PAPERS ON CHEMISTRY AND PHYSICS 323 



thp: adsorptiox of hydeogex ioxs by 

 chaecoal 



(Abstract from original paper.) 

 I. J. Jexks, State Teachers College. DeKalb 



IXTRODUCTIOX 



It is a well established principle of colloid chemistry 

 that the ions of an electrohte are adsorbed by certain 

 precipitates and the similarity of this adsorption of 

 gases by charcoal has been pointed ont. 



"W. Mansfield Clark in ' ' The Determination of the Hy- 

 drogen Ion'' (Page 34) mentions the work of Bovie as 

 showing the adsorption of both hydrogen and hydroxy! 

 ions by charcoal, when present dnring an electrometric 

 titration. Bo^ie (J. Med. Eesearch 295-317-1915) 

 found that the presence of .5g of Kahlbanm's animal 

 charcoal in a 0.01-X solution of alkali strongly depressed 

 the hydroxyl ions concentration and prevented also the 

 appearance of hydrogen when the solution is titrated 

 with .01-X HCl, the usual symmetrical curve being mark- 

 edly flattened out on both sides, with the vertical rise 

 which marks the end point entirely obliterated. 



Bovie points out the similarity of the effect to that ob- 

 tained in a true "buffer" solution, but attributes the 

 buft'er effect to adsorption of both hydrogen and hydroxyl 

 ions by the charcoal. 



Two objections to this interpretation of Bovie 's ex- 

 perimental curve may be noted. In the first place it is 

 not common to find both hydrogen and hydroxyl ions 

 equally adsorbed ; usually adsorption of hydrogen ions is 

 much more marked. In the second place, Bovie did not 

 take into account the possibility of salts contained 

 within the charcoal, in spite of the fact that animal or 

 bone charcoal almost certainly contains calcium phos- 

 phates which are among the most eft'ective buffers. (See 

 A. H. Clark, Masters Thesis, T. of C. 1920, Pages 19-23, 

 58-65.) 



This research was therefore undertaken to investigate 

 this factor and to determine whether pure charcoal shows 



