186 EXPERIMENTAL OBSERVATIONS ON 



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 points 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 equilibrium at this point, else why should the system come 

 permanently into rest and the reaction cease ? As has been pointed 

 out above, the action 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 equili- 

 brium point for no resistance, 

 in whichever direction the re- 

 action is proceeding. 



The matter may be illus- 



j? I0 . 3. trated graphically, as in the 



annexed diagram. Let the 



horizontal line XX X represent the path of the reaction, the sub- 

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

 other form at Xjj at intermediate points varying percentages are 

 in the two forms. Let the curved line, by its height above XX 13 

 represent the opposition to reaction 1 at each stage. Then the oppo- 

 sition where it is low will be overcome up to a certain distance from 

 either side, dependent upon the power of the catalyst. A catalyst of 

 sufficient power will carry the reaction up to the same point (c), in 

 no matter which direction the change is going: this point is what is 

 ordinarily called the equilibrium point or true equilibrium point. But 

 for a less powerful catalyst the diagram shows that there will be two 

 points of equilibrium, one on each side, according to the direction in 



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1 That is, p , where R 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 



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



