MIGRATION VELOCITY OF THE PROTEIN IONS 127 



mobility can be obtained, and the mean valency of the protein 

 ions deduced therefrom scarcely has a physical meaning. 



The mobility of the protein ions can be obtained from 

 measurements of conductivity in dilute solutions, provided a 

 well-defined and well-dissociated protein salt, which gives one 

 kind of negative ion only, is employed. The method of Whet- 

 ham, using the moving bounding surface, is also applicable in 

 suitable cases (Hardy). Yet another method has been adopted 



Table 69. 



1-256 per cent. Horse-serum albumin, of original conductivity 

 677 X lo- 5 . (Temperature 18.) 



by Pauli and Sven Oden,* whereby the mobility can be directly 

 found in cases in which the concentrations of each of the ions 

 can be accurately determined, e.g., in the case of the hydro- 

 chlorides of the proteins. If C H and CQ are the concentrations 

 of H- and Cr ions as determined electrometrically, then the 

 fraction of the Cl' ion content due to the protein, or the nor- 

 mality of the protein ions is C a C H . If the mobilities of 

 the H-, Cl' and protein ions are u u , i> a , and u x , then the 

 conductivity of the mixture of acid and protein, A, is the sum of 

 the products of the concentrations and the mobilities of the 

 respective ions : 



A = C H w H -h CaVci + (C C i C H ) u x , 

 and hence the mobility of the protein ions 



A (C H w H + CciUci) 



^x = p p . 



Ma ^H 



* Anzeiger. Akad. Wissensch. Wien., 1913, No. 24. 



