THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



DECEMBER 1892. 



LV. An Electrolytic Theory of Dielectrics, 

 By A. P. Chattock *. 



IT is well known that a displacement of electricity along 

 the axes of certain crystals is capable of accounting for 

 the phenomena of both pyro- and piezo-electricity observed in 

 them, the fact having been pointed out by Lord Kelvin in 

 1878. Such a displacement may be conceived of as taking 

 place (1) by the separation of the two electricities within 

 previously unelectrified conducting atoms or molecules, or 

 (2) by the relative motion of two sets of initially and oppo- 

 sitely charged molecules, distributed throughout the crystal. 

 There seems to be no third way for the displacement to occur 

 if electricity cannot exist apart from matter. 



To explain the displacement by the first of these hypo- 

 theses amounts, in the present state of our knowledge, to 

 little more than a confession of ignorance. The mechanism 

 for such a process has yet to be invented. But with the 

 second hypothesis the case is different. Given a certain 

 arrangement of unalterably and oppositely charged mole- 

 cules, and both pyro- and piezo-electric phenomena follow at 

 once from mechanical principles. Moreover, it is possible to 

 calculate an approximate value for the molecular charges 

 assumed ; and the fact that this comes out of the same 

 order of magnitude as that of the charges carried by ions in 

 electrolysis, seems to me to lend no little support to the view 

 that such charges exist. 



* Communicated by the Author. 

 Phil. Mag. S. 5. Vol. 34. No. 211. Dec. 1892. 2 K 



