ÖFVERSIGT AP K. VETENSK.-AKAD. FÖRHANDLINGAR 1899, N:0 9. 923 



the following: each time a certaiii volume of the reaction mix- 

 ture is pipetted out, the empty space in the flask becomes greater 

 and some of the ester vaporises into this space and thus reduces 

 the concentration of the ester in Solution. Every time also, that 

 the cork is withdrawn, some of the ester vapour escapes into the 

 outside air, and the replacement of this still more reduces the 

 concentration of the Solution. 



To obviate the above as much as possible the following 

 arrangement was used. The total volume used in titrating was 

 very small in coraparison with the volume of the liquid in the 

 flask. Thus if the flask contained 100 cc. when full, only five 



titrations of 2 ccs at a time were made. To prevent the neces- 

 sity of taking out the cork each time and thus exposing a com- 

 paratively large aperture to the air, a narrow tube, just large enough 

 for the stem of the pipette to pass down it, was fitted through 

 the cork, as shewn in the diagram, and stopped at the one end 

 by means of glass rod and indiarubber tubing. The result was 

 that only a very small surface was exposed to the air every 

 time the tube was unstopped, and very little evaporation into 

 the outer air could take place. 



In making up the reaction mixture and during the trans- 

 ference of the Solution of the ester, some of the latter would be 

 lost by evaporation, especially at the higher temperatures used. 

 This however would have no effect on the value of the constant, 



