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generally, but not always, more powerful than the deflection 

 produced by thermo-contact. 



XVII. The deflection caused by chemical action of a 

 menstruum on two associated metals has no observable depen- 

 dance on, or connexion with that produced by thermo-contact 

 or attrition of these metals. 



XVIII. The agent developed by the attrition of two 

 metals, even when rapid, forcible, and long-continued, does 

 not manifest any decomposing influence on chemical com- 

 pounds, nor is it conducted by aqueous liquids, even when 

 containing saline impregnations. 



The President commented briefly upon Mr. Donovan's 

 paper, noticing especially the labour and care which he had 

 bestowed upon the investigation ; at the same time he could 

 not avoid regretting that the laws of the tribothermic pheno- 

 mena had not been reduced to a smaller number, and to a 

 simpler expression. The subject was one of very great inte- 

 rest and importance in a theoretical point of view ; for it is in 

 electrical phenomena of this class, if anywhere, that we may 

 hope to gain an insight into the nature of the molecular agency 

 upon which they are probably dependent, and thus to connect 

 the science of electricity with other departments of physics. 



The Rev. Samuel Haughton read a paper on the Laws of 

 Propagation of Plane Waves in extended media. 



In a paper read before the Academy, May 25, 1846, Mr. 

 Haughton deduced the equations of solid and fluid bodies from 

 the hypothesis that the molecular action is in thejine joining 

 the molecules, and that there is no action at right angles to 

 that line. This hypothesis led to the conclusion that the 

 function F, on which the internal forces depend, consists of 

 six quantities ; 



d.v ' dy' dz' dz^ dy' dx ^ dz' dy^ dx' 



VOL. IV. Y 



