BLOOD ANALYSIS 



301 



2. Hemoglobin (so-called Reduced Hemoglobin). To blood which has been 

 diluted sufficiently to show well-defined oxyhemoglobin absorption bands add a 

 small amount of Stokes* reagent. l The blood immediately changes in color from 

 a bright red to violet-red. The oxyhemoglobin has been reduced through the 

 action of Stokes' reagent and hemoglobin (so-called reduced hemoglobin) has 

 been formed. This has been brought about by the removal of some of the loosely 

 combined oxygen from the oxyhemoglobin. Examine this hemoglobin spectro- 

 scopically. Note that in place of the two absorption bands of oxyhemoglobin we 

 now have a single broad band lying almost entirely between D and E. This is 

 the typical spectrum of hemoglobin. If the solution showing this spectrum be 

 shaken in the air for a few moments it will again assume the bright red color of 

 oxyhemoglobin and show the characteristic spectrum of that pigment. 



S 



FIG. 99. DIAGRAM OF ANGULAR-VISION SPECTROSCOPE. (Long.) 

 The white light F enters the collimator tube through a narrow slit and passes to the 

 prism, P, which has the power of refracting and dispersing the light. The rays then pass to 

 the double convex lens of the ocular tube and are deflected to the eyepiece E. The dotted 

 lines show the magnified virtual image which is formed. The third tube contains a scale 

 whose image is reflected into the ocular and shown with the spectrum. Between the light 

 F and the collimator slit is placed a cell to hold the solution undergoing examination. 



3. Carbon Monoxide Hemoglobin. The preparation of this pigment may be 

 easily accomplished by passing ordinary illuminating gas 2 through defibrinated 

 ox-blood. Blood thus treated assumes a brighter tint (carmine) than that im- 

 parted by oxyhemoglobin. In very dilute solution oxyhemoglobin appears 

 yellowish red whereas carbon monoxide hemoglobin under the same conditions 

 appears bluish red. Examine the carbon monoxide hemoglobin solution spec- 

 troscopically. Observe that the spectrum of this body resembles the spectrum 

 of oxyhemoglobin in showing two absorption bands between D and E. The 

 bands of carbon monoxide hemoglobin, however, are somewhat nearer the violet 

 end of the spectrum. Add some Stokes' reagent to the solution and again ex- 

 amine spectroscopically. Note that the position and intensity of the absorption 

 bands remain unaltered. 



1 Stokes* reagent is a solution containing 2 per cent ferrous sulphate and 3 per cent 

 tartaric acid. When needed for use a small amount should be placed in a test-tube and 

 ammonium hydroxide added until the precipitate which forms on the first addition of the 

 hydroxide has entirely dissolved. This produces ammonium f err otartr ate which is a reduc- 

 ing agent. 



2 The so-called water gas with which ordinary illuminating gas is diluted contains usu- 

 ally as much as 20 per cent of carbon monoxide (CO). 



