PAPERS OX CHEMISTRY AND PHYSICS 329 



COXCLUSIOXS 



A. H. Clarke defines a "Buffer", or regulator, as any 

 substance which tends to preserve the original hydrogen- 

 ion concentration of its solution upon addition of acid or 

 base, and states that the hydrogen ion concentration of a 

 buffer solution depends upon the disassociation of the 

 acid and base formed by hydrolysis of the salt used. This 

 could not well be caused by pure carbon. 



E. W. Washburn (Jour. Am. Chem. Soc. 30-31-46, 1908) 

 states that a solution will automatically keep itself at any 

 desired hydrogen concentration even though small quan- 

 tities of acid or base be added to it, pro^dded it contains 

 something which will remove both hydrogen and hydroxyl 

 ions when acid or alkali are added to the solution, and 

 states that a solution which contains the salt of a weak 

 acid or base together with an access of the acid or base 

 has the propertj^ of automatically maintaining itself at 

 practically constant concentration. He gives a list of 

 acids, including NaHoPO*, H0CO3, and bases including 

 Na,H PO4, NaHCOs, which will do this. These are the 

 common '^ buffers". 



Charcoal prepared from animal matter, wood, nut 

 shells, or other sources will naturally contain some of 

 these salts together with some adsorbed gases, which 

 cannot be removed by the ordinary methods of purifica- 

 tion, owing to the great adsorbant power of the charcoal, 

 and are therefore present in varying quantities in most 

 animal charcoals, which upon addition of the weaker 

 acids or bases Avill hydrolize to give the buffer effect ob- 

 served. 



From the fact that we are unable to obtain this buffer 

 effect from charcoal made from sources containing no 

 mineral salts, we are led to believe that the removal of 

 ions obtained from the commercial grades was caused by 

 such impurities and not by the pure carbon. 



The dift'erences between the various commercial char- 

 coals may be readily noted from the curves. 



The writer wishes to express his appreciation of the 

 help and criticism of Dr. G. L. Wendt, in the preparation 

 of this paper. 



