In 1829, Louis Jacques Mande Daguerre struck a partnership with fellow inventor Joseph-Nicephore Niépce to develop a method for capturing the fleeting images visible in a camera obscura. The two first successfully establish the daguerreotype process in 1834. The process begins with by buffing and polishing a sheet of silver-plated copper until it is completely reflective. This sheet is then treated with iodine and bromine in light-proof boxes in order to be more light-sensitive; at this point, the plate changes from a silver-colour to a yellow-rose colour. Next, the sheet of copper is exposed for at least several minutes under a lens with an image in a large box camera. In the earliest daguerreotypes, exposure often took up to fifteen minutes. But with improvements in the sensitization process, such as adding silver halides, exposure times would eventually be reduced to less than one minute. After the plate is exposed, it is developed over hot mercury, and then stabilized and fixed using a solution called “hypo”(sodium thiosulfate) or salt water. After this, the plate would be washed with distilled water and then finally toned and gilded with gold chloride (Taylor 2015; Cade 2013; Daniel "Daguerre").
In 1850, Louis Agassiz produced a series of slave daguerreotypes. This series consisted of 15 silver daguerreotype plates showing the highly detailed front and side views of seven (primarily) naked female and male slaves. These daguerreotypes were produced for “scientific” purposes, to physiognomically analyze the differences between European whites and African blacks, but also for implicit political purposes: to evoke the white race's inherent superiority over blacks. This seemingly scientific approach to race via photography is perhaps an early predecessor to Alphonse Bertillon’s attempts to capture physiognomy in photography, or the scientific measurement of the body in order to analyze non-physical characteristics. This series by Louis Agassiz led to more research by scientists, such as Dr. Samuel Morton, to analyze racial typologies (Wallis 1996).
Daniel, Malcom. "Daguerre (1787–1851) and the Invention of Photography." Daguerre (1787–1851) and the Invention of Photography. The Metropolitan Museum of Art, n.d. Web. 28 Nov. 2015.
Rogers, Molly. "Delia's Tears." Yale University Press. May 25, 2010. Accessed December 16, 2015. http://yalepress.yale.edu/book.asp?isbn=9780300115482.
Ron. "Black Bodies, White Science: Louis Agassiz's Slave Daguerreotypes." US Slave. October 13, 2011. Accessed December 16, 2015. http://usslave.blogspot.com/2011/10/black-bodies-white-science-louis.html.
Taylor, Alan. "The Gift of the Daguerreotype." The Atlantic. Atlantic Media Company, 19 Aug. 2015. Web. 27 Nov. 2015.
Wallis, Brian. "Black Bodies, White Science: The Slave Daguerreotypes of Louis Agassiz." The Journal of Blacks in Higher Education No. 12 (1996): 102. JSTOR. Web. 01 Dec. 2015.