142 M. Fremy on the Colouring Matter of Leaves. 



cocaine compound is distinguished by giving off benzoic acid 

 when it is distilled — a fact in which will probably be found the 

 key to its composition. Unlike atropine, cocaine does not act 

 on the pupil. 



Fremy has published* an important investigation on the 

 green colouring matter of leaves. He has found that it consists 

 of a blue and yellow principle, which he has succeeded in isolating. 



The colouring matter is contained in the green oil which is 

 extracted by alcohol from leaves. This oil may provisionally be 

 termed chlorophyll, but it contains several other substances 

 which render the separation of the colouring matter difficult. 

 The blue and yellow colouring principle have a different affinity 

 for hydrate of alumina. When a strong alcoholic solution of 

 chlorophyll was digested with hydrate of alumina, no alteration 

 took place ; but by adding a small quantity of water, a dark- 

 green, almost blue precipitate was obtained, and the alcohol solu- 

 tion was of a yellow colour. When a considerable quantity of 

 water was added, the precipitate had a colour like that of the 

 ordinary colouring matter. Although this experiment effected 

 some separation of the two colouring matters, the separation 

 could not be carried further by its means. 



Fremy next tried the action of different neutral solvents on 

 the combination of alumina with the green colouring matter. 

 He found that some, such as bisulphide of carbon, dissolved in 

 preference the combination of yellow colouring matter and alu- 

 mina ; others, such as ether, alcohol, turpentine, dissolved out 

 the green matter. By employing successively these different 

 solvents, after the use of bisulphide of carbon, he succeeded in 

 obtaining lakes of different shades, but was not able to carry 

 the separation further. 



The usual reducing agents, which change other colours, do 

 not affect chlorophyll. But by the action of bases this body is 

 converted into a yellow colour, which forms with alumina a 

 beautiful yellow lake, soluble in neutral solvents, such as ether, 

 alcohol, bisulphide of carbon. By acting on the solution of this 

 body with acids, especially hydrochloric acid, it was transformed 

 into the original green. Now, assuming that the green thus 

 formed was composed of blue and yellow colouring matters, the 

 point was to separate these two bodies at the moment of their 

 formation. This must be done by the simultaneous use of sol- 

 vents which act differently on the two colouring matters. Such 

 a solvent is a mixture of hydrochloric acid and ether ; and it was 

 used as follows : — 



Two parts of ether and one part of hydrochloric acid, diluted 



* Comptes Rendus, February 27, 1860. 



