18 



AET. 8. — S. KAWAMUEA I COAGULATION OF COLLOIDAL 



-4 .23 .40 .70 .85 -3 .22 .40 .^0 -2 



.70 -I 



oxalate (26)/ j^o^'^^^i^^^ ferricyanide (38), and fumaric acid (30) 

 are chosen as typical cases and represented in the annexed 

 diagram. In the case of ammonium oxalate, incij^ient coagulation 

 took place at the very low concentration of 0.0002, the con- 

 centration at which complete coagulation was effected was 0.0025 

 and the final value of the relative viscosity was very low being 

 only 1.26. In the case of potassium ferricyanide the concentra- 

 tion of the inci23ient coagulation was about the same, but com- 

 plete coagulation was reached at the somewliat lower concentration 

 of about O.OOlo, while the limiting value of the relative viscosity 

 was as high as 1.96. In the case of fumaric acid no coagulation 

 was observed at 0.001 while at 0.0017 it was already complete. 

 The limiting value of q is here middling, being 1.68. 



For a complete characterisation of an electrolyte with respect 

 to its coagulative power on a chosen colloidal solution a curve 

 such as shown in the foregoing diagram is necessary. But for 



1. The numbers in the brackets refer to the number in Table 11. 



