Douglass Color No. 2
“Douglass Color No. 2 (1919). The two negatives of the Douglass Color system No. 1 were printed on a positive. In this updated version of the process, rather than projecting the frames through red and green filters, both latent images were printed and then dye-toned on the same frame, one in contact with the emulsion side, the other with the base. This meant that the positive film had a layered emulsion.”
(Cherchi Usai, Paolo (2000): Silent Cinema. London: BFI, p. 36.)
“Although standard projecting machines could be used with this second system, Douglass Color apparently never became a commercially accepted process. No references toward its use in feature-length motion pictures could be found, nor is there any indication it was regularly employed in the production of short subjects.”
(Nowotny, Robert A. (1983): The Way of All Flesh Tones. A History of Color Motion Picture Processes, 1895-1929. New York: Garland Pub., pp. 130-131.)
Original Technical Papers and Primary Sources
Kelley, William Van Doren (1925): Color Photography Patents (cont.). In: Transactions of the Society of Motion Picture Engineers, 24, Oct., pp. 149–161, on pp. 155-156. Download PDF,
Cherchi Usai, Paolo (2000): Silent Cinema. London: BFI, p. 36.
Nowotny, Robert A. (1983): The Way of All Flesh Tones. A History of Color Motion Picture Processes, 1895-1929. New York: Garland Pub., pp. 130-131.
Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp 32-34.