134 THEORIES AS TO ACTION OF 



SUMMARY REGARDING THEORIES OF CATALYTIC ACTION 

 AND CORRELATION OF THESE THEORIES 



A review of the theories of catalysis such as is given above 

 appears to the author to indicate that the explanation lies not 

 in any one of them but in a correlation of all. Each of them 

 supplies a different path which may be used in different special 

 cases to reach the same end. The end to be reached, in order 

 that the reaction velocity may be increased, is to diminish the 

 resistance to reaction. The potential factor or vis a tergo to the 

 reaction is dependent upon the energy freed in the reaction, and 

 this in turn upon the initial and final chemical energies of the 

 reacting substances, hence this factor may be regarded as constant. 

 But the velocity with which equilibrium will be reached, and 

 in fact whether it will be reached at all, depends, as pointed out 

 previously, upon what the value of the resistance is to the reaction. 

 Now all the above theories are explanations of various means 

 by which the resistance may be altered, and so the reaction velocity 

 varied, and which of these means is taken must vary with the 

 circumstances of each case. 1 



Thus, increase of molecular vibration, as in chemical reactions 

 induced by detonation, or by mere contact with a chemical catalyst, 

 may decrease the molecular stability, and so increase the velocity, 

 and by analogy this may also occur in less easily provoked 

 reactions ; again, the formation of intermediate products may 

 break up by intermediate stages the molecular stability, pro- 

 ducing compounds in which the resistance to reaction is lessened ; 

 change in the properties of the solvent may induce or hasten 

 reaction by bringing new attractions to bear upon the constituent 

 groups of the molecule, so that the resistance to these parting 

 company may be increased or diminished, and the reaction velocity 

 correspondingly varied ; this change may be occasioned by the 

 presence of a heterogeneous system with different reaction velocities 

 due to different solvents in its two phases ; varying concentration 

 may alter the relationships and attractions between solvent and 

 substratum and so vary resistance and reaction velocity. 



1 Tt is not meant here that the means by which chemical resistance may be 

 studied are not of the highest value, and call for most careful study, but only 

 to point out that all these must be correlated and lead to the same end. 



