206 



represents the sum of that of the non-catalysed and that of the 

 purely catalysed reaction. In order to obtain the constants of the 

 purely catalysed reactions, which are recorded in the above table, 

 the reaction constants of the non-catalysed reactions must be sub- 

 tracted from the measured ones. It has been tacitly assumed, what 

 is, indeed, shown by the constancy of the measured reaction con- 

 stants, that the two reactions proceeding side by side, are of the 

 same order, as otlierwise this operation is not allowed. 



The energy increment calculated from the 1*^^ series of observations 

 without catalyst, and from these 2"^^ 3"', 4^'' , and 5^'' series is 

 respectively ± 10.000 calories — 23000 cal. — 20500 cal. — 20500 

 cal. — 20800 cal. 



The acetylation of diplienylamin decides, therefore, in favour of 

 Scheffer's theory, as it would e.^-. be entirely inexplicable according 

 to Lewis, why the sulphonic acid can act as catalyst, as the addition 

 of this substance about doubles the energy -increment; the number 

 of active molecules would, accordingly, be much smaller, hence also 

 the number of effective collisions. 



In the calculation of the factor B from Scheffer's formula, it 

 appears to be more than doubled by the catalyst. The favourable 

 chance of collision has, therefere, been enlarged, notwithstanding 

 the number of active molecules has become smaller. Hence if the 

 conversion is to be increased, this smaller number of active mole- 

 cules must collide more favourably. Accordingly every collision 

 between molecules that are sufficiently rich in energy does not 

 always eventuate in conversion, it is probably only a small percentage 

 of them that enters into reaction. 



One can form the following conception of this. 



It is not immaterial what part of the acetic acid anhydride 

 molecule impinges with the diphenylamin-molecule, nor with what 

 part of the latter. The reactive molecule parts, in this case the 



