i 3 4 CHEMICAL PROPERTIES AND COMPOSITION 



with the condition that for equilibrium the two velocities 

 must be equal, or 



*t\ v alcohol V acid = K 2^ ester ^ water i 



whence 



i- r r 



'^1 ^ ester ^ water jr 



17 n n 



'^2 ^alcohol ^acid 



Next, the fact must be taken into account mentioned on 

 p. ii 6, that the limit of esterification, and therefore /i, 

 does not vary much in passing from methyl alcohol to the 

 primary and secondary alcohols, and only sinks notably in 

 the case of tertiary ; this is shown by the following numbers, 

 which refer to the alcohols already mentioned (limit on 

 heating with acetic acid to 153 to 154): 



Methyl-, Ethyl-, Octyl-j Isobutyl-, Isopropyl- alcohol 

 70 67 72 67 61 



Dimethylallylcarbinol Phenol 



1 9 



It follows from this that, except in the case of the 

 tertiary alcohols, there must be, on the whole, a parallelism 

 between the velocities of esterification and saponification, 

 at least when these are determined under similar circum- 

 stances in dilute solution. 



The experimental data are insufficient to test these con- 

 clusions, and the velocity constants for saponification (& 2 ), 

 have hitherto only been determined for other, not directly 

 comparable circumstances. Still we shall quote the results 

 in order to make some observations in connexion with 

 them. 



The velocity of saponification has been determined in dilute 

 solution in presence of bases or acids. The velocity is only 

 dependent on the specific character of the base in so far 

 as its proportionality to the concentration of the hydroxyl 

 ions indicates ; consequently, for strong bases at sufficient 

 dilution, when the electrolytic dissociation may be regarded 

 as complete, it is simply proportional to the concentration 

 of the base, without regard to its nature. So in acids, the 

 concentration of the hydrogen ions is the measure of 



