ALUMINIUM HYDEOXIDE BY ELECTROLYTES. 23 



As the value of -yiim— 1 depends on the concentration of 

 the colloidal solution, it is not very well fitted for the charac- 

 terisation of an electrolyte. But perhaps it might be possible 

 to eliminate this effect by employing the empirical equation 

 given at the end of § ö : 



It is not improbable that the empirical constant <9 retains its 

 value for different electrolytes and that a alone varies with 

 different cases ; but this point must be left for further study. 



Another fact deserves mention in this place. The values 

 of •'jlim — 1 for electrolytes with particularly well developed co- 

 agulative ^^ower, are also high. Thus strong electrolytes with 

 trivalent anions have -^um— 1 between 0.9 and 1.0, while in one 

 electrolyte with tetra valent anion it is as high as 1.24. 



What the different values of ^yum— 1 may mean physically 

 and chemically it is difficult to say. They point no doubt 

 to some difference in the physical structure of the coagulum. 

 Microscopic observation may reveal in what the difference lies. 



In order to study the effect of the valency of ions on the 

 coagulative power, it is necessary to compare electrolytes of 

 chemically allied natures but of different valencies. For this pur- 

 pose we chose potassium salts of cyanogen complexes, Ag (CNjo K 

 (9), Pt(CN}4K2 (20), Fe(CN)GK3 (38), and Fe (CN)« K^ (41). 

 The relation between q and the concentration of the electrolytes 

 is shown in the annexed diagram. All the three aspects of the 

 coagulative power, which we have been discussing, are brought 

 so clearly before the eye, that it is needless to dilate upon them 

 in this connection. In short, the rule of Schulze finds the 



