1st series. 



207 

 2nd series. 



3rd series. 



4th series. 



5th series. 



oxygen bridge of the anhydride and the aminohydrogen of the aniin, 

 must be in each otlier's immediate neighbourhood. In a substance 

 which exercises an attraction on these two parts, these molecule 

 parts will be turned towards each other at a collision of the three 

 molecules (more probable is a collision of a molecule with the 

 complex of the two others). The sulphonic acids used certainly 

 exert an attraction on the amino hydrogen, and most likely also on 

 the bridge oxygen, because sulphuric acid impinges with the anhy- 

 dride at that place, and the sulphon group is the active component 

 in both substances. In my opinion the catalytic action of sulphonic 

 acid is for the greater part due to its directive action, and it owes 

 this directive action to its affinity towards the reaction components, 

 as Böeskken's dislocation theory demands for every catalyst, without 

 this aflinity leading to such a firm bond, that the affinity, hence also 

 the directive action on the other kind of molecule, would be 

 eliminated. ' 



Against these conclusions the question might be raised whether 

 the measured temperature coefficient represents indeed the real one. 

 The nature of the catalyst leads to the supposition that a part of the 

 sulphonic acid is bound to the diphenylamin resp. anhydride (or 

 both), and that this might not be active (or ranch less so). On rise 

 of temperature a stronger dissociation would appear in the components, 

 hence more free (i.e. more active) catalyst would be present. Then 



