- Ill - 



of the number of the constituents in the mixtTire-^^'-'-^, as illustrated 

 by Figure V,2, With a narrow zone of the mixture, electrolysis sepa- 

 rates the components of the mixture and provides a series of discrete 

 zones analogous to those in a chromatographic system-*^^' •'•^, as shown in 

 Figure V, 3„ 



Electrical migration is often accompanied by convection and by 

 variation of the density of the solution. For the production of well- 

 defined zones with sharp boiindaries, it is necessary to control this 

 convection and mixing, as by the use of porous or permeable stabilizing 

 mediate It is also essential to carry out the migration under condi- 

 tions such that the separated ions may be easily detected and isolated. 



Systems f or Differential Electrical Migration 



Several kinds of eqmpment have now been employed for analysis by 

 differential electrical migration in stabilized medial* 5>o^ ^he appa- 

 ratus usually consists of five principal parts, namely, electrodes for 

 cathode and anode, vessels for the electrodes and for reserve background 

 electrolytic solution, a long migration system of the stabilized back- 

 grotind solution joining the electrode vessels, a support for the migra- 

 tion system, and frequently an arrangement for cooling the migration 

 medium,, Some of these modifications are elaborated in Table V,Io 



Electrode vessels are usually adapted to meet the requirements of 

 the migration system. They may be of small capacity when background 

 solutions with much, partially dissociated electrolyte are employedo 

 But for solutions containing little, strongly dissociated electrolyte, 

 large vessels with large electrodes are more suitable'o 



