COLORING MATTERS. 103 



red color. Such a modification certainly takes place outside the body, 

 and it may also occur within the system, giving rise to the varying 

 proportions of red in the color of the urine under different healthy and 

 diseased conditions. 



6. Chlorophylle. 



This is the green coloring matter of plants. It is more widely 

 diffused than any other coloring matter in the vegetable world, and it 

 apparently constitutes the coloring principle of all the green parts of 

 the higher plants without exception. It has been obtained by Gautier* 

 in the crystalline form, as flattened, isolated, or radiating needles, of a 

 softish consistency and an intensely green color; afterward, by ex- 

 posure to light, they become yellowish-green, then brownish-green, 

 and are lastly decolorized. Its composition is as follows : 



COMPOSITION OF CHLOROPHYLLE. 



Carbon 73.97 



Hydrogen 9.80 



Nitrogen 4.15 



Oxygen 10.33 



Ash 1.75 



100.00 



Its incombustible residue consists mainly of alkaline phosphates. 

 It is completely destitute of iron. 



The similarity of chlorophylle to biliverdine, fully recognized by 



FIG. 15. 



SPECTRUM OF CHLOROPHYLLE IN ALCOHOLIC SOLUTION. 



Gautier in regard to some of its chemical reactions, is very strongly 

 marked in its spectroscopic characters. The principal absorption 

 band in the spectra of these two substances is identical in position 

 and appearance. It is the dark band situated in the red, extending 

 from the line C toward B. (Fig. 15.) In an alcoholic solution of 

 chlorophylle, extracted from green grass or leaves, there are three 

 additional bands, less prominent than the former, and differing from 

 those of bile. One of these additional bands is placed at the edge of 



* Comptes Eendus de 1' Academic des Sciences. Paris, 1879. Tom. Ixxxix., 

 p. 861. 



