154 



BIOPHYSICALLY ACTIVE LIGHT 



variable thickness be too thin, it will appear not only brighter but more 

 yellow-green. If too thick, it will appear darker and more blue-green. 



In a similar way one may use a red filter that produces a neutral 

 violet. 



Hemoglobinometer 



The hemoglobinometer is a colorimeter with which the amount of 

 hemoglobin in a sample of arterial blood is determined without resort- 

 ing to chemical analyses. 



To 5.7 



32 



28 



24 



£ 20 



1 16 



lj 



12 



4 - 



3760 A 



4146 



Oxyhemoglobin 



Absorption spectra 



76 gm/ liter] 



Acid 0.1 AT HC1 



3000 



4000 5000 



Wavelengths in A 



6000 



7000 



Fig. IV-14. Absorption spectrum of oxyhemoglobin with a and /3 band indicated. 

 The /3 band disappears first on dilution. (From data by Newcomer [1919].) 



Whole blood, as well as its various chemical modifications, shows 

 marked spectral absorption bands which cannot be matched by using 

 any single filter. A good match may be obtained, however, by convert- 

 ing the hemoglobin to acid hematin, in which the absorption bands are 

 less prominent, and choosing a yellow glass filter, placed below the cups, 

 whose absorption curve runs as a mean through that of the acid hematin. 



Acid hematin (globin hemochromogen) has, according to Newcomer 

 [1919], an absorption band near 6620 A and two weak bands extending 

 from 5100 A to 5900 A (Fig. IV-14). A " blue " filter can be inserted 



o 



to absorb most of the light having wavelengths greater than 5000 A. 



