Schunck . — The Chemistry of Chlorophyll. 103 
quantity of any acid be added, the colour of the solution 
changes slowly from green to brown, and now shows a pecu- 
liar and beautiful spectrum, characterised by two dark bands 
in the red and two pale but quite distinct bands in the green, 
bands I and IV a of the phyllocyanin or phyllotaonin-spec- 
trum having apparently each split up into two (see Fig. 11 
of the Plate). A further change takes place on standing, 
one of the bands in the green becoming darker, the other 
lighter. Here the action stops with dilute acids. In con- 
centrated hydrochloric acid phyllotaonin dissolves, giving a 
bright bluish-green solution which contains the same product 
as that formed by the slow action of dilute acids. On treat- 
ing phyllotaonin with boiling glacial acetic acid it dissolves, 
and the dark purple solution deposits on cooling crystalline 
needles of a fine purple colour, consisting doubtless of an 
acetate and showing in solution the same absorption spectrum 
as the ethyl and methyl compounds, which in other respects 
also they closely resemble. The products formed by the 
action of acids may in all cases be re-converted into phyllo- 
taonin by means of an alkali. The process of re-conversion 
may be followed through its various stages with the crystal- 
lised acetate. If this be treated with aqueous potash in the 
cold it dissolves ; acetic acid then gives a green precipitate 
which dissolves in ether, the solution showing the spectrum 
just described, but if boiling alcoholic potash be employed 
phyllotaonin is reproduced, as shown by the spectrum of the 
ethereal solution of the precipitate with acid. Under the 
influence of acetic acid the latter passes again through the 
series of changes previously described. That the changes, 
induced on the one hand by alkalis and on the other by 
acids, are due in the one case to hydration and in the other 
to dehydration, is exceedingly probable. It was the peculiar 
behaviour of phyllotaonin in presence of acids that led me to 
infer that it had never previously been observed. 
Though there can be little doubt as to the crystallised 
substance formed by the action of acid on an alcoholic solu- 
tion of alkaline chlorophyll being an ethyl compound, still 
