SPECTRUM OP CHLOROPHYLL. 293 



the first. The spectra of chlorophyll solutions from two different 

 sources can thus be at once compared. One of the combinations 

 can also be employed to project the solar spectrum (unchanged 

 by passing through any color whatever), and its constant lines 

 (Fraunhofer's lines) can be used for the determination of posi- 

 tion of the bands seen in the spectrum of the liquid by its side. 



778. The spectra of many substances, among which chloro- 

 phyll occupies a prominent place, have absorption-bands of such 

 constancy in position and appearance that they are justly regarded 

 as characteristic. 



779. The spectrum of an alcoholic solution of chlorophyll has 

 been shown to be essentially the same as that of the chlorophyll 

 granule itself. In order, however, to obtain all the absorption- 

 bands characteristic of chlorophyll, it is necessary to examine 

 successively solutions of different degrees of strength, some of 

 the bands appearing only in dilute and others only in strong 

 solutions. For comparison, absorption spectra obtained from 

 different sources are here given. 



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150 



FIG. 150. Spectra of chlorophyll. The upper figure shows the spectrum of an alco- 

 holic solution of medium concentration, while the middle figure gives all the absorption- 

 bands of chlorophyll ; those on the right as shown only in dilute solutions. The lowest 

 figure exhibits the spectrum of a living leaf of Deutzia scabra. (Kraus.) 



