SALTS OF ALBUMIN AND ACIDS 



E. Laqueur and O. Sackur * were the first to observe the 

 increase in viscosity on salt-formation by proteins. Such an 

 increase was found in sodium 

 caseinate, obtained by dis- 

 solving casein in caustic soda 

 solution, when, with rising 

 concentration of alkali, a 

 maximum and then a falling 

 off in viscosity was noted. 

 They attributed the increase 

 in viscosity to the free casein 

 ions. W. B. Hardy j found a 

 similar increase in viscosity 

 on dissolving globulin in acids 

 or bases. Laqueur and Sackur 

 concluded that the decrease 

 in viscosity with excess of 



00$ OW OVfnHCi 



FIG. 13. Viscosity of albumin in 

 hydrochloric acid. 



excess 



alkali was due to the effect of 

 the common ion of the sodium 

 hydroxide in repressing the ionisation of the protein salt, as 

 sodium chloride also produces this result. It is easy to show, 



0'01 0-02 0-03 OW O'OSrtHCt 



FIG. 14. Viscosity and difference in ion concentration. 



however, that neutral salts of varied cation affect the viscosity 

 of sodium caseinate in the same way. It is, in fact, an effect 

 produced by salts in general, as we shall see later, and thus the 



* Beitr. z. Chem. Physiol. u. Path., 1903, 3, 193. 

 f /. Physiol. , 1905, 33, 251. 



