OPTICAL PROPERTIES OF BLOOD. 



235 



must be white and between this and the collimator slit a cell must be 

 placed to hold the colored solution or diluted blood. This is shown in 

 the next figure, where B is an ordinary kerosene lamp with flat wick. 



FIG. 12. Diagram of simple spectroscope. 



The edge of the flame is turned toward the absorption cell and slit. The 

 apparatus here figured is arranged for absorption analysis and, with parts 

 to be described later, may be used for quantitative work. 



For most simple blood examinations the small direct vision spectroscope 

 shown below may be used. With proper ^combination of crown and flint 



FIG. 13. Spectroscope arranged for absorption analysis. 



glass prisms it is possible to practically correct the refraction and leave 

 a field with satisfactory dispersion. 



Variation in Spectra by Dilution. In all dilutions the 

 positions of the absorption bands remain the same, but their 



