CH, VI,~\ MICRO-SPECTROSCOPE AND POLAR/SCOPE. 133 



the oxy-hemoglobin to hemoglobin. This may be repeated many times 

 (Fig. 114). 



§ 202. Met-Hemoglobin. — The absorption spectrum of met-hemo- 

 globin is characterized 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 somewhat faint, wide band near F. 

 Such a met-hemoglobin spectrum is best obtained by making a solution 

 of blood in water of such a concentration that the two oxy-hemoglobin 

 bands run together (§201), and then adding three or four drops of a 

 y 1 ^- per cent, aqueous solution of permanganate of potash. Soon the 

 bright red will change to a brownish color, when it may be examined 

 (Fig. 113). 



§ 203. Carbon Monoxide Hemoglobin (CO Hemoglobin). — To 

 obtain this one may kill an animal, after anaesthetization, in illuminat- 

 ing gas, or one may allow illuminating gas to bubble through some 

 blood already taken from the body. The gas should bubble through a 

 minute or two. The oxygen will be displaced by carbon monoxide. 

 This forms quite a stable compound with hemoglobin, and is of a bright 

 cherry-red color. Its spectrum is nearly like that of oxy-hemoglobin, 

 but the bands are farther toward the blue. Add several drops of am- 

 monium sulphide and allow the blood to stand some time. No reduc- 

 tion will take place, thus forming a marked contrast to solutions of oxy- 

 hemoglobin. By the addition of a few drops of glacial acetic acid a 

 dark brownish red color is produced. 



§ 204. Carmine Solution. — Make a solution of carmine by putting 

 Y^th gram of carmine in 100 cc. of water and adding 10 drops of strong 

 ammonia. Put some of this in a watch-glass or in a small vial and com- 

 pare the spectrum with that of oxy-hemoglobin or carbon monoxide he- 

 moglobin. It has two bands nearly in the same position, thus giving 

 the spectrum a striking similarity to blood. If now several drops, 15 

 or 20, of glacial acetic acid are added to the carmine, the bands remain 

 and the color is not very markedly changed, while with either oxy-hemo- 

 globin or CO-hemoglobin the color would be very markedly changed 

 from the bright red to a dull reddish brown, and the spectrum, if any 

 could be seen, would be markedly different. Carmine and O-hemoglo- 

 bin can be distinguished by the use of ammonium sulphide, the carmine 

 remaining practically unchanged while the blood shows the single band 

 of hemoglobin (§ 201). The acetic acid serves to differentiate the CO- 

 hemoglobiu as well as the O-hemoglobin. 



§ 205. Colored Bodies not giving Distinctly Banded Absorp- 



