66 EXPERIMENTAL OBSERVATIONS ON 



stratum after the reaction had ceased caused a fresh quantity 

 to be converted. 



Removal of the products of conversion also had the effect of 

 causing conversion of further quantities. This last result is con- 

 firmed by other observers. 



These results of Tammann with regard to the alteration of the 

 position of the incomplete end-point by precisely such factors as 

 influence a true equilibrium point, are interesting in view of the usual 

 .statement that the point of rest in such incomplete reactions are so- 

 called false equilibrium points. That the equilibrium point is false in 

 the sense that it cannot be reached by the same catalyst working in 

 the reversed direction must be admitted, but it is a false equilibrium 

 point in this sense only ; and as far as the entire system, including 



the catalyst, is concerned, for 

 the given concentrations and 

 temperature it is in true equi- 

 librium at this point, else why 

 should the system come per- 

 manently into rest and the 

 reaction cease? As has been 

 pointed out above, the action 

 FIG. 3 of the catalyst is to diminish 



the resistance opposed to the 



driving force due to energy set free in the reaction. Now, as the 

 system approaches the true or absolute equilibrium point which it 

 would reach in the absence of resistance, the driving force diminishes, 

 and the movement against resistance will cease at a point, dependent 

 upon the power of the catalyst in diminishing the resistance, short of 

 the equilibrium point for no resistance, in no matter which direction 

 the reaction is proceeding. 



The matter may be illustrated graphically, as in the annexed 

 diagram. Let the horizontal line XX' represent the path of the reaction, 

 the substance being supposed to be all in one form at X and all in the 

 other form at X p at intermediate points varying percentages are in 

 the two forms. Let the curved line, by its height above XX', repre- 

 sent the opposition to reaction * at each stage. Then the opposition 



fj 



1 That is p, where K is resistance and P the potential tending to reaction 



of which R remains approximately constant while P continually diminishes 

 as the equilibrium point is approached, hence, as shown in the diagram, the 



-p 



opposition to reaction ~ increases as the equilibrium point is approached. 



