Photogenic Drawing 6
An experimental cyanotype of an engraving of a lady with a harp, by Sir John Herschel (1792-1871), 1842.
Herschel invented the cyanotype or 'blueprint' in 1842, employing iron salts (ferric ammonium citrate and potassium ferricyanide) which produce Prussian blue under the action of light. It was a simple process to use and required only water as a fixative.
The cyanotype was the only first-generation photographic technique to find any lasting use.
Computer-generated positive of the same image.
Museum home page
(c) Museum of the History of Science, Broad Street, Oxford, England.