1873.] Comparative Vegetable Chromatology . 455 



can be dissolved out from the deposit by means of absolute alcohol : at 

 all events it is free from chlorophyll, and perhaps only contains a small 

 quantity of the pale yellow substance. The colour of this solution is a 

 yellow-green, very much like that of a crude solution from green leaves. 

 The spectrum shows two dark absorption-bands, one between the red 

 and the orange, and another between the orange and the yellow. The 

 whole of the green is transmitted, but the whole of the blue cut off: ; and 

 when the solution is dilute, a broad and somewhat obscure band may be 

 seen in the centre of the blue, if excellent daylight is used. The addition 

 of a little ammonia slightly increases the intensity of the band nearest 

 the red end. When thus modified by dilute alkalies, chlorofucine is very 

 sparingly, if at all, soluble in bisulphide of carbon. Excess of hydro- 

 chloric acid causes immediate decomposition into a new compound, with 

 a single absorption-band in the orange. Weak acids slowly produce the 

 same effect ; and it is important to bear this in mind, since this product 

 of the action of acids, and not the original substance, is met with in 

 studying certain plants. 



The difference between the spectra of the above-named three green 

 substances will be better understood by means of the following figure, 

 which represents the absorption-bands as seen in solutions diluted so as 

 to show those at the blue end, and only the darkest and most charac- 

 teristic of those in the red. 



Pig. 1. Spectra of the chlorophyll group compared. 



Red end. Blue end. 



Blue chlorophyll ... 



Yellow chlorophyll. 



Chlorofucine 



Fluorescence of the Chlorophyll Group. 



The position of the narrow bright red bands seen in the spectra of the 

 light of fluorescence of these three members of the chlorophyll group 

 differs even more than that of the absorption-bands, since in the case of 

 chlorofucine the bright orange-red band almost coincides with the dark 

 band of absorption, whereas in the case of both blue and yellow chloro- 

 phyll the more red bands lie just on the red side .o£ the centre of their 

 absorption-bands. The result is that the three different narrow red 

 bands characteristic of the light of fluorescence of the three different 



2 n 2 



