184 Mr. C. A. Schunck. The Yellow Colouring Matters 



racteristic of allowing considerably more of the ultra-violet rays to pass 

 through its solutions. Comparing now the xanthophyll spectrum with 

 that given by crude chlorophyll solutions, it will at once be seen that 

 the character of the two spectra are quite different, and this points to 

 the fact that the bands are due to two distinct colouring matters. 

 This is supported by the fact that from crude alcoholic chlorophyll 

 solutions that have been acted upon with alkali, the xanthophyll can 

 be recovered unaltered by shaking up with ether, the chlorophyll being 

 so altered (though the colour of the solutions is unchanged) that animal 

 charcoal will not now absorb the green colouring matter ; this altera- 

 tion has been shown by Schunck* to be due to the formation of an 

 alkali compound of alkachlorophyll. Again, in crude chlorophyll solu- 

 tions which have been kept a little time, and which show signs of 

 decomposition, owing to the formation of phylloxanthin and phyllo- 

 cyanin, the bands in the violet are no longer discernible on proper 

 dilution, yet act upon such solutions with animal charcoal, and we 

 get a yellow solution giving the four-banded xanthophyll spectrum, 

 showing that the xanthophyll was there all the time unaltered, but did 

 not affect the spectrum. From the spectra of their alcoholic solutions 

 it will be observed the only xanthophyll band that could affect the 

 crude chlorophyll spectrum is the first, for it is the only one in a 

 similar position ; but I think I can show that this cannot be the case, 

 and that it is in no way connected with chlorophyll. If a crude chloro- 

 phyll solution be examined in ether compared to alcohol, it will be 

 found that in the former solvent, the bands are all shifted towards the 

 more refrangible end of the spectrum, while the xanthophyll bands in 

 both solvents are in identical positions (Plate 6, figs. 6 to 11), so that 

 we see now the first xanthophyll band no longer coincides with the first 

 band of crude chlorophyll, and therefore can not have any influence 

 upon the chlorophyll spectrum. And thus I came to the conclusion, 

 taking one experiment with another, that as with chrysophyll, xantho- 

 phyll is present in such a small relative quantity, compared to chlo- 

 rophyll, that the bands of its spectrum cannot be detected in the cruder 

 chlorophyll solution, and that the bands shown by the latter are due 

 to chlorophyll itself, and not to any of the accompanying yellow 

 colouring matters which the majority of former observers believed 

 they were due to. This belief may have arisen from the fact that 

 without the aid of photography, only the first two bands of chlorophyll 

 and the accompanying yellow colouring matters in the violet region 

 are discernible in alcoholic solutions to the eye, and they thus failed to 

 observe the complete spectrum which, from an inspection of the plate, 

 will be seen makes in each case a vast difference to the character of the 

 spectrum. 



That all freshly prepared chlorophyll extracts show in every case 

 * ' Boy. Soc. Proc.,' vol. 50, p. 312. 



