Schunck . — The Chemistry of Chlorophyll. 97 
red colour ; the solution turns lemon-yellow with caustic 
alkali, but the red colour is restored by an excess of hydro- 
chloric acid; the solution leaves on evaporation a reddish-brown 
amorphous residue, which with ether gives a reddish-brown 
solution showing a peculiar and interesting spectrum of six 
bands. This red colouring matter, though derived from 
chlorophyll by a very simple process, does not in any way 
reveal its origin : it rather resembles some of the colouring 
matters of flowers. 
The substance which is formed along with phyllocyanin by 
the action of hydrochloric acid on chlorophyll I call with 
Fremy phylloxanthin. Professor Stokes remarks that Fremy’s 
phylloxanthin may differ according to the mode of prepara- 
tion, and may be a mixture of several substances. This is no 
doubt possible, when Fremy’s method, which consists in add- 
ing a mixture of ether and hydrochloric acid to an alcoholic 
extract of leaves, is adopted, for in this case the ether may 
contain colouring matters pre-existing in the leaf, and not 
necessarily related to chlorophyll, as well as products due to 
the action of acids on the latter. When Fremy 1 describes 
phylloxanthin as crystallising in reddish prisms like potassium 
bichromate, it is certain that what he saw was not phylloxan- 
thin in the proper sense of the term ; it was probably chryso- 
phyll (erythrophyll), which has the appearance which he 
describes. Other observers — exhibiting a reprehensible want 
of accuracy in the use of terms— consider xanthophyll, the 
yellow colouring matter or mixture of colouring matters asso- 
ciated naturally with chlorophyll, and phylloxanthin to be 
synonymous ; the two are, however, quite distinct ; one occurs 
naturally, the other is a product of decomposition, and their 
properties are distinct. Let it be understood, then, that phyl- 
loxanthin is the product obtained by dissolving the precipitate 
formed by acids in an alcoholic extract of leaves in ether and 
adding concentrated hydrochloric acid to remove the phyllo- 
cyanin, when it remains dissolved in the upper ethereal liquid. 
This liquid, which has a dark greenish-yellow colour with a red 
1 Comptes Rendus, LXI. 190. 
H 
