CHEMICAL EQUILIBRIA 



109 



column, c is very nearly proportional to \/c . This 

 points to the circumstance that we here observe a 

 phenomenon of adsorption, for, when the concentra- 

 tions CQ are small, such a law as that found above is 

 found to hold good in similar cases. 



As an instance of a case of adsorption, we repro- 

 duce here some figures of PALME (Hoppe-Seyler's 

 Zeitschrift f. physiol. Chemie, 92, 184, 1914). He 

 added a certain quantity, generally 2 grammes, 

 of casein to 50 cc. of a solution of ferrocyanic acid 

 of known concentration. PALME observed that 

 a quantity of up to 37-8 milligrammes is bound 

 chemically by the casein. After this further 

 quantities of the ferrocyanic acid are taken up in the 

 casein by means of adsorption. The law of adsorp- 

 tion follows the same formula as the extended rule 

 of SCHUTZ (see p. 42), if we let t denote the con- 

 centration and x the adsorbed quantity, which 

 approaches asymptotically to a maximum A with 

 increasing t. The following table gives the observed 

 values of t and x., which latter are compared with 

 values ^r calo found on the supposition that K^ = 0-0333, 

 A is just equal to 150 milligrammes. 



ADSORPTION OF FERROCYANIC ACID ON CASEIN 



The agreement seems to be perfect within the errors 



