SCIENCE IN THE INDUSTRIAL WORLD 



but on the whole gradually growing, success. The 

 three necessary colors are put on the paper to begin 

 with, and the light destroys or bleaches those that are 

 not wanted. The method depends upon the fact 

 that light can affect a substance only when it is ab- 

 sorbed, and therefore when a mixture of unstable col- 

 ored substances is exposed to colored light, there is 

 always a tendency for those substances that are of the 

 same color as the light to survive the longest because 

 they reflect more of the light than the others." In 1907, 

 such a paper ready for exposure under the color plate 

 was actually prepared. "The colors are made more 

 sensitive by the addition of anethole, and after exposure 

 the print is soaked in benzine or acetone to remove 

 the sensitizer. This paper gives surprisingly vivid 

 reproductions of the color of the original, but the 

 prints are not very stable to light." 



When some means of making stable prints on such 

 a paper is found, color photography will probably 

 have reached its highest state of development, for, as 

 we have seen, the photography of color is something 

 the scientist as yet sees no possible way of accom- 

 plishing. 



CHRONO-PHOTOGHAPHY MOVING PICTURES 



A means of representing motion, which has reached 

 its highest development in the well-known and popular 

 moving-picture machines of the present day, was de- 

 vised long before the photographic plate came into 

 general use. As early as 1833, M. Plateau, a Belgian 



[248] 



