480 PROCEEDINGS OP THE AMERICAN ACADEMY. 



4. Moreover, since the equation represents this fundamental theorem, 

 its logarithmic quantity must represent the variables in the reacting 

 tendency, or the driving energy of reaction. 



5. When analyzed, this equation shows that the part played by each 

 substance in a reaction may be considered as the logarithm of the product 

 of its " physico-chemical potential " and its actually present pressure. 



G. The reaction metatherm may be simplified into a reaction-isobar 

 and a reaction-isochor, according as the pressure or volume is kept 

 constant during the reaction. 



7. While the reaction-isobar, expressed in terras of pressure, offers the 

 most convenient basis for the calculation of the cases to which it is 

 applicable, results obtained under constant volume are more conveniently 

 calculated if the reacting substances are expressed in terms of concentra- 

 tion, according to the equation of vau't Hoff. 



Harvard University, April 3, 1900. 



