( Ö8 ) 



The measnrement was started liere half a minnte after the 

 C'oiiinieiu'cnient of tlie filling. The filling lasted '/^ minute. 



The (hird column contains the values of k' calculated on the 

 supposilion that the reaction is z<7i/;»o/^c?Jrty' whilst the fourth cohimn 

 contains the values of /' assuming the reaction to be himoleadar, 

 as believed by Schenck and Zimmehmann. In concordance with what 

 has been found abo^'e, we see that the figures in the third column 

 are much more nearly constant tiian those in the fourth. During 

 the first 15 minutes the Nalues of /■ (third column) agree tairly well 

 with each other; afterwards a slow fall takes place. That the first 

 constant would be smaller than the next was to be expected, as 

 during the tirst 4 minutes a small expansion had still to take place. 



Although the starting point could not be fixed with the same 

 accuracy as before, owing to the greater velocity of the reaction, the 

 fall of k could not be attributed to experimental errors. It therefore, 

 made us suspect that the reaction might perhaps prove to be perceptibly 

 reversible at 445°. 



It is true that Boudouard^) had found that CO when in contact 

 with our catalyser was completely deconi})Osed at 445° into COg 

 and C, but as his method was not very accurate we felt we might 

 doubt this result '). 



In order to obtain certainty we made the following experiment. 

 We filled the apparatus at 445° with CO^ and observed whether an 



^) Schenck and Zimmermann have made a mistake calculating the value of k'. 

 2) Ann. de Ghira. et de Phys. [7] T. 24. Sept. p. 5-85 (1901). 

 s) Sabatier and Senderens noticed a complete transformation between 230° and 

 400^ Bull. Soc. Ghim. t. 29 p. 294 (1903). 



