CH. VI] MICRO-SPECTROSCOPE AND POLARISCOPE 



157 



4 3 c 



; 



I II 



FIG. 136. Various Spectrums. All except that of sodium were obtained 

 by diffused day-light with the slit of such a width as gave the most distinct 

 Fraunhofer lines. 



It frequently occurs that with a substance giving several absorption bands 

 (e.g., chlorophyll} the density or thickness of the solution must be varied to 

 show all the different bands clearly. 



Solar Spectrum. With diffused day-light and a narrow slit the spectrum 

 is not visible much beyond the fixed line B. In order to extend the visible 

 spectrum in the red to the line A, one should use direct sunlight and a piece of 

 ruby glass in place of the ivatch-glass in Fig. 138. 



Sodium Spectrum. The line spectrum ( \ 213} of sodium obtained by light- 

 ing the microscope with a Bunsen or alcohol flame in which some salt of sodium 

 is glowing. With the micro-spectroscope the sodium line seen in the solar 

 spectrum and with the incandescent sodium appears single, except under very 

 favorable circumstances ( \ 214], By using a comparison spectrum of day-light 

 with the sodium spectrum the light and dark D-lines will be seen to be contin- 

 uous as here shown. 



Permanganate of Potash. This spectrum is characterized by the presence of 

 five absorption bands in the middle of the spectrum and is best shown by using 

 a r \j per cent, solution of permanganate in water in a -Match-glass as in Fig. sj8. 



Met-hemoglobin. The absorption spectrum of met-hemoglobin is character- 

 ized by a considerable darkening of the blue end of the spectrum and of four 

 Absorption bands, one in the red near the line C and two between D and E 

 nearly in the place of the two bands of oxy-hemoglobin; finally there is a some- 

 what faint, wide, band near F. Such a met-hemoglobin spectrum is best ob- 

 tained by making a solution of blood in water of such a concentration that the 

 two oxy-hcmoglobin bands run together ( 233}, and then adding three or four 

 drops of a T ' f per cent, aqueous solution of permanganate of potash or a few 

 drops of hydrogen dioxid (H^O^). Soon the bright red will change to a 

 brownish color, when it may be examined. 



