90 Ingvar Jorgensen and Walter Stiles. 
^ 58 ^ 72 ^ 5 ^*Mg + 2C0 3 + 2H 2 0 = Mg(HC0 3 ) 2 C 65 H 74 0 5 N 4 . 
chlorophyll a phaeophytin a 
but he finds more carbon dioxide is absorbed than can be accounted 
for by these two processes. For example, 0505 g. chlorophyll 
(a + b) was used in 104-02 c.c. water. This absorbed 184-45 c.c. 
carbon dioxide at 0°C and 747-3 mm. partial pressure, i.e., 6-45 c.c. 
more than could be accounted for by the water. This is equivalent 
to 12‘6 mg. Of this 7 mg. would be used in the formation of 
phaeophytin according to the equation given above; there thus 
remains 5-6 mg. unaccounted for. 
We do not see any necessity to introduce a mystical and purely 
hypothetical peroxide in order to explain this result. Indeed, the 
assumption of the formation of such a peroxide is purely gratuitous 
in view of the fact that we have absolutely no information in regard 
to the behaviour of carbon dioxide towards the ester groups of the 
chlorophyll molecule. 1 
From his experiments on the absorption of carbon dioxide in 
the dark by living leaves and leaf powder, Willstatter concludes that 
in the leaf there is a mechanism for absorbing carbon dioxide as 
the leaves and leaf powder absorb many times as much carbon 
dioxide as can be explained as due to absorption by the chlorophyll. 
To explain this he puts forward exactly the same hypothesis that 
Siegfried had propounded ten years before, without, however, 
making any reference to Siegfried. It may be interesting to 
compare with Siegfried’s results already cited, the remark of 
Willstatter (1915 b, p. 345) “ It is possible that in the absorption 
phenomenon described, carbamino compounds of amino acids or of 
proteins are formed. Preparation work is here presented with a 
new problem.” This last sentence suggests that Willstatter is 
unaware of Siegfried’s work. 
1 It is interesting to note that the solubility of carbon dioxide in some 
alcohols and esters is much greater than in water, see i.g., Just (1901). 
