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



remove the green constituent of the mixture when a yellow coloured 

 solution remains, the colour of which he believes is evidently due to a 

 pre-existing colouring matter or matters associated with the green one. 

 Kraus — to whom we are indebted for a most elaborate study of the 

 physical properties of the yellow constituent of crude chlorophyll 

 solutions — confirmed the observations of Filhol, and added a number 

 •of new ones which lead, according to him, to an explanation of the 

 absorption spectrum of crude chlorophyll solutions which has hitherto 

 been universally accepted as the correct one. The author used 

 amongst other methods, for the purpose of separating the yellow 

 colouring matters from the green, their different solubility in alcohol 

 and benzol or, correctly speaking, benzoline. An alcoholic solution of 

 chlorophyll, treated with benzoline, retains, according to him, the yellow 

 colouring matter or mixture of colouring matters, while the benzoline 

 takes up the green constituent. By an investigation of the spectro- 

 scopic properties of these solutions, compared to the original one, 

 Kraus arrived at the result that the ordinary chlorophyll spectrum, 

 which has been described with considerable accuracy already by 

 Brewster, is a complex one, i.e., that some of the absorption bands are 

 due to the green constituent and some to the yellow. The former, he 

 says, is characterised by six bands, four of which (comprising the well- 

 known chlorophyll spectrum) are situated between the solar lines B 

 and E ■ the fifth between F and G, and the sixth in front of G. The 

 yellow constituent shows two bands, one at F or just behind it, and 

 the second in front of G. These observations, according to Kraus, 

 explain the constitution of the spectrum of crude chlorophyll solutions, 

 the first four bands of which being due solely to the green constituent, 

 the fifth to the yellow, and the sixth to a combination of the sixth 

 band of the green constituent and the second of the yellow. The fifth 

 band of the green constituent being very faint, and situated between 

 the fifth and sixth bands of the mixture, does not, according to him, 

 appear at all. These explanations, however, as will be shown, are 

 erroneous. 



Sorby using carbon bisulphide as the separator in place of benzoline 

 states that along with chlorophyll in the crude alcoholic extracts of 

 the green leaves of the higher plants there are three accompanying 

 yellow colouring matters present which he names orange xanthophyll, 

 xanthophyll, and yellow xanthophyll, each showing a couple of bands 

 in slightly different positions in the more refrangible visible portion of 

 the spectrum, but none in the less refrangible part, and also that 

 there are other yellow colouring matters present, which he groups 

 under the term lichnoxanthine, which obscure the more refrangible 

 portion but exhibit no bands. He also states that chlorophyll (the 

 green constituent) of the higher plants is separable by the same means 

 into two colouring matters which he terms " Blue Chlorophyll " and 



