueous sodium hyposulfite dissolves silver salts, most of which are otherwise insoluble in water. So by soaking your image in such a solution, the unexposed silver salts are washed away while the exposed areas remain. Voila! A permanent photographic image.
Now hold on there, cowboy. That's a heck of a theory, but it's still not a photo. Seems to me that the prize for first permanent photo goes to Nicéphore Niépce for his 1826 snapshot of the view outside his window.
Snapshot, indeed! The exposure took eight hours.
So? Anyhow, in 1829 Niépce hooked up with Louis Jacques Daguerre, who was wowing theater audiences with his elaborate special effects. Daguerre's "Diorama" involved projecting light through huge semi-transparent paintings, the motion of the lights and the paintings set to music. Daguerre used the camera obscura to sketch his huge paintings and looked to Niépce for inspiration on eliminating the tedious sketching. Niépce died in 1833, but not before Daguerre had caught the "photo bug." In 1837 he succeeded in producing a photo on silver-plated copper, developing the image with mercury vapor and fixing it with a solution of ordinary salt. All with an exposure under 20 minutes.
Impressive to him at the time, no doubt, but still not a photograph as we understand the term today. Both Niépce and Daguerre produced images on opaque metal plates. With such a system there is no way to copy the image, no way to enlarge it, no way to project it onto a screen. Without duplication and projection the I-dea of the motion picture would not have materialized; without motion pictures, no television; without television, no computer monitors. The metal-plate image is simply a fluke, an evolutionary dead end. I produced the first true photograph in 1835 in the person of Fox Talbot. This 10-minute exposure on translucent paper of the view through the windows of Lacock Abbey resulted in an image which could be projected, enlarged, and reproduced; all fundamental properties of photographs as we know them today.
An image which, like Daguerre's of 1837, deteriorated over time because silver salts are generally insoluble in water. In both instances the residual silver salts darkened with time, spoiling the original image. What can be a more important property of a photograph than that it should be permanent? I must remind you that Herschel discovered the solubility of silver salts in sodium hyposulfite in 1819 and I must further point out that he informed both Talbot and Daguerre of this in 1839, marking the beginning of true photography.
A step forward, to be sure.
It was a hum-dinger. Thanks. But to get back to the story, these Talbot prints were pretty fuzzy, as opposed to daguerreotypes, which were sharp as a tack. And what's more, talbotypes were funky, in that the parts of the photo which ought to be black were white and the parts that ought to be white were black. When you think about it, the talbotype image had everything except what was supposed to be there. In the daguerreotype, the parts of the photo which ought to be white were shiny silver and the parts that ought to be black were dark copper. Awesome! Napoleon III liked the daguerreotype so much that he gave Daguerre a nice pension and released the process to the public as a benefit to the human race.
Except in England; you were careful to patent the daguerreotype in Talbot's homeland. And for your information, the "funkiness" you complain about is called a negative image. It is a feature, not a problem. When you expose a second paper through the negative, the resulting print is a positive. My further research revealed that the image forms even before it is visible and that this latent image can be developed using gallic acid. I patented as this calotype process in 1842 and was able to use exposure times of 30 seconds, making portraiture possible.
That is, if you like fuzzy, funkified portraits. Plus, you had to pay for a license to produce calotypes, whereas daguerreotypes were patent-free (except in England). It just sounds too complicated to me, what with invisible negative latent images and all. Most folks agreed, and the daguerreotype business really took off, leaving the calotype in the dust.
Of course, the fuzziness of the calotype stemmed from the fact that the image penetrated the paper. A sharper negative image would result if it were produced on a glass plate rather than on paper, a suggestion Herschel made in 1839.
I was getting around to that; as Frederick Archer I formed an emulsion of silver salts and collodion on a glass plate in 1850. This thin emulsion enabled the production of sharp negatives. And in that same year, in the person of Louis Blanquart-Evrard I applied a similar technique to paper prints; I mixed silver salts with egg whites, forming a thin emulsion which coated only the surface of the paper. This "albumin paper," in combination with the collodion-glass negative, produced prints as sharp as the daguerreotype. With no way to duplicate or project daguerreotypes, it was only a matter of time before they went the way of the gaslight.
Well, it was a good business while it lasted. Eventually everybody and his dog had a somethingtype process named after him, what with little improvements here and there. The daguerreotype had made photography practical enough that pretty much anybody who wanted a picture could have one taken. But even the new-fangled somethingtypes had to be developed right after exposure, so unless you had a photographic darkroom, you couldn't take your own pictures. Then in 1889 a fellow named George Eastman, in the practical down-to-earth spirit of Daguerre, introduced celluloid roll film and a simple camera, the Kodak. For the first time you could take a whole roll of pictures and then send your film off to be developed and printed. From then on, it was "Momma don't take my Kodachrome away."
Reference , pp. 90-93.
For a general introduction to the history of photography, see Reference .