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".
James Ambrose Cutting
When dry, the glass plate was then backed either with black paint, metal, cloth, or paper; this black backing made light areas of the negative appear darker, turning the negative image into a positive. Some ambrotypes were made with ruby or dark green glass to simulate the effect of a backing without using one. Ambrotypes often were hand-colored, most commonly with dabs of red paint on the cheeks of the sitter. They were housed in wood or thermoplastic cases (also called 'Union cases'), like the daguerreotype photographs with which they are often confused; an ambrotype is easily distinguished from a daguerreotype because its surface is not reflective, as daguerreotype surfaces are. Ambrotypes were most popular during the mid- to late-1850s but continued to be available through the 1890s.