90 Schunck. — - The Chemistry of Chlorophyll. 
spectrum differing from that of phyllocyanin and more nearly 
approaching that of chlorophyll. In some works this spectrum 
is called the spectrum of phyllocyanin, but it is in fact the 
spectrum of the compound with hydrochloric acid, phyllocy- 
anin playing towards strong acids the part of a base. It forms, 
however, only loose combinations with acids ; consequently on 
adding water to a solution in either of the two acids named, 
it is precipitated unchanged. If the solution in sulphuric acid 
is left to stand for some time, or if the solution in hydrochloric 
acid is evaporated to dryness, the phyllocyanin undergoes 
a change of the same nature as that induced by the action of 
alkalis. Phyllocyanin shows no tendency to combine with 
phosphoric, oxalic, tartaric, or citric acid, which is not sur- 
prising considering that its character as a base is so little 
pronounced. Glacial acetic acid acts merely as a solvent, the 
solution showing nearly the same absorption-spectrum as that 
in alcohol, ether, and other menstrua. Nitric and chromic 
acids decompose phyllocyanin, yielding yellow products of no 
interest. 
On passing chlorine gas through a solution of phyllocyanin 
in chloroform, the colour changes from dull-green to a bright 
grass-green, like that of a solution of chlorophyll itself ; it still 
shows absorption-bands, but these do not coincide with those 
of chlorophyll nor with those of phyllocyanin. On continuing 
to pass chlorine through the solution the colour changes to 
yellow, and it now shows no trace of absorption-bands ; the 
products of the action are amorphous. Bromine acts in a 
similar manner. 
Any one who has observed the ease and rapidity with 
which a solution of chlorophyll is bleached on exposure to 
light and air must be struck with the extraordinary perma- 
nence exhibited by phyllocyanin solutions under the same 
circumstances. A moderately strong solution of phyllocyanin, 
when exposed to sunlight, retains its colour for a long time, 
the last trace disappearing only after many weeks’ exposure. 
In order to observe the changes which take place, it is best 
to take a chloroformic solution of phyllocyanin and expose it 
