COLOURS OF FADED LEAVES. 37 



derivative of chlorophyll, by some process not purely che- 

 mical. I have, indeed, obtained as one of the products of 

 decomposition of chlorophyll a substance crystallizing in 

 red laminse, having a semimetallic appearance by reflected 

 light ; but this substance is entirely distinct from the red 

 colouring-matter of faded leaves. The latter may easily be 

 procured, at least in an impure state, by extracting the 

 reddened leaves of th e garden Azalea or the Virginian Creeper 

 with boiling spirit of wine, evaporating the extract at a 

 gentle heat, and treating the residue with water, in which 

 the colouring- matter dissolves. The solution has a fine 

 crimson colour like that of red ink. The colour does not 

 change on the addition of such acids as exert no oxidizing 

 action. Nitric acid gradually turns it yellow. By the 

 addition of alkalies, such as ammonia, its colour changes to 

 a yellowish green, and it has then very much the appear- 

 ance of an alcoholic solution of chlorophyll ; bat it does not 

 show either before or after the addition of alkali the least 

 indication of absorption-bands, merely a general darkening 

 of the more refrangible end of the spectrum. With lead 

 acetate it gives a grass-green precipitate. These reactions 

 show that the colouring-matter belongs to the same class 

 as that of the rose and red flowers generally ; but in the 

 present state of our knowledge regarding this class of sub- 

 stances, it is quite impossible to say whether any two mem- 

 bers belonging to the series are identical or not. One thing, 

 however, is certain, viz. that the red colouring-matter of 

 faded leaves is actually formed during the process of decay ; 

 it does not pre-exist in the green leaf, though there can be 

 no doubt that leaves which are naturally more or less red, 

 such as those of the copper beech and various species of 

 colium, contain a ready formed red colouring-matter. 



As to the yellow colouring-matter of faded leaves, whether 

 it preexists in the green leaf or is formed from chlorophyll 



