PROTEINS 245 



(b) Spectroscopic Study of Blood Pigment. By means of a 

 spectroscope observe the spectrum produced by a luminous gas 

 flame and by electric light. The spectrum is continuous. Ob- 

 serve also the incomplete spectrum of the non-luminous bunsen 

 flame. Introduce a small amount of a sodium compound into the 

 flame and observe the yellow band. Such a spectrum is called a 

 bright line spectrum and the particular bands observed are char- 

 acteristic of sodium. Observe the spectrum produced by sunlight. 

 Notice the fine dark lines at various intervals. These are the 

 Fraunhofer lines, and the most prominent of them will be used 

 to orient the absorption bands produced by the hemoglobin solu- 

 tions examined. In making a spectroscopic examination and in 

 charting the result, have the red end of the spectrum always on 

 the left. This avoids confusion and error in interpreting notes. 

 Observe and chart the following lines in your notebook, and in- 

 dicate them on all your spectrum records. From left to right 

 (beginning in the red) B and C, two prominent lines in the red; 

 D, a prominent line in the yellow (really two lines if observed 

 with a delicate spectroscope) . This line corresponds to the bright 

 lines observed above in the sodium spectrum; E and b, two 

 prominent lines in the green ; F at the beginning of the purple. 



(c) Examine oxyhemoglobin solutions of various concentra- 

 tions spectroscopically as directed below. Blood contains be- 

 tween 13% and 14% hemoglobin so the percentage concentra- 

 tion of hemoglobin may be calculated for any dilution. The 

 observations are made through a flat sided cell. Each successive 

 dilution may be made by adding an equal volume of distilled 

 water to any volume of the liquid to be diluted. Make observa- 

 tions on blood in the following dilutions : Blood shaken with air 

 and diluted 10 times, 20, 40, 80, 160, 320, 640 and 1280 times. 

 If the solution at a dilution of 1280 still shows two absorption 

 bands, dilute further until only one band remains. Kecord 

 results. 



(d) Spectrum of Hemoglobin. Potfr blood diluted 40 times 

 into the cell, reduce it by adding a small amount of Stokes' rea- 



