ASPECTS OF ADSORPTION PHP:NOMENA 227 



actions of distilled water which has been in contact with polished metal, 

 are, in all probability, due to the presence of colloidal metallic hydroxides. 

 Various solids, such as paper, are known to remove this toxic pro- 

 perty. It occurred to me, therefore, that perhaps the adsorption of 

 congo-red which occurs to some extent, even from distilled water, might 

 be due to these hydroxides. I found that the ordinary laboratory 

 distilled water caused considerably more adsorption of congo-red than 

 that which I had prepared myself, using a tin condenser. From this 

 latter, nevertheless, 22 per cent, was taken up. By allowing filter- 

 paper to soak in this water previously the value was reduced to 

 i 8 per cent. It did not seem possible to get below this no doubt the 

 electrolytes dissolved from the glass and the traces remaining in the 

 paper were sufficient to account for the effect. 



VIII. SUMMARY OF RESULTS 



1. The hyperbolic form of the curve of adsorption is confirmed. 



2. The curve of electrical conductivity of successive distilled 

 water extracts of gelatin has the same form. 



3. It is impossible to wash out all the electrolytes from gelatin 

 except by a practically infinite number of changes of water, each change 

 removing a less percentage than the previous one. 



4. The electrolytes are, therefore, neither chemically combined 

 nor merely admixed, but in the intermediate form known as 

 adsorption. 



5. When gelatin has been washed nearly free from electrolytes 

 it is capable of diminishing the conductivity of solutions of electrolytes 

 in which it is placed. This it does by adsorbing them in a non- 

 ionized condition. 



6. The rate at which congo-red is taken up by paper is greatly 

 accelerated by rise of temperature, but the total amount taken up 

 when equilibrium is attained is less the higher the temperature. 



7. The temperature-coefficient of the reaction-velocity is 

 extremely low, so that the theory of Nernst as to the part taken by 

 diffusion in heterogeneous reactions seems to apply to the case of 

 adsorption. 



