Reilly AM) HicKiNBOTTOM — Distillation of Volatile Fatty Acids. 125 



The left-hand side expression is the /i calculated from the observed 

 results = /(„. 



2iu 



■ /V-v\' 



i-n 



log V - log (V - v) 



When the volume distilled is small compared with the total volume, 



fia = u - /Uf<o approximately = ju (1 - x/k/C„ ), 



where Co is the concentration initially in the tlask for the range over which 

 fjia has been calculated.' 



In Table I the experimentally derived values for fj„ are given, and also 

 the values of the constant after correcting for the ionisation of the acid. 



Table I. 



* No. of c.e. 0-1 N.Ba(0H)2 to neutralize. 



The values for the other acids are also tabulated (Table 11). 



' la the calculations the following values for the dissociation constant k have been 

 taken : - 



Formic acid . . 2-1 x lO-* 



Acetic acid . • . 1-8 x 10"* 



Propionic acid . . 1-3 x 10"* 



n-Butyric acid . . 1-5 x 10 * 



With reference to the calculation of ix„, this has been done by substituting the 

 appropriate values of a, x, V, and v in the formula : — 



log a - log (a - x) 

 log V - log(F-^)' 



