COLOR PHOTOGRAPHY BY MEANS OF BODY COLORS, AND 

 MECHANICAL COLOR ADAPTATION IN NATURE.' 



By Otto Wiener. 



I. — Scope op the Investigation. 



In the investigation of fixed lightwaves z I came at once upon the 

 question of the fundamental possibility of color photography. Zenker 

 had explained the processes then in use by the action of stationary 

 lightwaves. 5 Objections to the explanation not as yet overthrown are 

 offered in an article by Schultz-Sellack. 4 On this account, and because 

 I was unacquainted with the possibility of the production of thicker 

 transparent photographic films, I considered the solution of the ques- 

 tion must be sought in other directions. These difficulties were, how- 

 ever, soon after overcome by Lippman, 5 and he succeeded in obtaining 

 a process of color photography by a suitable production of stationary 

 lightwaves, and thus by the application of Zenker's theory. 



That this theory, however, explained the older processes was not yet 

 proved, and I was unable to find anything looking to such a proof 

 thoroughly established. I determined, therefore, to discover by new 

 experiments the cause of the color production in the older procedures. 

 These experiments form the point of departure and a considerable 

 portion of the following communication. 



The objections of Schultz-Sellack are by no means to be brushed aside 

 without further consideration. He disputed the fact of regular fixed 

 lightwaves in powders. Powdered substances had been used for color 

 production in the first process of Seebeck, whose observations were 



1 Translated from Annaleu der Physik und Chemie, Neue Folge. Band 55. 1895. 

 Leipzig. 



' 2 Wiener, Annalen der Physik und Chemie, 40: p. 205, 1890. 



3 Zenker, Lehrhuch der Photochromie, Berlin, private publication by the author, 

 1868. In my earlier investigation I found that Lord Eayleigh also, in connection 

 with the investigation of wave propagation in a medium of periodic structure (Philo- 

 sophical magazine (5) 24: p. 158, 1887), had considered the possibility of this expla- 

 nation. He was, however, unacquainted with the theory of Zenker published nine- 

 teen years before. 



4 Schultz-Sellack, "Upon the coloration of turbid media and the so-called color 

 photography." Annalen der Physik und Chemie, 143: p. 449, 1871. 



r ' Lippman. Comptcs rendus, 112: p. 274, 1891. 



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