Schunck . — The Chemistry of Chlorophyll. 73 
variably found the ash to have an acid reaction due to the 
presence of phosphoric acid, or rather of an acid phosphate, a 
fact, I believe, not previously noticed. These phosphates must 
have originally existed in a state of combination, the com- 
pound or compounds being soluble in alcohol and ether ; and 
if chlorophyll be, as Hoppe-Seyler thinks, a kind of lecithin, 
the presence of phosphoric acid or phosphates in the ash 
would be easily explained ; but here the usual doubts arise, 
since we cannot tell whether the phosphates may not have 
been derived from something else than chlorophyll. I shall 
reserve the few remarks that I have to make as to the probable 
constitution of chlorophyll for another paragraph. 
Absorption-Spectrum of Chlorophyll. 
The characteristic phenomena seen when light after passing 
through a solution of chlorophyll is examined with a prism 
have been so frequently described, and are so well known, that 
it would seem to be unnecessary to add anything to the state- 
ments of the many eminent observers who have made them 
the subject of study. A few remarks on the bands at the 
more refrangible end of the spectrum may, however, not be 
out of place. The band in the green, usually named band IV , 
is sometimes represented as very faint, sometimes as rather 
dark, — a circumstance which is easily explained. The purer 
the chlorophyll under examination the fainter is this band ; 
when decomposition or change commences, more especially in 
presence of an acid, then this band becomes darker by degrees, 
until at last it appears nearly as dark as the band in the red. 
It is just possible, therefore, that with a solution of chemically 
pure chlorophyll this band might not be seen at all. Much 
controversy has taken place regarding the broad indistinct 
bands at the blue end of the ordinary chlorophyll -spectrum, 
which are only seen by sunlight and are distinguished as bands 
V and VI} Some observers consider these as true chloro- 
1 The notation employed for the bands of the chlorophyll spectrum is that found 
in German works on the subject. 
