CHAPTER III 



THE ELECTRIC CHARGE ON NATURAL SOLUBLE 

 ALBUMIN: THE ISO-ELECTRIC REACTION 



WHILE the general experience of the behaviour of lyophobe 

 colloids paves the way to a realisation of the connection 

 between the electric charge and the stability of the disperse 

 phase, it is obviously necessary to obtain definite proof that 

 albumins behave in a similar way. 



A direct method of showing the charge on protein particles 

 is that of investigating the direction of their motion in an electric 



S 



A 



M 



FIG. 2. Electrophoresis of albumin. 



field (electrophoresis). This investigation was first undertaken 

 to find out the effect of the addition of various substances to the 

 protein solution. A simple transport apparatus in which that 

 portion of the colloid solution which is in the neighbourhood of 

 the poles can be abstracted for analysis serves the purpose. 

 Thus Wo. Pauli,* in the original investigation of natural pro- 

 teins, used a series of three small beakers connected by syphons 

 filled with water. Platinum electrodes were put into the two 

 outer beakers, and after the current had been passed for some 

 time the syphons were withdrawn and the protein content of the 

 * Beitr. z. Chem. Physiol. u. Path., 1906, 7, 531. 



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