88 Conductivities and Viscosities in Pure and in Mixed Solvents. 



chloride and iodide of cadmium. They measured the conductivity 

 and viscosity of the solutions at the concentrations and temperature 

 employed in the experiments, and from these calculated the degree of 

 ionization. 



The work was carried out under the same conditions employed by 

 Kellogg. They found that all of the salts used, even at concentrations 

 as low as 0.1 normal, increase the rate of the reaction. As the concen- 

 tration of the salt increases the effect becomes less and, finally, when 

 the solution becomes concentrated, the salt has a retarding effect. 



The curves they obtained for these salts were found to be very similar 

 to those for the alkali chlorides, but showed a larger effect. Cadmium 

 chloride and iodide were found to give a very large value, due probably 

 to their hydrolysis, since they have an acid reaction. 



Henderson and Kellogg found that the salts which produced the 

 greatest effect were those that were least ionized. From this they 

 drew the conclusion that the solution of the problem was to be sought 

 in the effect of the non-ionized portion of the salt rather than in the 

 ionized portion. If the hydrolysis of the ester is controlled by the 

 concentration of the salt molecules, the cause of the observed maximum 1 

 is easily explained, since as the total concentration of the salt increases, 

 not only does the concentration of the molecules increase, but the vis- 

 cosity also varies. The maximum, then, was the resultant between the 

 acceleration produced by the salt molecules which increases with the 

 concentration, and the resistance to the contact of the ester and water, 



due to the increasing viscosity. 



+ 



Measurements of the H and OH ions, had they been carried out, 

 would have had an important bearing on Euler's 2 hypothesis; that at 

 higher salt concentrations water is much more ionized than in dilute 

 solutions, and it is the increase in the ions from water that accelerates 

 the reaction. 



HYDROLYSIS. 



The presence of hydrogen or hydroxyl ions other than those from 

 water must be guarded against with greatest care. Since the ions 

 from water are relatively so few in number, the introduction of ions 

 from other sources would render the results of little value. Ions might 

 easily be introduced in the ester and in the solutions of the salts. The 

 ester must be distilled until it gives a neutral reaction. Salts of weak 

 acids or weak bases can not be used on account of hydrolysis : 



KCN ^ K + CN 

 HOH ^=10 + H + H 



A 



A 



V 



KOH HCN 



iJourn. Amer. Chem. Soc., 31, 886 (1909). 2 Zeit. phys. Chem., 32, 348 (1900). 



