accompanying Chlorophyll and their Spectroscopic Relations. 477 



of such leaves as ivy and Virginia creeper that contain much acid in 

 their juices, as evidenced by the condition of their chlorophyll 

 spectrum, the alcoholic portion exhibits this changed spectrum, but if 

 means be taken during extraction to neutralise the acid the normal 

 spectrum is obtained. 



Sorby considers* that the alcoholic portion, in addition to his 

 lichnoxanthine, contains two colouring matters which he terms xantho- 

 phyll and yellow xanthophyll, and that the action of acid on the latter 

 produces the colouring matter giving the above changed spectrum and 

 afterwards the blue coloration. 



The CS^ fractions were evaporated at a gentle heat to dryness, and 

 taken up with alcohol and examined successively. In the first one 

 or two fractions the ultra-violet is visible to a considerable extent, the 

 spectrum consisting of three pronounced well-defined bands, which are 

 slightly shifted, more especially the first towards the red end as com- 

 pared to the first three bands in the crude solution, the fourth band 

 being absent. The subsequent fractions one by one transmit less and 

 less of the ultra-violet, the three bands are gradually shifted little 

 by little towards the violet in succeeding fractions, the first band 

 gradually becomes fainter, while a fourth band more refrangible than 

 the other three, makes its appearance and becomes inter] ser as we 

 pass from fraction to fraction, and it will be found that one of the 

 latter fractions corresponds in its spectrum to that of the crude 

 solution (Plate 5, B, 1-5). Lastly the final fractions as a rule exhibit 

 the spectrum produced by acid on the alcoholic portion, the colouring 

 matter to which it is due appearing to be more soluble in CS 2 than 

 in alcohol. The greater part of the colouring matter is found in the 

 first two or three fractions, which are coloured a rich yellow, the 

 succeeding fractions becoming paler and paler until the final fractions 

 are almost colourless, and in order to exhibit their spectra have to be 

 greatly concentrated. 



The interpretation of this series of spectra is, I believe, that the 

 crude solution is a mixture of chrysophyll and the colouring matters 

 or matter remaining in the alcohol after fractionation, together with 

 the colouring matter formed from the latter by the action of acid. 

 For on comparing the spectrum of the first fractions with that of 

 chrysophyll they are identical, save that the bands in the former are 

 very slightly shifted towards the violet (Plate 5, D, 1-2); these first frac- 

 tions also transmit the ultra-violet to a considerably greater extent than 

 does the crude solution, which, together with the three pronounced 

 bands, is a characteristic of chrysophyll ; and further, if we mix chryso- 

 phyll and the colouring matter remaining in the alcohol after fractiona- 

 tion together, in proper proportions, the spectrum obtained is identical 

 with that of the crude solution (Plate 6, E, 2 and 3). Likewise, I believe, 

 * 'Roy. Soc. Proc.,' vol. 21, p. 459. 



