20 



The Philippine Journal of Science 



1913 



was kept at 25°. Saponification, with a large excess of the ester, 

 was carried on in small bottles filled to the neck with the 

 standard solution. A separate bottle was used for each titra- 

 tion, and all were kept tightly stoppered with glass stoppers 

 until titrated. By this means no carbon dioxide was allowed 

 to escape. Under these conditions it is theoretically possible to 

 calculate the concentration of the free base and the velocity 

 constants, but the complexity of the mathematical treatment 

 necessary is such as to render it impractical. The experimental 

 data are given in Table VI for purposes of comparison with 

 Table VII, which contains the same data for methyl benzoate. 

 It will be seen that a similar relationship exists between the 

 rates of saponification of methyl benzoate and methyl salicylate, 

 whether sodium hydroxide or carbonate is used for saponifica- 

 tion (fig. 3). Saponification practically ceases when all the 

 carbonate has been converted into the bicarbonate. 



Table VI. — T—25°±0.1. Methyl salicylate— excess. Na,COs=0.3998 N. 



t. 



60 ' 



X. 



a — x. 



1000 Kmono. 



1 



0. 0130 



0.3868 



0.240 



3 



0.0250 



0. 3748 



0.155 



e 



0. 0334 



0,3664 



0.126 



8 



0.0467 



0, 3531 



0.112 



12 



0.0572 



0.3426 



0.093 



20 



0. 0777 



0.3221 



0.079 



30 



0. 0919 



0.3079 



0.063 



50 



0. 1180 



0. 2880 



0.047 



100 



0.1539 



0. 2459 



0.035 



190 



0. 1797 



0. 2201 



0.023 



Table VII. — Methyl henzoate— excess. NchCOs=0.S998 N. T=25°±0.1. 



t 



60' 



X. 



a — x. 



1000 Kmono. 



1 



0.0098 



0.3900 



0.180 



3 



0. 0145 



0.3853 



0.090 



5 



0. 0215 



0.3783 



0.080 



8 



0.0305 



0. 3693 



0.072 



12 



0.0335 



0. 3663 



0.053 



20 



0.0394 



0. 3604 



0.035 



30 



0.0450 



0.3548 



0.029 



50 



0.0748 



0. 3250 



0.027 



100 



0.1267 



0. 2731 



0.027 



190 



0. 1982 



0.2016 



0.026 



