Contributions to the Chemistry of Chlorophyll. 305 



which by decomposition with acid yielded phyllocyanic acid, while 

 his phylloxanthin remained dissolved in the alcoholic liquid, and was 

 left behind on evaporation in yellow or red crystals resembling bi- 

 chromate of potash. This process the author considers to be one of 

 saponification, chlorophyll itself being a species of fat, which by the 

 action of bases splits up, the process being described by him as 

 follows: " La chlorophylle, espece particuliere de corps gras colore, 

 eprouve done par 1'action des bases energiques une sorte de saponifica- 

 tion dont la phylloxanthine, corps neutre jaune, serait la glycerine, et 

 1'acide phyllocyanique serait 1'acide gras colore en vert bleuatre." 

 The process may, however, be explained in a simpler manner. On 

 coming into contact with caustic baryta chlorophyll simply combines 

 with the latter forming an insoluble compound, and is again set at 

 liberty by a strong acid, but is at the same time decomposed by the 

 acid yielding phyllocyanin, the so-called phyllocyanic acid being 

 simply identical with the latter. The properties of his acid, as de- 

 scribed by the author, are just those of phyllocyanin in my sense of 

 the term. It is hardly necessary to refer here to Fremy's third 

 memoir,* in which he endeavours to prove that the colouring matter 

 of leaves is a mixture of phylloxanthin and phyllocyanate potash, of a 

 conclusion even less probable than those previously arrived at. 



As regards Fremy's phylloxanthin, it is evident that it must, con- 

 sidering the method of preparation employed, have consisted of 

 several more or less yellow substances, some of which may have been 

 present as such in the solution of chlorophyll taken, while others were 

 formed by the action of the hydrochloric acid on the chlorophyll in 

 solution. In his first memoir Fremy states that his phylloxanthin is, 

 in his opinion, identical with the yellow colouring matter of leaves 

 developed in the dark as well as that of yellow autumnal leaves. 

 Whether the colour of etiolated and that of faded leaves is due to the 

 same substance, and whether the latter is identical with the yellow 

 colouring matter which always accompanies chlorophyll in healthy 

 gieen leaves is uncertain, but there can be no doubt that the latter, 

 the constant companion of chlorophyll, was present in Fremy's phyllo- 

 xanthin solution. Though still an imperfectly known substance, 

 its general properties have been ascertained, and it is now usually 

 called xanthophyll. In his second memoir Fremy gives a description 

 of his phylloxanthin, from which it is evident that the substance 

 obtained by his new process was identical with Hartsen's chrysophyll 

 and Bougarel's erythrophyll, a body yielding beautiful red crystals, 

 giving solutions of a deep yellow colour, and apparently present in 

 all green leaves. This then is the second constituent of Fremy's 

 phylloxanthin, but there is yet a third, which, though overlooked by 

 that chemist, must have been present along with the two others, at 

 * ' Comptes Bendus,' vol. 84, p. 983. 



