606 E. W. Dean — Hydrolysis of Esters of 



fully described. The list included ethyl acetate, ethyl glycol- 

 late, three alkyloxy acetates, ethyl propionate, ethyl lactate, 

 and ethyl alpha and beta ethyloxy propionates. The meth- 

 ods of preparation and properties of these esters need no discus- 

 sion here. 



Solutions of hundredth normal barium hydroxide and approx- 

 imately fortieth normal sodium hydroxide were prepared free 

 from carbonate by the usual methods. Hundredth normal 

 hydrochloric acid was prepared and standardized by silver pre- 

 cipitation. 



Procedure. 



Measurements were made of reactions at two temperatures, 

 zero degrees and twenty-five degrees. For the former series 

 was used a small thermostat filled with ice and water and vig- 

 orously stirred. A temperature constant within a tenth of a 

 degree was easily maintained in this manner. For work at 

 twenty-five degrees the thermostat fully described in a previous 

 paper* was employed. 



The actual experiments were carried on by a slight modifi- 

 cation of the method recommended by Ostwald.f In the ther- 

 mostat were placed two flasks, one containing a measured 

 amount of fortieth normal sodium hydroxide solution, the 

 other a solution of the ester of slightly smaller concentration 

 than that of the alkali. At the proper time an amount of the 

 ester solution equal to that taken of the sodium hydroxide was 

 withdrawn by means of a pipette and allowed to flow rapidly 

 into the reaction flask. This was shaken vigorously, replaced in 

 the thermostat and a ten cubic centimeter portion removed and 

 allowed to run into a known quantity (15 cm3 ) of hundredth nor- 

 mal hydrochloric acid. The excess of acid was then determined 

 by titration with centinormal barium hydroxide. Eosolic acid 

 was used as an indicator, this having been proven by experience 

 to be better than phenolphthalein under the conditions described. 



To obtain good constants by the method thus described 

 requires a moderate amount of skill in manipulation. We ane 

 at present unable to compare its advantages with those of the 

 conductivity method of Walker,^ employed by Findlay and 

 Hickman s.§ We therefore limit ourselves to stating the sources 

 of error and the precautions adopted. In order to be able 

 to check the reaction abruptly at the end of any interval of 

 time, a pipette which discharged the major portion of its con 

 tents in four or iive seconds was used. By vigorously rotat- 

 ing the flask into which the pipette was emptied the alkali was 



* This Journal, xxx, 72. 



f Ostwald-Lnther, Physiko-Chemische Messungen. 3ded., p. 529. 



X Proc. Roy. Soc, Series A., Ixxviii, 157. § Loc. cit. 



