352 



Messrs. I. Jorgensen and F. Kidd. 



•determine whether the illuminated chlorophyll sol has any action on carbon 

 dioxide. If any disappearance of carbon dioxide, due to a catalytic action of 

 chlorophyll, takes place under the conditions, it might be possible, even 

 with small quantities of chlorophyll, to get appreciable diminution of the 

 carbon dioxide present.* 



The apparatus consists of a glass vessel provided with a side tube and a 

 manometer with a tap. The procedure is as follows : the chlorophyll sol is 

 introduced through the side tube, the vessel is evacuated, carbon dioxide 

 introduced, and the side tube sealed off. The apparatus is placed in a 

 thermostat, and, by noting the barometric pressure, the pressure of the gas 

 can be accurately determined. An apparatus of this description enables one 

 to follow from time to time changes in the gas-content of the vessel. 



If a strong concentration of the sol is used precipitation takes place. 

 Hence, only the results of experiments with moderate concentrations of the 

 sol are here described. Strong concentrations up to 200 mgrm. in 

 100 c.c. are employed, but the question of absorption here becomes so 

 complex that a detailed investigation is required.f With moderate con- 

 centrations no appreciable absorption was found, although in most cases 

 an absorption of O'OOl grm. of carbon dioxide could have been detected. 

 The following is a typical result : 20 c.c. of a sol (concentration 40 mgrm. in 

 300 c.c. water) were contained in the vessel of volume 120 c.c, filled with 

 carbon dioxide under a pressure of 820 mm. of mercury, at a temperature of 

 20° C. The pressure of the gas remained unchanged for 24 hours. The 

 following Table indicates the colour change taking place in the experiment. 



Time 

 of illuminations. 



Pressure. 



Colour. 



hr. 



mm. Hg. 









821 



Green. 



4 



821 



Yellowish green. 



5 



820 





8 



822 



Yellow brown. 



10 



819 



No further change. 



20 



820 





The slight variations in pressure are within the limits of experimental error. 



* It is possible, on the other hand, that catalysis, though occurring, might not 

 proceed to any appreciable degree in vitro, while in the living plant it might nevertheless 

 proceed vigorously owing to a continual removal of products. 



t It is clear three processes are possible here : (1) absorption of carbon dioxide by 

 the dispersion medium, (2) absorption of carbon dioxide by the chlorophyll phase, 

 ;(3) removal of carbon dioxide by chemical action during illumination. The method here 

 employed would give information concerning the last process only. 



