72 



Miss D. J. Lloyd and Mr. C. Mayes. 



system. If this is represented as [HC1], and « is the degree of ionisation of 

 the acid, then 



[HC1] = [H]/«-[HJ, (1) 



The values of a are taken from Lewis's ' Text-book of Physical Chemistry ' 

 (3rd edition). Using Blasel and Matula's formula (1), if n' represents the 

 concentration of acid removed from independent solution by the gelatine, then 

 »' = N-[H],/«, or n = N-([H] + [HC1]). (2) 



Equation (2) only holds if the Value of « in (1) is the same both in the 

 presence and absence of dissolved gelatine. In Table I, Column I gives the 

 concentration of acid used, Column II the corresponding values of a, and 

 Column III the values of —log N«. Column IV gives the electrode 

 reading in millivolts, and V the value of Pu calculated from the formula 



Pn = (E-248-8)/581. 



Columns VI and VII give [H] and n' respectively. 



The two curves — logN«:N and Pu : 1ST from the values given in Table I 

 are shown in fig. 2, and are designated as A and B respectively. 



A 

 B 



/■o 



2 



5-0 



FiC 2- 



Bhsas-sae - M>f?na//fy of ac/tf. 

 Oscfinates P„ 



— ^> 



O '02 Ol , 02 ZS 



Buffer curve of gelatine in hydrochloric acid. 



