Sharpness of Resonance under Sustained Forcing. 467 



of molecular hydrolytic activity accompanying dilution o£ 

 the acid is not only easily explained but appears to be 

 demanded by this view of the mechanism of hydrolytic 

 change andithe reverse change of etherification — for, as dilu- 

 tion is increased the acid becomes more and more hydrated 

 towards a maximum ; or at least, more under control of the 

 water; and the more its activity is exerted in this direction, 

 the less will it have left for combination with a hydrolyte. 

 The large influence which water has on the activity of acids 

 in alcoholic solution, as shown by Goldschmidt, Lapworth 

 and Bredig, is quite in accordance with this view and 

 exceedingly difficult to explain on the ionic hypothesis. 



In conclusion, I may urge that, in my opinion, the hydro- 

 lytic activity of acids and indeed the chemical activity o£ 

 electrolytes generally does not support the hypothesis of 

 ionic dissociation, though it most emphatically shows the 

 close connexion between chemical and electrolytic activity, 

 irrespective of any theory of the nature of electrolytic acti- 

 vation. Chemists have greatly neglected the distinction 

 between these two issues and have advanced as evidence in 

 favour of the Arrhenius hypothesis what really is evidence 

 only of the close connexion between electrolytic activity 

 and chemical activity. This is especially true of hydrolytic 

 phenomena. 



LIL A Note on Prof. Edwin H. Barton's Article "Range and 

 Sharpness of Resonance under Sustained Forcing and their 

 Variations with Pitch " *. By Prof. Dr. E. Waetzmann, 

 of the Physical Institute of the University of Breslaic\. 



IN the above mentioned article Prof. E. H. Barton treats at 

 length the damping of resonators, and discusses in par- 

 ticular the difference between the damping coefficient and 

 the logarithmic decrement. In the introduction to his article 

 Prof. Barton says : " It may be noted here that several writers 

 have shown that the character of the resonance is a function 

 of the responding system. But the decrement appears to 

 have been treated as a single quantity measuring the 

 damping. The possibility of changing the logarithmic 

 decrement and therefore the sharpness of resonance, by a 

 change in frequency, the damping coefficient remaining con- 

 stant, seams to have escaped their attention." 



I entirely agree with Prof. Barton in the opinion that 



* Phil. Mao-. No. 151, July 1913. 

 + Communicated by the Author. 



