53 
gradually disappears and is succeeded by red, yellow, or 
purple. Therefore, it is argued, the respective colouring 
matters must be derivatives of chlorophyll. Nevertheless, 
this view is open to some objection. As regards, in the 
first place, the red colouring matter, since no one has suc- 
ceeded in obtaining it artificially, it must be formed, if a 
derivative of chlorophyll, by some process not purely chemi- 
cal. I have, indeed, obtained as one of the products of 
decomposition of chlorophyll a substance crystallising in 
red laminae, having a semi-metaliic 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 the garden Azalea or the Virginia Creeper 
with boiling spirits 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 oxidising 
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, but 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 
