46 



Dr. B. S. Clay. On the Application of 



90 



7 



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7 



I 



46 48 SO 52 64 66 >d 60 



64 66 e>d 70 T& 



No. 27. Filter curves for inks with abrupt absorptions at X 49 and X 59. The 

 ordinates show the percentage area to be left free from ink, and therefore 

 indicate the opacity to be obtained on the corresponding negative, or for au 

 orthochromatic plate the transparency of the filter. 



Absorptions at 57 - 5 and 5O5. 



The total excess of white is about the same, but the distribution is 

 not so good, as the ends of the spectrum, when the luminosity is small, 

 have large excesses. 



