Background. The combination of a camera to focus an image onto a light-sensitive surface and the series of subsequent chemical reactions to produce a permanent print constitutes modern photography. The development of optical component of this process—the camera—began in the 17th century with the camera obscura, a dark room with a pinhole on one wall through which an image of the outdoors was projected onto a wall. Artists used these projected images, later sharpened with lens substituted for the pinholes, for making preliminary drawings for paintings. In time, the camera obscura became smaller and portable, as predecessor to the modern camera.

Daguerreotype, Paul Messier Collection

The light-sensitivity of silver chloride, AgCl, was well known in the early eighteenth century and crude photographs were produced using papers impregnated with silver nitrate or silver chloride. These "photographs" darkened with time; a method to prevent the continued reaction of light with the Ag-treated photographic papers had yet to be discovered. In 1839, however, Louis J. M Daguerre patented the discovery that produced light-fast images on copper plates, the daguerreotype. William Henry Fox Talbot’s improved process for coating silver halides directly on paper in combination with a hyposulfite fixative replaced the daguerreotype by the end of the nineteenth century. Although technologically more advanced, the basic procedures developed by Fox Talbot, the "Inventor of Modern Photography," are used in all silver-based photography today.

Chemistry 103 students explore the chemistry of both silver-based and alternative (non-silver) photographic processes by making light-sensitive papers to produce a series of contact prints. Examples from the Spring 2001 class are shown in the Student Exhibition.

References
1. Chemistry of silver-based photographic processes: Mary Virginia Orna and Madeline P. Goodstein, Chemistry and Artists’ Colors, 2nd Edition
(New Rochelle, NY, 1998), Chapter 20, page 355-369.
2. Summary of chemistry of photographic processes: Download PDF: Photographic Processes

Experiment
Download PDF: Photography 01

Links
1. History of photography:
a. http://www.rleggat.com/photohistory/
b. http://www.geocities.com/CapeCanaveral/6794/index.html
2. Chemistry of photography at Hampton-Sidney College: http://cator.hsc.edu/~mollusk/ChemArt/photo/index.html
3. Alternative photographic processes:
a. The Alternative Photographic Process FAQ: http://duke.usask.ca/~holtsg/photo/faq.html
b. Mike Ware’s alternative photographic site: http://www.mikeware.demon.co.uk/
4. Paul Messier’s site: http://www.paulmessier.com/PhotoID/index.htm
5. Albumen photography: http://albumen.stanford.edu/
6. Images from several photographers. http://members.aol.com/sixbysixcm/photographers.html

Student Exhibition: Photography

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• Professor Margaret Merritt, Wellesley College Chemistry Department
  
• Created by: Leslie Chang '04 & Jerina Hajno '04
  
• Page Created: July 23, 2001
  
• Last Modified: August 10, 2001
  
• Page Expires: August 31, 2002