Spectral and Cumulative Absorption Measurements

56Wright, W. (1969) As reproduced in Boynton, R. (1979) Human Color Vision. NY Holt, Rinehart Winston, pp. 393-405 

The saturation characteristic of complex organic molecules also becomes more complex. As the solution approaches saturation, the solute may undergo changes of molecular configuration which drastically change the absorption characteristic of the solution. 

To obtain meaningful spectral measurements in vision, it is important that the energy environment be controlled. This environment is represented by the pH of the surrounding solution as well as the methods of de-excitation available to the chromophore. 

The photographic community encountered the problem of the appropriate energy environment many years ago. They found that the materials of interest in extending the spectral range of photography were very particular about the 

1 The Table illustrates three distinct chemical conditions, a true solution, a mixture and a precipitate. 

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