﻿CATALYSIS. 133 



This result is characteristic of iron salts when they are used as 

 catalyzers in decomposing solutions of oxalic acid; at first the reaction 

 proceeds quite rapidly, but it becomes slower until finally it is almost 

 imperceptible. 



Solution (&) was colored as given above because it was thought that 

 perhaps the color of the uranium solution might have some connection 

 with the absorption of the energy of the sunlight and consequently with 

 the catalysis. This idea was especially suggested because ferric chloride, 

 which also acts as a catalyzer in this reaction, is likewise yellow. Another 

 solution, colored yellow with aniline yellow (Griibler & Co.) likewise 

 gave negative results. 



It was thought that possibly the ionization of the oxalic acid or of the 

 water might be increased in the sunlight, and that this change in 

 conditions might have an effect on the reaction. Xichols and Merritt 3 

 have recently demonstrated that fluorescent solutions conduct the current 

 better in the sunlight than in the dark. Fluorescent substances absorb 

 light and do not follow Kirchoff's law ; nonfluorescent substances do not 

 increase the conductivity in sunlight. The amount of fluorescence and 

 conductivity are proportional to one another. Unfortunately, the original 

 paper is not accessible to me, so that I was not able to follow the 

 experimental methods employed by the authors, but 1 measured con- 

 ductivities of boiling uranium solutions in the sunlight and in the dark 

 in the usual Kohlrausch cell. Xo difference could be detected between 

 the sunlight and darkness. I also studied the speed of hydrolysis of 

 ethyl acetate by water at a boiling temperature in the sunlight and in 

 darkness. Xo increase in the ionization of water in the sunlight could 

 be detected by this method, nor does sunlight have any effect on the 

 speed of esterineation of ethyl acetate from glacial acetic acid and 

 alcohol. 



Experiment 10. — p. m. 



(a) 1 gram fenie chloride sublimed. 

 5 grams oxalic acid. 



100 cubic centimeters water. 



(b) 2 grams ferric chloride sublimed. 

 5 grams oxalic acid. 



100 cubic centimeters water. 



Time. 



(«) 



(6) 



2.10 to 3.00 



13 



40 



3.02 to 3.25 



23 



40 



3.30 to 3.53 



20 



33 



Phys. Rev. (1905) 19, 396. 



