BLOOD. 



VIII. SPECTRA or HEMOGLOBIN AND ITS COMPOUNDS. 



A convenient instrument to use is the micro-spectroscope or 

 spectroscopic ocular which fits into the tube of the microscope in 

 place of the ordinary eyepiece. 



First study the solar spectrum. With a narrow slit identify the 

 Fraunhofer lines. 



1. In a darkened room place a Bunsen flame in line with the re- 

 flecting mirror of the microscope so that the light from any body 

 made luminous in the flame, will pass through the prisms of the 

 spectroscope. Dip a platinum wire in a solution of sodium chlorid 

 and heat in the flame. What is the nature of the resulting spec- 

 trum? Compare this with the spectrum of sunlight or the light 

 frcm a Welsbach burner. What part of the spectrum is luminous ? 

 To what absorption band or Fraunhofer line does this correspond ? 



2. Repeat the observations with other metallic salts, such as 

 strontium, potassium, barium, and copper. 



3. Make a two-per-cent solution of eosin in water. Place this in a 

 vial and clamp in the holder at the side of the eyepiece. Tilt the 

 mirror until light passes through the solution and prism. Arrange 

 the substage mirror for reflecting sunlight through the comparison 

 prism so that the two spectra may be viewed side by side. The 

 eosin absorbs certain parts of the spectrum. What are the ab- 

 sorption bands of eosin ? 



4. Oxy-hsemoglobin. Fill the test vial with defibrinated blood 

 diluted with ten volumes of distilled water. Place in the holder 

 of the spectroscope and note what part of the spectrum is visible 

 and what part has been absorbed. Increase the dilution until 

 more and more of the spectrum becomes visible. Increase the 

 dilution until the absorption bands can no longer be distinguished 

 and the whole of the spectrum is visible. 



What are the absorption bands of oxy-haemoglobin? In what 

 part of the spectrum do they occur ? Make a drawing, comparing 

 the absorption spectrum of oxy-haemoglobin with the solar spec- 

 trum. (See text-book for pictures of various spectra.) 



[75] 



