6o 



COLLOID CHEMISTRY OF THE PROTEINS 



maximum, which amounts in this case to i-S X io~ 2 N per 

 litre in 1-09 per cent, albumin solution. The Cl' ions, on the 

 other hand, remain to a large extent free in the beginning, 

 and only above a concentration of 0-02 N acid does the combina- 

 tion of the chlorine 

 increase rapidly. If, 

 now, the difference of 

 the combined H> and 

 Cl' ions is plotted as 

 ordinates (Fig. 10), a 

 direct view of the 

 behaviour of the ioni- 

 sation in acid albumin 

 is obtained (the fine 

 dotted curve). The 



ionisation increases to a maximum in about o -02 N HC1, and 

 then falls off, until at a concentration of 0-05 N it is almost 

 completely suppressed. This phenomenon indicates that the 

 free acid which accumulates on further acidification, after con- 

 siderable saturation 

 of the protein finally 

 suppresses almost 

 completely the ionisa- 

 tion of the albumin 

 chloride. It is only 

 this work and similar 

 experiments with 



0-Ob 



serum albumin which 

 proved that the theory 

 of the ionisation of 

 albumin chloride for- 



H ict in 



__ Cl 



O'Oi 



FIG. ii. Glutin and hydrochloric acid. 



mulated by Bugarsky and Liebermann was based on facts, 

 whereas the alternative conception of T. B. Robertson is 

 definitely refuted. 



Experiments with glutin confirm the main result obtained 

 in the work on albumin, that is, that ionisation of the acid- 

 protein occurs with splitting off of chlorine ions, indeed, in 

 this case the fraction dissociated is still larger than with serum 



