472 Dr. Meyer Wilderman on the Velocity of 



a solid, the reaction is very much quicker when the solid is 

 taken in the form of a powder instead of in big lumps, i e., 

 the velocity of chemical reaction in heterogeneous systems is 

 dependent on the surface of the solid substance. In attempt- 

 ing to conceive chemical equilibrium in heterogeneous systems 

 in the same manner as we conceive it in homogeneous systems, 

 i. e., as two opposite reactions which at equilibrium become 

 constant, the above modification of the existing conceptions 

 becomes a priori inevitable, because we have to view equili- 

 brium here, as we did in homogeneous systems, in the light 

 of velocity of reaction. We shall, however, have first to see 

 more carefully what is the advance made in this manner, and 

 whether it is possible or not on this modified basis to bring all 

 kinds of equilibrium, complete equilibrium, points of transition, 

 and incomplete equilibrium, as well as velocity of reaction in 

 all these regions, under one general law, under one general 

 principle. If this does not prove possible, we shall have to 

 look out for other ways and methods to arrive at such general 

 principles or laws, if possible. 



B. Let us again consider the equation concerning complete 

 equilibrium as well as the points of transition. 



The general equations for the velocity of reaction I found 

 to be 



(£) =c ' ( '°-' )( '-^ +K) >- • • • {a} 



i. e., the velocity of reaction is, in all cases of complete equili- 

 brium and of the points of transition, directly proportional to 

 the remoteness from the point of equilibrium, T — T, to the 

 surface of contact of the parts of the heterogeneous system 

 which act one upon another, T — T 0M 4 the instability con- 

 stant K. Let us start with a supersaturated solution. 

 Equation (a) may in this case be written : 



(20=c'(c»-a)(S T +K), .... («o 



where C is the concentration of the solutions at the point of 

 equilibrium, Ct, 2 t are the concentration of the solution and 

 the surface of contact of the reacting parts at the time t. 

 Equation {a') can be written : 



^=c / a(S T + K)- C 'a(Sx4-K); . . . (a") 

 aT 



this equation [a") can be conceived as the total velocity of 



reaction of two partial reaction velocities : 



(g) = c 'C„(2 T + K) and (0-flU(S,+K). 



