64 Dr. Meyer Wilderman on the Velocity of 



partly in the solidified phenol, following the laws of van't 

 Hoff. The velocities of reaction have been investigated as in 

 the case of (1), and I arrived here at the same equation as 

 above for (1). The same complications have been observed 

 here as in the case of (1). 



3. Ihe Velocity of Crystallization of over cooled liquids and 

 solutions. (^Equilibrium between the solidified and the liquid 

 solvent or solution : Water and Aqueous Solutions, Acetic 

 Acid and Solutions in Acetic Acid?) 



The method employed is based on the principle that the 

 heat set free during the reaction is completely absorbed by 

 the liquid. The reaction consists in the separation of the 

 solidified solvent from the overcooled liquid. This reaction 

 goes on until the latent heat of melting has warmed up the 

 system to its point of equilibrium. From the results observed 

 I find that the equation 



log(/ 2 — t ov )— log(f r — *o*) + log(* — *i) 



-logfe-^) = 0(T 2 -T 1 )(^-U, 



especially = &(r 2 — t{). holds good. From this equation the 

 differential equation 



% =0(*-«J (t-t) 



follows, in which t ov is the temperature to which the system 

 was overcooled, t is the point of equilibrium or the freezing- 

 point, t is the temperature of the liquid at the time r, i. e. the 

 velocity of crystallization is directly proportional to the re- 

 moteness of the system from the point of equilibrium, t — t r 

 and to the surface of separated solid in contact with the 

 liquid, t — tov, at the time t. The condition for this equation is 

 that t — t ov >0, i. e. the system must be heterogeneous not 

 homogeneous. 



4. The Velocity of Melting of the solidified solvent in the liquid 

 solvent or solution (e. g. of Ice in Water or Aqueous Solu~ 

 tions) . 



I succeeded in proving that the equation 



holds good, where C T is the surface of the solid in contact 

 with the liquid at the time t. Cubes of ice were used. Their 

 surface was directly measured at the beginning and the end 



