621 



TABLE IV 



5. On considering 'these results we notice, of course, first of all the 

 great influence of the valency of the cation; as this gets liigher the 

 capillar}" gets more strongly discharged at an equal concentration. This 

 had also been observed by Ei.issafoff when measuring the electric 

 endosmose and maj- be noticed with Riety from his e.xperiments with 

 nni- and bivalent ions. The latter has observed a change of poles only 

 once, namely with copper nitrate and that only at a high concen- 

 tration^). In the case of AICI^ about 0.8 [i mol. or about 0.1 iwj. 

 per liter appears to he sufjicient to lower the current potential from 

 about 350 mV. to zero. It seems remarkable that this charge reversal 

 does not take place with BaCl^ (see Table 111) neither with ZnSO^ 

 or CuSO^ (Riety) nor with substances with a univalent cation. 



Still more striking is the fact that according to Elissafoff, the 

 electro-endosmotic transport requires, in a glass capillar3^ 100 micro- 

 mols of Al"- to be reduced to without a reversal occurring, whereas 

 the same investigatoi-, although attaining the zero point, with a quartz 

 capillary, at about the same concentration as required in our research 

 [he found 1.6 ft mol. i Al^ (80^)3] could not even then notice a 

 reversal of the transport direction. This creates the impression that 



1) The exact concentration cannot be made out from his experiments. In any 

 case, however, it lies above 900 /w mol p. L. 



