Daguerreotype
It is said that Daguerre has found the means to collect, on a plate prepared by him, the image produced by the camera obscura, in such a way that a portrait, a landscape, or any view, projected upon this plate by the ordinary camera obscura, leaves an imprint in light and shade there, and thus presents the most perfect of all drawings ... a preparation put over this image preserves it for an indefinite time ... the physical sciences have perhaps never presented a marvel comparable to this one.
A further clue to fixing the date of invention of the process is that when the Paris correspondent of the London periodical "The Athenaeum" reported the public announcement of the daguerreotype in 1839, he mentioned that the daguerreotypes now being produced were of considerably better quality than the ones he had seen "four years earlier".
Photography in Denmark
A number of other techniques developed in parallel with the use of daguerreotypes. The ambrotype, using collodium to produce a positive image on glass, and the pannotype, also collodium-based, were both used in Denmark from around 1855. Negative-based paper prints, used from the beginning of the 1850s, were produced on salt paper until around 1857 when salt was replaced by albumen. Collodion emulsion chloride paper was used from 1865 and in 1880 gelatin emulsion paper was introduced.