282 Ingvar Jorgensen and Walter Stiles. 
from the phyllins by the action of acids are called porphyrins. 
Thus aetiophyllin gives setioporphyrin, C 31 H SG N 4 . 
While the action of alkalis on chlorophyll produces no change 
in the optical properties of the chlorophyll derivatives, with acids 
the colour becomes olive-green and the fluorescence becomes less. 
It is another group of the chlorophyll that is attacked, but the 
resulting substance is incapable of forming salts: no saponification 
has taken place. 
For instance, the action of oxalic acid or dilute alcoholic 
hydrochloric acid on an alcoholic extract of leaves is to produce a 
wax-like chlorophyll derivative called phaeophytin. It contains no 
magnesium, and the replacement of that metal by hydrogen is the 
only change which takes place. The substance is not easily soluble 
in alcohol and so is precipitated easily. Its solution differs from 
that of chlorophyll in colour, but if a metal is introduced into the 
molecule again, it regains the chlorophyll colour. This may easily 
be effected with copper and zinc by adding their acetates to 
phaeophytin. Magnesium is not so easily replaced, but Willstatter 
has succeeded in doing this by treating phaeophytin with magnesium 
methyl iodide. 
If phaeophytin is saponified with alkali, nitrogen-containing 
acids are produced and a nitrogen-free alcohol called phytol of the 
formula C 20 H 39 OH. Willstatter has also shown that a—COOCH 3 
group is broken up by this hydrolysis. 
From the results of the treatment of chlorophyll with alkalis 
and acids Willstatter has thus been able to write the formula of 
chlorophyll a as (C 32 H 30 ON 4 Mg) (COOCH 3 ) (COOC 20 H 39 ), 
that ofchlorophyllbas(C 32 H 28 O 2 N 4 Mg)(COOCH 3 )(COOC 20 H 3 9 ). 
When a mixture of chlorophyll a and b is saponified with alkali 
the green colour changes first to a deep brown (chlorophyll a 
changes to yellow, chlorophyll b to red). After a few minutes 
the colour changes back to the original green. Willstatter 
explains this as possibly due to the presence of a lactam ring 
CO—NH which is opened when the brown phase is produced. 
I I 
The reappearance of the green colour is supposed to be due to the 
formation of another lactam ring which is more alkali-stable. 
During the production of the brown phase the complex 
combination of the magnesium is affected. On the reproduction of 
the green colour the carboxyl group might combine with the same 
nitrogen group or with a different nitrogen group, or the nitrogen 
