Contributions to the Chemistry of Chlorophyll. 349 



which increases in quantity on standing. After the precipitate has 

 settled, the liqnid appears greenish-yellow ; it shows the spectrum of 

 acid chlorophyll, due to the presence of colouring matters from the 

 precipitate, these being not entirely insoluble in alcohol, but it also 

 contains yellow colouring matters which darken the blue end of the 

 spectrum, as well as other bodies extracted from the leaves which 

 have no connexion with chlorophyll. 



The dark green precipitate is now filtered off and washed with 

 spirits until the filtrate appears nearly colourless. It contains besides 

 impurities, which are chiefly of a fatty nature, two distinct colouring 

 matters identical with the phyllocyanin and phylloxanthin of Fremy. 

 These names I see no reason to change. They have been retained by 

 Tschirch,* one of the latest writers on the subject. The method I 

 adopt for separating the two substances is essentially the same as 

 that of Fremy. I have tried other methods, but they have led to no 

 result. The use of alkaline solvents is to be avoided, since both 

 colouring matters are changed by the action of alkalis. The crude 

 product of the action of the acid is first treated with ether, in which 

 nearly the whole dissolves. The insoluble matter having been 

 filtered off, the filtrate is mixed with about its own volume of fuming 

 hydrochloric acid. The mixture, after being well shaken, is left to 

 stand, when it separates into two layers, an upper yellowish-green 

 one, containing phylloxanthin and a great part of the fatty matters, 

 and a lower dark blue one, containing phyllocyanin. This is the 

 experiment of Fremy, which is so often referred to in memoirs on 

 chlorophyll, as having led him to the conclusion that chlorophyll was 

 a compound or mixture of a blue and a yellow colouring matter. I 

 propose first to give an account of phyllocyanin, the colouring matter 

 of the blue layer. 



The two liquids obtained in the manner just described are 

 separated in the usual way, and the lower blue one is agitated with 

 fresh ether, the process being repeated until the ether appears nearly 

 colourless, and the phylloxanthin has been removed. After a short 

 exposure, to allow the ether contained in it to evaporate, it is mixed 

 with water, which produces a dark blue precipitate. This is filtered 

 off, washed to remove hydrochloric acid, then dissolved in boiling 

 glacial acetic acid. This solution on cooling gives a crystalline 

 deposit of phyllocyanin, which is filtered off and recrystallised from 

 acetic acid. If, on decomposing a little of it with boiling dilute nitric 

 acid, nothing is left undissolved, the product may be considered pure, 

 but if yellow oily drops appear on the surface of the boiling acid, the 

 process of crystallisation from acetic acid must be repeated. The 

 product is finally filtered off, washed with acetic acid, and dried. 



By the process just described, I have obtained phyllocyanin from 

 * " Untersuchungen uber das Chlorophyll," Berlin, 1884. 



