Cklo7'ophyll, Carotin and Xantliophyll. 179 



addition of talc and filtering, no xanthophyll could be extracted 

 from the films decomposed by carbon dioxide. 



Nevertheless., that the first stage in photo-synthesis might be a 

 ■direct addition synthesis with carbon dioxide is by no means im- 

 possible. It has long been known that direct addition syntheses of 

 ■carbon dioxide can be produced with the aid of strong reducing 

 agents such as sodium or potassium (Wanklyn, Kolbe), Bremmer 

 .(Annalen, 350, 1906, p. 313) has shown that hydroquinone heated 

 with potassium carbonate, bicarbonate, glycerine and sodium sul- 

 phate in a stream of carbon dioxide yields oxysalicylic acid and 

 dicarbosylic acid (CgHgOj;). Similar results were obtained with 

 phenol and resorcin, while gallic acid yielded a gallocarboxylic 

 acid. Presumably phenols may be transformed into Ketone com- 

 binations with a free affinity to which carbon dioxide can attach 

 itself, that is a direct addition synthesis with carbon dioxide takes 

 place. 



The action of watery solutions of carbon dioxide on chlorophyll 

 in light and in darkness. 

 Pure dry carbon dioxide does not appear to exercise any action 

 upon chlorophyll films in darkness, or even in light, after several 

 weeks' exposure the films being still green and not appreciably 

 altered. As the presence of water is necessary, a large bulb tube 

 was lined with chlorophyll half way from the bulb end. The tube 

 was filled with pure carbon dioxide over mercury, and after intro- 

 ducing 0.5 c.c. of water saturated with carbon dioxide, was exposed 

 to light for three weeks. The films were still green, but with a 

 yellow tinge. The weight of chlorophyll used was 0.216 gram. 

 Out of 2440 c.c. of carbon dioxide 15.6 c.c. disappeared, and the 

 residual gas contained 0.4% of nitrogen, but no oxyyen. Appar- 

 ently a rapid reaction between chlorophyll and carbon dioxide only 

 takes place when the former is in direct contact with a watery 

 solution of the latter. 



Repeating the experiment with a tube containing sufficient wat«r 

 to cover the film, the upper end being drawn out, sealed, and the 

 tube exposed for one week, the water became pale yellow, and the 

 chlorophyll yellowish green. Eight c.c. of saturated water were 

 used, 40 c.c. of carbon dioxide and 0.22 gram of chlorophyll. 

 After bringing the whole tube to the original temperature, and 

 allowing for the pressure, the gas had decreased in volume only 3.8 

 c.c. (i.e., 0.007 gram COtj per 0.006 gram of Magnesium). On 

 evaporating the water to dryness, and adding the chlorophyll film 



