“To offset the possible effects of poor contact between the various members of the tripack, J. H. Smith coated the emulsions directly one on top of the other, but with an insulating layer of collodion between them. In this manner there was obtained a very compact pack, since the collodion layers could be made as thin as desired. Filter dyes could be placed in this insulating layer, so that there was removed the possible interaction between filter dye and sensitizer. The presence of the intermediate dyed collodion layers made it possible to strip the component emulsions apart, and process them individually.
This scheme is disclosed in United States patents 781469 and 886883; German patents 165544 and 185888; and English patent 19940/04. The idea crops up again in a disclosure by S. Schapavoloff (Eng. P. 205807) and more
recently by W. T. Tarbin (U.S.P. 1871479).”
(Friedman, Joseph Solomon (1945): History of Color Photography. Boston: The American Photographic Publishing Company, p. 86.)
Original Technical Papers and Primary Sources
U.S.P. 781469, Sept. 13,1904 and 886883, May 15, 1905 , D.R.P. 165544 and 185888; and E.P. 19940/04
Friedman, Joseph Solomon (1945): History of Color Photography. Boston: The American Photographic Publishing Company, pp. 94-107.