William Henry Fox Talbot, born on February 11, 1800 in England, was a chemist and more importantly a pioneer photographer. He went to the University of Cambridge and was an outstanding scholar. He published over 50 scientific papers and two books. In 1840, he helped improve the daguerreotype by creating the calotype. It is a process that uses paper coated with silver iodide, which when exposed to light decomposes to silver. This leaves the iodide as a free element. Gallo-nitrate is then used to wash away the excess silver. Since silver oxide is black, the image that is left is visible. Then potassium bromide is used to stabilize the image. Ultimately, this created a negative for which many copies of the positives could be printed. He also created the photoglyphic engraving process. He was seeking for prints that would not fade, so they made images on plates that could not be etched. The plates could be used in a printing press. This was a precursor to the photogravure. Talbot's pictures today are difficult to exhibit because they cannot be exposed to light without risk of change to the picture.
(basic photography negative by Talbot)
JAM
