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BIO-CHEMICAL JOURNAL 



than the salt, so that the amoimt of kation which would suffice to 

 discharge the salt would be insufficient to discharge the acid, it would 

 therefore be comparatively ineffective in promoting adsorption. 



In view of the theory set out in the preceding paragraphs it will 

 be of interest to. give two curves showing the form of the relation 

 between the concentration of the kation and its effect on congo-red. 

 The ordi nates in Fig. 6 represent the percentages of congo-red taken 

 up from a ^^ solution containing electrolyte of the concentration 

 given by the abscissae. The upper curve is that of Caso 4 , the lower 

 curve that of KCI. 



FIG. 6 



The commencement of the Caso 4 curve is irregular, owing to 

 partial precipitation of the dye having taken place. The inclination 

 to an S-shape at the beginning of the KCI curve is, probably, also an 

 indication of incipient precipitation. The extreme sensitiveness of 



