VI.] 



THE COLOURED BLOOD CORPUSCLES. 



47 



6. I. Spectrum of Oxy-hsemoglobin. 



(a.) Begin with a strong solution and gradually dilute it. Place 

 some defibrinated blood in a test-tube, and observe its opacity and 

 bright scarlet colour, 



(fj.) Adjust the spectroscope as follows : — Light a fan-tailed gas 

 burner, fix the spectroscope in a suitable holder, and between the 

 light and the slit of the spectroscope place a test-tube containing 

 the blood or its solution. Focus the lo?ic/ image of the gas-flame on 

 tlie slit of the spectroscope. The focal point can be readily ascer- 

 tained by holding a sheet of white paper behind the test-tube. 



Red. Orange. Yellow. 



Green. 



Blue. 



Fio. 24. — Spectra of Haemoglobin, and its Compounds. 1. Oxy-hgemoglobin, 0.8 per cent,; 

 2. Oxy-haemoglobin, a 18 per cent.; 3. Carbonic oxide haemoglobin; 4, Reduced haemo- 

 globin, 



(c.) Add 10 to 15 volumes of water, and note that only the red 

 part of the spectrum is visible. INIake a sketch of what you see, 

 noting the dilution. 



(d.) Add more water until the green appears, and observe that 

 a single dark absorption-band appears between the red and green 

 (fig. 24, i). Continue to dilute until this single broad band is 

 resolved into two by the transmission of yellow-green light. Burn 

 a bead of sodic chloride in the gas-flame, to note distinctly the 

 position of the D Hne, and observe that of the two absorption 

 bands the one nearest D, conveniently designated by the letter a, 

 is more sharply defined and narrower; while the otlier, cou- 



