HISTORICAL NOTES ON CARBON PRINTING.
Photographic Carbon Printing may be said to have commenced with the labors of M. Nicephore de Niepce, in 1814. His pictures were produced by the action of the solar rays upon certain hydro-carbons, which were rendered insoluble in the usual menstrua, wherever they had been submitted to the influence of light.
In 1839, Mr. Mungo Ponton announced, in the Edinburgh New Philosophical Journal, a process of producing images by the action of light on paper which had been impregnated with a solution of bichromate of potash.
M. Becquerel shortly afterwards investigated the action of chromic salts on organic substances under the influence of light, and arrived at the conclusion that the coloration and insolubility were due to the reaction which took place between the chromic acid and the sizing matter in the paper, as, on using unsized paper, the effect could only be produced in course of time. Upon this, he used another modification of the process: employing a paper sized with starch, he subsequently treated the image, obtained by the aid of the bichromate, in a weak alcoholic solution of iodine, and so obtained a blue tint. In 1852, Mr. Fox Talbot patented a method of photo-engraving, in which he availed himself of the reaction between organic matter and chromic acid under the influence of light.
In 1855, M. Poitevin announced the first carbon process. He proposed to render the reaction between a chromic salt and organic matter available in producing photographs in permanent pigments, the image being formed either of coloring matter miscible in water, or of a fatty ink.
