170 MICRO-SPECTROSCOPE AND POLAR/SCOPE [ CM. VI 



To obtain this, kill an animal in illuminating 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 ammonium 

 sulphide and allow the blood to stand some time. No reduction 

 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. 



§ 235. Carmine Solution. — Make a solution of carmine by 

 putting ^ 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 compare the spectrum with that of oxy-hemoglobin or car- 

 bon monoxide hemoglobin. It has two bands in nearly the same 

 position, thus giving the spectrum a striking similarity to blood. 

 If now several drops', 1 5 or 20, of glacial acetic acid are added to 

 the carmine, the bands remain and the color is not markedly 

 changed, while with either oxy-hemoglobin or CO-hemoglobin the 

 color is decidedly changed from the bright red to a dull reddish 

 brown, and the spectrum, if any can be seen, is markedly different. 

 Carmine and O-hemoglobin can be distinguished by the use of 

 ammonium sulphide, the carmine remaining practically unchanged 

 while the blood shows the single band of hemoglobin (§ 232). The 

 acetic acid serves to differentiate the CO-hemoglobin as well as the 

 O-hemoglobin. 



§ 236. Colored Bodies not giving Distinctly Banded 

 Absorption Spectra. — Some quite brilliantly colored objects, like 

 the skin of a red apple, do not give a banded spectrum. Take the 

 skin of a red apple, mount it on a slide, put on a cover-glass and 

 add a drop of water at the edge of the cover. Put the preparation 

 under the microscope and observe the spectrum. Although 110 bands 

 will appear, in some cases at least, yet the ends of the spectrum will 

 be restricted and various regions of the spectrum will not be so 

 bright as the comparison spectrum. Here the red color arises from 

 the mixture of the unabsorbed waves, as occurs with other colored 

 objects. In this case, however, not all the light of a given wave 

 length is absorbed, consequently there are no clearly defined dark 



