Schunck . — The Chemistry of Chlorophyll . 99 
stances which together constitute ordinary chlorophyll, remains 
doubtful. 
Some leaves, such as those of the dandelion, show, when 
immersed in dilute hydrochloric acid, very distinctly the 
successive formation of the two colouring matters. The 
leaves first turn greenish-yellow owing to the formation of 
phylloxanthin, but after some time this tint changes to a 
greenish-grey, indicating the presence of phyllocyanin. The 
hypochlorin of Pringsheim, as well as other derivatives of 
chlorophyll described by various observers as appearing in 
brown crystalline needles, are, I think, all phylloxanthin 
more or less pure. The nature of the change which chloro- 
phyll undergoes by the action of acids is not known. In my 
opinion it is a chemical process, not a mere molecular one. 
Action of Alkalis on Chlorophyll. 
The action of alkalis on chlorophyll has been less frequently 
studied than that of acids, partly perhaps because alkalis do not 
produce such marked changes as acids do. When caustic potash 
is added to an alcoholic solution of chlorophyll the colour of 
the solution remains unchanged, and no alteration is observed 
in the spectrum. But when the alkaline solution is heated, 
a change in the spectrum takes place, which was first de- 
scribed by Chautard 1 , who states that the band in the red, 
called by him ‘bande specihque,’ is now found to have split 
into two, the addition of an excess of acid causing it to appear 
single again, the doubling re-appearing with alkali, and so on. 
The fainter bands of the chlorophyll-spectrum disappeared 
almost entirely in Chautard’s experiment. Russell and La- 
praik have also examined the effect produced by alkali on a 
solution of chlorophyll : they obtained in the first instance 
what they call a one-banded modification of chlorophyll, the 
single band of this modification dividing into two on the addi- 
tion of a considerable excess of alkali. The chlorophyll-green 
of Hansen, obtained by treating chlorophyll with boiling 
1 Comptes Rendus, LXXVI. 570, 1273. 
H 2 
