The Titration Curve of Gelatine. 



73 



/0-4 



J 1:4 



Pic. 3. 



flbs-c/ssde = A/orma/iry of Base I > 



Oftf/netes* = 



/3-# 



OS O-/ O 



Buffer curve of gelatine in sodium hydroxide. 



Blasel and Matula, in calculating n', the hydrochloric acid fixed by gelatine, 

 as n' = N — [H]/«, assume that the value for « is the same when [H] = [CI] 

 as when [H] ^ [01], provided that the values for [H] are equal. This, 

 however, is not true. A closer approximation is obtained by taking the 

 square root of the product of [H] and [CI] as the basis of the calculation. 

 The value for [H] is obtained experimentally from hydrogen-electrode 

 readings. The value for [CI] is obtained by assuming that the gelatine 

 chloride is completely ionised, and that therefore, [CI] = [H] + n'. This 

 assumption is also made by Procter and Wilson (21), though Bugarsky and 

 Liebermann's experimental figures on the concentration of the chlorine ions 

 do not support it (3). The amount of un-ionised acid [HC1] depends, 

 therefore, not upon [H] but on [H] corr ., where 



[H] eorr . = */([H]x[Cl]X 

 and a new value for the acid fixed, say N', follows as before. This is given in 

 Column VIII and is shown plotted in fig. 4 [In the values for n' calculated 



